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[Display omitted] Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are essential for the development of excellent bifunctional electrocatalysts, which are key functions in clean energy production. The emphasis of this study lies in the rapid design and investigation of 153 MN 4 –graphene (Gra)/ MXene (M 2 NO) electrocatalysts for ORR/OER catalytic activity using machine learning (ML) and density functional theory (DFT). The DFT results indicated that CoN 4 –Gra/Ti 2 NO had both good ORR (0.37 V) and OER (0.30 V) overpotentials, while TiN 4 –Gra/M 2 NO and MN 4 –Gra/Cr 2 NO had high overpotentials. Our research further indicated orbital spin polarization and d-band centers far from the Fermi energy level, affecting the adsorption energy of oxygen-containing intermediates and thus reducing the catalytic activity. The ML results showed that the gradient boosting regression (GBR) model successfully predicted the overpotentials of the monofunctional catalysts RhN 4 –Gra/Ti 2 NO (ORR, 0.39 V) and RuN 4 –Gra/W 2 NO (OER, 0.45 V) as well as the overpotentials of the bifunctional catalyst RuN 4 –Gra/W 2 NO (ORR, 0.39 V; OER, 0.45 V). The symbolic regression (SR) algorithm was used to construct the overpotential descriptors without environmental variable features to accelerate the catalyst screening and shorten the trial-and-error costs from the source, providing a reliable theoretical basis for the experimental synthesis of MXene heterostructures. [ABSTRACT FROM AUTHOR]

[Display omitted] Lignin upgrading to various functional products is promising to realize high-value utilization of low-cost and renewable biomass waste, but is still in its infancy. Herein, using industry waste lignosulfonate as the biomass-based carbon source and urea as the dopant, we constructed a heteroatom-doped porous carbon nanosheet structure by a simple NaCl template-assisted pyrolytic strategy. Through the synergistic effect of the NaCl template and urea, the optimized lignin-derived porous carbon catalyst with high content of active nitrogen species and large specific surface area can be obtained. As a result, the fabricated catalysts exhibited excellent electrocatalytic oxygen reduction activity, as well as good methanol tolerance and stability, comparable to that of commercial Pt/C. Moreover, rechargeable Zn-air batteries assembled with this electrocatalyst have a peak power density of up to 150 mW cm-2 and prominent long-term cycling stability. This study offers an inexpensive and efficient way for the massive production of highly active metal-free catalysts from the plentiful, inexpensive and environmentally friendly lignin, offering a good direction for biomass waste recycling and utilization. [ABSTRACT FROM AUTHOR]

[Display omitted] • 2D GnP/MoS 2 and 3D (GnP/MoS 2)/MWNT composites are prepared by a facile, robust and ecofriendly method. • Effects of N-doping of GnPs and mass fraction of MWNTs on ORR activity are explored and rationalized. • Best synergistic ORR activity is obtained for N-doped catalyst with 3:1 2D-to-1D ratio. • Catalysts exhibit excellent stability and methanol resistance in alkaline medium. • Promising route to develop bifunctional ORR/OER catalysts. Nanocomposites have garnered attention for their potential as catalysts in electrochemical reactions vital for technologies like fuel cells, water splitting, and metal-air batteries. This work focuses on developing three-dimensional (3D) nanocomposites through aqueous phase exfoliation, non-covalent functionalization of building blocks with surfactants and polymers, and electrostatic interactions in solution leading to the nanocomposites assembly and organization. By combining molybdenum disulfide (MoS 2) layers with graphene nanoplatelets (GnPs) to form a binary 2D composite (MoS 2 /GnP), and subsequently incorporating multiwalled carbon nanotubes (MWNTs) to create ternary 3D composites, we explore their potential as catalysts for the oxygen reduction reaction (ORR) critical in fuel cells. Characterization techniques such as X-ray photoelectron spectroscopy, scanning electron microscopy, and X-ray diffraction elucidate material composition and structure. Our electrochemical studies reveal insights into the kinetics of the reactions and structure–activity relationships. Both the (MoS 2 /GnP)-to-MWNT mass ratio and nitrogen-doping of GnPs (N -GnPs) play a key role on the electrocatalytic ORR performance. Notably, the (MoS 2 / N -GnP)/MWNT material, with a 3:1 mass ratio, exhibits the most effective ORR activity. All catalysts demonstrate good long-term stability and methanol crossover tolerance. This facile fabrication method and observed trends offer avenues for optimizing composite electrocatalysts further. [ABSTRACT FROM AUTHOR]

In this study, Co/Ni‐NC catalyst with hetero‐diatomic Co/Ni active sites dispersed on nitrogen‐doped carbon matrix is synthesized via the controlled pyrolysis of ZIF‐8 containing Co2+ and Ni2+ compounds. Experimental characterizations and theoretical calculations reveal that Co and Ni are atomically and uniformly dispersed in pairs of CoN4‐NiN4 with an intersite distance ≈0.41 nm, and there is long‐range d–d coupling between Co and Ni with more electron delocalization for higher bifunctional activity. Besides, the in situ grown carbon nanotubes at the edges of the catalyst particles allow high electronic conductivity for electrocatalysis process. Electrochemical evaluations demonstrate the superior ORR and OER bifunctionality of Co/Ni‐NC catalyst with a narrow potential gap of only 0.691 V and long‐term durability, significantly prevailing over the single‐atom Co‐NC and Ni‐NC catalysts and the benchmark Pt/C and RuO2 catalysts. Co/Ni‐NC catalyzed Zn–air batteries achieve a high specific capacity of 771 mAh g−1 and a long continuous operation period up to 340 h with a small voltage gap of ≈0.65 V, also much superior to Pt/C‐RuO2. [ABSTRACT FROM AUTHOR]

The shortage and unevenness of fossil energy sources are affecting the development and progress of human civilization. The technology of efficiently converting material resources into energy for utilization and storage is attracting the attention of researchers. Environmentally friendly biomass materials are a treasure to drive the development of new‐generation energy sources. Electrochemical theory is used to efficiently convert the chemical energy of chemical substances into electrical energy. In recent years, significant progress has been made in the development of green and economical electrocatalysts for oxygen reduction reaction (ORR). Although many reviews have been reported around the application of biomass‐derived catalytically active carbon (CAC) catalysts in ORR, these reviews have only selected a single/partial topic (including synthesis and preparation of catalysts from different sources, structural optimization, or performance enhancement methods based on CAC catalysts, and application of biomass‐derived CACs) for discussion. There is no review that systematically addresses the latest progress in the synthesis, performance enhancement, and applications related to biomass‐derived CAC‐based oxygen reduction electrocatalysts synchronously. This review fills the gap by providing a timely and comprehensive review and summary from the following sections: the exposition of the basic catalytic principles of ORR, the summary of the chemical composition and structural properties of various types of biomass, the analysis of traditional and the latest popular biomass‐derived CAC synthesis methods and optimization strategies, and the summary of the practical applications of biomass‐derived CAC‐based oxidative reduction electrocatalysts. This review provides a comprehensive summary of the latest advances to provide research directions and design ideas for the development of catalyst synthesis/optimization and contributes to the industrialization of biomass‐derived CAC electrocatalysis and electric energy storage. [ABSTRACT FROM AUTHOR]

Low cathodic oxygen reduction reaction (ORR) efficiency is one of the important factors limiting the hydrogen fuel cells. Platinum can effectively reduce the ORR activation energy and improve the reaction rate; However, platinum's low reserves, versatility, and high price still limit its use in commercial, large-scale applications. It is very important to reduce the amount of Pt and improve the utilization rate and the stability of Pt-based catalyst. Here, an ultra-low Pt content catalyst Pt&Fe 2 O 3 /PM has been synthesized. The Pt content of the catalyst is only 4 wt%, and its nanoparticles are about 3 nm. Pt&Fe 2 O 3 /PM exhibit excellent ORR catalytic performance and longevity in acidic electrolyte. The ORR mechanism on Pt&Fe 2 O 3 /PM involves a direct four-electron path. The mass activity and specific activity of Pt&Fe 2 O 3 /PM is 4.8 and 10.3 times than that of commercial Pt/C, respectively. Furthermore, the catalyst's synthesis method is straightforward and amenable to scaling up, offering significant guidance for the creation of low-Pt catalysts. [Display omitted] • High dispersion low-Pt catalyst Pt&Fe 2 O 3 /PM was prepared by heat treatment. • The particle size of the Pt&Fe 2 O 3 /PM is ca. 3 nm, and the Pt content is ca. 4 wt%. • Pt&Fe 2 O 3 /PM has higher ORR activity and durability than commercial Pt/C. [ABSTRACT FROM AUTHOR]

Proton exchange membrane fuel cells (PEMFCs) and alkaline membrane fuel cells (AEMFCs) have received great attention as energy devices of the next generation. Accelerating oxygen reduction reaction (ORR) kinetics is the key to improve PEMFC and AEMFC performance. Platinum‐based catalysts are the most widely used catalysts for the ORR, but their high price and low abundance limit the commercialization of fuel cells. Non‐noble metal‐nitrogen‐carbon (M−N−C) is considered to be the most likely material class to replace Pt‐based catalysts, among which Fe−N−C and Co−N−C have been widely studied due to their excellent intrinsic ORR performance and have made great progress in the past decades. With the improvement of synthesis technology and a deeper understanding of the ORR mechanism, some reported Fe−N−C and Co−N−C catalysts have shown excellent ORR activity close to that of commercial Pt/C catalysts. Inspired by the progress, regulation strategies for Fe−N−C and Co−N−C catalysts are summarized in this Review from 5 perspectives: (1) coordinated atoms, (2) environmental heteroatoms and defects, (3) dual‐metal active sites, (4) metal‐based particle promoters, and (5) curved carbon layers. We also make suggestions on some challenges facing Fe−N−C and Co−N−C research. [ABSTRACT FROM AUTHOR]

Fe–N–C catalysts are emerging as promising alternatives to Pt‐based catalysts for the oxygen reduction reaction (ORR), while they still suffer from sluggish reaction kinetics due to the discontented binding affinity between the Fe‐N4 sites and oxygen‐containing intermediates, and unsatisfactory stability. Herein, a flexible multichannel carbon fiber membrane immobilized with atomically dispersed Fe‐N4 sites and neighboring Fe nanoclusters/nanoparticles (FeN4‐FeNCP@MCF) is synthesized. The optimized geometric and electronic structures of the Fe atomic sites brought by adjacent Fe nanoclusters/nanoparticles and hierarchically porous structure of the carbon matrix endow FeN4‐FeNCP@MCF with outstanding ORR activity and stability, considerably outperforming its counterpart with FeN4 sites only and the commercial Pt/C catalyst. Liquid and solid‐state flexible zinc–air batteries employing FeN4‐FeNCP@MCF both exhibit outstanding durability. Theoretical calculation reveals that the Fe nanoclusters can trigger remarkable electron redistribution of the FeN4 sites and modulate the hybridization of central Fe 3d and O 2p orbitals, facilitating the activation of O2 molecules and optimizing the adsorption capacity of oxygen‐containing intermediates on FeN4 sites, and thus accelerating the ORR kinetic. This work offers an effective approach to constructing coupling catalysts that have single atoms coexisting with nanoclusters/nanoparticles for efficient ORR catalysis. [ABSTRACT FROM AUTHOR]

Tuning the electrocatalytic selectivity and long‐term stability for industrially significant, yet reactively unfavorable products, remains a challenge in oxygen reduction. Herein, the Au/TiO2 catalysts with strong metal–support interactions (SMSI) are designed and synthesized through an in situ auto‐reduction of Au‐modified Ti‐MOF. Highly dispersed ultra‐low loading of Au NPs strongly capsulated in porous TiO2 substrate, together with conductive carbon derivated from MOFs, enables Au/TiO2 electrocatalysts to achieve excellent H2O2 electrosynthesis through the two‐electron oxygen reduction reaction (2e ORR). Au(1.0)/TiO2 (0.52 wt% Au loading) exhibited a high selectivity of 90%, a remarkable Faradaic efficiency of 98%, and 72.2 mg L−1 h−1 H2O2 production. Highly dispersed Au NPs promote active site exposure, while the conductive carbon and the porous superstructure enhance mass diffusion. Notably, the SMSI between Au NPs and TiO2 substrate leads to superb stability (over 168 h) of the electrocatalysts, as it ensures continuous electronic interactions. Experimental characterizations and density functional theory (DFT) simulations further revealed that the SMSI effect medicates the activation of the *OOH intermediate formation and the d‐band center, which are conductive to 2e ORR. Moreover, this strategy provides a potential way toward high‐performance electrocatalysts in flow system devices for continuously purifying sewage and chemical bleaching in extreme environments. [ABSTRACT FROM AUTHOR]

The oxygen reduction reaction (ORR) in neutral media is of great importance due to its potential to optimize energy generation and storage application. With the increasing urgency for sustainable and efficient energy solutions, comprehensively understanding and enhancing ORR performance in such media have become crucial. This review aims to shed light on this critical yet challenging area. This review encapsulates the fundamental principle of ORR and the latest breakthrough in the field of electrocatalysts, with a distinct focus on innovative synthesis strategies for creating novel, efficient, and robust electrocatalysts. A succinct evaluation of the strengths, limitations, performance, and reaction mechanism is presented. The essential findings are analyzed and their implications for future research directions. Finally, an outlook on current advances, challenges, and future research recommendations is provided. This review serves as a stepping‐stone toward harnessing the underutilizing energy potential within the extensive aquatic environment. [ABSTRACT FROM AUTHOR]

Due to structural complexity and limited understanding, precise chemical modification in atomically dispersed metal-nitrogen-carbon (M-N-C) catalysts requires theoretical calculations to optimize electronic, geometric, and catalytic performance and experimental implementation of learned lessons to improve their catalytic performance towards oxygen reduction reaction (ORR). Herein, we conducted a density functional theory (DFT) investigation to understand the effect of the replacement of O-atoms in Fe–O 4 –C by N-atoms in the first coordination shell of Fe-site (constructing five models: Fe–O 4 –C, Fe–O 3 N–C, Fe–N 2 O 2 –C, Fe–ON 3 –C and Fe–N 4 –C) towards ORR. The geometric and electronic calculations of these models suggested that replacing all the O-atoms with N-atoms around the Fe-site would make it more conducive to the adsorption of ORR intermediates. Moreover, the Gibbs free energy calculations demonstrated that the Fe-site becomes the active centre for 2e− ORR, leading to the dominant generation of H 2 O 2 when Fe is coordinated with four O-atoms (Fe–O 4 –C). Whereas in compounds like Fe–N 2 O 2 –C, Fe–O 3 N–C, and Fe–N 4 –C, where the Fe-site displays 4e− ORR, form water is a preferred product if the O-atoms are replaced by N-atoms, as in Fe–N 2 O 2 –C, Fe–O 3 N–C, and Fe–N 4 –C. This study would provide a fundamental understanding of how atomically dispersed M-N-C catalysts' electrocatalytic activity is affected by changes in the coordination environment of metal sites. [Display omitted] • A theoretical approach was used to construct the models of Fe-NxOy-C-based electrocatalysts. • The models Fe–O 4 –C, Fe–NO 3 –C, M–N 2 O 2 –C, M–N 3 O–C, and M-N4-C, were completely investigated via DFT approaches. • The O 2 adsorption at the Fe–N 4 –C catalyst was the determining step during the associative pathway. • The M-N 4 -C catalytic moel displayed 4e- ORR, while the M-O 4 -C catalyst showed 2e- ORR. [ABSTRACT FROM AUTHOR]

Facile synthesis of highly-dispersed Pt-based electrocatalysts on porous carbon supports with strong durability is extremely desirable for oxygen reduction reaction but remains challenging. The influence of pores in carbon supports on the stability and activity of catalysts is ambiguous and needs to be elucidated. Targeting this aim, herein, we prepared a series of carbon nanofibers with tunable pore diameter and specific surface area using the resorcinol-formaldehyde (RF) resins as a model system. Homogeneous composite precursors composed of RF resins and silica colloids were synthesized by the surfactant-assisted simultaneous polycondensation of RF resins and tetraethylorthosilicate (TEOS). The diameter of the pores induced by removal of silica could be controllable tailored through thermal treatment of the composite under various target temperatures. Pt 3 Co alloy nanoparticles loaded on the as-synthesized porous carbon nanofibers were prepared by an optimized wet-impregnation method. The experimental results indicated that the carbon nanofibers with pore size distribution focused on ∼1.27 nm and ∼2.34 nm provided the best stability without limiting current density decay, and negative shift of half-wave potential (E 1/2) and mass activity (MA) loss of Pt after 20000 potential cycles are relatively mild. Conversely, negative shift of 21 mV, 15 mV and 22 mV in E 1/2 and mass activity loss of 51.8%, 30.2% and 33.0% were observed for the Pt 3 Co nanoparticles supported on MC-60, MC-100 and MC-140 matrices which have pore size distribution focused on ∼2.73 nm, ∼2.73 nm as well as ∼4.66 nm, and ∼4.66 nm, respectively. This work demonstrates the importance of micropores and small mesopores for activity and long-term stability enhancement of carbon supported Pt-based electrocatalysts. Porous carbon nanofibers with tunable pore size distribution were synthesized by combining the surfactant-assisted simultaneous polycondensation of resorcinol-formaldehyde resins and TEOS with elaborate designed thermal treatment. Pt 3 Co nanoparticles loaded on the carbon with pore size distribution focuses on ∼1.27 nm and ∼2.34 nm provided the highest activity and best stability with no performance decay for ORR after 20000 potential cycles. [Display omitted] • Composite fibers of RF resins and Silica were synthesized by the developed surfactant-assisted polycondensation strategy. • Diameters of the mesopores in the synthesized carbon fibers could be controllable tuned. • Mesopores with diameter of ∼2.34 nm are efficient for boosting the stability of the carbon supported Pt 3 Co for the ORR. [ABSTRACT FROM AUTHOR]

[Display omitted] Fe N C single atom catalysts (SACs) have attracted great interest due to their highly active FeN 4 sites. However, the pyrolysis treatment often leads to inevitable metal migration and aggregation, which reduces the catalytic activity. Moreover, due to the Fenton reaction caused by Fe N C in alkaline and acidic solutions, the presence of Fe and peroxide in electrodes may generate free radicals, resulting in serious degradation of the organic ionomer and the membrane. Herein, we report an original strategy of introducing Co single atoms into Fe N C catalysts, forming atomically dispersed bimetallic active sites (Fe Co NC) and improving the activity and stability of the catalyst. Benefiting from this strategy, Fe Co NC catalyst exhibits excellent oxygen reduction reaction (ORR) activity in alkaline media (E 1/2 = 0.88 V) and in acidic media (E 1/2 = 0.77 V). As the cathode of Zn-air battery (ZAB), Fe Co NC shows an excellent peak power density of 142.8 mW cm−2 and a specific capacity of 806.6 mAh/g Zn. This work provides a novel avenue to optimize and enhance the ORR performance of atomic dispersed Fe N C catalysts. [ABSTRACT FROM AUTHOR]

In order to study the oxygen reduction activity（ORR） of Fe/Co/Ni-N doped graphenes, the influences of single metal atom and nitrogen co-doping on ORR activity of graphene were compared. The Fe/Co/Ni-N doped graphene models were established using Materials Studio, and then oxygen molecules were adsorbed respectively on the surfaces of Fe/Co/Ni-N doped graphene models. CASTEP module was used to optimize the structure of the model and simulation calculation. The adsorption energies, desorption energies and conductivities of Fe/Co/Ni-N doped graphenes were analyzed. Based on the simulation results, it is found that the ORR activity of Fe doped graphene is better than that of Co or Ni doped graphene when graphene is doped with single metal atom. As graphene is Co-doped with single metal atom and nitrogen, the ORR activity of Fe-N doped graphene is better than that of Co-N or Ni-N doped graphene, and the ORR activity of M-N4-G was better than those of M-N1-G M-N2-G and M-N3-G. [ABSTRACT FROM AUTHOR]

The insufficient durability of Pt‐based catalysts and the sluggish kinetics of oxygen reduction reaction (ORR) is hampering the development of proton exchange membrane fuel cells (PEMFCs) for commercialization. Herein, a single atom Ti‐modified activated nitrogen‐doped porous carbon (Ti‐a‐NPC) is designed to equalize O2‐activation/*OH‐removal through regulating the charge rearrangement of ultra‐small L12‐Pt3Co for efficient and durable oxygen reduction. The Ti single‐atom modified in the surface/pore of Ti‐a‐NPC can anchor the Pt‐based intermetallic nanoparticles (NPs) not only guarantees Pt‐based intermetallics’ ultra‐fine size (≈2.62 nm) but also maintains Pt‐based intermetallics during ORR process. The enhanced catalyst (L12‐Pt3Co/Ti‐a‐NPC) achieves 11‐fold mass activity (1.765 A mgPt−1) compared to commercial Pt/C. Notably, after 30 000 cycles of accelerated durability tests, the mass activity of the L12‐Pt3Co/Ti‐a‐NPC only decreased by 3.7%, while that of commercial Pt/C decreased by 37.1%. Rationalized by theoretical simulation, the introduction of Ti atoms can form charge channels between L12‐Pt3Co NPs and Ti‐a‐NPC, accelerating the charge transfer in the ORR process. Furthermore, the charge of L12‐Pt3Co will accumulate to Ti atoms and buffer the electron transfer of L12‐Pt3Co to the N atoms, thus optimizing the adsorption performance of the active site to the oxygen‐containing intermediate and improving the intrinsic activity of the catalyst. [ABSTRACT FROM AUTHOR]

In this paper, a new design principle for bimetallic catalysts is proposed by combining strongly adsorbed atoms (SAA) with weakly adsorbed atoms (WAA) where the SAA and WAA are classified by the free adsorption energy of oxygen-containing intermediates on the metal atom. And the ORR performances of the bimetallic catalysts designed by the method are compared with the common single metal atom catalysts. The method is successfully confirmed as the overpotential of the Mn-based bimetallic catalysts decreases from 0.63 V in G-MnN 4 to as low as 0.33 V, and that of the Fe-based bimetallic catalysts decreases from 0.76 V in G-FeN 4 to 0.23 V. In addition, the correlation between adsorption free energy and adsorption bond length is revealed for the first time, and the optimal adsorption bond length is determined. Finally, the adsorption energy of O 2 is plotted versus the free adsorption energy of three oxygen-containing intermediates for the first time, and a suitable adsorption energy of O 2 is found to be -1.4∼-1.0 eV. These findings provide a new perspective for the design of high-performance bimetallic catalysts. • Catalysts obtained by combining strongly adsorbed atoms with weakly adsorbed atoms show superior performance. • Correlation between adsorption free energy and adsorption bond length is revealed for the first time. • Adsorption energy of O 2 can be used as a descriptor of ORR performance. • ORR performance is related to the energy difference of hybridization between metal atom and adsorbed species. [ABSTRACT FROM AUTHOR]

Shifting from the typical 4e– pathway to H2O in electrochemical oxygen reduction to the 2e– pathway to H2O2 is increasingly recognized as an environmentally friendly approach for producing H2O2. However, the competitive 4e− pathway is a significant obstacle to the production of H2O2 since H2O is the thermodynamically favored product. Here, a series of Pt, Pd, and Rh active atoms diluted within inert‐Au matrices with precisely controlled atomic arrangements and coordination environments are synthesized via facet engineering for O2‐to‐H2O2 production. Surprisingly, individually dispersed Pt atoms within the Au surface enclosed by the square atomic arrangements exhibit superior H2O2 selectivity and achieve a maximum selectivity of 90% at 0.36 V versus the reversible hydrogen electrode. Operando synchrotron ambient pressure X‐ray photoelectron spectroscopy identifies the presence of *OOH key intermediates on these isolated Pt active sites. Grand canonical density‐functional theory also reveals that the kinetic energy barrier for the 2e− pathway (0.08 eV; OOH* + H+ + e− → H2O2) on the isolated Pt sites is significantly lower than the 4e− pathway (0.29 eV; OOH* + H+ + e− → O* + H2O). This work enables atomic‐scale control in dilute binary alloy surfaces with specific configurations of isolated active atoms and provides essential guidance for catalyst design to boost O2‐to‐H2O2 production. [ABSTRACT FROM AUTHOR]

Iron‐nitrogen‐carbon (Fe‐N‐C) single‐atom catalysts are promising sustainable alternatives to the costly and scarce platinum (Pt) to catalyze the oxygen reduction reactions (ORR) at the cathode of proton exchange membrane fuel cells (PEMFCs). However, Fe‐N‐C cathodes for PEMFC are made thicker than Pt/C ones, in order to compensate for the lower intrinsic ORR activity and site density of Fe‐N‐C materials. The thick electrodes are bound with mass transport issues that limit their performance at high current densities, especially in H2/air PEMFCs. Practical Fe‐N‐C electrodes must combine high intrinsic ORR activity, high site density, and fast mass transport. Herein, it has achieved an improved combination of these properties with a Fe‐N‐C catalyst prepared via a two‐step synthesis approach, constructing first a porous zinc‐nitrogen‐carbon (Zn‐N‐C) substrate, followed by transmetallating Zn by Fe via chemical vapor deposition. A cathode comprising this Fe‐N‐C catalyst has exhibited a maximum power density of 0.53 W cm−2 in H2/air PEMFC at 80 °C. The improved power density is associated with the hierarchical porosity of the Zn‐N‐C substrate of this work, which is achieved by epitaxial growth of ZIF‐8 onto g‐C3N4, leading to a micro‐mesoporous substrate. [ABSTRACT FROM AUTHOR]

Isolated dual‐atom catalysts (DACs) have sparked enormous research enthusiasm in new energy community due to their great potentials to substitute the state‐of‐the‐art Pt‐based catalysts. Nevertheless, explicitly unraveling the underlying catalytic mechanisms is of critical significance for performance enhancement, yet remains a huge challenge. Herein, the study reports a reliable hard template‐mediated strategy to accomplish the construction of atomically isolated binuclear Co2‐N6 sites stabilized by ultrathin hollow carbon nanospheres (abbreviated as Co2‐DAs@CHNSs). Systematic spectroscopy characterization and theoretic calculations uncover that the Co2‐N6 sites follow a self‐adjusting mechanism caused by the intrinsic OH intermediate. The involvement of the ‐OH energy‐level modifier is found to induce the electron redistribution and alternation of antibonding orbital fillings for the generated Co2‐N6‐OH site, leading to reduced potential‐determining step (PDS) energy barrier, and thus boosted intrinsic activity. Consequently, the well‐managed Co2‐DAs@CHNSs afford outstanding oxygen reduction reaction (ORR) activity with a half‐wave potential of 0.87 V in alkaline electrolyte, overmatching the Pt benchmark. Furthermore, the Co2‐DAs@CHNSs‐assembled aqueous and all‐solid‐state rechargeable zinc–air batteries (ZABs) demonstrate high power density, large specific capacity, and robust stability. The findings offer an innovative avenue to rationally manipulate the electronic structures of active sites for DACs via a powerful self‐ligand modification strategy. [ABSTRACT FROM AUTHOR]

Doping–dedoping chemistry lays the cornerstone for converting heteroatom dopants into intrinsic defects as the emerging active sites of carbon catalysts, but the defect content is yet hindered by inadequate doping efficiencies. Comprehending crucial factors behind the doping of pristine carbon and their correlation to the catalytic properties of dedoped carbon is thus of high significance. Here, the overlooked impact of native defects in pristine carbon on dopant‐mediated defect engineering of carbon catalysts is explicitly unveiled. Intact fullerene (C60), C60‐derived carbon, and carbon black in distinct pentagon/edge defect states are employed as respective precursors to undergo a nitrogen doping–dedoping treatment. Theoretical and experimental evidence consistently indicates that native pentagons change the preferred N doping site from the edge to the basal plane, leading to a substantially higher doping level. Importantly, in addition to pentagons from the removal of zigzag‐edged pyridinic N, N dopants in in‐plane pentagons are more easily dedoped than those in hexagons, generating even more pentagons in a new pentagon–heptagon–pentagon structure as oxygen reduction active sites. The optimized defect‐rich carbon gives an outstanding half‐wave potential of 0.834 V (0.846 V for Pt/C) via the four‐electron pathway, excellent long‐term durability, and prospective applicability in zinc–air batteries. [ABSTRACT FROM AUTHOR]

Recent years have witnessed great research interests in developing high‐performance electrocatalysts for the two‐electron (2e−) oxygen reduction reaction (ORR) that enables the sustainable and flexible synthesis of H2O2. Carbon‐based electrocatalysts exhibit attractive catalytic performance for the 2e− ORR, where oxygen‐containing functional groups (OFGs) play a decisive role. However, current understanding is far from adequate, and the contribution of OFGs to the catalytic performance remains controversial. Therefore, a critical overview on OFGs in carbon‐based electrocatalysts toward the 2e− ORR is highly desirable. Herein, we go over the methods for constructing OFGs in carbon including chemical oxidation, electrochemical oxidation, and precursor inheritance. Then we review the roles of OFGs in activating carbon toward the 2e− ORR, focusing on the intrinsic activity of different OFGs and the interplay between OFGs and metal species or defects. At last, we discuss the reasons for inconsistencies among different studies, and personal perspectives on the future development in this field are provided. The results provide insights into the origin of high catalytic activity and selectivity of carbon‐based electrocatalysts toward the 2e− ORR and would provide theoretical foundations for the future development in this field. [ABSTRACT FROM AUTHOR]

S‐scheme heterojunction has emerging as a new star in the field of photocatalysis, attributing to its superior separation of photogenerated charge carriers and strong redox abilities. The general designing criteria and several types of S‐scheme heterojunction were provided. Advanced characterization techniques, including Kelvin probe force microscopy, electron paramagnetic resonance spectroscopy, and in‐situ irradiated X‐ray photoelectron spectroscopy, were presented for disclosing the transfer mechanism in S‐scheme heterojunctions. The recent innovations in the application of photocatalytic oxygen reduction reaction in S‐scheme heterojunction based polymeric carbon nitride photocatalyst were discussed. To conclude, this concept highlights the role of S‐scheme heterojunction in photocatalysis and gives future perspectives on their further applications. [ABSTRACT FROM AUTHOR]

This article presents results about the catalytic activity of the cathode in a Direct Methanol Fuel Cell (DMFC) across various operating temperatures. The Dynamic Electrochemical Impedance Spectroscopy (DEIS) technique coupled with a linear current scan was applied for this purpose. An equivalent model based on the thin-film flooded agglomerate model describing the cathode's behaviour was presented, and changes in its parameters were compared with the current load and different temperatures. Studies reveal shifts in cathodic kinetics with increasing load and temperature, alongside changes in resistance curves' slopes. The study identifies 351 K as the most optimal temperature, impacting parameters such as carbon layer resistance, diffusion parameter 1/Yo, and double electric layer capacitance significantly. Differences in slopes of resistance changes for different temperatures were also observed. • Simultaneous impedance measurement of the cathode in a direct methanol fuel cell during changing current density loads. • Obtain changes in the cathode behaviour at different working temperatures. • Slope changes of the polarization resistance curves during an increase in current load for the oxygen reduction reaction. • Obtained polarization resistance values for platinum and carbon support. [ABSTRACT FROM AUTHOR]

A Platinum-based graphene nanosheet electrocatalyst (Pt/GNS) was modified by changing its surface chemical composition (or functionalization), using citric acid via solid state method. The physical characterizations were orderly carried out by Raman spectroscopy, Fourier transform infrared spectroscopy, thermo-gravimetric analysis,X-ray powder diffraction, field emission scanning electron microscope, and transmission electron microscope. Electrocatalytic activity concerningto oxygen reduction reaction (ORR) of the synthesized catalyst was measured using a rotating disk electrode coupled with potentiostat/galvanostatinalkaline (0.1 M KOH) solution, and the performance was compared to conventional Pt/C catalyst. The developed electrocatalyst holds superior electrocatalytic properties compared to the unfunctionalized catalyst and Pt/C. Functionalized Pt/GNS exhibited better oxygen reduction activity of (0.86 V half-wave potential) and demonstrated 3.9 e− transfer against a single oxygen molecule. After 10,000 potential cycles of stability performance, the developed electrocatalyst showed remarkable durability. • Pt anchored graphene nanosheets were employed as electrocatalyst for ORR. • Pt/GNS was functionalized by using citric acid via the solid state method. • Pt/GNS showed improved electrocatalytic activity for ORR. • Pt/GNS showed the long-term stability towards ORR activity. [ABSTRACT FROM AUTHOR]

Carbon nanomaterials doped with N and B could activate nearby carbon atoms to promote charge polarization through the synergistic coupling effect between N and B atoms, thus facilitating adsorption of O2 and weakening O−O bond to enhance oxygen reduction reaction. Herein, a simple and controllable self‐assembly strategy is applied to synthesize porous B, N co‐doped carbon‐based catalysts (BCN‐P), which employs the macrocyclic molecule cucurbit[7]uril (CB7) as nitrogen source, and 3D aromatic‐like closo‐[B12H12]2− as boron source. In addition, polystyrene microspheres are added to help introduce porous structure to expose more active sites. Benefitting from porous structures and the synergistic coupling effect between N and B atoms, BCN‐P has a high onset potential (Eonset=0.846 V) and half‐wave potential (E1/2=0.74 V) in alkaline media. The zinc‐air battery assembled with BCN‐P shows high operating voltage (1.42 V), peak power density (128.7 mW cm−2) and stable charge/discharge cycles, which is even comparable with Pt/C. [ABSTRACT FROM AUTHOR]

Designing effective electrocatalysts tailored for targeted reactions requires fundamental insights into the structure dependence of the reaction microenvironment. Herein, inspired by finite element simulations, N,O co‐doped carbon nanosheets featuring a hierarchical micro/mesoporous structure to form an oxygen‐rich and local alkaline‐like microenvironment for the two‐electron oxygen reduction reaction (2e− ORR) in a neutral medium are designed. The in situ and ex situ test results confirmed that the micro/mesoporous carbon architecture can elevate the local pH and accelerate the generation of intermediates (*O2, *OOH), leading to high‐efficiency H2O2 production. Utilizing this favorable microenvironment, N,O‐CNS0.5 demonstrated exceptional H2O2 electrosynthesis performance in neutral media, achieving a superior H2O2 yield rate (6705 mmol gcatalyst−1 h−1 in a flow cell). Additionally, comparative experiments and density‐functional theory calculations provided confirmation of the bi‐doping of N and O as the active origin responsible for the electrochemical 2e− ORR. This study synergistically manipulates the reaction microenvironment and active sites, providing an opportunity for efficient H2O2 electro‐production in a neutral medium. [ABSTRACT FROM AUTHOR]

Electrochemical oxygen reduction reaction (ORR) via the 2e− pathway in an acidic media shows great techno-economic potential for the production of hydrogen peroxide. Currently, carbon-based single-atom catalysts (C-SACs) have attracted extensive attention due to their tunable electronic structures, low cost, and sufficient stability in acidic media. This review summarizes recent advances in metal centers and their coordination environment in C-SACs for 2e−-ORR. Firstly, the reaction mechanism of 2e−-ORR on the active sites of C-SACs is systematically presented. Secondly, the structural regulation strategies for the active sites of 2e−-ORR are further summarized, including the metal active center, its species and configurations of nitrogen coordination or heteroatom coordination, and their near functional groups or substitute groups, which would provide available and proper ideas for developing superior acidic 2e−-ORR electrocatalysts of C-SACs. Finally, we propose the current challenges and future opportunities regarding the acidic 2e−-ORR pathway on C-SACs, which will eventually accelerate the development of the distributed H2O2 electrosynthesis process. [ABSTRACT FROM AUTHOR]

[Display omitted] The zinc-air battery (ZAB) performance and stability strongly depend on the structure of bifunctional electrocatalyst for oxygen reduction/evolution reaction (ORR/OER). In this work, we combine the tip and heterogeneous effects to construct cobalt/cobalt oxide heterostructure nanoarrays (Co/CoO-NAs). Due to the formed heterostructure, more oxygen vacancies are found for Co/CoO-NAs resulting in a 1.4-fold higher ORR intrinsic activity than commercial carbon supported platinum electrocatalyst (Pt/C) at 0.8 V versus reversible hydrogen electrode (vs. RHE). Moreover, a fast surface reconstruction is observed for Co/CoO-NAs during OER catalysis evidenced by in-situ electrochemical impedance spectroscopy and Raman tests. In addition, the tip effect efficiently lowers the mass transfer resistance triggering a low overpotential of 347 mV at 200 mA cm−2 for Co/CoO-NAs. The strong electronic interplay between cobalt (Co) and cobalt oxide (CoO) contributes to a stable battery performance during 1200 h galvanostatic charge–discharge test at 5 mA cm−2. This work offers a new avenue to construct high-performance and stable oxygen electrocatalyst for rechargeable ZAB. [ABSTRACT FROM AUTHOR]

[Display omitted] • The FeCoNiMnV HEA/ N -CNTs catalyst was prepared by a one-step pyrolysis. • The multi-metal synergy favored the ORR catalytic performance. • Clustered N -CNTs had rich shared boundaries and interstitial space to expedite the charge/mass transfer. • The built battery showed high OCV, large power density and long-term durability. Efficient and stable oxygen reduction reaction (ORR) catalysts are essential for constructing reliable energy conversion and storage devices. Herein, we prepared noble metal-free FeCoNiMnV high-entropy alloy supported on nitrogen-doped carbon nanotubes (FeCoNiMnV HEA/ N -CNTs) by a one-step pyrolysis at 800 °C, as certificated by a set of characterizations. The graphitization degree of the N -CHTs was optimized by tuning the pyrolysis temperature in the control groups. The resultant catalyst greatly enhanced the ORR characteristics in the alkaline media, showing the positive onset potential (E onset) of 0.99 V and half-wave potential (E 1/2) of 0.85 V. More importantly, the above FeCoNiMnV HEA/ N -CNTs assembled Zn-air battery exhibited a greater open-circuit voltage (1.482 V), larger power density (185.12 mW cm−2), and outstanding cycle stability (1698 cycles, 566 h). This study provides some valuable insights on developing sustainable ORR catalysts in Zn-air batteries. [ABSTRACT FROM AUTHOR]

A Fe-Co dual-metal co-doped N containing the carbon composite (FeCo-HNC) was prepared by adjusting the ratio of iron to cobalt as well as the pyrolysis temperature with the assistance of functionalized silica template. Fe1Co-HNC, which was formed with 1D carbon nanotubes and 2D carbon nanosheets including a rich mesoporous structure, exhibited outstanding oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalytic activities. The ORR half-wave potential is 0.86 V (vs. reversible hydrogen electrode, RHE), and the OER overpotential is 0.76 V at 10 mA cm−2 with the Fe1Co-HNC catalyst. It also displayed superior performance in zinc–air batteries. This method provides a promising strategy for the fabrication of efficient transition metal-based carbon catalysts. [ABSTRACT FROM AUTHOR]

Significant advancements in the activity of nitrogen‐coordinated iron single‐atom catalysts (Fe–N–C) have attracted attention as potential alternatives to Pt‐based cathodes in proton exchange membrane fuel cells. However, their limited stability in acidic environments hinders their practical application. Moreover, achieving a synchronous enhancement of both the activity and stability of the Fe sites while preventing demetallation or carbon corrosion remains a formidable challenge. Herein, a synthesis method for Fe–N–C is introduced that exhibits remarkable durability, featuring a protective carbon encapsulation formed by applying an additional heterocyclic organic compound coating. It is demonstrated that stability can be enhanced by converting edge‐rich Fe sites into highly stable FeN4 moieties through precise control of the robustness and packing density of the carbon encapsulation. Furthermore, electrochemical redox behavior along with in situ spectroscopies and online differential electrochemical mass spectrometry provide insights into the structural characteristics of each Fe site and their stabilities. The accelerated stress testing and a long‐term test (>100 h) exhibit that the robust carbon encapsulation can successfully prevent corrosion of carbon support and ensure durable Fe sites during operation. [ABSTRACT FROM AUTHOR]

The main group metals are commonly perceived as catalytically inert in the context of oxygen reduction reactions (ORR) due to the delocalized valence orbitals. Regulating the local environment and structure of metal center coordinated by nitrogen ligands (M‐Nx) is a promising approach to accelerate catalytic dynamics. Herein, we, for the first time, report the atomically dispersed Al catalysts coordinated with N and C atoms for 4‐electron ORR. The axial coordinated pyrrolyl N group (No) is constructed in the Al‐N4‐No moiety to regulate the p‐band structure of Al center, effectively steering the local environment and structure of the square planar Al‐N4 sites, which typically exhibit too strong interaction with ORR intermediates. The dynamic covalency competition of axial Al‐No and Al‐O bonding could endow the Al center with moderate hybridization between Al 3p orbital and O 2p orbital, alleviating the binding energy of ORR intermediates. The as‐prepared Al‐N4‐No electrocatalyst exhibits excellent ORR activity, selectivity, and durability, along with the rapid kinetics as demonstrated by in situ Raman spectroscopy. This work offers a fundamental comprehension of the fine regulation on p‐band and guides the rational design of main‐group metal‐based single atom catalysts. [ABSTRACT FROM AUTHOR]

The main group metals are commonly perceived as catalytically inert in the context of oxygen reduction reactions (ORR) due to the delocalized valence orbitals. Regulating the local environment and structure of metal center coordinated by nitrogen ligands (M‐Nx) is a promising approach to accelerate catalytic dynamics. Herein, we, for the first time, report the atomically dispersed Al catalysts coordinated with N and C atoms for 4‐electron ORR. The axial coordinated pyrrolyl N group (No) is constructed in the Al‐N4‐No moiety to regulate the p‐band structure of Al center, effectively steering the local environment and structure of the square planar Al‐N4 sites, which typically exhibit too strong interaction with ORR intermediates. The dynamic covalency competition of axial Al‐No and Al‐O bonding could endow the Al center with moderate hybridization between Al 3p orbital and O 2p orbital, alleviating the binding energy of ORR intermediates. The as‐prepared Al‐N4‐No electrocatalyst exhibits excellent ORR activity, selectivity, and durability, along with the rapid kinetics as demonstrated by in situ Raman spectroscopy. This work offers a fundamental comprehension of the fine regulation on p‐band and guides the rational design of main‐group metal‐based single atom catalysts. [ABSTRACT FROM AUTHOR]

The oxygen reduction reaction (ORR) represents a cornerstone for many clean energy conversion technologies such as fuel cells and metal‐air batteries. Nevertheless, the commercialization of these technologies is largely impeded by the slow kinetics of ORR, for which active, durable and cost‐effective ORR catalysts are needed. In recent years, zeolitic imidazolate framework (ZIF) derived carbon materials emerge as a new class of non‐precious metal catalysts (NPMCs) toward ORR, largely benefiting from their high surface area, abundant porosity, tunable chemical/electronic structure, and superior ORR activity which is comparable or even surpasses those state‐of‐the‐art Pt‐based ORR catalysts. This review offers a comprehensive overview of the recent advances in ZIF‐derived carbons for ORR. The synthesis strategies and the key factors affecting the ORR performance of ZIF‐derived carbon materials are discussed. Future research directions and perspectives on exploring ZIF derived carbons as efficient ORR catalysts are highlighted, with a focus on the principles of rationally engineering the coordination structures of active sites. [ABSTRACT FROM AUTHOR]

Microwave heating provides a rapid method for the heterogeneous nucleation of noble metal particles on perovskite support materials for electrocatalytic purposes. To succeed, dielectric tuning of perovskite materials becomes fundamental. Herein, the dielectric engineering of the BaMnO3 perovskite system is carried out through the use of B‐site doping to give BaTi0.5Mn0.5O3. Using a combination of atomic‐scale imaging and electron energy loss spectroscopy (EELS), the preferential filling of the M1 and M3 B‐sites with Mn and Ti ions in the 12R‐rhombohedral perovskite structure is established. While the addition of Ti in the BaMnO3 system has no detrimental effects on the presence of the oxygen reduction reaction (ORR) active Mn3+ states at the surface, it does alter the dielectric constant and loss tangent, thus facilitating the heterogeneous nucleation of Pt nanoparticles on BaTi0.5Mn0.5O3 via rapid microwave heating. Higher Pt loading regimes are found to increase the size and aggregation of the nucleated particles, thus reducing their ORR activity. Therefore, lower Pt loading not only reduces costs but improves overall activity. This work represents future possibilities for the dielectric engineering of perovskite and similar support materials to aid in the quick and easy formation of stable noble metal‐support catalytic systems. [ABSTRACT FROM AUTHOR]

Modulating of electronic structure of photocatalyst and integration of dual channel pathway are promising strategy for efficient photosynthesis of hydrogen peroxide (H2O2) from pure water without sacrificial agent and oxygen exposure. In this work, nontoxic aromatic dialdehyde is used to replace the commonly used toxic formaldehyde to form resorcinol‐phthalaldehyde resins through a hydrothermal method. The introducing of aromatic ring as π spacer increases the separation distance of electrons and holes to avoid their recombination. H2O2 can be produced via integrated oxygen reduction reaction (ORR) and water oxidation reaction (WOR) due to the suitable energy band positions and spatially separated reaction sites. Resorcinol‐p‐phthalaldehyde (RP) resin exhibits a promising H2O2 yield of 3351 µmol g−1 h−1 with high apparent quantum yield (AQY) of 14.9% at 420 nm and solar‐to‐chemical conversion (SCC) efficiency of 1.54%. This work provides a simple strategy to modulate the charge separation efficiency and redox reaction pathway on photocatalyst at molecular level design. [ABSTRACT FROM AUTHOR]

Minimizing the use of platinum (Pt) in proton exchange membrane fuel cells (PEMFCs) is crucial for expanding the PEMFC market. The most straightforward approach would be to reduce the size of Pt particles. However, small Pt clusters, particularly those <2 nm in size, typically exhibit reduced activity for the oxygen reduction reaction (ORR) due to the overly strong adsorption of oxygen intermediates. Additionally, these small Pt clusters tend to degrade more quickly, resulting in lower durability. In this study, carbon‐embedded Pt alloy cluster catalysts (PtFe, PtCo, PtNi) that demonstrate high activity and durability in the PEMFC cathode are presented. Density functional theory calculations indicate that carbon atoms stably adsorb onto the Fe sites of PtFe clusters, making the neighboring Pt sites active for ORR with an optimal adsorption strength for oxygen intermediates. This research can pave the way for developing durable and efficient ORR catalysts while significantly reducing Pt usage in PEMFCs. [ABSTRACT FROM AUTHOR]

Photocatalytic oxygen reduction to produce hydrogen peroxide (H2O2) is a promising route to providing oxidants for various industrial applications. However, the lack of well‐designed photocatalysts for efficient overall H2O2 production in pure water has impeded ongoing research and practical thrusts. Here we present a cyanide‐based covalent organic framework (TBTN‐COFs) combining 2,4,6‐trimethylbenzene‐1,3,5‐tricarbonitrile (TBTN) and benzotrithiophene‐2,5,8‐tricarbaldehyde (BTT) building blocks with water‐affinity and charge‐separation. The ultrafast intramolecular electron transfer (<500 fs) and prolonged excited state lifetime (748 ps) can be realized by TBTN‐COF, resulting in a hole accumulated BTT and electron‐rich TBTN building block. Under one sun, the 11013 μmol h−1 g−1 yield rate of H2O2 can be achieved without any sacrificial agent, outperforming most previous reports. Furthermore, the DFT calculation and in situ DRIFTS spectrums suggesting a Yeager‐type absorption of *O2⋅− intermediate in the cyanide active site, which prohibits the formation of superoxide radical and revealing a favored H2O2 production pathway. [ABSTRACT FROM AUTHOR]

With respect to the potential of palladium (Pd)‐based nanomaterials in catalyzing typical electrochemical reactions, herein, a strategy that couples the quick Joule‐heating with a solid phase synthesis for producing carbon‐supported Pd–Se nanoparticles with welcome features is reported, e.g., fine sizes, clean surfaces, and controlled crystal phases toward electrocatalysis of oxygen reduction reaction (ORR) and ethanol oxidation reaction (EOR) in an alkaline medium. Principally, the introduction of Se into Pd alters its electronic properties and weakens the adsorption of key reaction intermediates on the Pd–Se nanoparticles during the ORR and EOR process, thus endowing them with better electrocatalysis for the same electrochemical reactions. Impressively, the carbon‐supported Pd–Se nanoparticles exhibit phase‐dependent electrocatalysis toward ORR and EOR. In particular, the cubic Pd17Se15 nanoparticles supported on carbon substrate show mass activity of 0.206 A mgPd−1 and specific activity of 0.546 mA cm−2 at 0.9 V for ORR in 0.1 m KOH electrolyte, while the orthorhombic PdSe2 nanoparticles show a mass activity of 3.79 A mgPd−1 for EOR, higher than that of their cubic counterpart and commercial Pd/C catalyst. The universality of this synthetic strategy in manufacturing carbon‐supported noble metal chalcogenide nanoparticles and highlighting its potential in designing highly efficient electrocatalysts are emphasized. [ABSTRACT FROM AUTHOR]

The sluggish kinetics of the oxygen reduction reaction (ORR) and susceptibility to CO 2 poisoning present significant challenges in the application of intermediate temperature solid oxide fuel cells (IT-SOFCs). In this study, bismuth (Bi) was introduced as a dopant for the first time to enhance both the ORR activity and CO 2 tolerance of PrBaCoCuO 5+ δ (PBCCO) cathode. Bi doping serves to concurrently modulate the oxygen vacancy content and carrier concentration. This dual regulation enhances the processes of oxygen adsorption, dissociation, and charge transfer, as evidenced by the distribution of relaxation time (DRT) technique. Furthermore, PBBCCO demonstrates exceptional CO 2 tolerance and remarkable performance recovery following exposure to CO 2 -induced degradation. At 800 °C, the polarization resistance (R p) and maximum power density (MPD) of PBBCCO were 0.026 Ω cm2 and 631 mW cm−2, respectively. Notably, R p was reduced by 52.45%, and MPD exhibited an improvement of 45.11% at 800 °C. These findings highlight the significant impact of Bi doping on the performance of the PBCCO double perovskite cathode, underscoring its crucial importance for future developments of novel cathode materials. [ABSTRACT FROM AUTHOR]

Photocatalytic oxygen reduction to produce hydrogen peroxide (H2O2) is a promising route to providing oxidants for various industrial applications. However, the lack of well‐designed photocatalysts for efficient overall H2O2 production in pure water has impeded ongoing research and practical thrusts. Here we present a cyanide‐based covalent organic framework (TBTN‐COFs) combining 2,4,6‐trimethylbenzene‐1,3,5‐tricarbonitrile (TBTN) and benzotrithiophene‐2,5,8‐tricarbaldehyde (BTT) building blocks with water‐affinity and charge‐separation. The ultrafast intramolecular electron transfer (<500 fs) and prolonged excited state lifetime (748 ps) can be realized by TBTN‐COF, resulting in a hole accumulated BTT and electron‐rich TBTN building block. Under one sun, the 11013 μmol h−1 g−1 yield rate of H2O2 can be achieved without any sacrificial agent, outperforming most previous reports. Furthermore, the DFT calculation and in situ DRIFTS spectrums suggesting a Yeager‐type absorption of *O2⋅− intermediate in the cyanide active site, which prohibits the formation of superoxide radical and revealing a favored H2O2 production pathway. [ABSTRACT FROM AUTHOR]

[Display omitted] Novel two-dimensional MXene with unique optical and electrical properties has become a new focus in the field of sensing. In particular, their metallic conductivity, good biocompatibility and high anchoring ability to biomaterials make them attractive candidates. Despite such remarkable properties, there are certain limitations, such as low oxidative stability. MXene-Metal interactions are an effective strategy to maintain the long-term stability of MXene, while also improving the electrochemical activity and optical properties. Herein, a series of MXene/Ag nanocomposites including Ti 3 C 2 /Ag, Nb 2 C/Ag and V 2 C/Ag were designed based on the surface chemistry characteristics of MXene, where MXene served as the substrate for in-situ growth of silver nanoparticles via self-reduction of Ag(NH 3) 2 +. The results showed that V 2 C MXene has the strongest self-reducing ability due to its multiple variable valence states, larger interlayer space and more reactive groups. Moreover, V 2 C/Ag exhibited unexpected oxygen reduction reaction catalytic activity and photothermal performance. In view of which, an electrochemiluminescence-photothermal (ECL-photothermal) immunosensor was developed using V 2 C/Ag as ECL anchor and photothermal reagent for ultrasensitive detection of Lipolysis stimulated lipoprotein receptor. This work not only provides a simple and effective synthesis method of MXene supported metal nanocomposites, but also provides more inspirations for exploring the efficient biosensing strategies. [ABSTRACT FROM AUTHOR]

[Display omitted] • N -doped carbon nanotube confined CoFe nanoparticles were synthesized using solvothermal and high-temperature calcination methods. • The synergistic effect between CoFe nanoparticles and N -doped carbon nanotubes showed excellent electrocatalytic activity for OER/ORR. • Rechargeable zinc-air battery exhibited high power density, excellent specific capacity and good stability. • This work provides an approach for establishing low-cost and highly active multifunctional electrocatalysts of non-precious metal. Building efficient and stable bifunctional electrocatalysts toward oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is crucial for the advancement of rechargeable zinc-air batteries (ZABs). Here, a convenient in situ strategy is reported to controllably encapsulate CoFe alloy nanoparticles within N -doped carbon nanotubes (CoFe@NCNT). The abundant Co(Fe)-N x active sites and the synergistic interaction between CoFe alloys and carbon nanotubes facilitate mass transfer and interfacial charge transfer, resulting in excellent dual functional electrocatalytic activity of OER/ORR with minor potential difference (ΔE = 0.73 V). Thus, the corresponding rechargeable ZAB displays high power density (194 mW cm−2), excellent specific capacity (795 mAh g Zn -1), and favorable stability (900 cycles@5 mA cm−2). This work provides an approach for establishing low-cost bultifunctional electrocatalysts with excellent performance of non-noble metal nanoalloys. [ABSTRACT FROM AUTHOR]

[Display omitted] • FeNb 2 O 6 /3D interconnected N -doped carbon cages were synthesized by methanol-induced assembly and pyrolysis strategy. • The methanol evaporation promotes the assembly and crosslinkage of ZIF-8, resulting in 3D interconnected cage-like superstructure. • The 3D structure provides a spacious surface area and abundant defects for interfacial mass and electron transfer. • FeNb 2 O 6 /NICC showed excellent performances of the ORR and Zn-air battery. Three-dimensional (3D) hollow carbon is one of advanced nanomaterials widely applied in oxygen reduction reaction (ORR). Herein, iron niobate (FeNb 2 O 6) nanoparticles supported on metal-organic frameworks (MOFs)-derived 3D N -doped interconnected open carbon cages (FeNb 2 O 6 /NICC) were prepared by methanol induced assembly and pyrolysis strategy. During the fabrication process, the evaporation of methanol promoted the assembly and cross linkage of ZIF-8, rather than individual particles. The assembled ZIF-8 particles worked as in-situ sacrificial templates, in turn forming hierarchically interconnected open carbon cages after high-temperature pyrolysis. The as-made FeNb 2 O 6 /NICC showed a positive onset potential of 1.09 V and a half-wave potential of 0.88 V for the ORR, outperforming commercial Pt/C under the identical conditions. Later on, the as-built Zn-air battery with the FeNb 2 O 6 /NICC presented a greater power density of 100.6 mW cm−2 and durable long-cycle stability by operating for 200 h. For preparing 3D hollow carbon materials, this synthesis does not require a tedious removal process of template, which is more convenient than traditional method with silica and polystyrene spheres as templates. This work affords an exceptional example of developing 3D N -doped interconnected hollow carbon composites for energy conversion and storage devices. [ABSTRACT FROM AUTHOR]

The reaction of oxygen reduction is essential for media of energy storage and transformation, such as fuel cells. The development of effective and highly stable electro-catalysts, such as single-atom catalysts, poses a definite limitation in clean power technologies. Currently, metal–organic frameworks (MOFs) with a flexible structure and regularly-separated active sites have been developed as unusual and promising precursors for the development of composite particles based on carbon, exhibiting outstanding properties for various applications, particularly in electrochemistry. In this mini-review, the synthesis, characterization, and the role of different MOF-based electro-catalysts, including MOF-based single atom electro-catalysts have been summarized. The impact of active sites (like hetero-atoms and metal central ions), chemical structure, electronic composition, and porosity of MOF-based nano-composites on the behavior of oxygen reduction reaction were explained by combining both laboratory results and analytical estimates. Taking into account ways to improve mass density of sufficient active sites and preserving them from destruction and corrosion. [ABSTRACT FROM AUTHOR]

A proton exchange membrane fuel cell (PEMFC) is an efficient and environmentally friendly power production technology that uses hydrogen energy. The cathodic oxygen reduction electrode is a critical component in the development of PEMFC. Most techniques deposit catalyst nanoparticles in areas that are inaccessible for catalytic processes, reducing platinum utilization. The substrate used in this study was carbon paper (CP) with a self-supporting structure. First, electrochemical acidification technology was employed to modify the CP's surface, followed by nanoparticle manufacturing and fixation on the CP in a single step by electrodeposition. The Pt/C0.5V2.24CP catalyst electrode demonstrated high-quality activity in the oxygen reduction reaction (ORR), with a homogeneous particle dispersion and particle size of around 50 nm. The mass activity and electrochemical active surface area (ECSA) of the Pt/C0.5V2.24CP catalyst electrode were 1.74 and 3.98 times higher than those of the Pt/C/CP-1 electrodes made with commercial catalysts, respectively. After 5000 cycles of accelerated durability testing (ADT), the mass activity and ECSA were 1.28 times and 6.16 times more than Pt/C/CP-1. This paper successfully proved the viability of electrodepositing Pt nanoparticles on CP following acidification, and that the electrochemical acidification methods have a positive influence on improving electrode ORR activity. [ABSTRACT FROM AUTHOR]

Pt nanoparticles are electrodeposited on nitrogen-doped graphene nanosheets using different electrodeposition procedures such as cyclic voltammetry, chronoamperometry and pulse deposition while keeping the overall deposition time and precursor concentration constant. A comparison of electrodeposition in Ar-saturated and O2-saturated solutions was also made to study the influence of competing oxygen reduction and hydrogen adsorption/desorption on the electroreduction of Pt ions. Scanning electron microscopy results showed that the surface morphology of the Pt catalysts is dependent on the electrodeposition protocol and nucleation overpotential. The particle size and number density of the electrodeposited Pt nanoparticles vary from sample to sample. Cyclic voltammetry and CO stripping experiments in 0.1 M HClO4 solution showed different surface electrochemistry of the Pt catalysts. Rotating disk electrode measurement revealed that all the catalysts are highly active towards the oxygen reduction reaction in perchloric acid. [ABSTRACT FROM AUTHOR]

The output power and combination property of microbial fuel cells (MFCs) are often limited by the sluggish kinetics of the cathodic oxygen reduction reaction (ORR). Therefore, seek noble metal-free materials with good ORR catalytic efficiency and durability is of great significance for practical MFC application. In this paper, ternary transition metal sulfide was successfully loaded on activated carbon by hydrothermal method. In the MnCo2S4@AC nanocomposite, the synergistic effect existing between MnCo2S4 and activated carbon (AC) gives the advantages of large specific surface area, special microstructure, fast electron transmission rate and good electro-catalytic activity of MnCo2S4 for ORR. The electrochemical tests showed that the ORR event of MnCo2S4@AC was the four-electron (4e−) pathway. Therefore, the highest output power density of MFC assembled with MnCo2S4@AC was 239.41 mW m−2, 3.59-fold stronger than AC (66.66 mW m−2). This method can provide the ideas for the synthesis of efficient ORR catalyst. [ABSTRACT FROM AUTHOR]

The development of cost-effective and highly active catalysts for the oxygen reduction reaction (ORR) is crucial for the successful commercialization of Zn-air batteries. Single-atom catalysts are considered to be the most promising alternatives to Pt-based catalysts on account of their high atomic utilization and adjustable coordination environment, but their activity and durability are not ideal. Herein, a porous nitrogen-doped graphene with atomically-dispersed Fe sites (Fe SAs/NG) is developed by utilizing g-C 3 N 4 as the nitrogen source. The Fe SAs/NG exhibits superior ORR property in alkaline electrolyte with a high half-wave potential (E 1/2 = 0.883 V vs. RHE) and remarkable stability, mainly due to atomically-dispersed Fe sites, abundant N species, and porous structure. Moreover, the Fe SAs/NG-based Zn-air battery achieves the maximum discharge power density of 272.6 mW cm−2, surpassing that of benchmark 20% Pt/C catalyst (238 mW cm−2). This study offers a valuable reference for the rational design and synthesis of high efficiency single atom catalysts specifically tailored for Zn-air batteries. • A porous nitrogen-doped graphene with atomically-dispersed Fe sites (Fe SAs/NG) is successfully prepared. • The porous two-dimensional nanosheet structure possesses more accessible active sites. • The catalyst exhibits superior catalytic activity and stability toward ORR in alkaline electrolyte. • Fe SAs/NG-based Zn-air battery demonstrates a maximum power density of 272.6 mW cm−2. [ABSTRACT FROM AUTHOR]

Platinum group catalysts are still the most effective catalysts for oxygen reduction reaction (ORR) of proton exchange membrane fuel cells. Thus, the high cost and susceptibility to deactivation during working process are becoming more and more prominent with the proceeding of the application. To meet the requirements of enhancing reaction kinetics and decreasing the cost of Pt-based catalysts, we design a N -doped hollow carbon nanorods (HCNR) supported platinum-nickel based catalyst for ORR. Compared with the benchmark commercial Pt/C catalyst, the HCNR supported PtNi catalysts (PtNi/HCNR) show excellent catalytic activity for ORR and long-time running durability. The onset potential (E 0) and half wave potential (E 1/2) of medium platinum content catalyst (PtNi/HCNR-2) catalyzed ORR are 1.02 V and 0.914 V, separately, which surpass than that of the 20 wt% Pt/C catalyst. Furthermore, PtNi/HCNR-2 catalyzed ORR has a lower Tafel slope (92.05 mV dec−1), faster electron transfer rate, lower H 2 O 2 yield rate and better stability. The synergistic effect between N -doped HCNR and PtNi alloy assures the high performance for ORR. HCNR improves the electrical conductivity, while the doped nitrogen provides "coordination nests" for PtNi catalyst, which provide more catalytic active sites for ORR. PtNi/HNCR-based catalysts have great potential to be low-cost, high performance catalysts for ORR. [Display omitted] • N -doped hollow carbon nanorods support for catalysts were synthesized. • HCNR supported PtNi catalysts show 20 mV higher onset potential for ORR than Pt/C. • Doping with nitrogen enhanced the affinity between HCNR and PtNi catalyst. • Hollow structure facilitates the transport of oxygen and electrons for ORR. [ABSTRACT FROM AUTHOR]