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The unique properties of solid acid electrolytes, in particular CsH2PO4, are in many ways ideal for fuel cell operation. However, the technology is constrained by high cathode overpotentials. Here a simplified cathode geometry is employed to obtain the fundamental electrochemical parameters (exchange current density and charge transfer coefficient) describing the oxygen reduction reaction (ORR) at the CsH2PO4‐Pt‐gas interface. The parameters are incorporated into a 1D model of the voltage–current characteristics of realistic SAFC cathodes, which reproduced the measured polarization behavior of such cathodes without recourse to fitting adjustable parameters. Following this validation, the model is utilized to evaluate the impact of changes to cathode properties, microstructure, and operating conditions. Of these, the charge transfer coefficient, measured to have a value of ≈0.6 for ORR on Pt in the SAFC cathode environment, is found to have the greatest impact on power output. Nevertheless, even without material modifications, a combination of microstructural and operational modifications are identified with projected performance metrics meeting Department of Energy targets (0.8 V at 300 mA cm−2, and peak power density of 1 W cm−2), albeit at high Pt loadings. However, the analysis indicates that truly meaningful advances will likely necessitate the discovery of alternative ORR catalysts. [ABSTRACT FROM AUTHOR]

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Coordination environment engineering is developed to synthesize Fe SA /NSC catalysts with the tailored N, S co-coordinated Fe atomic site. [Display omitted] • The Fe-N 3 S active site with the optimized electronic structure is constructed. • S doping promotes the OH* desorption, thus leading to enhanced kinetics process. • The catalyst displays impressive ORR activity in both alkaline and acidic mediums. • The catalyst exhibits excellent performance in Zn-air batteries and fuel cells. Atomically dispersed iron–nitrogen-carbon (FesbndNsbndC) materials have been considered ideal catalysts for the oxygen reduction. Unfortunately, designing and adjusting the electronic structure of single-atom Fe sites to boost the kinetics and activity still faces grand challenges. In this work, the coordination environment engineering is developed to synthesize the Fe SA /NSC catalyst with the tailored N, S co-coordinated Fe atomic site (Fe-N 3 S site). The structural characterizations and theoretical calculations demonstrate that the incorporation of sulfur can optimize the charge distribution of Fe atoms to weaken the adsorption of OH* and facilitate the desorption of OH*, thus leading to enhanced kinetics process and intrinsic activity. As a result, the S-modified Fe SA /NSC exhibits outstanding catalytic activity with the half-wave potentials (E 1/2) of 0.915 V and 0.797 V, as well as good stability, in alkaline and acidic electrolytes, respectively. Impressively, the excellent performance of Fe SA /NSC is further confirmed in Zn-air batteries (ZABs) and fuel cells, with high peak power densities (146 mW cm−2 and 0.259 W cm−2). [ABSTRACT FROM AUTHOR]

Fe−N−C catalysts with single‐atom Fe−N4 configurations are highly needed owing to the high activity for oxygen reduction reaction (ORR). However, the limited intrinsic activity and dissatisfactory durability have significantly restrained the practical application of proton‐exchange membrane fuel cells (PEMFCs). Here, we demonstrate that constructing adjacent metal atomic clusters (ACs) is effective in boosting the ORR performance and stability of Fe−N4 catalysts. The integration of Fe−N4 configurations with highly uniform Co4 ACs on the N‐doped carbon substrate (Co4@/Fe1@NC) is realized through a "pre‐constrained" strategy using Co4 molecular clusters and Fe(acac)3 implanted carbon precursors. The as‐developed Co4@/Fe1@NC catalyst exhibits excellent ORR activity with a half‐wave potential (E1/2) of 0.835 V vs. RHE in acidic media and a high peak power density of 840 mW cm−2 in a H2−O2 fuel cell test. First‐principles calculations further clarify the ORR catalytic mechanism on the identified Fe−N4 that modified with Co4 ACs. This work provides a viable strategy for precisely establishing atomically dispersed polymetallic centers catalysts for efficient energy‐related catalysis. [ABSTRACT FROM AUTHOR]

High-porosity, crystalline, and surface-area-rich metal–organic frameworks (MOFs) may be employed in electrochemical energy applications for active catalysis. MOFs have recently been modified using secondary building blocks, open metal sites with large pore diameters, and functional ligands for electronic conductivity. They have the potential for excellent performance in fuel cell applications, and they have several possibilities to enhance the fundamental characteristics of mass and electron transportation. MOFs may be combined with other materials, such as solitary metal nanoparticles and carbon and nitrogen composites, to increase their catalytic efficacy, especially in oxygen reduction reaction (ORR). As a result, this study focuses on MOF derivatives for ORR applications, including porous carbon MOF, single metal MOF-derived composites, metal oxides, and metal phosphides. An efficient MOF electrocatalyst platform for ORR applications is presented, along with its prospects. These initiatives promote promising MOF electrocatalysts for enhancing fuel cell efficiency and pique curiosity for possible growth in subsequent research. [ABSTRACT FROM AUTHOR]

Sluggish oxygen reduction reaction (ORR) of electrodes is one of the main challenges in fuel cell systems. This study explored the kinetics of the ORR reaction mechanism, which enables us to understand clearly the electrochemical activity of the electrode. In this research, electrocatalysts were synthesized from platinum (Pt) catalyst with multi-walled carbon nanotubes (MWCNTs) coated by three polymers (polybenzimidazole (PBI), sulfonated tetrafluoroethylene (Nafion), and polytetrafluoroethylene (PTFE)) as the supporting materials by the polyol method while hexachloroplatinic acid (H2PtCl6) was used as a catalyst precursor. The oxygen reduction current of the synthesized electrocatalysts increased that endorsed by linear sweep voltammetry (LSV) curves while increasing the rotation rates of the disk electrode. Additionally, MWCNT-PBI-Pt was attributed to the maximum oxygen reduction current densities at −1.45 mA/cm2 while the minimum oxygen reduction current densities of MWCNT-Pt were obtained at −0.96 mAcm2. However, the ring current densities increased steadily from potential 0.6 V to 0.0 V due to their encounter with the hydrogen peroxide species generated by the oxygen reduction reactions. The kinetic limiting current densities (JK) increased gradually with the applied potential from 1.0 V to 0.0 V. It recommends that the ORR consists of a single step that refers to the first-order reaction. In addition, modified MWCNT-supported Pt electrocatalysts exhibited high electrochemically active surface areas (ECSA) at 24.31 m2/g of MWCNT-PBI-Pt, 22.48 m2/g of MWCNT-Nafion-Pt, and 20.85 m2/g of MWCNT-PTFE-Pt, compared to pristine MWCNT-Pt (17.66 m2/g). Therefore, it can be concluded that the additional ionomer phase conducting the ionic species to oxygen reduction in the catalyst layer could be favorable for the ORR reaction. [ABSTRACT FROM AUTHOR]

Highly efficient and stable oxygen reduction reaction (ORR) electrocatalysts are remarkably important but challenging for advancing the large-scale commercialization of practical proton exchange membrane fuel cells (PEMFCs). In this work, we report that the introduction of interstitial hydrogen atoms into PtPd nanotubes can significantly promote ORR performance without scarifying the durability. The enhanced mass activity was 8.8 times higher than that of commercial Pt/C. The accelerated durability test showed negligible activity attenuation after 30,000 cycles. Additionally, H2/O2 fuel cell tests further verified the excellent activity of PtPd-H nanotubes with a maximum power density of 1.32 W·cm−2, superior to that of commercial Pt/C (1.16 W·cm−2). Density functional theory calculations demonstrated the incorporation of hydrogen atoms gives rise to the broadening of Pt d-band and the downshift of d-band center, which consequently leads to the weaker intermediates binding and enhanced ORR activity. [ABSTRACT FROM AUTHOR]

Single crystal surfaces with highly coordinated sites very often hold high specific activities toward oxygen reduction reaction (ORR) and others. Transposing their high specific activity to practical high‐surface‐area electrocatalysts remains challenging. Here, ultrathin Pt(100) alloy surface is constructed via epitaxial growth. The surface shows 3.1–6.9 % compressive strain and bulk‐like characteristics as demonstrated by site‐probe reactions and different spectroscopies. Its ORR activity exceeds that of bulk Pt3Ni(100) and Pt(111) and presents a 19‐fold increase in specific activity and a 13‐fold increase in mass activity relative to commercial Pt/C. Moreover, the electrochemically active surface area (ECSA) is increased by 4‐fold compared to traditional thin films (e.g. NSTF), which makes the catalyst more tolerant to voltage loss at high current densities under fuel cell operation. This work broadens the family of extended surface catalysts and highlights the knowledge‐driven approach in the development of advanced electrocatalysts. [ABSTRACT FROM AUTHOR]

The weak interaction between common carbon support and Pt nanoparticles results in low efficiency for the oxygen reduction reaction (ORR) with high overpotentials, which greatly limits the practical application of proton exchange membrane fuel cells. Employing strong metal–support interaction (SMSI) is a promising method for tuning the electronic structure of Pt to boost the ORR, accompanied by rapid improvement in durability. Herein, titanium carbide (TiC) was grown on the surface of carbon black by the sol–gel method coupled with high-temperature treatment (denoted as TiC-C). Based on the SMSI that occurred between TiC and Pt, the obtained Pt/TiC-C catalyst exhibits higher mass ORR activity, which is twice that of the commercial Pt/C-JM under the same conditions. In addition, the Pt/TiC-C exhibits superior durability relative to the Pt/C-JM by preventing the aggregation and dissolution of Pt nanoparticles during the ORR process. [ABSTRACT FROM AUTHOR]

By pyrolyzed the products from hydrothermal reaction of 1, 4, 5, 8‐naphthalene tetramethyl anhydride, NaOH and FeSO4, the nanoparticles of FeFe2O4 were produced, and then its electrochemical performance of oxygen reduction reaction (ORR) was evaluated in O2 saturated 0.1 M KOH solution. The results indicated that, among all the as‐prepared samples, FeFe2O4‐0.50 was mainly composed of uniformly dispersed spherical nanoparticles of 20‐30nm and behaved the best ORR catalytic performance. Its half‐wave potential and limiting diffusion current density was 0.61 V and −1.85 mA cm−2@0.4 V vs. RHE), respectively, higher about 20 mV and 1.29 mA cm−2 than that of FeFe2O4 (0.59 V and −0.56 mA cm−2@0.4 V vs. RHE). In addition, FeFe2O4‐0.50 also showed stronger stability as well as methanol/CO tolerance than that of commercial 20 % Pt/C. It was the evenly dispersed FeFe2O4 nanoscale and Fe−O bond in FeFe2O4‐0.50 that contributed its excellent electrochemical performance and tolerance for CO and methanol. The as‐prepare FeFe2O4‐0.50 might be a potential alternative catalyst for ORR in fuel cell. [ABSTRACT FROM AUTHOR]

Oxygen reduction reaction (ORR), an essential reaction in metal–air batteries and fuel cells, still faces many challenges, such as exploiting cost-effective nonprecious metal electrocatalysts and identifying their surface catalytic sites. Here we introduce bulk defects, Frank partial dislocations (FPDs), into metallic cobalt to construct a highly active and stable catalyst and demonstrate an atomic-level insight into its surface terminal catalysis. Through thermally dealloying bimetallic carbide (Co3ZnC), FPDs were in situ generated in the final dealloyed metallic cobalt. Both theoretical calculations and atomic characterizations uncovered that FPD-driven surface terminations create a distinctive type of surface catalytic site that combines concave geometry and compressive strain, and this two-in-one site intensively weakens oxygen binding. When being evaluated for the ORR, the catalyst exhibits onset and half-wave potentials of 1.02 and 0.90 V (versus the reversible hydrogen electrode), respectively, and negligible activity decay after 30,000 cycles. Furthermore, zinc–air batteries and H2–O2/air fuel cells built with this catalyst also achieve remarkable performance, making it a promising alternative to state-of-the-art Pt-based catalysts. Our findings pave the way for the use of bulk defects to upgrade the catalytic properties of nonprecious electrocatalysts. [ABSTRACT FROM AUTHOR]

The series of electrodes were fabricated by the scalable and manufacturable slot-die coating method for proton exchange membrane fuel cell (PEMFC) application. The inks with different amounts of solids were studied by rheological methods in order to establish a coating window with minimum manufacturing defects. The obtained electrodes were characterized by SEM, AFM, and optical microscopy, which showed that they were uniform and homogeneous with minimum defects. The electrochemical evaluation of the manufactured gas diffusion electrodes (GDE) showed that the main characteristics of the electrodes, like electrochemical surface area, proton resistivity, and double layer capacitance, were found to be close for all samples confirming the reproducibility of the slot-die process. Additionally, we studied the effects of membrane thickness on the performance of the GDE membrane electrode assemblies and determined that a decrease in membrane thickness favored the performance. The obtained results clearly demonstrated the applicability and feasibility of the approach for the Manufacturing of catalyst layers for the fuel cell application with potential for future mass production. [Display omitted] • Pt/C inks with high solid content were formulated. • Scalable Roll-2-Roll approach was used to coat 300 × 22cm electrode. • The electrodes possessed minimal inhomogeneities. • PEM fuel cell tests confirmed promising performance of scaled electrodes. [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]

This work proposes a cost-effective strategy to massively synthesize high-efficiency ORR electrocatalyst. [Display omitted] • A novel type of composite Co/N C was prepared. • A potential strategy was proposed to massively synthesize ORR catalysts. • High ORR activity of Co/N C triggered by Co-N heteroatomic interface. • The high stability of Co/N C in 0.1 M KOH. The development of high-efficiency and low-cost oxygen reduction electrocatalysts have become an urgent need to push fuel cells into practical application. Herein, an effective electrocatalyst Co/N C was successfully constructed, which was derived from abundant peanut shells, obtained by doping with cobalt ions and pyrolyzing in NH 3 atmosphere. Due to the abundant Co-N active sites triggered by Co-N heteroatomic interface, the prepared electrocatalysts present excellent oxygen reduction reaction (ORR) performance with more positive half-wave potential (E 1/2 = 0.83 V), incremental limiting current density (J L = 5.45 mA cm−2), higher durability and stronger resistance to methanol, which is superior to that of Pt/C (E 1/2 = 0.81 V and J L = 5.19 mA cm−2). This work proposes a potential strategy to synthesize efficient ORR electrocatalysts to instead of Pt-based catalysts. [ABSTRACT FROM AUTHOR]

A non-precious metal electrocatalyst was obtained through the in-situ growth of iron phosphide (Fe 2 P) encapsulated by carbon nanotubes (CNTs) decorated with zeolitic imidazolate framework-8 (ZIF-8). Upon pyrolysis at a specific temperature, the ZIF-8/Fe 2 P@CNT catalyst exhibits high oxygen reduction reaction (ORR) ability and is close to the ideal electron transfer, which number is 3.99. The structure, high number of nitrogen-containing functional groups, and suitable surface properties of ZIF-8/Fe 2 P@CNT are critical for enhancing the ORR activity. ZIF-8/Fe 2 P@CNT exhibits a decay in electrocatalytic activity of 26 mV in the half-wave potential after 30 000 cycles, which is considerably superior to the decay of 123 mV for Pt/C after the same number of cycles. Therefore, ZIF-8/Fe 2 P@CNT exhibits excellent ORR activity and long-term stability and can be used as a fuel cell catalyst. [Display omitted] • ZIF-8 is grown in-situ on synthesized CNTs to form a ZIF-8/Fe 2 P@CNT catalyst. • Specific structure and unoccupied graphitic π∗ could catalyze the ORR activity. • ZIF-8/Fe 2 P@CNT exhibits excellent activity and long-term stability for fuel cell. [ABSTRACT FROM AUTHOR]

With the increasing consumption of the global energy demand, the electrochemical conversion and storage of new energy sources have drawn increasing attention in scientific research. As a promising energy conversion technology, fuel cells have attracted extensive attention in academia and industry due to their high energy conversion efficiency, environmental friendliness, high power density and wide range of fuels. Especially, oxygen reduction reaction (ORR) at the cathode is considered as an important electrode reaction in fuel cells. However, several factors, including slow kinetic process, extreme dependence on noble metal platinum, and rapid degradation of catalytic performance and durability after long-term operation, have severely restricted the large-scale promotion and application of these fuel cells commercialization. Therefore, the development of low-cost, highly active and stable catalysts is of great significance to promote the commercialization. Recently, Titanium nitride (TiN), as a highly durable support, has attracted extensive attention because of its superior properties of high conductivity, high melting point, high hardness, abrasion resistance and super anti-corrosion to acid and alkaline. When the advanced TiN material with favorable morphology and porous structure, high surface area and nanostructure is used as catalyst support, the electrocatalytic performance of Pt-based catalysts will be enhanced significantly due to the improved utilization of Pt, enhanced metal-support interactions, promoted mass/charge transfer as well as corrosion resistance. Interesting, TiN has also electronic properties similar to noble metal, and exhibits superior catalytic performance and durability toward ORR, thus obtaining widely attention in non-precious metal catalysts. Based on the above analysis, this review has summarized the current preparation method and synthesis mechanism of TiN materials, and elaborated the latest research progress including TiN, transition metal-doped TiN and its carbon-based composite materials as support or catalyst toward ORR. Based on the presented progress, we finally prospect the future application of TiN materials and directions for designing and developing practical fuel cell cathode catalysts. [ABSTRACT FROM AUTHOR]

The development of new synthetic methods for methanol-tolerant catalysts with improved performance is of fundamental importance for the commercialization of fuel cells. Herein, we reported a facile displacement reaction-assisted synthesis of graphene-supported sub-nanometer Pt/Bi catalysts (Pt/Bi/rGO). Bismuth (0) nanoparticles produced by NH3BH3 reduction can be further dissolved into the ethylene glycol, implying Bi(0) has a strong interaction with the hydroxyl group. That is the key interaction between Bi(0) and the functional group on the rGO to form the ultra-small Bi/rGO catalyst. Furthermore, Pt clusters are obtained by the displacement between Bi(0) and HPtCl4 and are directly anchored to the rGO surface. The as-synthesized Pt/Bi/rGO catalyst exhibits high oxygen reduction mass activity and high tolerance to methanol poisoning. In the presence of 0.5 mol/L CH3OH, the initial potential and activity of ORR were almost unchanged, which demonstrated great potential in the application of direct methanol fuel cells. [ABSTRACT FROM AUTHOR]

At present, fuel cell is considered to be one of the most ideal application technologies of hydrogen energy. In order to develop fuel cells on a large scale and in a sustainable way, low platinum or non-platinum oxygen reduction catalyst has become a research hotspot. In this work, a kind of doped carbon-based catalyst MPFe 1 Cu 1 -850 is prepared by high temperature synthesis. The catalyst has an ultra-thin lamellar porous structure. In an acidic medium, the MPFe 1 Cu 1 -850 displays good oxygen reduction reaction (ORR) activity (ΔE 1/2 = 0.725 V). In addition, it shows better stability (91%) and higher methanol tolerance than that of commercial Pt/C catalyst. In our catalyst MPFe 1 Cu 1 -850, the contents of nitrogen, iron and copper are 10.31 at.%, 0.51 at.%, and 0.50 at.%, respectively. This work shows that high N content, and the proper ratio of iron to copper (Fe:Cu = 1:1), are conducive to the enhancement of ORR activity. • Design a Fe and Cu bimetallic load on N- and F co-doped carbon material. • The N content of the doped carbon catalyst, MPFe 1 Cu 1 , is up 10.31 at.%. • When the ratio of Fe: Cu = 1, the ORR activity of the catalyst is enhanced. [ABSTRACT FROM AUTHOR]

Summary: The oxygen reduction reaction (ORR) that occurs in the cathode of fuel cells is a major issue in proton exchange membrane fuel cells (PEMFCs) due to their sluggish kinetics. Exploring suitable materials for use as cathode catalysts can be challenging because the materials should be chemically active yet must be stable in an extremely corrosive environment in fuel cells. Since the successful introduction of graphene, 2‐dimensional (2D) materials have received extensive research interest regarding their use as support materials for cathode catalysts due to their large surface area for catalyst dispersion. Recently, research on 2D MXene‐based catalyst supports has started to increase. Excellent electronic properties, electrical conductivity, hydrophilicity and chemical and thermal stability are the key properties of potential MXenes used as catalyst supports. Therefore, in this review, the properties and performance of 2D MXene‐based catalyst supports in the ORR are comprehensively discussed. This finding provides the groundwork for the exploration of MXenes in electrocatalysis, especially in the ORR. Challenges and future research directions are also discussed in this review. [ABSTRACT FROM AUTHOR]

Summary: The exploitation of high efficiency non‐precious electrocatalysts for oxygen reduction reaction (ORR) is of great significance for large‐scale commercialization of next‐generation fuel cells. Herein, we report the synthesis of conjugated polymers (CP) based on poly(o‐phenylenediamine) as a nitrogen‐containing precursor for preparation of Co‐ and FeCl3‐doped N‐rich carbon for ORR (abbreviated as Co‐OPD and FeCl3‐OPD). Based on their high specific surface, excellent porosity and large pyridine nitrogen content, the as‐synthesized FeCl3‐OPD, which is prepared at a pyrolysis temperature of 800°C (FeCl3‐OPD‐800), exhibits highest catalytic activity among the resulting electrocatalysts, that is, it possesses a largest half‐wave potential of 0.854 V (≈20 mV more positive than Pt/C), a high diffusion limiting current density of 3.95 mA cm−2 and a biased 4e− reaction pathway. In addition, this catalyst also discloses an excellent methanol tolerance and better durability than the commercial Pt/C. Taking advantage of their high ORR activity as well as simple fabrication which makes it possible using inexpensive FeCl3 as both catalysts for CP precursors and metal dopant for FeCl3‐OPD only by a one‐step pyrolysis, thus such FeCl3‐OPD may hold great potentials as promising alternative of precious metal catalysts for next generation fuel cells. [ABSTRACT FROM AUTHOR]

The unique chemical and physical properties of graphene and its derivatives (graphene oxide, heteroatom‐doped graphene, and functionalized graphene) have stimulated tremendous efforts and made significant progress in fuel cell applications. This review focuses on the latest advances in the use of graphene‐based materials in electrodes, electrolytes, and bipolar plates for fuel cells. The understanding of structure‐activity relationships of metal‐free heteroatom‐doped graphene and graphene‐supported catalysts was highlighted. The performances and advantages of graphene‐based materials in membranes and bipolar plates were summarized. We also outlined the challenges and perspectives in using graphene‐based materials for fuel cell applications. [ABSTRACT FROM AUTHOR]

In this paper, CoMn 2 O 4 /NC nanocomposites were synthesized via a facile ionothermal synthesis route, and their electrocatalytic performance for oxygen reduction reaction (ORR) was investigated in a direct glucose alkaline fuel cell (DGAFC). The CoMn 2 O 4 spinel supported on nitrogen-doped carbon was successfully synthesized with the assistance of the ionic liquid [C 6 mim]Cl. The nanocomposite exhibited excellent electrocatalytic activity towards ORR. Especially, CoMn 2 O 4 /NC achieved a half wave potential of 0.81 V (vs RHE) and a maximum diffusion limiting current density of 5.2 mA cm−2, that are very close to commercial Pt/C catalyst (E 1/2 = 0.83 V vs RHE, J d = 5.0 mA cm−2). In addition, the catalytic performance of CoMn 2 O 4 /NC was investigated in DGFC. The fuel cell with a CoMn 2 O 4 /NC air cathode achieved a peak power density of 23.72 W m−2, which was even superior to that with a commercial Pt/C air cathode. This work revealed that ionic liquid is a viable reaction medium for preparation of catalyst with robust activity. [Display omitted] • CoMn 2 O 4 /NC nanostructure was prepared via an ionothermal method. • The nanocomposite exhibited excellent electrocatalytic ability for ORR. • The fabricated material was employed in a DGAFC. • Ionothermal synthesis method is facile to fabricate novel catalysts. [ABSTRACT FROM AUTHOR]

The development of metal-free carbon-based catalysts for alkaline fuel cells has been the subject of current interest, because of the low cost and improving fuel cell efficiency. Particularly, nitrogen-doped carbon shows prominent results. Here, we show an oxygen reduction reaction (ORR) activity of nitrogen-doped graphene-like carbon materials (N-GLC) prepared by heating bagasse-derived carbon and melamine in a 1:15 ratio. The N-GLC catalyst displays excellent electro-catalytic activity towards the ORR with an onset potential of 0.92 V vs. reversible hydrogen electrode (RHE) in alkaline media (0.1 M KOH). Moreover, the half-wave (E1/2) potential 0.83 V is almost the same compared to Pt-C (40 wt%) catalyst and the diffusion limiting current of 4 mA cm–2. The rotating ring disc experiment showed a four-electron pathway (n = 3.65) with the moderate peroxide ( HO 2 - ) yield. Due to its promising ORR activity and long-term electrochemical stability, N-GLC catalyst is used in alkaline anion exchange membrane fuel cell (AEMFC) as a single cell, about 6 mW cm–2 peak power density was achieved at the load current density of ~20 mA cm–2. So the N-GLC can be a cheap alternative ORR catalyst for AEMFC applications. [ABSTRACT FROM AUTHOR]

To accelerate the commercialization of fuel cells, many efforts have been made to develope highly active and durable Pt-based catalyst for oxygen reduction reaction (ORR). Herein, PtCu porous nanowires (PNWs) with controllable composition are synthesized through an ultrasound-assisted galvanic replacement reaction. The porous structure, surface strain, and electronic property of PtCu PNWs are optimized by tuning composition, which can improve activity for ORR. Electrochemical tests reveal that the mass activity of Pt 0.5 Cu 0.5 PNWs (Pt/Cu atomic ratio of 1:1) reaches 0.80 A mg Pt −1, which is about 5 times higher than that of the commercial Pt/C catalyst. Notably, the improved activity of the porous nanowire catalyst is also confirmed in the single-cell test. In addition, the large contact area with the carrier and internal interconnection structure of Pt 0.5 Cu 0.5 PNWs enables them to exhibit much better durability than the commercial Pt/C catalyst and Pt 0.5 Cu 0.5 nanotubes in accelerated durability test. [Display omitted] • Porous nanowires are prepared by ultrasound-assisted galvanic replacement method. • The ultrasound plays an important role in the formation of porous structure. • PtCu porous nanowires (PNWs) show highly activity and durability for ORR. • The combined advantages of PtCu PNWs lead to enhanced ORR performances. • The porous nanowires show higher activity and stability than the hollow nanotubes. [ABSTRACT FROM AUTHOR]

• The catalytic activity of a series of Fe-BC 3 NT has been theoretically explored in the ORR. • O 2 molecule can be directly dissociated on the Fe-BC 3 NT with 4e pathway. • It is reacting more favorable for the ER mechanism of OH* to convert into H 2 O. • The ORR reaction was found to be thermodynamically favorable in the Fe-BC 3 NT. A critical issue in enhancing the performance of polymer electrolyte membrane fuel cells (FCs) is the slow kinetics of the cathodic oxygen reduction reaction (ORR). The development of electrocatalysts with selectivity toward the four-electron (4e) pathway and high electrochemical activity to ORR reaction is important for fuel cell applications. Within the present study, it was found that boron carbide nanotube (BC 3 NT) is an encouraging ORR-EC based on density functional theory computations. In the pristine BC 3 NT, the neighboring B atoms with positive charges on the surface of the material surface were incapable of providing active sites for the dissociation of O. However, the ORR catalytic activity of BC 3 NT improved under the ligand effect due to the replacement of Fe atom, where there was a slight over-potential that was similar or lower than that of platinum (1 1 1), which demonstrated its superior ORR activity. The results suggest that BC-based materials are considered promising for ORR catalysis and for designing highly efficient ORR-ECs as alternatives to platinum-based catalysts. [ABSTRACT FROM AUTHOR]

Various catalysts were synthesized by incorporating phosphorus and iron into nitrogen-containing carbon derived from shrimp shell with pyrolysis. These catalysts had high specific surface area, uniform atomic doping and various active sites, which resulted in the high kinetics activity towards oxygen reduction reaction (ORR) under various pH conditions. Based on different doping sources to analyse ORR activity, phosphorus-doped catalyst was suitable for alkaline medium and iron doping for acidic medium, while their synergistic effect induced the highest ORR activity in neutral medium. Besides, the stability measurements investigated their abilities for application. Introducing iron into nitrogen-containing carbon could gradually strengthen the long-term stability for different catalysts in various pH conditions. Especially, phosphorus doping promoted the best ORR performance in alkaline condition with an extremely poor stability, which could be overcome by further adding iron. This work provides a strategy for the doped biomass-based carbon to accommodate different fuel cells. Phosphorus and iron are incorporated in nitrogen-containing carbon derived from shrimp shell to prepare dual-doped and tri-doped catalysts with excellent ORR performance and stability under various pH conditions for different fuel cells. Image 1 • Shrimp shells were oxidized as carbon support to promote efficient active sites. • Various catalysts were designed to meet different pH conditions for ORR. • Introducing phosphorus improved ORR performance and iron enhanced stability. • Phosphorus and iron synergistically facilitated excellent activity and stability in neutral. [ABSTRACT FROM AUTHOR]

Non-precious metal doped carbonaceous materials are currently the most promising alternative towards oxygen reduction reaction (ORR) electrocatalysts in terms of cost, accessibility, efficiency and durability. In this work, a simple one-step pyrolysis process was used for the synthesis of copper doped graphitic carbon nitride (Cu-g-C 3 N 4) as electrocatalyst. The as-synthesized Cu-g-C 3 N 4 material is displaying excellent electrocatalytic response towards ORR in alkaline medium. In comparison to commercial Pt/C catalyst, Cu-g-C 3 N 4 exhibits high methanol tolerance, long term stability, without compromising (4e−) electron transfer pathway process and attaining less than 4% H 2 O 2 formation. The enhanced electrocatalytic behaviour may be ascribed to the formation of active sites strongly coupled into the nitrogen-rich carbon matrix. Such a low-cost, extremely durable and stable electrocatalyst can therefore be regarded as an efficient cathodic material, which can be utilized for several renewable energy conversion technologies such as fuel cell, biofuel cell and metal-air battery. [ABSTRACT FROM AUTHOR]

Oxygen reduction reaction (ORR) is a core reaction of fuel cell and metal-air cell. In recent years, it has been a hot topic to study non-precious metal catalysts for ORR. Herein, we have used waste wine mash-derived carbon, melamine and ferric chloride to prepare a Fe- and N- co-doped carbon catalyst. The specific surface area of the catalyst is up to 1066.6 m2 g−1. And its wave potential is 15 mV higher than that of commercial Pt/C catalyst. The ORR on our catalyst followed a four-electron pathway; and it has high stability and high impressive immunity to methanol. After continuous oxygen reduction of 30,000s, the retention rate is 90%. • A N- and Fe-co-doped carbon material is prepared by waste wine mash. • ORR half wave potential of WA-Fe-N is 15 mV higher than that of the commercial 40% Pt/C. • N- and Fe-co-doped and activation treatments improve the electrocatalyst properties. • WA-Fe-N is a new type of low cost ORR catalyst for fuel cell and metal-air cell. [ABSTRACT FROM AUTHOR]

Metal-nitrogen/carbon (Me-N/C) coordination is the most alternative to Pt/C catalyst for oxygen reduction reaction (ORR). In this work, we utilized carbon nanotube (CNT) as carriers, synthesized Fe@CNT-Fe/N/C via high temperature. The Fe@CNT-Fe/N/C catalyst has a tubular structure, which can well coat the metal particles in the tube, protect the metal particles from corrosion by the acidic solution, and maintain the long-term effectiveness of the catalyst. Fe-Nx and Fe3C structures are the ORR active centers of the catalyst, and Fe-Nx and Fe3C coexist to promote the oxygen reduction reaction activity. The as-prepared catalyst possesses high ORR catalytic activity as well as good stability. [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]

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]

A simple approach towards preparation of non-noble metal electrocatalyst for oxygen reduction reaction in low temperature fuel cells has been necessity for a sustainable green technology. Herein, a cost-effective and facile method of preparation of TiC@N-doped graphene like carbon nanocomposite (TiC@NC) has been discussed. The composite structure of as-prepared TiC@NC was confirmed using structural analysis and morphological studies. Interestingly, the optimized TiC@NC(0.2)-800 electrocatalyst shows remarkable oxygen reduction reaction (ORR) kinetics with better onset potential +1.08 vs RHE and significant current density of 4.8 mA/cm2 in alkaline medium. Further, obtained catalyst exhibits four electron transfer mechanism similar to Pt-based electrocatalysts. Additionally, TiC@NC(0.2)-800 shows better mass activity (∼410 mA/mg) as compared to other compositions. Moreover, the single step kinetics mechanism has been seen due to lower (<5%) peroxide yield. The relatively lower charge transfer resistance at electrode/electrolyte interface of TiC@NC (0.2)-800 electrode supports for higher catalytic activity. Additionally, electrochemical cycling reveals the better stability by TiC@NC(0.2)-800 even after 10,000 cycles (10 mV negative shift in E 1/2) than that of state of art Pt/C catalyst (80 mV negative shift in E 1/2). The presence of N-doped carbon around TiC crystals is responsible for better electrocatalytic activity (due to optimal doping synergy), though the support of TiC makes the electrocatalyst more stable in nature (thanks to strong TiC-NC interactions). Additionally, TiC@NC(0.2)-800 does not show any response towards methanol oxidation reaction, annulling the cross-over effects. Hence, TiC@NC(0.2)-800 could be hopeful substitute for conventional Pt/C electrocatalyst for energy conversion. TiC@NC nanocomposite makes it a significant electrocatalyst for oxygen electroreduction. Image 1 • A simple and facile approach towards synthesis. • Enhanced electroreduction kinetics by titanium carbide and N-doped carbon interface. • Substantial higher E onset of +1.08 vs RHE with J L of 4.8 mA cm−2 under alkaline condition. • Optimized catalyst exhibits much better stability and methanol tolerance property than state-of-the-art Pt/C catalyst. [ABSTRACT FROM AUTHOR]

Design of high‐performance non‐Pt electrocatalyst for fuel cell applications is greatly anticipated. Herein, we have developed a unique half‐embedded and half‐exposed interfacial PdFeCu nanoalloy anchored onto carbon matrix. The stable electronic coupling between the carbon matrix and PdFeCu nanoalloy possess very fast interfacial electron transfer which in turn enhances the electron conductivity. This makes the trimetallic nanoalloy high performing oxygen reduction reaction (ORR) electrocatalyst in both basic and acidic media. The PdFeCu/C nanoalloy exhibits enhanced electrochemically active surface area than various PdFe/C bimetallics as well as benchmark 20 wt% Pt/C and Pd/C. As a result, it offers larger active sites for ORR and eased the electron transport during the electrocatalysis. It exhibits 1.5‐ and 2.4‐fold higher mass activity in comparison to the Pt/C and Pd/C. Furthermore, it exhibits long‐term stability and low onset potential compared to those of the other catalysts. Thus, the present investigation shows potential strategy for the design and synthesis of Pt‐free electrocatalyst with remarkable catalytic activity and stability. [ABSTRACT FROM AUTHOR]

It has been proposed previously that protic ionic liquids (PILs) such as diethylmethylammonium triflate could be used as the electrolytes in nonhumidified, intermediate temperature H2 fuel cells, potentially offering the prospect of high conductivity and performance, even under anhydrous conditions. In this contribution, a combination of electroanalytical chemistry and fuel-cell polarization analyses is used to demonstrate for the first time that the pure PILs cannot support proton shuttling between the electrodes of fuel cells. Only through the inclusion of dissolved acidic or basic proton shuttles can viable protic ionic fuel cells be fabricated, which has major consequences for the use of these neoteric electrolytes in fuel cells. [ABSTRACT FROM AUTHOR]

Hybrid faceted‐Ag3PO4/cube‐Cu2O composite materials have been fabricated and employed as oxygen reduction electrocatalysts for proton exchange membrane fuel cells (PEMFCs). The charge separation effect via the formation of PN junction has been demonstrated to boost the electrocatalysis toward oxygen reduction reaction. The as‐prepared rhombic dodecahedron‐Ag3PO4/cube‐Cu2O/C hybrid catalyst shows a mass‐specific activity of 109.80 mA/mgAg, which is about 6.4 times that of pure rhombic dodecahedron‐Ag3PO4/C catalyst (17.20 mA/mgAg). The density functional theory (DFT) calculation based on the density of states (DOS) further proved the optimal tunable effect, which is in pace with demonstration of electron transfer direction revealed by X‐ray photoelectron spectroscopy (XPS) analysis. Our work establishes a theoretical and practical basis for the rational design of newly non‐Pt hybrid catalysts, moreover, advances the future efficient application of PEMFCs. [ABSTRACT FROM AUTHOR]

Abstract Porous carbon materials (PCM) hold great promise for multifarious applications (like energy conversion and storage devices, biological applications, photo-catalysis etc.) owing to their outstanding properties such as high surface area, accessible active sites, mass transport, diffusion etc. Interestingly, they appear as futuristic substitutes to replace the conventional and economically unviable Pt-based electrocatalysts for the oxygen reduction reaction in Fuel cells. PCM synthesized using biomass-derived sources have some clear advantages, vis-a-vis. their abundance in nature, characteristic sustainability, economic viability and environmental friendliness. Also, no harsh chemicals are being used for their synthesis, and they inherently contain variety of heteroatoms (N, P, S etc.) vital for the electrocatalytic activity. This review article will help researchers gain an in-depth understanding of bio-waste sources and composition; synthesis methods and their dependence on various parameters; templating methods and vital information like role of dopants and transition metals in influencing electrocatalytic activity, and will result in enabling biomass based PCM as electrocatalysts in future energy devices. [ABSTRACT FROM AUTHOR]

In this paper, regarding outstanding electrocatalytic properties of metal organic frame works for fuel cell applications, we have synthesised and investigated comprehensively the elecrocatalytic stability of PCN-222 (PCN = porous coordination network) for the oxygen reduction reaction (ORR) in acidic media. ORR is a main reaction that take parts in cathodic part of a fuel cell and preparation of a stable and efficient electrocatalyst for this reaction will effectively improve the fuel cell output. The 3D heme-like metal organic framework (MOF) was constructed from Fe(III) porphyrin linkers and Zr6 clusters. The catalyst stability tests manifested that the PCN-222 is much more stable than the other metal macrocycles. The assembled PCN-222 catalyst possesses ultra stability, high activity and excellent tolerance to the crossover effect of methanol, which could be used as a unique alternative to common ORR catalysts in an acidic direct methanol fuel cell.Graphical Abstract: [ABSTRACT FROM AUTHOR]

Abstract Novel hierarchically porous titanium-metal organic frameworks/nitrogen-doped graphene (Ti-MOFs/NG) nanocomposite derived from titanium-metal organic frameworks (Ti-MOFs) and the nitrogen-doped graphene (NG) has been originally synthesized successfully. Notably, the Ti-MOFs/NG nanocomposite has been for the first time investigated in detail, as oxygen reduction reaction (ORR) catalyst of cathodic materials for fuel cells. The results show that the Ti-MOFs/NG nanocomposite possesses excellent ORR performances, whether in alkaline or acidic medium, due to existences of the Ti 3 N 2-x , C 2 O 7 Ti 2.3 , H 2 Ti 5 O 11 , Ti and TiO active ORR segments. Specifically, the onset potential (E 0) and the Tafel slope value of the Ti-MOFs/NG nanocomposite are 1.14 V and 17.84 mV dec−1 in 0.1 M HClO 4 , respectively. Similarly, high ORR efficiency of the Ti-MOFs/NG nanocomposite also exhibit in alkaline medium. The relative current density can still keep 99.88% of the original value after 10800 s measurements in 0.1 M KOH. Additionally, small electrochemical impedance and excellent tolerance toward fuel molecules have been exhibited in both electrolytes. These ORR properties are superior to those of most of previously reported materials derived from other MOFs, in both alkaline and acidic media. Thus, the Ti-MOFs/NG nanocomposite is as a novel promising candidate for ORR catalyst to solve the main problems of sluggish reaction kinetics of the ORR, high cost of precious metal catalysts and low durability of the traditional catalysts, applied to fuel cells, metal-air batteries and further to water splitting in energy conversion and storage devices. [ABSTRACT FROM AUTHOR]

Abstract Due to the depletion of fossil fuels and severe environmental pollution problems, the urgent demand for clean and sustainable energy sources is constantly emphasized. In recent decades, platinum (Pt)-based fuel cells have achieved tremendous advances as a green energy source, but there is still a need to further improve energy production efficiency in order to realize practical applications. Conventional Pt electrocatalysts are usually insufficient in catalytic activity and the selectivity of electrochemical reactions due to sluggish kinetics and surface poisoning. In contrast, metal alloy nanocatalysts exhibit exceptional electrocatalytic performance on fuel cells, more than pure Pt catalysts, owing to the synergistic effect by systematic modification of the surface geometry and electronic structure of the catalytically active metal component. This review provides overviews and advances in the applications of metal alloy nanohybrid particles enabling the improvement of electrocatalytic efficiency and discusses the challenges and outlooks in the fields of green energy production based on metal alloy nanocatalysts. Graphical abstract Synergistic effects (d -band shift, surface-lattice strain and surface-defects formation) of metal alloy nanocatalysts for the improvement of electrochemical activity. fx1 Highlights • Metal alloy nanocatalysts exhibit exceptional electrocatalytic activity on fuel cell. • Advances of metal alloy particles enhancing electrocatalytic activity are reviewed. • Outlooks in the field of fuel cell based on metal alloy nanocatalysts are discussed. [ABSTRACT FROM AUTHOR]

Abstract Solution combustion synthesis was used to prepare cobalt oxide nanoparticles at different fuel ratio (φ = 0.5, 1, and 1.75). The synthesized particles were characterized using XRD, SEM, TEM, FTIR and XPS to study the morphological and structural features. The fuel rich condition provides a reducing atmosphere limiting further oxidation of synthesized nanoparticles but produces more carbon residue on the catalyst surface compared to fuel lean conditions. Increasing the fuel ratio (φ value) from 0.5 to 1.75 increases the crystallite size and lowers the surface area. The electrocatalytic performance studies conducted by cyclic voltammetry (CV) and linear sweep voltammetry (LSV) indicate significant changes in catalytic activities due to variation in synthesis conditions. The LSV results obtained between potential of −1.2 V and 0.75 V shows all the three cobalt oxide catalysts to have bifunctional properties of being active for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), with Co synthesized at lower fuel ratio (φ = 0.5) displaying the highest current density. The onset potential for Co (φ = 0.5) is more positive than Co (φ = 1) and Co (φ = 1.75). The kinetic current density for Co (φ = 0.5) is 6.45 mA cm−2 and decreases with increase in fuel ratio. The OER current starts at ∼0.45 V for all the catalysts showing maximum density for Co (φ = 0.5) and gradually decreasing for catalysts synthesized at higher fuel ratio. Highlights • Cobalt oxide nanoparticles were synthesized using solution combustion synthesis. • Increasing the fuel ratio during synthesis leads to more reduced phase of cobalt oxide. • All the cobalt oxide catalysts are bi-functional, active for both oxygen reduction and oxygen evolution reactions. • Low fuel ratio during synthesis leads to better catalytic performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • The catalytic activity of a series of Ni-BC 3 NT has been theoretically explored in the ORR. • O 2 molecule can be directly dissociated on the Ni-BC 3 NT with 4e pathway. • It is reacting more favorable for the ER mechanism of OH* to convert into H 2 O. • The ORR reaction was found to be thermodynamically favorable in the Ni-BC 3 NT. One of the most significant types of electrocatalysts, especially for fuel cell applications, are those that undergo oxygen reduction reaction (ORR). These materials require more attention due to their considerable selectivity and superior activity towards efficient four-electron path (4e-). In present work, boron carbide nanotube (BC 3 NT) is identified as an ORR electrocatalyst via first-principles computations. Pristine BC 3 NT, neighboring positively charged B atoms over surface of material, does not have ability to supply an active site for dissociation of oxygen. While, ORR catalytic activity of BC 3 NT can be effectually improved under ligand effect due to nickel replacement, where partial over-potential was reachable and even comparative to platinum (1 1 1) or less, indicating it delivers extensively high ORR activity. It is expected present research supply outstanding option for ORR catalysis, and relevant investigations will open a novel window for designing high-performance ORR electrocatalysts to replace platinum-based catalysts. [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]