Search

Achieving high performance and stability in cathodes for the oxygen reduction reaction is crucial for the advancement of proton ceramic fuel cells (PCFCs). The introduction of non-metal doping method presents an opportunity to simultaneously optimize the perovskite structure and augment the activity and stability of the oxygen reduction reaction. Herein, we develop a phosphorus-doped SrCo 0·8 Fe 0·15 P 0·05 O 3-δ (SCFP) cathode for PCFCs. The SCFP cathode shows a low area specific resistance of 0.24 Ω cm2 at 650 °C in wet air (5% H 2 O), which is smaller than that of the phosphorus-free SrCo 0·8 Fe 0·2 O 3-δ (SCF) electrode (0.34 Ω cm2). The Ni–BaZr 0.1 Ce 0·7 Y 0.1 Yb 0.1 O 3-δ (BZCYYb) anode-supported single cell with BZCYYb electrolyte and SCFP cathode exhibits a superior performance of 865 mW cm−2 at 650 °C under H 2 atmosphere. This underscores the effectiveness of the phosphorus-doping strategy as a promising approach for advancing cathode development in PCFCs. [Display omitted] [ABSTRACT FROM AUTHOR]

A porous nano-metal oxide composite consisting of zirconium oxide and vanadium oxide (ZrVNPs) was prepared using precipitation hydrothermal technique, followed by microwave sintering process in order to enhance the catalytic activity toward oxygen reduction reaction (ORR) which is a key reaction in the development of low-temperature fuel cell technology. Microwave sintering process conditions were optimized using response surface methodology models (RSM) and the optimized produced material was called ZrV-T. The physiochemical and electrochemical activities of the fabricated materials were investigated and the results elucidated that, the catalytic efficiency of prepared samples is influenced by morphology, lattice structure, and porosity, as well as metal–support interactions and interfacial structural changes that affect oxygen molecules adsorption and activation. The thermally treated composite (ZrV-T) exhibits higher oxygen reduction performance than the non-sintered material (ZrVNPs). Both materials have different half-wave potentials (E1/2 = −0.36 V) and (E1/2 = −0.29 V) for ZrVNPs and ZrV-T respectively. In addition, ZrV-T has a higher stability than the Pt/C catalyst in 0.1 M KOH solution by 4% after 120 min. Using ZrV-T is likely to reduce costs in FCs and promote the use of electrochemical energy devices and it may also be beneficial in other systems that promote catalytic activity. [ABSTRACT FROM AUTHOR]

Graphene supported FeN5 active sites, exhibiting high activity and stability of oxygen reduction reaction, enable a H2-air fuel cell to decay little during the latter 20–100 h operation. [Display omitted] • Electrochemically-exfoliated graphene improves forming FeN 5 with NH 3. • Graphene benefits catalytic stability of oxygen reduction reaction. • Fuel cell keep stable with little decay in latter 80 h operation. • High half-wave potentials in alkaline medium (0.940 V). Metal-nitrogen-carbon catalytic material, generally thought as a promising low-cost electrocatalyst of oxygen reduction reaction (ORR), surfers from long-term catalytic durability for fuel cell and metal-air battery. Here, we describe an approach of synthesizing electrochemically exfoliated graphene supported penta-nitrogen coordinated iron exhibiting encouraging ORR catalytic activity and durability. The synthesized catalyst exhibits high half-wave potentials in alkaline medium (E 1/2 0.940 V) enabling high-performance zinc-air battery and in acidic condition for durable fuel cell with a high peak power density (630 mW cm−2). The current density of a proton exchange membrane fuel cell loading the catalyst as cathode tends to decay little after initial hours under H 2 -air measurement, remarkably inhibiting commonly decline tendency of iron–nitrogen-carbon catalysts. DFT calculation combined with extensive experimental investigations demonstrate that penta-nitrogen coordinated iron supported by graphene is thermodynamically stable, and thus benefits the catalytic stability of ORR. [ABSTRACT FROM AUTHOR]

The exploration of non-Pt catalysts with high electrocatalytic activity and durability is especially important for cathodic oxygen reduction reaction (ORR) in fuel cell. Here, cobalt and nitrogen doped hollow carbon sphere-bamboo like carbon nanotube (Co/NHCS-BCNT) is prepared by using SiO 2 sphere as sacrificial template. Co nanoparticles are confined in the cavity and top end of the in-situ formed BCNT, which can not only avoid the agglomeration of Co nanoparticles but also inhibit corrosion in caustic electrolyte. The synergistic effect between NHCS and well-dispersed Co particles makes Co/NHCS-BCNT have superior catalytic activity toward ORR. The electrochemical surface area (ECSA) of Co/NHCS-BCNT is 222 cm2, which is higher than those of NHCS (164 cm2) and HCS (135 cm2). The onset potential and half-wave potential of Co/NHCS-BCNT are 0.941 V and 0.814 V, respectively, which are close to commercial Pt/C (0.949 V, 0.807 V). The Tafel slope of Co/NHCS-BCNT (63.8 mV dec-1) is lower than that of Pt/C (71.7 mV dec-1). In addition, Co/NHCS-BCNT shows excellent durability and fuel selectivity. [Display omitted] [ABSTRACT FROM AUTHOR]

Electrocatalysts play a pivotal role in advancing proton-exchange membrane fuel cell (PEMFC) for hydrogen energy applications. In this study, we investigate a novel PtCu/C N electrocatalyst synthesized via a gram-scale synthesis approach, which demonstrates remarkable activity and stability in the oxygen reduction reaction (ORR). The catalyst's effectiveness stems from its unique structure, combining bimetallic nanoparticles (NPs) and an N-doped carbon support. Employing identical location transmission electron microscopy (IL-TEM) imaging, we observe significant NP structure reorganization upon activation influenced by the upper limiting potential. Notably, the PtCu/C N catalyst activated to 1.0 V surpasses the United States Department of Energy (DOE) target for ORR activity by 3.3-fold. These findings underscore the potential of this catalyst in enhancing the performance of PEMFCs, marking a significant advancement in hydrogen energy technology. [Display omitted] • Catalyst's effectiveness attributed to unique structure of bimetallic NPs and N-doped support. • Vital reorganization of NPs occurs under the upper limiting potential of activation. • PtCu/C N catalyst activated to 1.0 V surpasses DOE target for ORR activity by 3.3-fold. • IL-TEM method comes to the rescue in assessing NPs' reorganization. • Findings highlight potential of bimetallic catalyst in enhancing PEMFC performance. [ABSTRACT FROM AUTHOR]

Due to its exorbitant expense and scarcity on Earth, there is a need to anticipate a cost-effective and widely accessible catalyst that can effectively replace platinum, which is known for its efficiency in fuel cells. In this context, catalysts such as OH, H, and COOH group-functionalized cobalt-doped Graphyne-like boron nitride (referred to as BNyen) are being examined to enhance the mechanism of oxygen reduction reaction (ORR) via direct 4e− reduction. According to findings derived from DFT, it has been observed that reactions predominantly take place above Co metal center rather than edge site of BNyen. Additionally, the thermochemical characteristics point to the fact that these reactions release a significant amount of heat, suggesting their feasibility. By examining reversible potential of products and intermediates on phthalocyanines as well as adsorption energy (E ads), it has been determined that Co-BNyen(OH) serves as a superior catalyst for ORR process. In conclusion, this research affirms that BNyen materials hold significant promise as catalysts for ORR, a crucial process in fuel cell applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Platinum-based catalysts remain the top choice for oxygen reduction reaction (ORR) in fuel cells. However, their activity and durability in the acidic medium are still under improvement. In this work, the Pt nanoclusters anchored the nitrogen-doped carbon nanotubes (Pt-NCNTs) have been synthesized by using a series process of pyrrole coating on the CNTs and subsequent pyrolysis to the chemical immersion reduction of Pt ions. The inner CNTs of Pt-NCNTs function as the nanowires offering a high-speed pathway for electron transport, and the Pt nanoclusters increases the active sites. The theoretical calculation demonstrates that the local structural defects and the uneven charge distribution induced by nitrogen-containing functional groups and porous structure are favorable to capture Pt ions for the nucleation of Pt nanoclusters. Compared with the commercial 40 wt% Pt/C (0.94 and 0.80 V), the Pt-NCNTs-1000 with Pt loading amount of 33.0 wt% owns the more positive onset potential and half-wave potential of 0.97 and 0.81 V in the sulfuric acid medium. Meanwhile, the strong attachment of Pt nanoclusters on the nitrogen-doped porous carbon layer results in a stable interface to effectively prevent the metallic species from migration and agglomeration during the electrode reactions. Therefore, the ORR current of Pt-NCNTs-1000 retained 84.3% of the initial value after 50000 s operation superior to the commercial Pt/C (64.6%). [Display omitted] • N-doped porous carbon layer coated CNT was used as support to enhance Pt deposition. • Micropores and nitrogen groups strongly anchor Pt nanoclusters deposited on NCNTs. • CNTs act as nanowires to promote charges transport of electrode reactions. • Pt-NCNTs has a good ORR activity and durability compared with commercial 40 wt% Pt/C. [ABSTRACT FROM AUTHOR]

[Display omitted] • HME was applied as an oxygen electrode of the AEM-URFCs. • Introducing 3 D CNT framework provided high ECSA of catalysts, electron transport, mass transport. • The HME_URFC exhibited superior round-trip efficiency of 55% at 20 mA cm−2 with enhanced durability and cyclability. Developing three-dimensional porous oxygen electrodes (OE) is crucial for enhancing round-trip efficiency (RTE) of anion-exchange membrane-based unitized regenerative fuel cells (AEM_URFCs). Herein, a novel OE design of AEM_URFCs is presented based on a hierarchical mesh electrode (HME) with a porous carbon nanotube (CNT) framework. The HME, featuring square-shaped macropores achieved by dispersing catalyst nanoparticles on the CNT framework enhances surface area, mass transport, and electron transport. Half-cell test demonstrated superior oxygen reduction reaction and oxygen evolution reaction activity compared to conventional electrodes. Moreover, the HME maintained stable ORR and OER activity during the stability test. In single-cell tests, the AEM_URFCs with the HME exhibited higher RTE (55% at 20 mA cm−2), surpassing the conventional electrode (52%). Furthermore, RTE was maintained at a remarkable 41% under ultrahigh current density (250 mA cm−2), which is unprecedented in the literature. The AEM_URFCs featuring the HME displayed superior cyclability over 5 cycles and durable performances under both fuel cell and water electrolysis modes. [ABSTRACT FROM AUTHOR]

• Resonance structure as substrate molecules are introduced to form highly ordered PtCo alloys. • Synthesis of PtM (Co, Fe, Ni) ordered alloys use the same low temperature heat treatment conditions. • The ordered PtCo shows efficient electrocatalytic performance. Platinum-based ordered alloys have excellent catalytic performance for the cathodic oxygen reduction reaction (ORR) in fuel cells. However, these alloys exhibit a lower degree of ordering and larger crystal grains after heat treatment. Herein, a series of cyanamide group molecules (cyanamide, dicyandiamide, melamine) was employed as substrates to modify Pt-based alloys by promoting the binding between metal ions, leading to the preparation of ∼ 4 nm PtM (M = Co, Fe, Ni) ordered alloys after heat treatment. Among them, the PtCo ordered alloy prepared using hydrolyzed cyanamide with a unique resonance structure exhibits a high degree of order (93.1 %), and its mass activity of 0.915 A mg Pt -1 at 0.9 V is superior to that of Pt/C. The theoretically calculated adsorption energies of these alloys demonstrate that the resonance structure of the cyanamide substrate is beneficial for alloy formation, thereby facilitating ordered alloy synthesis. [ABSTRACT FROM AUTHOR]

High-efficiency catalysts are required for the oxygen reduction reaction (ORR) in fuel cell applications. Herein, we present a novel hybrid material that is based on uniformly deposited nanoscale molybdenum phosphide (Mo x P y) nanoparticles on the structure of graphene nanolayers doped with phosphorus atoms (PG). With a positive onset potential of only −0.046 V and a half-wave potential value of roughly −0.17 V (vs. Ag/AgCl), the obtained hybrid showed good catalytic activity for ORR in 0.1 M KOH electrolyte. It also demonstrated remarkable durability for oxygen reduction reaction in 0.1 M KOH electrolyte when compared to state-of-the-art Pt/C material. The excellent ORR performance can be correlated to the development of a highly conducting microporous structure with highly active sites, which in turn encourages optimal adsorption of intermediates during the ORR process and thus enhances the catalytic process. This work can open a new path for the growth of promising highly efficient catalysts for affordable fuel cell applications. [Display omitted] • Uniform Mo x P y nanoparticles dispersed P-doped G was prepared by a facile route. • The hybrid offered high catalytic performance for ORR, close to Pt/C. • The synergistic effect from Mo x P y and P-doped Gr produced enhanced ORR performance. • The hybrid showed much better durability and methanol tolerance than Pt/C. [ABSTRACT FROM AUTHOR]

The success of the next generation of anion-exchange membrane fuel cells (AEMFCs) depends on the development of active, reliable, and economical oxygen reduction reaction (ORR) catalysts. Here, we synthesize a series of ultra-low-cost metal-free ORR catalysts by doping a common pristine graphite precursor with chemically singular-type heteroatoms, namely I, S, N, or B, using single-step planetary ball milling technique. All doped-graphites show substantially enhanced ORR performance relative to the pristine (undoped) graphite. Among all the tested catalysts, N-graphite exhibited the highest ORR onset potential of 0.87 V vs. reversible hydrogen electrode. These results are supported by density functional theory calculations. The ORR catalysts also exhibit remarkable stability as evaluated through electrochemical tests. Most importantly, the AEMFCs prepared using these ultra-low-cost doped graphites deliver notable peak power densities with impressive voltage efficiencies, which further supports their efficacy in ORR catalysis and the broad implementation of this technology. [Display omitted] • Highly active metal-free doped-graphite catalysts for alkaline ORR are developed. • Comprehensive alkaline ORR investigation by structural and DFT modeling. • Remarkable catalyst stability is shown by electrochemical and corrosion tests. • High-performance anion-exchange membrane fuel cells using metal-free cathodes. • Ultra-low-cost ORR metal-free catalyst materials and fabrication process. [ABSTRACT FROM AUTHOR]

Fe-N-C catalysts have developed into the most promising substitute for Pt-based precious metal catalysts toward cathodic oxygen reduction reaction (ORR) of fuel cells and Zn-air batteries. Hypercrosslinked polypyrrole microspheres coordinated with Fe (HCP-Py-Fe) were first prepared by condensation of pyrrole (Py) and dimethoxymethane (FDA) in the presence of FeCl 3 as both catalyst and Fe source, and then thermally activated with KOH during pyrolysis followed by acid leaching and heat-treatment, thus constructing hierarchically porous Fe-N-C microspheres (denoted as PPy/FDA-Fe y -HT2-x). The morphology and structural properties of the final synthesized PPy/FDA-Fe y -HT2-x could be tailored to a certain extent by controlling the adding quantities of KOH (x) in the initial solid mixture before pyrolysis and FeCl 3 (y) during condensation of Py and FDA. As a result, the PPy/FDA-Fe 0.4 -HT2–0.25 demonstrated the highest half-wave potential of 0.87 V vs. RHE, with a desired 4-electron transfer for ORR in alkaline medium, which is attributed to the hierarchically micro/mesoporous structure, high surface area and extremely low content of magnetic iron species. Remarkable methanol resistance and durability with only a loss of ∼4 mV in half-wave potential after 10000 potential cycles were obtained as well. The aqueous Zn-air battery (ZAB) fabricated with the PPy/FDA-Fe 0.4 -HT2–0.25 as cathode catalyst delivered a comparable discharge performance to that of the Pt/C-based ZAB but far superior cycling stability. This facile route is promising for large-scale production of Fe-N-C materials as cathodic electrocatalyst applied in practical energy conversion devices. [Display omitted] • Fe3+-catalyzed Friedel-Crafts reaction, pyrolysis with in situ activation was adopted. • Texture, Fe/N species percentages could be tuned by Fe3+-catalysis and KOH activation. • The Fe-N-C favored ORR in 4-e- way with a bit higher activity than that of the Pt/C. • The Fe-N-C microspheres showed better methanol resistance and stability than the Pt/C. • The ZAB assembled with Fe-N-C display superior discharge performance and durability. [ABSTRACT FROM AUTHOR]

[Display omitted] • A highly curved and ultrathin P-doped PdMo bimetallene is engineered. • The catalyst has superior performance in electrooxidation of various alcohols. • The activity for ORR surpasses that of commercial Pt/C catalyst. • DFT reveals that P doping enhances both OH adsorption and CO desorption. The commercialization of direct alcohol fuel cells (DAFCs) relies on the development of high performance electrocatalysts for both the alcohol oxidation reaction and the oxygen reduction reaction (ORR). In this study, a novel phosphorus-doped palladium-molybdenum (P-PdMo) bimetallene with a partially amorphous structure is demonstrated. The ultrathin and curved morphology of the nanosheets, combined with electronic regulation by phosphorus atoms, facilitates OH adsorption and CO desorption. Consequently, the catalyst exhibits significantly enhanced activity and durability in the electrooxidation of alcohols, including methanol, ethanol, ethylene glycol, and glycerol. Particularly toward ethanol oxidation, the P-PdMo bimetallene displays exceptional mass and specific activities up to 4.95 A mg-1 Pd and 8.28 mA cm−2, respectively. Furthermore, the P-PdMo bimetallene demonstrates outstanding ORR performance, with an onset potential of 1.0 V and a half-wave potential of 0.88 V. Overall, this study opens new avenues in metallene electrocatalysts and advancing toward the practical implementation of DAFCs. [ABSTRACT FROM AUTHOR]

Efficient and stable electrocatalysts with low platinum content are crucial for the practical application of fuel cells. The development of Pt-based single atom catalysts (SACs) has emerged as a promising research direction. In this study, we design and prepare a SACs based on MoS 2 with Pt–S–Mo and Pd–S–Mo active sites (Pd, Pt–MoS 2) by successively occupying vacancies, while maintaining the individual characteristics of the active sites. The resulting Pd, Pt–MoS 2 catalyst exhibits excellent electrocatalytic activity for oxygen reduction reaction (ORR), long-term stability, and resistance to common poisons (SCN−, S2−, and methanol) under neutral conditions. Meanwhile, the microbial fuel cell (MFC) equipped with Pd, Pt–MoS 2 exhibits excellent performance in terms of actual electricity generation performance and sewage purification capacity with an ultrahigh power density, average chemical oxygen demand (COD) removal rate, and coulombic efficiency (CE) of 1398.6 ± 43.5 mW m−2, 96.2 ± 2.2 %, and 22.5 ± 0.5 %, respectively. This strategy will provide new insights into the development of advanced bimetallic as well as polymetallic doped vacancies of MoS 2 SACs. [Display omitted] • A feasible approach for the design of bimetallic single atom catalysts. • One SACs based on MoS 2 was prepared by successively occupying vacancies. • Pd, Pt–MoS 2 catalyst exhibits excellent electrocatalytic activity for ORR. • Optimized catalyst exhibits excellent capacity in electricity generation. [ABSTRACT FROM AUTHOR]

• A catalyst consisting of Pt 2 Ni 4 clusters adjacent to Pd nanoparticles on Ni-hydroxide is developed. • It surpasses the commercial J.M.-Pt/C catalyst by ∼75 times in alkaline ORR. • It shows progressively increasing mass activity up to 15 K stability test cycles. The oxygen reduction reaction (ORR) is a key "showstopper" for the commercial viability of alkaline fuel cells (AFCs). In this study, we developed a ternary nanocatalyst (NC) coloaded with Pt 2 Ni 4 atomic clusters and palladium (Pd) nanoparticles (NPs) on oxygen vacancies (OVs) enriched nickel hydroxide-support (henceforth denoted as NiPP). This material outperforms the commercial J.M.-Pt/C (20 wt%) catalyst by ∼75 and ∼38 times with exceptionally high mass activities (MA)s of 5050.3 mAmg Pt -1 and 952.3 mAmg Pt -1 at 0.85 V and 0.90 V vs RHE, respectively, in alkaline ORR (0.1 M KOH). The high structural reliability of the Pt 2 Ni 4 endows the NiPP NC with outstanding durability, where it achieves an optimum MA of 5755.9 mAmg Pt -1 after 10 K cycles in an accelerated durability test (ADT) and retains the original performance up to 15 K cycles. Moreover, NiPP delivers an outstanding power density (339.1.4 mW cm−2) and short circuit current density (910.8 mA cm−2), which exceeds the commercial J.M.-Pt/C (174.9 mW cm−2 and 720.4 mA cm−2) when serving as the cathodic catalyst in an AFC. The results of physical characterizations, electrochemical analysis and in-situ XAS analysis suggest that the exceptional performance is originated from the potential synergism between the neighbouring reaction sites of Pt 2 Ni 4 (OV in Ni(OH) x and Pd NPs). During ORR, the Pt 2 Ni 4 atomic clusters and OVs boost the O 2 splitting, while the adjacent Pd NPs promote the subsequent relocation of OH– ions. The obtained results provide the potential design strategies for the atomic-scale surface engineering of advanced ORR NCs in alkaline fuel cells. [ABSTRACT FROM AUTHOR]

Iron,nitrogen-codoped carbon (FeNC) has emerged as promising alternatives to precious metals for oxygen reduction reaction (ORR). Herein, we demonstrate that the ORR activity of FeNC can be markedly enhanced by the incorporation of adjacent Fe few-atom clusters (Fe AC), where the octahedral field of Fe AC boosts the splitting of the parallelogram field of FeN 4 , and facilitates the transition from high-spin (t 2g 3e g 2) Fe(III)N 4 to medium-spin (t 2g 5e g 1) Fe(II)N 4 and hence the interaction with the π* antibonding orbitals of oxygen. This leads to a remarkable ORR performance due to optimized desorption of the OH* intermediate on FeN 4 , with a half-wave potential of +0.80 in 0.1 M HClO 4 , in comparison to that with only FeN 4 single-atom moieties. In H 2 -O 2 fuel cell tests, a high peak power density of 0.80 W cm−2 is obtained. Results from this work highlight the significance of spin engineering in the manipulation and optimization of the ORR activity of single-atom catalysts. [Display omitted] • Pyrolytic treatment of Fe-doped ZIF-8 and C 3 N 4 at controlled feed ratios. • Formation of Fe few-atom clusters (Fe AC) adjacent to Fe single atom centers (Fe SA). • Transition from high-spin Fe(III)N 4 to medium-spin Fe(II)N 4 by Fe AC. • Enhanced ORR/PEMFC performance by optimized desorption of OH* on FeN 4. [ABSTRACT FROM AUTHOR]

[Display omitted] • Interfacial electronic structure of metal-support is regulated by heteratom doping. • N/S doping promotes the oxidation of Pt-Lewis acid center to a higher valence state. • S atom re-doping causes the d-band center of Pt to shift upward towards Fermi level. • High content of Ptx+ sites enhance the binding of Pt-Lewis acid to *OOH intermediate. • PtNi@N,S-HMCS with more Pt-Lewis acid shows high ORR activity and 4e- selectivity. Elucidating the mechanism of metal-support interface domain regulation is crucial for designing efficient fuel cell electrocatalysts. Herein, we propose an emerging strategy to enhance oxygen reduction reaction (ORR) activity and selectivity by regulating the Lewis alkalinity of carbon support to adjust the Lewis acidity of metal sites. The experimental results and density functional theory (DFT) simulations show that the introduction of N/S atoms into the carbon support structure will break the charge balance of the carbon skeleton and effectively regulate the charge distribution in the Pt-carbon interface domain, thus promoting the oxidation of the Lewis acid Pt atoms to a higher valence state Ptx+, so as to optimize the adsorption energy of oxygen-containing intermediates. Moreover, Bader charge analysis also verifies that N,S-HMCS, as a Lewis base, can receive more electrons from the Pt sites of Lewis acid, and the electron loss at Pt sites caused by N,S-HMCS strengthens interfacial electron effect. Meanwhile the strong electron adsorption ability of N/S atoms causes the d-band center of Pt atom orbital to shift upward to the Fermi level, which strengthens the binding of metal Lewis acid Pt sites with *OOH intermediates, and improves the 4-electron transfer mechanism. This research reveals the direct role of Lewis acid sites in ORR of fuel cell cathode, and provides a feasible way to guide the design of electrocatalysts with Lewis acid/base double centers. [ABSTRACT FROM AUTHOR]

In this work, we report the high-temperature confinement synthesis of N-doped graphitic carbon shells encapsulated PtCo nanoparticles embedded into porous Ketjenblack (KB) carbon architectures (PtCo@NGCS/KB) for fuel cells by a facile ligand carbonization strategy. [Display omitted] • The confinement synthesis of PtCo@NGCS/KB-800 is achieved by ligand carbonization. • Carbon shell reconstruction effectively improves the accessibility of surface sites. • PtCo@NGCS/KB-800 exhibits more outstanding ORR performance than commercial Pt/C. • PtCo and NGCS synergically account for the enhanced ORR performance. High-temperature reduction technology significantly improves the alloying process but inevitably causes the sintering of metal. Herein, we report the high-temperature confinement synthesis of PtCo nanoparticles encapsulated with N-doped graphitic carbon shells (NGCS) in porous Ketjenblack (KB) carbon architectures (PtCo@NGCS/KB) for fuel cells via ligand carbonization strategy. The optimal PtCo@NGCS/KB-800 exhibits outstanding mass and specific activities (840.2 mA/mg Pt and 0.94 mA/cm2, respectively) for oxygen reduction reaction (ORR), and possesses excellent stability with a smaller peak power density loss rate of 7.1 % than commercial benchmark Pt/C (23.7 %) after the accelerated durability test (ADT) in practical H 2 /air fuel cells. Experimental and theoretical investigations reveal that carbon shell reconstruction improves the accessibility of surface sites, and PtCo and NGCS synergically promote the enhancement of ORR performance. The NGCS encapsulation significantly reduces the energy level of the d-band center of Pt, promotes the desorption of intermediates, and lowers the reaction barrier for efficient ORR. [ABSTRACT FROM AUTHOR]

Designing efficient and stable single-atom catalysts (SACs) for the oxygen reduction reaction (ORR) is essential to promote fuel cell commercialization. In this study, the Bayesian Regularization Neural Network (BRNN) has been used to determine the carbothermal shock (CTS) conditions for preparing high-loading Pt-Fe/C SACs. The BRNN model effectively identified a low reaction temperature of 283 °C for achieving high-loading (15 wt %) Pt-Fe/C SACs. Based on this model, we successfully synthesized Pt-Fe/C SACs with a metal mass content of 11.31 wt % using the CTS method. These ultrahigh content metal Pt-Fe/C SACs consisted of dispersed single atoms and foam-like atomic constructions, namely Pt-Fe/C atom foam catalysts (AFCs), rendered them promising candidates for electrocatalysis applications. The Pt-Fe/C AFCs exhibited good catalytic activity and durability toward ORR in alkaline conditions. The Pt-Fe/C AFCs were employed in a direct borohydride fuel cell (DBFC) as cathode catalyst, which resulted in a maximum power density of 214 mW cm−2 at 60 °C and demonstrated stable discharge for 40 h at room temperature. The electrocatalytic performance of the Pt-Fe/C AFCs surpassed that of low-loading Pt-Fe/C SACs and commercial Pt/C catalysts. The rapid ramp-up rate and the rapid cooling rate of the CTS process enabled the incorporation of high-loading Pt and Fe metal atoms into the graphitized carbon layer, resulting in an increased number of active sites of the Pt-Fe/C AFCs. This work provides an effective strategy for manufacturing efficient and stable SACs for practical applications in fuel cells. [Display omitted] • The Bayesian Regularization Neural Network is used to determine the CTS conditions. • Pt-Fe/C AFCs with metal content of 11.31 wt % is successfully synthesize by the CTS method. • The Pt-Fe/C AFCs exhibit good catalytic activity and durability towards ORR. • The DBFC using Pt-Fe/C AFCs cathode achieves a maximum power density of 214 mW cm−2. [ABSTRACT FROM AUTHOR]

[Display omitted] • MOF-PPy composites were synthesized in a one-pot reaction. • The CoFe-NC-PPy with single-atom of Fe and Co was successfully synthesized. • PPy served as secondary nitrogen sources for enhanced ORR activity. • The CoFe-NC-PPy showed excellent ORR activity and durability in alkaline media. • The AEMFC performance with CoFe-NC-PPy exhibited remarkable efficiency. Metal-nitrogen-doped carbon (M−N−C) catalysts have emerged as highly active noble-metal-free catalysts for oxygen reduction reactions (ORR) in anion-exchange membrane fuel cells (AEMFCs). However, the performance of existing M−N−C catalysts is limited by the inaccessibility of internal M−N x active sites and loss of nitrogen doping after the carbonization process. Here, a single-atom Co, Fe and N-doped porous carbon catalyst (CoFe-NC-PPy) were constructed using a complex of metal–organic frameworks (MOFs) and polypyrrole (PPy). As a new approach, we synthesized MOF and PPy composites by combining in situ MOF synthesis and pyrrole polymerization in a one-pot reaction. Through pyrolysis, the PPy and MOF composites demonstrated an enhanced specific surface area, a high active-site density, and a high concentration of nitrogen species in the M−N−C catalyst. These contributed to a superior ORR performance (E 1/2 of 0.915 V) and high durability in alkaline media. Additionally, the CoFe-NC-PPy material studied in an AEMFC enabled high performance with a current density of 550 mA cm−2 at 0.6 V and a peak power density of 352 mW cm−2. This study suggests potential in combining polymers and MOFs in the synthesis of ORR catalysts for fuel cells. [ABSTRACT FROM AUTHOR]

The metal-nitrogen-carbon (M-N-C) type oxygen reduction reaction (ORR) catalysts are promising for hydroxide exchange membrane fuel cells, but catalysts with further improved performance are challenging. Here, we report the efficient improvement of the ORR activity of M-N-C catalysts by employing highly polarizable metal cation Ag+. Ag, Fe single atomic sites embedded in concave nitrogen doped carbon (Ag 1 Fe 1 /CNC) is successfully synthesized and shows high performance towards ORR, indicating by both the ultra-high half-wave potential of 0.917 V and membrane electrolyte assembly performance of peak power density up to 1.26 W cm−2. The binding energy of the ORR intermediates on the highly polarizable Ag site in Ag 1 Fe 1 /CNC was significantly tuned by the adjacent Fe site by more than 0.2 eV, and thus leading to a low theoretical ORR overpotential of only 0.398 V. The employment of the highly polarizable metal cation brings a novel and efficient approach to construct highly active catalysts. [Display omitted] • High performance oxygen reduction reaction catalyst Ag 1 Fe 1 /CNC is synthesized. • The highly polarizable Ag site shows ultra-high catalytic activity. • The Ag sites are significantly affect by the adjacent metals. • High membrane electrolyte assembly performance is achieved by using Ag 1 Fe 1 /CNC. [ABSTRACT FROM AUTHOR]

Oxygen reduction reaction (ORR) is one of the key reactions in electrochemical energy conversion systems such as fuel cells, and it is significant to develop stable, efficient, and low-cost ORR electrocatalysts for future large-scale application of fuel cells. Metal-organic frameworks (MOFs) are a kind of porous materials that combine organic and inorganic components through coordination bonds. Compared with the conventional MOFs, the MOFs-derived materials can not only retain the unique high specific surface area and high porosity of the precursors, but also improve the electrical conductivity and charge transfer, which are more suitable to be used as efficient ORR catalysts. The research on MOFs-derived electrocatalyst has been long-standing and chaotic, especially with its widespread application in the field of ORR for the past few years. Therefore, this article reviews the latest research progress in MOFs-derived ORR electrocatalysts in recent years, introduces the relevant mechanisms of ORR, and looks forward to the development prospects of MOFs-derived electrocatalysts for ORR. [Display omitted] • The basic principles of ORR and the modification methods of MOFs-derived electrocatalysts were introduced. • MOFs-derived electrocatalysts in the field of ORR in recent years were classified and updated. • The prospect of MOFs-derived electrocatalysts for ORR were presented. [ABSTRACT FROM AUTHOR]

• Fe-N-C catalyst was prepared for electrochemical oxygen reduction reactions. • Wetting with water and drying treatments introduced non-negligible activity loss. • Extend of the activity loss was affected by the treatment conditions. • Subtle changes in Fe-N-C surface were observed after the treatments. The membrane electrode assembly (MEA) is a core component of low-temperature fuel cells. The first step of MEA manufacturing is the preparation of a catalyst ink suspension in which the catalyst powder is homogeneously dispersed in a liquid solvent through mechanical or sonic agitation. In this work, we have studied the effects of catalyst dispersion in water or alcohol solutions and subsequent drying processes on the physicochemical properties of Fe-N-C catalysts and their electrocatalytic oxygen reduction activities. We find that dispersing the model Fe-N-C catalyst comprising only FeN x C y moieties in water and subsequent drying treatment change neither its bulk structure nor surface composition, as indicated by various spectroscopic measurements before and after treatment. However, zeta potential measurements, which are very sensitive to the chemistry of functionalities present on the carbon surface, reveal that the Fe-N-C catalyst becomes slightly more acidic, and that the change in their acido-basicity is magnified with a) increasing treatment temperature and b) repetitions of a same wetting/drying treatment. This small change in the surface acido-basicity of the Fe-N-C catalyst results in a measurable and reproducible decrease in its electrocatalytic activity, which shows a positive correlation with the zeta potential changes measured at pH = 1. Observed on the Fe-N-C catalyst but not on Pt/C, it is surmised that the electrocatalytic activities of the oxygen-reducing FeN x C y moieties are influenced by the surface chemistry of the carbonaceous support. Since catalyst wetting and drying processes are essential for MEA fabrication for fuel cells, these results suggest that careful attention should be paid to the conditions employed to prepare and dry catalytic inks for the family of Fe-N-C catalysts in order to obtain their highest possible ORR activity. [ABSTRACT FROM AUTHOR]

• Nanoporous biomass-derived carbons were successfully applied as ORR ECs. • The electrocatalysts showed good electrocatalytic performances. • Excellent stability/durability and tolerance to methanol crossover were achieved. Electrocatalysts (ECs) for the oxygen reduction reaction (ORR) are crucial in fuel cells and for this reason developing cost-effective metal-free ECs with high electrocatalytic activity and high-volume production remains a huge challenge. Herein, we report the application as ORR electrocatalysts of a series of high grade nanoporous carbons, prepared by chemical activation of acid-chars obtained from the H 2 SO 4 digestion and polycondensation (acid-mediated carbonization) of a biomass residue (Agave sisalana). All the nanoporous carbons presented good ORR electrocatalytic activities in alkaline medium. The AC 1 carbon exhibited the most promising ORR performance with E onset = 0.84 vs. RHE, j L, 0.26 V, 1600 rpm = -3.12 mA cm−2 and n O2 = 3.6 electrons. The Tafel slopes of all carbons varied between 47 mV dec−1 (AC 3) and 250 mV dec−1 (AC 1). Furthermore, the carbons revealed superior tolerance to methanol when compared with commercial Pt/C and a competitive long-term electrochemical stability, with current retentions of 75–85 % after 20,000 s. The results obtained in this work suggest a promising method based on sustainable and economical biomass residues towards the development and engineering of novel value-added biomass-derived carbons as effective metal-free electrocatalysts for alkaline fuel cells. [ABSTRACT FROM AUTHOR]

• Bifunctional OER/ORR electrocatalysts based on Fe-Ni-Co/MWCNT were synthesized. • Both the OER and the ORR activity varied with the Fe:Ni:Co ratio. • Superior bifunctional ORR/OER activity was achieved for trimetallic Fe-Ni-Co oxides. • (Fe-Ni):Co ratio close to 1 led to catalysts with the highest bifunctional ORR/OER activity. • Synergistic interactions improve the stability and selectivity of the electrocatalysts. Fabrication of efficient and cost-effective bifunctional oxygen electrocatalysts for both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) remains a challenge for the development of rechargeable metal-air batteries and unitized regenerative fuel cells technologies. Herein, we report high-performance bifunctional ORR/OER electrocatalysts consisting of mixed transition metal (Fe, Co, Ni) oxide nanoparticles supported on oxidized multi-walled carbon nanotubes (MWCNT). Investigation of the ORR and OER activity of samples with different metal compositions showed that trimetallic/MWCNT composites having Fe:Ni:Co = x:x:(1-2x) ratios, with 0.25 ≤ x ≤ 0.4, exhibit highest bifunctional activity in terms of the reversible ORR/OER overvoltage at a given current density. Moreover, the trimetallic catalysts exhibited improved selectivity with respect to the reduction of O 2 to OH− compared to the bimetallic Fe-Ni, Fe-Co and Co-Ni catalysts, thus revealing synergistic interactions among the metal oxide components. Correlation of the electrocatalytic activity with the structure of the composites is discussed for the most representative cases. [ABSTRACT FROM AUTHOR]

• α-MnO 2 nanorods have been in-situ supported on 3D-G via a facile hydrothermal method. • α-MnO 2 nanorods are evenly deposited on 3D-G surface which possesses more defects. • The synergistic interaction between α-MnO 2 nanorods and 3D-G improve ORR performance. • α-MnO 2 /3D-G catalyst exhibites excellent activity and durability for ORR in MFCs. Magnesium-air fuel cells are considered as a potential energy conversion device owing to a high theoretical specific capability, economic viability and environmental friendliness. In this work, α-MnO 2 nanorods are supported on three-dimensional graphene (3D-G) which is fabricated with coal tar pitch as the carbon precursor and MgO as the template via hydrothermal reaction. The synergistic interactions between α-MnO 2 nanorods and 3D-G improve the activity and durability performance for oxygen reduction reaction in 0.1 mol L−1 KOH solution. α-MnO 2 /3D-G exhibits a high half-wave potential (0.81 V) and superior to α-MnO 2 /C (0.72 V) and α-MnO 2 /rGO (0.76 V), and close to 20 wt% Pt/C (0.83 V). α-MnO 2 /3D-G also possesses higher durability than commercial Pt/C. Furthermore, the magnesium-air fuel cells based on α-MnO 2 /3D-G, air-cathode display the peak power density (106.2 mW cm−2), and continuously durability (discharge for 16 h at 50 mA cm−2 with the mere decay of cell voltage by 7.6%). These results prove that α-MnO 2 /3D-G catalyst with high activity and durability can be a promising electrocatalyst in magnesium-air fuel cells. [ABSTRACT FROM AUTHOR]

• ∼3 nm sized Pt nanoparticles supported on rGO using a facile polyol method. • Systematic XPS analyses for oxygen related functional concentration investigations. • Pt/rGO with superior catalytic activity and durability as 1.6 and 3.8 times higher than that of Pt/CB. Proton exchange membrane fuel cells (PEMFCs) are mainly used as a power source of hydrogen fuel cell vehicles. Also, their catalytic activity and durability of oxygen reduction reaction are important because they operate at high voltage and strongly acidic conditions. In this research, we studied the characteristics of the Pt nanoparticles (NPs) supported on the graphene oxide (GO), partially reduced graphene oxide (GO-r), and reduced graphene oxide (rGO) to investigate the enhancement of the activity and durability of oxygen reduction catalysts for PEMFCs. Pt catalysts supported on carbonaceous materials were synthesized through a facile polyol method, and the characteristics of the synthesized catalysts were analyzed with transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, linear sweep voltammetry, cyclic voltammetry, electrochemical impedance spectroscopy, and Raman spectroscopy. The outcomes demonstrated that the rGO was superior to the carbon black support in oxygen reduction activity and long-term durability. Here, the reduced concentration of oxygen related functional groups on the graphene support was the key factor to enhance the oxygen reduction properties and long-term durability of the Pt/rGO catalyst. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) flower-like Bi 2 SiO 5 nanomaterials (FLB) and 3D flower-like Bi 2 SiO 5 @nitrogen doped graphene nanomaterials (FLBNG) have been originally synthesized. Notably, as-synthesized FLB and FLBNG nanomaterials have not yet been discussed in previous reports. The FLBNG nanomaterials have been for the first time studied as the cathodic catalysts for Fuel cell. Research results have shown that the FLBNG-2 possesses perfectly 3D flower-like Bi 2 SiO 5 with numerous uniformly coiled nanowires and exhibits good methanol immunity, high activity and high durability during oxygen reduction reaction (ORR) process under acidic and basic electrolytes. The value of onset potential (E 0) for FLBNG-2 in alkaline electrolyte can reach to 1.091 V, Tafel slope of FLBNG-2 is 45.637 mV dec−1 and its limiting current density (J L) is 6.49 mA cm−2. Similarly, These ORR performances in acidic electrolyte are also better than those of 20 wt% commercial Pt/C and most of the associated reports. Thus, the FLBNG-2 could be a potential ORR catalyst, applied in the cathode of fuel cells to enhance the kinetic rate, decrease costs and enhance durability. And this synthesis method may be provide a good design to synthesize other 3D flower-like nanomaterials with desirable properties. [ABSTRACT FROM AUTHOR]

• Hierarchical CNT hollow microspheres with tunable size are successfully synthesized. • CNT HMS show superior electrochemical activity for ORR than solid carbon particles. • Optimized CNT HMS deliver a mass-loading independent high performance for ZAB. • CNT HMS endow the highly efficient utilization of active materials. Although carbon materials have shown large potential as efficient electrocatalysts for oxygen reduction reaction (ORR), their practical performance with high energy density and power density is difficult to maintain under high mass-loading due to the compact restacking that seriously hinders mass/charge diffusion. To overcome this issue, we demonstrate the design and synthesis of hierarchical Co-N-codoped carbon nanotube hollow microspheres (CNT HMSs) with high disperse, large surface area and uniform mesopores, which effectively guarantees the high electrochemical activity and stability towards ORR even under high mass-loading. As a result, the power density of Zn-air battery based on CNT HMS gradually enhances from 52.8 to 183.8 mW cm−2 with a good linear relationship when the mass-loading increases from 1.5 (traditional used for most reported works) to 6.0 mg cm−2, indicating a well-preserved catalytic activity with high mass-loading. In addition, the long-term stability (10 h) test illustrates that monodisperse morphology and uniform size distribution of CNT HMS have been well maintained, while the referent carbon particles show serious agglomeration and obvious increased particle size. This suggests a much enhanced stability of CNT HMS compared with traditional particles, which offers large opportunity for the practical applications in metal-air batteries or fuel cells. [ABSTRACT FROM AUTHOR]

Intermetallic electrocatalysts have demonstrated significant potential in facilitating the cathodic oxygen reduction reaction (ORR) in fuel cells with enhanced activity and durability. However, it is still an enormous challenge to the facile synthesis of Pt-based intermetallic catalysts with uniform size and high ordering degree. Here, we innovatively fabricate the core-shell structured L1 0 -PtFe intermetallics with Pt skins supported on N-doped porous carbon matrix through one-step pyrolysis of PtFe Hofmann-type metal-organic frameworks (denoted as L1 0 -PtFe/NC). Under the constraints of the porous structure and cyano-ligand bonding, most Fe atoms are alloyed with Pt to form uniform-ordered PtFe intermetallics, while some Fe atoms are atomically dispersed in the carbon framework to form FeN x moieties. Notably, a series of intermetallic PtFe catalysts with different ordering degrees are successfully constructed by adjusting the pyrolysis temperature, which verified that the increase of ordering degree is beneficial to promote the electrocatalytic performance. In particular, the ordered L1 0 -PtFe/NC-800 exhibits superb ORR activity with both mass and specific activities, which are 2.7-folds higher than those of commercial Pt/C. Moreover, after an accelerated durability test, L1 0 -PtFe/NC-800 retains over 90 % mass activity. This work provides a promising approach for the development of efficient Pt-based intermetallic electrocatalysts for fuel cells. [Display omitted] • Core-shell L1 0 -PtFe intermetallics supported on N-doped porous carbon are prepared. • The enhancement of the ordering degree facilitates electrocatalytic performance. • The L1 0 -PtFe/NC exhibits competitive ORR activity and outstanding stability. [ABSTRACT FROM AUTHOR]

Designing an efficient and stable non-precious metal cathode catalyst is essential to reduce fuel cell cost and promote fuel cell commercialization. Herein, ZIF-67 and carbon powder are rapidly heated using a transient Joule heat device to pyrolyze ZIF-67 to form a CoO/N/C nanocatalysts. The prepared CoO/N/C-90 is comprised of 3–4 nm CoO nanoparticles loaded on a carbon substrate. In alkaline medium the Tafel slope of CoO/N/C-90 is 50 mV dec−1, and a half-wave potential (E 1/2) of 0.82 V towards oxygen reduction reaction (ORR). The E 1/2 only experiences a negative shift of 4 mV after 40,000 cyclic voltammetry (CV) cycles, demonstrating excellent catalytic reaction kinetics and durability. The CoO/N/C-90 is assembled into direct borohydride fuel cells (DBFC) as a cathode, achieving a maximum power density (P max) of 526 mW cm−2 at 60 °C. This work indicates that the CoO/N/C-90 is an efficient and stable non-precious metal catalyst for DBFCs. [Display omitted] • CoO/N/C nanoparticle with a size of 3–4 nm is prepared by CTS method. • CoO/N/C exhibits superior stability and highly electrochemically active area. • A DBFC with maximum power density of 526 mW cm−2 is achieved at 60 °C. [ABSTRACT FROM AUTHOR]

[Display omitted] • Poisoning effect of benzene-containing hydrocarbon-based ionomers on Pt catalysts. • Two types of orientation-dependent adsorption of benzenesulfonic acid anion for Pt. • Changes in PZTC of Pt surface according to the sequence of electrolyte replacement. • Combination of various electrochemical analyses and XPS/TPD measurements. • Time-dependent anion adsorption affecting the long-term stability of fuel cell electrodes. Membrane electrode assembly (MEA) is an essential component that mainly determines the performance of proton exchange membrane fuel cells (PEMFCs). In the electrodes of the MEA, ionomers are mixed with Pt-based nanoparticles to transfer protons to the Pt surface where electrochemical reactions take place. However, Pt catalysts suffer from the poisoning effect of ionomers with proton-conducting groups such as sulfonic acid (SA), resulting in performance deterioration. In particular, for emerging hydrocarbon-based ionomers, the benzene group, which is commonly used to improve their chemical structure, accelerates the poisoning effect. Herein, we experimentally simulate the adsorption of SA and benzenesulfonic acid (BSA) on Pt nanoparticles, revealing the orientation-dependent poisoning effect of BSA on the Pt surface. [ABSTRACT FROM AUTHOR]

[Display omitted] • ORR reaction mechanism in CW-MFCs occurred through the 4-electrons pathway. • Maximum power density was produced with 1 mg/cm2 of G/TiO 2 in CW-MFCs. • Photosynthetic compounds were used as substrate for the anodic biofilm in CW-MFCs. Constructed wetlands-microbial fuel cells (CW-MFC) are an innovative technology used for simultaneous bioelectricity generation and wastewater treatment. This is possible due to the installation of macrophytes in an electrode configuration, in which electroactive microorganisms use organic substrates as biofuel. One way to improve the electrochemical performance of CW-MFCs is through the impregnation of cathodic electrocatalysts. Therefore, in this study the bioelectricity production capacity of CW-MFCs was evaluated from the oxygen reduction reaction (ORR). For this study, the concentrations 0 (CW-MFC1), 0.5 (CW-MFC2), and 1 mg/cm2 (CW-MFC3) of graphene/titanium dioxide (G/TiO 2) as electrocatalyst on the cathodes were evaluated. Using the Koutecky-Levich analysis, it was determined that the ORR transfer mechanism arises via a 4-electron pathway. The electrokinetic parameters of Tafel slope, charge transfer coefficient, and exchange current density determined the efficiency of the ORR, registering 92 mV/dec, 0.93 (α), and 2.30 x10-3 mA/cm2, respectively for CW-MFC3. The highest electrochemical performance was obtained at a concentration of 1 mg/cm2 (CW-MFC3) of G/TiO 2 , generating 144 mW/m2 of power density, 157 Ω of internal resistance, −150 mV of anodic potential, and 383 mV of cathodic potential. The surface modification carried out on the cathodes resulted in a catalytic increase in the ORR. [ABSTRACT FROM AUTHOR]

Single-atom manganese catalysts possess high stability in the oxygen reduction reaction (ORR) due to their lower Fenton reaction activity. Here, we employ N- and S-co-coordination strategy to modulate the microstructural Mn sites towards high-efficiency ORR. The fabricated Mn-N/S-C catalyst with isolated Mn-N 2 S 2 sites demonstrates a positive half-wave potential of 0.91 V for the ORR. The fabricated zinc–air battery with Mn-N/S-C as the cathode affords a maximal power density of 193 mW cm−2 and superior output stability. Moreover, the maximal power density is increased by 1.53 times compared with S-free Mn-N-C catalyst in anion exchange membrane fuel cells (AEMFCs). Both experimental characterizations and theoretical simulations unveil that the main active sites in the Mn-N/S-C should be Mn-N 2 S 2 moiety embedded into the graphene framework (Mn-N 2 S 2 G). Further computational results demonstrate that the S atom doping and asymmetry of structure lead to higher ORR activities of ortho-Mn-N 2 S 2 G than Mn-N 4 G, Mn-N 3 SG, para-Mn-N 2 S 2 G and Mn-NS 3 G. [Display omitted] • N- and S-co-coordination to isolated Mn sites improves the catalytic activity. • The Mn-N/S-C exhibits a positive half-wave potential of 0.91 V for the ORR. • The Mn-N/S-C-based zinc–air battery affords a peak power density of 193 mW cm−2. • The Mn-N/S-C-based AEMFC affords a peak power density of 247 mW cm−2. • Ortho-Mn-N 2 S 2 G shows higher activity than Mn-N 4 G, para-Mn-N 2 S 2 G and Mn-NS 3 G. [ABSTRACT FROM AUTHOR]

• Iodine and Fe-N x were simultaneously introduced into carbon (FeNI-CNS) by a solution plasma process. • Iodine dopants contribute to the oxygen reduction reaction rate with a higher current density. • A synergistic effect further enhances the catalytic activity of the FeNI-CNS. • FeNI-CNS exhibits better durability than commercial Pt/C catalysts. The oxygen reduction reaction (ORR) plays a critical role at the cathode of fuel cells and metal–air batteries. In this study, we report the one-pot synthesis of iodine- and Fe-N x impregnated carbon nanospheres (FeNI-CNS) using a solution plasma process and their effect on electrocatalytic activity. FeNI-CNS exhibits a fast four-electron transfer reaction with a high current density and superior durability in both alkaline and acidic media. The excellent catalytic performance is attributed to the synergetic effect between the iodine and Fe-N x sites, which provide a higher reaction rate and faster ORR, respectively. We believe that these findings represent a new approach for enhancing ORR catalytic performance and catalyst synthesis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mn-N-C catalysts were developed by a newly designed bis(imino)-pyridine precursor. • The structures of Mn-N-C are dependent on the growth of the precursor with NaCl. • The Mn-N-C nanosheets with short Mn-N length shows excellent ORR performance. • This work provides new understanding for the rational design of M−N−C. Revealing the correlation between the micro–macro structures and active sites of transition metal-nitrogen-carbon (M−N−C) for electrochemical oxygen reduction reaction (ORR) is essential to develop non-precious metal catalyzed fuel cells and metal-air batteries. Herein, Mn-N-C catalysts with various morphologies and microstructures were prepared using Mn2+ coordinated bis(imino)-pyridine-based polymer with N-rich content as a new platform of precursor, which was synthesized via a condensation reaction of 1H-1, 2, 4-Triazole-3, 5-Diamine and 2, 6-Diacetylpyridine. Results demonstrate that morphologies and fine structures (pore structure, N dopants, surface area, and atomic Mn-N bond length, etc.) of Mn-N-C catalysts are strongly dependent on the growth of the specific precursor with and without NaCl as a template and the secondary calcination temperature can further optimize the bond length of Mn-Nx moieties, resulting in significant activity differences between correspondingly derived Mn-N-C catalysts for ORR. Compared to Mn-N-C derived from the synthesized precursor without NaCl, Mn-N-C obtained by the precursor grown directly on NaCl features an ultra-thin nanosheet-like structure with a hierarchical pore distribution and a shorter Mn-N bond, presenting high ORR performance with a half-wave potential of 0.88 V in 0.1 M KOH and a tiny potential loss of 11 mV after 30 K cycles, which is also proved by high-performance practical single Zn-Air battery (139 mW·cm−2) and proton exchange membrane fuel cell (400 mW·cm−2). This work provides a new understanding of the critical role of morphology and Mn-N bonding length of M−N−C for enhancing ORR and a new route of developing non-Fe/Co-based M−N−C catalysts for electrocatalysis. [ABSTRACT FROM AUTHOR]

The design of a new electro-catalyst with rich active sites, sufficient surface areas, low cost, and excellent stability for promoting the oxygen reduction reaction (ORR) efficiency is a crucial research topic in the fuel cell's application. Herein, the successful preparation of 2D WS 2 and MoS 2 functionalized NiO nanoparticles onto the surface of nanodiamond and carbon support is reported. The effect of WS 2 and MoS 2 doping on nickel oxide/nanodiamond activity supported carbon composites (NiO/ND/C) as electro-catalysts for oxygen reduction reaction in an alkaline medium was evaluated. The combination of activated carbon with sp2 hybridization and nanodiamond with sp2 and sp3 hybridization allows for better materials support conductivity. All prepared electro-catalysts exhibit good electrochemical activity towards ORR. It's noticed that the most efficient electro-catalyst for ORR among all the prepared composites is WS 2 /NiO/ND/C, which exhibits the highest current density of −7.47 mA·cm−2 at a rotating speed of 2500 rpm and a retention stability of 94.3 % after 100-repetitive cycles. Moreover, the WS 2 /NiO/ND/C composite forces the ORR reaction through the direct four-electron pathway. This work spotlights the effect between the electronegative oxygen atoms, the electropositive Mo and W atoms, and the synergistic effect between WS 2 and carbon support. All this information confirms that the as-reported WS 2 /NiO/ND/C nanocomposite may be considered a hopeful cathodic electrode for ORR catalysis as an alternative catalyst for platinum-based ones. [Display omitted] • A support containing activated carbon and nanodiamond was prepared. • The activated carbon and nanodiamond support was functionalized with NiO nanoparticles (NiO/ND/C). • The compound was further functionalized with transition metal dicalcogenides namely WS 2 and MoS 2. • These composites were tested as electro-catalysts for oxygen reduction reaction (ORR). • WS 2 /NiO/ND/C exhibits the highest current density of –8.27 mA.cm–2 and a retention stability of 94.3%. [ABSTRACT FROM AUTHOR]

A cathode catalyst possessing increased activity for oxygen reduction reaction (ORR) with superior durability is greatly required for polymer electrolyte membrane fuel cells (PEMFCs). Although Platinum (Pt) alloys have been widely studied for ORR, their real time application in fuel cells still remains a challenging task. Chemically ordered Pt alloys have attracted widespread attention due to the unique electronic and geometric factors that boost their electrocatalytic activity. Therefore, it is highly urgent to fabricate such ordered alloys as efficient cathode catalysts in fuel cells. Herein we report for the first time, a one-step solid-state method for the preparation of Pt 3−x Co 0.5+y Ni 0.5+y /C (x = 0, 1, 2; y = 0, 0.5, 1) nanoparticles on carbon support. Different compositions of this catalyst were studied and Pt 2 Co 1 Ni 1 /C was found to be the optimal, best performing catalyst both under half-cell and full-cell conditions. Interestingly, the mass activity of Pt 2 Co 1 Ni 1 /C was found to be seven times higher than that of commercial Pt/C in an acidic medium, achieving the Department of Energy (DOE) target for 2025. Moreover, a retention in mass activity after 50k cycles confirmed the superiority of this catalyst in effectively catalysing ORR reactions under an acidic medium. Importantly, the peak power density achieved by Pt 2 Co 1 Ni 1 /C under actual PEMFC operating conditions outperforms the commercially used Pt/C. Thus, this work provides a new approach for the simple and scalable synthesis of optimal cathode catalysts for fuel cells, opening up new dimensions in the field of energy research. • One-step solid-state method for the preparation of Pt 3−x Co 0.5+y Ni 0.5+y /C (x = 0, 1, 2; y = 0, 0.5, 1) nanoparticles. • I m of Pt 2 Co 1 Ni 1 /C found to be seven times higher than that of commercial Pt/C in an acidic medium. • Retention in mass activity after 50k cycles. • The peak power density of Pt 2 Co 1 Ni 1 /C under PEMFC conditions outperforms Pt/C. [ABSTRACT FROM AUTHOR]

Surface engineering has been identified as an effective way to maximize the utilization of noble atoms and facilitate the oxygen reduction reaction. However, a cost-effective and highly durable platform for tailoring the electrocatalytic activity, is still absent. Herein, we demonstrate a new and promising catalytic material of antiperovskite-typed PdNFe 3 and construct a high performance PdNFe 3 @Pd catalyst with atomic layers of strained Pd shell. The PdNFe 3 @Pd/C catalyst presents a high mass activity (MA) of 1.14 A mg−1 Pd at 0.9 V, which is 9 and 6 times higher than those of the Pt/C and Pd/C, respectively. More importantly, the excellent performance of PdNFe 3 @Pd/C was also verified in anion-exchange membrane fuel cells and rechargeable Zn−air batteries. Density functional theory calculations reveal that the strain effect aroused by the lattice mismatch between PdNFe 3 core and Pd shell contributes to the enhanced ORR performance by optimizing the binding strength of oxygen intermediates on Pd. [Display omitted] • Demonstrating a new class of platform/core materials for constructing core-shell catalysts. • Elucidating catalytic mechanism of PdNFe 3 @Pd towards ORR. • Extraordinary catalytic performance towards oxygen reduction. [ABSTRACT FROM AUTHOR]

The development of the fuel cell catalysts with high durability and high activity for oxygen reaction reduction remains a great challenge. Various material designs such as alloys, core@shell structure and shape control provide the promising ways to improve the electrocatalytic performance. Herein, on the basis of both the alloy effect and the nanotube structure effect, we demonstrate a high-performance PtNi alloy catalyst with one-dimensional nanotube structure via a galvanic replacement reaction combined with Kirkendall effect. Meanwhile, the PtNi alloy phase and the tube structure are selectively controlled by tuning the PtNi atomic ratio and the wall thickness of the nanotube, respectively. Subsequently, the understanding of the composition effect and the shape effect on the activity and the durability is systematically investigated. The optimized PtNi nanotube catalyst shows significant improvements on the activity (6.2-fold increase in specific activity compared to the commercial Pt/C) and the durability (only 8.6% loss in mass activity after 10000 cycles), attributing to the alloy effect by introducing Ni to the Pt lattice, the Pt-rich surface and the shape effect of the unique one-dimensional hollow tube structure. Image 1 • PtNi alloy NTs are synthesized with tunable compositions and wall thicknesses. • Composition, size and nanotube effects on the performance are systematically studied. • PtNi-NTs show 1.1 times higher in MA and 6.2 times higher in SA at 0.9 V than Pt/C. • PtNi-NTs achieve an enhanced durability of 8.6% loss in MA after 10 k cycles. [ABSTRACT FROM AUTHOR]

Abstract High-efficiency cathode catalysts are essential for microbial fuel cell development since they are one of the key components in chemical energy conversion in organic compounds into electricity. Here, novel Fe Mn bimetallic nanocatalysts are designed and hydrothermally synthesized for microbial fuel cells. Fe:Mn (atom%) = 1:4, 1:2, 1:1, and α-MnO 2 are applied in air-cathodes with Pt/C and activated carbon catalysts as benchmarks, and Fe Mn catalysts can enhance the performance. When Fe:Mn = 1:2, the FeMn 2 achieves a maximum power density of 1940 ± 31 mW m−2 in microbial fuel cells and a current density of 19.4 A m−2 at −0.056 V in abiotic electrochemical tests, 24% and 37% higher than Pt/C respectively. Material characteristics are systematically analyzed since they are directly related to the catalytic performance. The high catalytic activity of FeMn 2 proves to result from a combination of the weak Mn O bonds, large quantity of defects, large specific surface area and high Mn(III):Mn(IV) ratio, according to the proposed possible mechanisms of Fe Mn catalysts to enhance the output. This work not only puts forwards an easy-to-accomplish method to design and prepare bimetallic nanocatalysts, but also provides a potential alternative to Pt/C in microbial fuel cells for sustainable energy generation. Graphical abstract Image 1 Highlights • Fe Mn nanocatalysts were designed and prepared for MFC via hydrothermal method. • FeMn 2 air-cathode exhibited the highest MFC maximum power density of 1940 mW m−2. • The synergism of Fe3+ and α-MnO 2 lattice has been demonstrated. • The best performance of FeMn 2 was illustrated by proposed catalytic mechanisms. • The FeMn 2 outperformed commercial Pt/C and could be a potential alternative. [ABSTRACT FROM AUTHOR]

Abstract Novel cathode electrocatalysts based on Pd and cerium oxide nanorods (CeO 2-NR), supported on home-obtained graphene (G) and N-doped graphene (G D1, G D2), were synthesized. The electrocatalysts were identified as Pd CeO 2-NR /G, Pd CeO 2-NR /G D1 and Pd CeO 2-NR /G D2. In half cell measurements in 0.5 mol L−1 KOH, these electrocatalysts showed higher mass and specific activity for the Oxygen Reduction Reaction (ORR) than Vulcan-supported Pd/C and comparable to Pd CeO 2-NR /C. Tests in a dual-chamber Microbial Fuel Cell (MFC) were performed using pharmaceutical residual water (PRW) as anode substrate, while KOH (pH = 9.6) was the electrolyte in the cathode compartment. The bioanode was formed by commercial Pt/C electrocatalyst and Bacillus subtilis as the microorganism grown as a biofilm. Meanwhile, the gas diffusion electrode (GDE) cathode contained the above-mentioned Pd-based electrocatalysts. The MFC equipped with the Pd CeO 2-NR /G D1 electrocatalyst as cathode delivered an Open Circuit Voltage of 0.308 V and a maximum power density of 12.47 mW m−2. This performance was higher than those of the MFC with Pd/C (0.21 V and 4.50 mW m−2) and commercial Pt/C (0.21 V and 5.43 mW m−2) cathodes. Thus, Pd CeO 2-NR /G D1 is a promising cathode for MFCs. Moreover, B. subtilis demonstrated to be an active microorganism to generate electrical energy from PRW. Graphical abstract Image 1 Highlights • Application of cerium oxide nanorods (CeO 2-NR) as cathode co-catalyst. • CeO 2-NR and N-doped graphene enhance the performance of Pd for the ORR in KOH. • B. subtilis is an active microorganism to generate energy. • Pharmaceutical Residual Water is a suitable substrate for Microbial Fuel Cells. • Pd CeO 2-NR /G D1 cathode shows the higher performance in a Microbial Fuel Cell. [ABSTRACT FROM AUTHOR]

Abstract Nanostructuring of electrocatalysts is an important aspect of catalyst design as catalytic performance depends not only on the specific activity (reaction rate per surface area), but also on the dispersion of the catalyst. We present an industrially compatible, but effective preparation method for support-free nanostructured catalyst layers. Alternating sputtering was used to prepare heterogeneous Pt Cu templates ranging from 95 up to 99.5 at. % Cu. These templates were then electrochemically leached to form a nanostructured Pt Cu network and benchmarked with respect to the oxygen reduction reaction. It is shown that the templates with lower Cu:Pt ratios exhibit the highest initial specific activity but have a relatively low electrochemically active surface area. Subjecting the samples to extended accelerated stress tests, it is found that the support-free nanostructured Pt Cu networks are relatively resistant to high potential cycling, which can be explained by the lack of carbon corrosion. The loss in electrochemical surface area thereby depends on the initial Pt content. The specific oxygen reduction activity, however, approaches the value of bulk Pt. Although this decrease is not desirable, still an (specific) activity improvement of two to four times as compared carbon supported nanoparticles can be preserved. Graphical abstract Image 1 Highlights • Novel industrially scalable ORR electrode production method demonstrated. • Porous nanostructured material with a specific surface area up to 47 m2 g−1 Pt. • Specific activity at 0.9 V RHE up to 5.8 mA cm−2 Pt and mass activity up to 1.9 A mg−1 Pt. • Remaining Cu has positive effect on specific activity. • Electrochemical active surface area depends on as-deposited Cu content. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A novel low-temperature hydrothermal method is developed to prepare Co-N-rGO. • Co-N-rGO demonstrates higher catalytic activity for ORR than pyrolyzed Co-N-rGO. • Co is coordinated with N which is doped into the rGO structure via covalent bond. • Co and N show synergetic effect in enhancing the ORR activity of rGO. • The active sites responsible for ORR are proposed to be CoN 2 /C and CoN 4 /C species. Abstract Cobalt and nitrogen co-doped reduced graphene oxide (Co-N-rGO) composites are prepared by a facile low-temperature hydrothermal method. Structure characterization reveals that cobalt and nitrogen are co-ordinately attached to the rGO sheets with the formation of covalent C-N and Co-O-C linkages. Cyclic voltammetry and linear sweep voltammetry show that the Co-N-rGO composite possesses higher electrocatalytic activity and four-electron selectivity for oxygen reduction reaction (ORR) as compared to the rGO, Co-rGO and N-rGO. In addition, the Co-N-rGO composite presents excellent stability and durability in alkaline medium comparable to commercial Pt/C. The edge plane CoN 2 /C, CoN 4 /C, and basal plane macrocyclic CoN 4 /C species within the Co-N-rGO structure are proposed to be the active sites performing catalysis in the ORR. The strong covalent linkages between the cobalt/nitrogen and rGO not only enable potent synergy of cobalt, nitrogen and rGO in catalysis, but also ensure structure stability of the composite. Due to the superior ORR activity of Co-N-rGO, high-temperature heat treatment is not able to improve its activity any more. The low-temperature hydrothermal method is anticipated to be used as a low-cost and facile preparation approach for ORR catalysts, and the superb ORR performance of Co-N-rGO endow it with great application potential in fuel cells, metal-air batteries and other ORR-related electrochemical industries. [ABSTRACT FROM AUTHOR]

Abstract The exploration of cheap and stable electrocatalysts with high activity towards oxygen reduction reaction in the acidic and alkaline medium is a vital activity for large-scale applications of fuel cells. In recent years, one-dimensional nanofibrous electrode materials with high surface area and specific porosities have been drawing great attention in energy conversion devices such as fuel cells and metal-air batteries. Nanofibers with a one-dimensional nanostructure can be produced by electrospinning, which has been considered as a particularly low-cost and versatile method. In this review, we summarize the properties of electrospun nanofibers and the recent progress in designing of non-precious nanostructured electrocatalysts for oxygen reduction reaction in fuel cells. More importantly, we also highlight the interesting nanostructures, new synthetic approaches, and the electrocatalytic performance including active sites and stability of electrospun-based electrocatalysts. In addition, we describe the research challenges and future developmental perspectives of electrospun materials in energy technology. Highlights • Non-precious nanostructured electrocatalysts by electrospinning are summarized. • The active sites and reaction mechanism of the electrocatalysts are discussed. • Research challenges and future perspectives are described. [ABSTRACT FROM AUTHOR]

Abstract To improve the sluggish oxygen reduction reaction from the cathode of solid oxide fuel cells (SOFCs), a conformal layer of catalytic CoO x grains was deposited onto the internal surface of LSM/YSZ composite cathode of commercial cells, through atomic layer deposition (ALD). Upon the electrochemical operation, the ALD coated cell has dramatic reduction of the polarization resistance, and the power density exhibits continuous increase over the course of 172 h operation at 750 °C and reaches the cell performance enhancement by a factor of 1.6, in comparison with that from the baseline operated for 96 h. Such performance enhancement was attributed to the combination of the newly added triple phase boundaries for promoting the oxygen reduction reaction, as well as the accelerated oxygen transport on the cathode surface. The present work opens the further research direction for ALD coating of non-precious metal catalyst to boost the performance of as-fabricated SOFCs. Highlights • Conformal CoO x layer is deposited on LSM/YSZ backbone of SOFC cathode using ALD. • CoO x ALD layer continuously improves the oxygen reduction reaction upon operation. • CoO x ALD layer interacts with the backbone and formed catalytic Co 0.7 Mn 0.3 O x. • Co 0.7 Mn 0.3 O x exhibits Bi-model distribution on LSM and YSZ surfaces. [ABSTRACT FROM AUTHOR]

Abstract The sluggish oxygen reduction reaction (ORR) in cathode is the bottleneck of polymer electrolyte membrane fuel cell. Discovery of ORR catalysts with high activity and low cost is the key solution for the cell development. In this work, we synthesized a novel polypyrrole modified carbon supported FeS (FeS-PPy-BP) through two-step reaction and used it as cathode catalyst in direct borohydride fuel cell (DBFC). The catalyst had an onset ORR potential of 0.89 V (vs. reversible hydrogen electrode (RHE)), little lower than the onset potential of commercial Pt/C. The ORR on the FeS-PPy-BP was mainly through 4-electron process with a low yield of H 2 O 2 (below 5%). The FeS-PPy-BP exhibited a good catalytic stability. The half-wave potential shift of the FeS-PPy-BP after 5000 cycles was 31 mV while that of the Pt/C was 42 mV. The DBFCs using the FeS-PPy-BP as cathode catalyst achieved a maximum power density of 140.5 and 78.8 mW cm−2 at 60 and 30 °C, respectively. The outstanding electrochemical properties and the cell performances strongly support the FeS-PPy-BP as a promising cathode catalyst for DBFC. Graphical abstract Image 1 Highlights • A new FeS-PPy-BP catalyst was synthesized. • FeS-PPy-BP had high ORR activity and good catalytic stability. • DBFC using FeS-PPy-BP as cathode achieved high power density. • FeS-PPy-BP is promising cathode catalyst for DBFC. [ABSTRACT FROM AUTHOR]

Abstract Presently, the practical application of Fe/N/C catalysts as replacements of Pt for oxygen reduction reaction is still limited by insufficient activity. Herein, we demonstrate a novel design for such catalyst. On one hand, the obtained Fe/N/C SiO 2 ZnCl 2 catalyst owns high densities of well-exposed active-sites derived from three-dimensional well-balanced macro-, meso-, and microporous structures constructed by adopting ZnCl 2 salt and SiO 2 microspheres as combined templates. On the other hand, simulation reveals that a high loading of catalyst in cathode catalyst layer would not benefit cell performance and fast oxygen reduction reaction process occurs only inside a limited thickness of catalyst layer. Particularly, the Fe/N/C SiO 2 ZnCl 2 shows a maximal output power density as high as 480 mW cm−2 at an ultra-low loading of 0.5 mg cm−2. This study firstly exhibits that development of catalysts with high-density active sites and construct of ultra-thin catalyst layer are of great significance for improving the performance of fuel cell. Highlights • Fe/N/C SiO 2 ZnCl 2 was synthesized using ZnCl 2 templating and silica templating. • Fe/N/C SiO 2 ZnCl 2 shows superior ORR activity in both alkaline and acidic medium. • The P max of Fe/N/C SiO 2 ZnCl 2 is as high as 480 mW cm−2 at a 0.5 mg cm−2 loading. [ABSTRACT FROM AUTHOR]

[Display omitted] • Different preparation schemes of PBAs are systematically summarized. • Strategy developing high-performance PBAs-based electrocatalyst is proposed. • An insight into the future research direction of PBAs-based electrocatalyst is highlighted. Electrolytic water, metal-air cells and fuel cells are the key fields in the application of new energy. However, these fields are subject to the high overpotential of ORR (oxygen reduction reaction), OER (oxygen evolution reaction) and HER (hydrogen evolution reaction), and these reactions are limited by the efficiency of electrocatalysts. Therefore, developing highly active electrocatalysts becomes a key step to solve the above problems. Prussian blue analogues (PBAs) are ancient synthetic cyanide coordination polymer materials, which are widely used in ORR, OER and HER. The unique three-dimensional open metal frame structure and large specific surface area of PBAs greatly increase the contact area between catalyst and electrolyte, and improve the number of active sites. The easy adjustment of components is beneficial to enhance the inherent activity of each active site in the catalyst. In this paper, the recent progress of PBAs derived materials in electrocatalysis is reviewed. Firstly, different preparation methods of PBAs were summarized, and then the regulatory strategies to improve the electrocatalytic activity of ORR, OER and HER when PBAs derived materials were used as electrocatalysts were discussed in detail, including the chemical composition regulation of doping, as well as the structure and morphology regulation of core–shell structure, open nanoccages structure and composite with other materials. Finally, the major challenges and possible future research orientations in this field were discussed, providing a new vision for further application of PBAs derived materials in electrocatalysis. [ABSTRACT FROM AUTHOR]

Supported ordered intermetallic nanoparticles are of significant interest for catalysis applications owing to their unique surface/near-surface structures and electronic properties. However, the synthesis of small-sized intermetallic catalysts with high mass activity remains a formidable challenge, as high temperatures annealing treatments are generally requisite to achieve ordered intermetallic structures but lead to undesired larger crystallites. Here, we report an industrially relevant impregnation approach for the scalable synthesis of small-sized platinum-based intermetallic nanoparticle catalysts by regulating inter-particle distance on carbon black supports to mitigate metal sintering in high-temperature annealing. We construct a library consisting of 18 binary Pt-based intermetallic nanoparticle catalysts with an average size of < 5 nm. The prepared intermetallic catalyst libraries exhibit outstanding proton-exchange-membrane fuel cells performance, including high mass activities of 1.3–1.8 A mg Pt –1, large peak power densities of 1.2–1.4 W cm–2 in H 2 -air cells, and efficient Pt utilization of ∼0.07 g kW–1 at rated power. [Display omitted] • Intermetallic compounds (IMC) have unique strain/electronic effects in catalysis. • A family of small size Pt-based IMCs was achieved by regulating inter-particle distance. • Small size and ordered IMC structure guarantee outstanding performance in fuel cell. [ABSTRACT FROM AUTHOR]