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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]

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]

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]

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]

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]

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]

Single‐atom catalysts (SACs) are widely studied in various chemical transformations due to their high catalytic activity and atom utilization. However, modulating the catalytic performance of catalysts by adjusting the microenvironment remains a great challenge. In this paper, a novel master‐double guest vulcanization‐assisted strategy is reported for synthesizing Fe single‐atom catalysts on N,S codoped porous hollow leaf carbon (FeSA/N,S‐PHLC) with highly exposed FeN3SOH sites. Fe(mIm) (guest I) is loaded on the surface of ZIF‐L (host) and then trithiocyanuric acid (TCA, guest II) is bonded with Fe(mIm), and the resulting ZIF‐L@Fe(mIm)@TCA precursors can be converted to FeSA/N,S‐PHLC with controllable structures. In addition, XPS analysis yield an increase in pyridine N content in FeSA/N,S‐PHLC compared to FeSA/N‐PHLC. It can be demonstrated by theoretical calculations that the N,S‐coordinated axially hydroxy‐coordinated asymmetric Fe centers synergistically with the abundance of pyridinic nitrogen facilitate the adsorption and desorption of oxygen intermediates, and the 3d orbitals of the Fe active centers can be optimized. The prepared FeSA/N,S‐PHLC catalyst has a half‐wave potential (E1/2) of 0.91 V under alkaline conditions, and E1/2 = 0.75 V under acidic conditions. It shows excellent cycle stability (882 h) and power density (217 mW cm−2) in the assembly of zinc–air battery (ZABs) devices. [ABSTRACT FROM AUTHOR]

Atomically dispersed iron–nitrogen–carbon catalysts are promised, low‐cost, and high‐performance electrocatalysts for the Oxygen Reduction Reaction (ORR) in fuel cells. However, most Fe–N–C materials are produced via pyrolysis at a high temperature and it is difficult to characterise the precise Fe–N configurations. This can lead to confusion surrounding the best chemical and coordination environment for Fe and understanding the subsequent ORR mechanisms. In this work, Fe porphyrin is used to produce a specific Fe–N environment, therefore allowing the role and activity of this environment to be studied. Carbon nanotubes (CNTs) are covalently functionalized with iron 5,10,15,20‐triphenylporphyrin (FeTPP) motifs via aryl diazonium methodology, enabling the exact role of only the Fe‐Pyrrolic N4 configuration of FeTPP in ORR to be studied and better understood. Upon covalent functionalization, a high electrochemical active site density of 1.12 × 1015 sites cm−2, approximately six‐fold more than that of noncovalently functionalized samples with 12.7% electrochemical active site. The heightened active site density and superior electrochemical active site utilization (12.7%) lead to the more favorable 4‐electron pathway for the ORR. Furthermore, a preliminary discussion regarding the selectivity of the ORR pathway is initiated. [ABSTRACT FROM AUTHOR]

The missions in extreme environments such as the moon, the Arctic/Antarctic, and the plateau require the operation of batteries at low temperatures even below the freezing point of water. Herein, it is reported that compressively stressed Co single atoms exhibit enhanced oxygen reduction reaction (ORR) activity and enable the effective operation of zinc–air battery at a subzero temperature. The compressive strain is generated by depositing Co single atoms on highly arced carbon layers with ultra‐small curvature radii ≈2 nm. The locally compressive strain on Co single atoms redistributes the electron fillings in d orbitals with different spatial orientations, thereby strengthening the adsorption of active intermediates and enhancing the activity toward ORR. As expected, compressively stressed Co single atoms outperform Co single atoms on a flat support without strain in terms of kinetic current density (31.09 mA cm−2 vs 0.35 mA cm−2) at 0.85 V during ORR. The integration of the catalyst into a Zn–air battery generates a superior power density of 54.8 mW cm−2 than the commercial Pt/C counterpart (24.1 mW cm−2) at −40 °C. [ABSTRACT FROM AUTHOR]

Reversible proton‐conducting solid oxide cells (R‐PSOCs) are considered to be one of the most promising devices for efficient power generation and hydrogen production. However, the requirement of high catalytic activity for fast oxygen reduction/evolution reaction (ORR/OER) and durability under high steam concentration of air electrode materials remains the major challenge for the practical application of R‐PSOCs. Here, a series of cobalt‐free Ruddlesden–Popper perovskite of Nd0.8Sr1.2Ni1‐xFexO4±δ are reported with mixed conductivity for enhanced ORR/OER kinetics. The R‐PSOCs with an optimal Nd0.8Sr1.2Ni0.7Fe0.3O4±δ air electrode show a high peak power density of 1.28 W cm−2 in the fuel cell mode and a promising current density of 3.24 A cm−2 at 1.3 V in the electrolysis cell mode at 700 °C. In addition, the R‐PSOCs show favorable stability under the fuel cell, electrolysis, and reversible modes for hundreds of hours. This work demonstrates that the Ruddlesden–Popper materials can be utilized as suitable air electrodes for R‐PSOCs. [ABSTRACT FROM AUTHOR]

Doping engineering is an effective strategy to improve the electrocatalytic activity of manganese oxides by enhancing their poor electrical conductivity and oxygen adsorption capacity. Herein, p‐block aluminum group metal ions (Al3+, Ga3+, and In3+) are introduced into cryptomelane‐type manganese oxide octahedral molecular sieves (OMS‐2), leading to p−d orbital hybridization between the p‐orbitals of the aluminum group metals and d‐orbitals of Mn, facilitating the oxygen reduction reaction. The aluminum group metal‐doped OMS‐2 exhibits excellent catalytic activity, rapid reaction kinetics, and favorable stability compared to commercial Pt/C. Among the three prepared catalysts, Ga‐doped OMS‐2 (Ga‐OMS‐2) has stronger oxygen reduction activity. Experimental and theoretical calculations show that the superiority of Ga‐OMS‐2 is attributed to p−d hybridization, which enriches the reaction sites and enhances the binding strength of the catalyst to the O2 reaction intermediates. As a proof of concept, Zinc−air batteries assembled with Ga‐OMS‐2 as a catalyst exhibit superior power density and cycle life to commercial Pt/C. This p−d hybridization strategy gives insight into the p‐block metal doping of catalysts prepared with other transition metals with excellent electrocatalytic activity and durability for energy storage and conversion. [ABSTRACT FROM AUTHOR]

The oxygen reduction reaction (ORR) plays a fundamental role in sustainable energy technologies. However, the creation of non‐precious metal electrocatalysts with high ORR activity and durability under all pH conditions is of great significance but remains challenging. Herein, the aim is to overcome this challenge by creating a Fe single atom catalyst on a 2D defect‐containing nitrogen‐doped carbon support (Fe1/DNC) via a microenvironment engineering strategy. Microkinetic modeling reveals that FeN4(OH) moieties are the real active sites under reaction conditions. Due to the synergistic promotion effect of denser accessible FeN4(OH) moieties and defect‐induced electronic properties, Fe1/DNC catalyst achieves extraordinary ORR activity under alkaline, acidic, and neutral conditions, with half‐wave potentials of 0.95, 0.82, and 0.70 V, respectively. Moreover, a negligible performance decay is observed with this Fe catalyst in stability and methanol tolerance tests. Zn‐air battery employing Fe1/DNC delivers remarkable peak power density and long‐term operational durability. Theoretical analysis provides compelling evidence that the defects adjacent to FeN4(OH) moieties can endow an inductive effect to reshape electronic properties to balance the OOH* formation and OH* reduction. This work offers insight into the regulation of asymmetric coordination structure and electronic properties of metal sites for boosting electrocatalytic activity and stability. [ABSTRACT FROM AUTHOR]

Atomically distributed transition metal coordinated with nitrogen is considered as a class of promising oxygen reduction reaction (ORR) catalyst. However, the challenge of ineffective distribution of Fe‐Nx active sites have been long existing, leading to low active site density and unstable performance, which needs be overcome for next generation ORR electrocatalysts. Herein, yttrium (Y) is introduced into atomically dispersed iron (Fe) nitrogen co‐doped carbon materials to integrate nanoparticles, nanoclusters, and atomic sites, which endow the Fe‐N4‐Y2O3 and Fe4N0.94‐Y2O3 (FeY‐NC) with outstanding ORR activity. The FeY‐NC achieves half‐wave potential of 0.926 and 0.809 V in alkaline and acidic condition, respectively. The kinetics current density at 0.9 V in alkaline condition is 31.2 mA cm−2, which is 7.8 times of Fe‐NC and 32.4 times of Pt/C. This outstanding activity of FeY‐NC is enabled by the generated atomic FeN4 and Fe4N nanoparticles dual active‐sites, and further the synergistic effect between the Fe‐Nx/Fe4N0.94 with Y2O3 nanoclusters are loaded on nitrogen‐doped carbon (NC) network. The superior performance of FeY‐NC is demonstrated in a primary Zinc‐air battery, deliver a peak power density of 233 mW cm−2. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) are crystalline organic porous polymers that can be precisely integrated by building blocks to achieve pre‐designed composition, components, and functions, making them a powerful platform for the development of molecular devices in the field of electrocatalysis. The precise control of channel/dopant positions and highly ordered network structures of COFs provide an ideal material system for the applications of advanced electrocatalysis. In this paper, the topological structure design and synthesis methods of COFs are reviewed in detail, and their design principles are deeply analyzed. In addition, the applications of COFs and their derivatives in the field of electrocatalysis are systematically summarized and the optimization strategies are proposed. Finally, the application prospects of COFs and their derivatives in electrocatalysis and the challenges that may be encountered in the future are prospected, providing helpful guidance for future research. [ABSTRACT FROM AUTHOR]

Challenges in rational designing dual‐atom catalysts (DACs) give a strong motivation to construct coordination‐activity correlations. Here, thorough coordination‐activity correlations of DACs based on how the changes in coordination shells (CSs) of dual‐atom Cu,Co centers influence their electrocatalytic activity in oxygen reduction reaction(ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) is constructed. First, Cu,Co DACs with different CSs modifications are fabricated by using a controlled "precursors‐preselection" approach. Three DACs with unique coordination environments are characterized as secondary S atoms that directly bond to Cu,Co‐N6 in lower CSs, indirectly bond in neighboring CSs, and are doped in higher CSs, respectively. Then, experimentally and theoretically, a coordination correlation resembling a planet‐satellite system, where satellite coordinated atoms (heteroatom N, S) surround Cu‐Co dual‐atom entity in various orbitals CSs. By evaluating electrocatalytic activity indicators, differences are identified in electronic structure and electrocatalytic performance of Cu and Co centers in ORR, OER, and HER. Interestingly, initial CSs modifications for DACs may not always be advantageous for electrocatalysis. This work offers valuable insight for designing DACs for diverse applications. [ABSTRACT FROM AUTHOR]

Local geometric strain engineering is useful for modulating the performance of nitrogen‐coordinated transition metal‐carbon catalysts. However, realizing the nano‐level strain is technically challenging. Additionally, the structure‐property relationship between strain degree and performance remains poorly understood. Herein, it is conceptually predict that geometric bending induces more electron transfer from Zn to the coordinated N in Zn─N─C, leading to a positive shift of the d‐band center of the Zn atom, which promotes the adsorption reduction process of the O2 molecule and thus increases the intrinsic oxygen reduction reaction (ORR) activity. Moreover, a low‐temperature non‐saturated coordination strategy is proposed to prepare spherical porous carbon catalysts with surface‐enriched geometrically bent (20‐50°) Zn─N─C sites. Benefiting from the highly active Zn─N─C sites, large specific surface area and abundant pore structure, the optimized catalyst (S─Zn─N─C‐950) exhibited excellent intrinsic alkaline ORR activity (half‐wave potential E1/2 = 0.89 V) and high zinc‐air battery performance (peak power density of 229.2 mW cm−2), exceeding that of commercial Pt/C catalysts. Density functional theory (DFT) calculations show that when the geometrical bending angle is 30–45°, Zn centers with suitable charge transfer to the surrounding N can produce a moderate adsorption strength to the oxygen intermediate state, resulting in optimal ORR activity. [ABSTRACT FROM AUTHOR]

Fe single‐atom catalysts (SACs) are a promising catalyst for oxygen reduction reaction (ORR) in both Zn–air batteries (ZABs) but have a certain distance to compete with Pt‐based catalysts. Rational modulation of the coordination environment in the second coordination shell of SACs offers an opportunity to improve the intrinsic ORR activity, yet a challenge. Here, a novel strategy is reported to construct a dual‐metal catalyst by introducing a single Co atom in the second coordination shell of the Fe center. The dual‐metal N3─Fe─N─Co site with a certain Fe─Co distance of 0.312 nm is constructed. It allows for manipulation of the positive shift of the Fe center charge state, driving the d‐band center up‐shift by 0.63 eV, thereby offering the optimal adsorption of intermediates. Benefiting from this structure, the as‐prepared Fe(Co2nd)‐NC enables an excellent ORR activity with a half‐wave potential of 0.948 V in 0.1 M KOH. As a cathode in ZABs, it delivered an outstanding peak power density of 218 mW cm−2 and a specific capacity of 915 mAh gZn−1 at 5 mA cm−2, respectively, with superior long‐term durability over 680 h. The second shell layer alignment regulation strategy shows great potential for energy storage applications. [ABSTRACT FROM AUTHOR]

Engineering the electronic configuration and intermediates adsorption behaviors of high‐performance non‐noble‐metal‐based catalysts for the sluggish oxygen reduction reaction (ORR) kinetics at the cathode is highly imperative for the development of anion exchange membrane fuel cells (AEMFCs), yet remains an enormous challenge. Herein, a rare‐earth metal oxide engineering tactic through the formation of Fe3O4/La2O3 heterostructures in N,O‐doped carbon nanospheres (Fe3O4/La2O3@N,O‐CNSs) for efficient oxygen reduction electrocatalysis is reported. The theoretical calculations reveal that the interfacial bonds formed by the La─O─Fe heterogeneous interface effectively optimize the electronic structure of the Fe d‐band center relative to the Fermi level, which results in a significant reduction of the reaction barriers of rate‐limiting steps during the ORR. The modulation in intermediates chemisorption enables Fe3O4/La2O3@N,O‐CNSs an outstanding ORR performance and improved stability, with a significantly higher half‐wave potential value (0.88 V). More impressively, this integrated catalyst delivers a remarkable power density of 148.7 mW cm−2 in practical AEMFC operating conditions, along with negligible performance degradation over 100 h using an H2‐air atmosphere, which is higher than commercial Pt/C‐coupled electrodes. The results presented here are believed to provide guidelines for fabricating high‐performance AEMFCs electrocatalysts in terms of heterointerface engineering and strong electronic coupling effect induced by rare‐earth oxides. [ABSTRACT FROM AUTHOR]

Highly active and durable air electrodes are crucial for the commercialization of reversible proton ceramic electrochemical cells (R‐PCECs) for large‐scale energy conversion and storage that may be developed by introducing oxygen ion, electron, and proton triple conducting species into the electrode materials. Here, a new triple conducting nanocomposite is reported as a promising air electrode of R‐PCECs, which consists of a dominated cubic perovskite Ba0.5Sr0.5Co0.72Fe0.18Er0.09O3‐δ and a minor Er2O3 phase, developed by Er doping induced phase separation of Ba0.5Sr0.5(Co0.8Fe0.2)0.9Er0.1O3‐δ precursor. The Er doping stimulates the primary perovskite phase to possess excellent hydration capability and oxygen activation ability, while the Er2O3 minor phase, as a high‐speed proton transport channel, further cooperates with the perovskite main phase to boost the kinetic rate of the electrode for both oxygen reduction and evolution reactions (ORR/OER). As a result, the corresponding R‐PCEC achieves extraordinary electrochemical performance in fuel cell (1.327 W cm−2 at 650 °C) and electrolysis modes (−2.227 A cm−2 at 1.3 V and 650 °C), which exceed the similar cell with a typical Ba0.5Sr0.5Co0.8Fe0.2O3‐δ single‐phase perovskite air electrode by 82.3% and 122.7%, respectively. This Er‐doping induced phase separation provides a new way for new bifunctional electrodes development. [ABSTRACT FROM AUTHOR]

Owing to their exceptional properties, high‐entropy alloys (HEAs) have received considerable attention in the field of electrocatalysis. However, few studies focus on the origin of their outstanding performance. Here, carbon‐supported PtFeCoNiMn (with an atomic ratio of 21:20:20:20:19) HEA nanoparticles via shock‐heating and shock‐cooling strategy are rationally designed and successfully prepared. The above five metal elements are rationally selected from the perspective of thermodynamics and geometric effects. Subsequently, the alloying process of the PtFeCoNiMn HEA is investigated via operando X‐ray diffraction characterizations. The electronic structures of each metal atom on the PtFeCoNiMn HEA and monometallic nanoparticles surface are revealed by density function theory calculations for illustrating the performance enhancement mechanism. It is found that Pt atoms on the PtFeCoNiMn HEA surface exhibit a wider range of d‐band center distribution range than the corresponding monometallic nanoparticles, which contributes to the enhanced selective adsorption of O2 reactants/intermediates. Importantly, some Fe, Co, Ni, and Mn atoms on the HEA surface manifest less positive d‐band center values than the corresponding monometallic nanoparticles, with similar d‐band center positions to some Pt atoms. This indicates that the inactive atoms in monometallic nanoparticles can be transformed into ORR active sites in the HEA matrix owing to the electronic interaction between adjacent atoms. [ABSTRACT FROM AUTHOR]

Pt‐based intermetallics are recognized as effective catalysts for oxygen reduction reaction (ORR) in fuel cells. However, the synthesis of intermetallics often requires prolonged annealing and the effect of different crystal structures on ORR still need to be investigated. Herein, L12‐Pt3Mn and L10‐PtMn intermetallics with Pt‐skin are rapidly synthesized through an emerging periodic carbothermal shock method to investigate their ORR‐activity difference. The formation of L12‐Pt3Mn and L10‐PtMn can be well‐controlled by the Pt/Mn feeding ratio, pulse cycles, and temperature. Electrocatalytic investigations show that L12‐Pt3Mn presents a more positive half‐wave potential (0.91 V vs RHE) and onset potential (1.02 V vs RHE) than those of L10‐PtMn. The mass activity and specific activity of L12‐Pt3Mn are respectively fourfold and threefold greater than those of L10‐PtMn. Theoretical calculations indicate that the L12‐Pt3Mn has a more substantial work function than L10‐PtMn, thereby conferring L12‐Pt3Mn with an increased electron density allocation for catalytic involvement. This electron confinement imparts L12‐Pt3Mn with a Pt d‐band center lower than that of L10‐PtMn, consequently attenuating the adsorption of strongly bonded *O intermediates during the rate‐determining step. This study not only employs a straightforward method for intermetallic preparation but also elucidates the discrepancies in ORR activity across intermetallics with distinct structures. [ABSTRACT FROM AUTHOR]

Molecular electrocatalysis requires the immobilization of molecular catalysts on electrode materials for practical uses. Direct adsorption of catalyst molecules on electrode materials is simple, but grafting molecules through chemical bonds can significantly improve electrocatalytic efficiency and durability. However, designing and synthesizing catalyst molecules to simultaneously improve catalytic activities and realize easy grafting on electrodes is challenging. The study herein reports on a one‐pot strategy to graft Co corroles on pyridine‐modified carbon nanotubes (CNTs) for oxygen electrocatalysis. By modifying CNTs with pyridines, the resulting pyridine‐modified CNTs can function as platforms to grab in situ generated Co corroles through the axial pyridine ligation on Co. Such an immobilization strategy combines three effects for the regulation of electrocatalysis, including the axial ligand effect, the electron transfer effect, and the chemical bond effect. The resulting hybrid materials show high efficiency for oxygen electrocatalysis, and the Zn–air battery assembled using these materials displays comparable performance as the Pt/Ir‐based battery. Moreover, the electrocatalytic efficiency of these hybrid materials can be systematically tuned by using different pyridines, highlighting the controllable feature of this strategy. Therefore, this work is significant to present a one‐pot three‐in‐one strategy to immobilize catalyst molecules on CNTs for electrocatalysis. [ABSTRACT FROM AUTHOR]

Atomically dispersed metal‐nitrogen‐carbon catalysts have been extensively explored for various sustainable energy‐related reactions. From a material perspective, these catalysts are likely to consist of a combination of single‐atom, dual‐atom and possibly even multi‐atom sites. However, pinpointing their true active sites has remained a challenging task. In this study, a model catalyst is introduced, Co/CoMn‐NC, featuring both Co single‐atom sites and CoMn dual‐atom sites on a nitrogen‐doped carbon substrate. By employing a combination of X‐ray adsorption spectroscopy and density functional theory calculations, the atomic configuration of Co/CoMn‐NC has been determined. Density functional theory calculations are also used to unequivocally identify Co‐atom within the CoMn dual‐atom motif as the predominate active site of the Co/CoMn‐NC model catalyst toward oxygen reduction reaction (ORR), which is further confirmed by in situ Raman spectroscopy. The cooperative interactions between Co single‐atom sites and CoMn dual‐atom sites can finely tune the d‐band center and ameliorate the adsorption and desorption behaviors of the intermediates, thereby facilitating ORR kinetic. Overall, the study introduces a systematic strategy to elucidate the structure and the superiority of the model system and provides new insights into atomically dispersed multi‐metal active sites, showcasing that enhanced catalytic performance extends beyond unified diatomic sites or monatomic sites. [ABSTRACT FROM AUTHOR]

The sluggish kinetics of oxygen reduction reaction (ORR) at low temperatures and the fast degradation of the cathode are the main obstacles to the commercialization of solid oxide fuel cells (SOFCs). However, it is still very challenging to achieve both high catalytic activity and favorable stability for single‐phase materials. Herein, a highly active and durable nanocomposite cathode (Ba0.5Sr0.5)0.75Pr0.25Co0.575Fe0.3W0.125O3‐δ (BSPCFW) for low‐temperature SOFC (≤650 °C) is presented, which self‐assembles into two cubic perovskites: the simple perovskite Pr0.38Ba0.25Sr0.37Co0.62Fe0.38O3‐δ (PBSCF‐c) and the B‐site cations ordered double perovskite Ba1.30Sr0.70Co1.0Fe0.25W0.75O6‐δ (BSCFW‐c). The former PBSCF‐c serves as the highly conductive and active catalyst for ORR, while the latter BSCFW‐c with a large lattice parameter introduces a key beneficial lattice tensile strain into the PBSCF‐c phase through a coherent interface, which significantly promotes the ORR activity at low temperatures with the area specific resistance of 0.034 Ω cm2 at 650 °C, and the long‐term stability of 2 years storage and 1280 h operation in symmetrical cell. The introduction of the beneficial lattice tensile strain in self‐assembled composite catalysts is an effective way to synergistically enhance the electrochemical activity and durability of the electrode materials for electrochemical devices. [ABSTRACT FROM AUTHOR]

While Pt‐based binary alloys hold promising potential as cathode catalysts in proton exchange membrane fuel cells (PEMFCs) due to their desirable properties compared with monometallic counterparts, their weak interactions with carbon support make them challenging for practical cell implementation. Here, the PtFe alloys are uniformly deposited onto the surface of Fe‐Nx‐enriched nanocubes (FeNC) via surface confinement and internal vapor phase etching. The combined action of PtFe alloy and FeNC support acts as the electronic structure modulator resulting in the optimized intermediate adsorption (revealed by density function theory calculations), thereby boosting intrinsic activity to oxygen reduction reaction (ORR) and simultaneously enhancing their interactions. The resultant Pt1Fe1 @ Fe0.5NC‐900 catalyst with a low Pt loading (0.065 mgPt cm−2) exhibits excellent mass activity and stability toward ORR in acidic media. When incorporated into a PEMFC, it delivers a superior peak power density of 1.05 W cm−2 and satisfactory stability performance. [ABSTRACT FROM AUTHOR]

Edge engineering has emerged as a powerful strategy to activate inert carbon surfaces, and thus achieve a notable enhanced electrocatalytic activity. However, the rational manipulation of carbon edges to achieve enhanced catalytic performance remains a formidable challenge, primarily hindered by immature synthesis methods and the obscured understanding of the structure‐activity relationship. Herein, an organic–inorganic hybrid co‐assembly strategy is used to fabricate a series of mesoporous carbon nanofibers (MCNFs) with controllable edge site densities and the impact of edge population on electrochemical oxygen reduction reaction (ORR) pathways is investigated. The optimized MCNFs catalyst exhibits a remarkable 2e− ORR performance, as evidenced by a high H2O2 selectivity (>90%) across a wide potential window of 0.6 V and a large cathodic current density of −3.0 mA cm−2 (at 0.2 V vs. reversible hydrogen electrode). Strikingly, the density of carbon edge sites can be changed to tune the ORR activity and selectivity. Experimental validation and density functional theory calculations confirm that the presence of edge defects can optimize the adsorption strength of *OOH intermediates and balance the selectivity and activity of the 2e− ORR process. This study provides a new path to achieve high ORR activity and 2e− selectivity in carbon‐based electrocatalysts. [ABSTRACT FROM AUTHOR]

Transition metal single atoms anchored on nitrogen‐doped carbon (M‐N‐C) matrix with M‐N‐C active sites have shown to be promising catalysts for both hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR). Herein, a hybrid catalyst with low‐level loading of atomic Pt and Co species encapsulated in nitrogen‐doped graphene (Pt@CoN4‐G) is developed. The Pt@CoN4‐G shows low overpotential for HER in wide‐pH electrolyte and manifests improved mass activity with almost eight times greater than that of Pt/C at an overpotential of 50 mV. The Pt@CoN4‐G also exhibits a top‐level ORR activity (half‐wave potential, E1/2 = 0.893 V) and robust stability (>200 h) in alkaline medium. Using theoretical calculations and comprehensive characterizations , the strong metal–support interactions between Pt species and CoN4‐G support and synergistical cooperation of multiple active sites are clarified. A flow alkali‐Al/acid hybrid fuel cell using Pt@CoN4‐G as cathode catalyst delivers a large power density of 222 mW cm−2 with excellent stability to achieve simultaneously hydrogen evolution and electricity generation. In addition, Pt@CoN4‐G endows a flow Zn‐air battery with high power density (316 mW cm−2), good stability under large current density (>100 h at 100 mA cm−2), and long cycle life (over 600 h at 5 mA cm−2). [ABSTRACT FROM AUTHOR]

Atomically dispersed iron–nitrogen–carbon (FeNC) catalysts have sparked great interest by virtue of the highly active isolated FeN4 sites. The catalysts with pyrolysis treatment usually induce inevitable FeN4 sites agglomeration, leading to fast degradation in catalytic activity. Herein, a pre‐coordinated protection strategy is proposed to eliminate the aggregation of Fe atoms by suppressing the thermal migration during the pyrolysis process. To this end, the S atom is introduced into the graphitic support by enhancing the metal‐support interaction. The proposed atomic structure is revealed by multiple advanced characterizations including Fe Mössbauer spectroscopy, X‐ray absorption spectroscopy, and theoretical calculations. By employing S atom into the structure, the center atom Fe is oxidized to a higher valence, improving the bonding energy with the graphitic support, which accordingly endows catalyst anti‐sintering capacity and improved catalytic activity. Compared to commercial Pt/C and the reported catalyst with secondary pyrolysis, the proposed catalysts exhibit enhanced ORR activity in alkaline media (E1/2 = 0.91 V). This work provides a new avenue toward optimizing and improving ORR performance of atomically dispersed Fe catalysts. [ABSTRACT FROM AUTHOR]

Introducing sulfur functionalities is reported as an efficacious route to regulate the electron distribution of single‐atomic Fe sites for improving the oxygen reduction reaction (ORR) activity, however, it remains controversial about the role of type of sulfur functionalities in enhancing the ORR activity. Herein, this study revisits the role of sulfur functionalities in regulating the electron distribution of single‐atomic Fe sites by the construction of single‐atomic Fe‐N4 sites with sulfur functionalities (FeSNC) using sulfur‐containing molecules with different molecular structures. X‐ray absorption spectroscopy and theoretical calculations confirm that thiophene S and oxidized S both possess the electron‐donating properties for regulating the electronic distribution of Fe‐N4 sites, which is beneficial to weaken the adsorption of the ORR intermediates. As expected, the optimal FeSNC has attractive ORR activity with half‐potential of 0.76 V in 0.5 m H2SO4 and 0.91 V in 0.1 m KOH along with remarkable Zn‐air battery performance. Moreover, the developed synthetic method has also been extended to construct B and P regulated FeNC catalysts. [ABSTRACT FROM AUTHOR]

The anion‐exchange membrane direct ammonia fuel cell, as a carbon‐free fuel cell type, has recently received increasing attention albeit suffering from high cost of using the platinum‐group metal oxygen reduction reaction (ORR) catalysts. To pave the development of this promising power source, the atomically dispersed transition metal‐nitrogen‐carbon (M‐N‐C) materials with low cost and high ORR performance have allured to investigate their ammonia tolerance during the ORR. Herein, it is initially deconvoluted how compositional and structural elements of FeN4 sites modulate catalyst's performance. Furthermore, ORR catalytic activities of the M‐N‐C (M = Fe, Co or Mn) and Pt/C catalysts are investigated in ammonia‐containing electrolytes, showing that M‐N‐C catalysts have better ammonia tolerance than Pt/C. Among others, the Fe‐N‐C exhibits the best ammonia tolerance with only 4 mV negative shifts of half‐wave potential, 2.7% decrease of current, and negligibly irreversible activity loss. The superior ammonia tolerance of MN4 sites to Pt (111) surface is further confirmed by density functional theory calculations. The adsorption capacity of MN4 for O2 is higher than NH3 and the bonding force between MN4 and O2 is stronger than NH3, whereas opposite adsorption capacity and bonding force trends are observed on Pt (111) surface. [ABSTRACT FROM AUTHOR]

Multifunctional electrocatalysts play an increasingly crucial role in various practical electrochemical energy conversion devices. Especially, on the air cathode of rechargeable zinc–air batteries (ZABs), oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), requiring efficient bifunctional electrocatalysts, are switched during discharging and charging process. Here, supported by the theoretical computations, a facile strategy for the in situ assembly of NiFe‐MOFs nanosheets on heteroatoms‐doped porous activated carbon spheres is developed. The newly designed electrocatalyst (NP‐ACSs@NiFe‐MOFs) shows excellent performance toward bifunctional oxygen electrocatalysis. Specifically, a remarkable low value of potential gap (ΔE = 0.61 V), which is the difference between the potential to reach an OER current density of 10 mA cm−2 and ORR half‐wave potential, is achieved in 0.1 m KOH. Notably, the aqueous ZAB based on NP‐ACSs@NiFe‐MOFs shows super cycle stability with small voltage gap of only 0.79 V when cycled for 450 h at 10 mA cm−2. Also, the quasi‐solid‐state ZAB indicates excellent flexibility and cycling stability. This study presents a facile strategy for the rational integration of different catalytically active components, and can be extended to prepare other strongly competitive multifunctional electrocatalysts. [ABSTRACT FROM AUTHOR]

The two‐electron pathway to form hydrogen peroxide (H2O2) is undesirable for the oxygen reduction reaction (ORR) in iron and nitrogen doped carbon (Fe–N–C) material as it not only lowers the catalytic efficiency but also impairs the catalyst durability. In this study, a relay catalysis pathway is designed to minimize the two‐electron selectivity of Fe–N–C catalyst. Such a design is achieved by introducing two other sites, that is, MnN4 site and α‐Fe(110) face. A combination of transmission electron microscopy image and X‐ray absorption spectra verify the three site formation. Electrochemical test coupled with post‐treatment confirm the improvement of MnN4 site and α‐Fe(110) face on catalyst performance. Theoretical calculation proposes a relay catalysis pathway of three sites, that is, H2O2 released from the FeN4 site migrates to the MnN4 site or α‐Fe(110) face, on which the captive H2O2 is further reduced to H2O. The relay catalysis pathway positioned the as‐prepared catalyst among the best ORR catalysts in both aqueous electrode and alkaline direct methanol fuel cell test. This study examples an interesting relay catalysis pathway of multi‐sites for the ORR, which offers insights into the design of efficient electrocatalysts for fuel cells or beyond. [ABSTRACT FROM AUTHOR]

Oxygen reduction reaction (ORR) is the core reaction of fuel cell/metal–air battery at the cathode, and it is of great significance to develop high‐performance ORR catalyst. Generally speaking, ORR catalysts are classified according to the class of materials they use, which often makes it difficult for different types of catalysts to have a clear connection with some unified optimization mechanism and creates difficulties in designing improvement strategies. Here, this review proposes three major strategies that can affect the activity of ORR catalysts: designing morphology, defect control, and heteroatom doping. The core content of this review is to analyze the principles of various optimization strategies that affect the performance of catalysts individually or synergistically at the micro level. In addition, the problems and challenges still faced in the design of ORR catalysts are sorted out, and possible solutions are proposed. This review makes the research direction of ORR catalysts clearer, and provides theoretical support and new ideas for the design of high‐efficiency electrocatalysts. [ABSTRACT FROM AUTHOR]

Strengthening the interface interaction between metal and support is an efficient strategy to improve the intrinsic activity and reduce the amount of noble metal. Amorphization of support is an effective approach for enhancing the metal‐support interaction due to the numerous surface defects in amorphous structure. In this work, a Pd/a‐MnO2 electrocatalyst containing ultrafine and well‐dispersive Pd nanoparticles and amorphous MnO2 nanosheets is successfully synthesized via a simple and rapid wet chemical method. Differing from the crystal counterpart (Pd/c‐MnO2), the flexible structure of amorphous support can be more favorable to electron transfer and further enhance the metal‐support interaction. The synergism between Pd and amorphous MnO2 results in the downshift of the d‐band center, which is beneficial for the desorption of critical intermediates both in oxygen reduction reaction (ORR) and in ethylene glycol oxidation (EGOR). Due to the lower *.OH desorption energy of Pd/a‐MnO2 surface, the rapid dissociation of *OH from Pd facilitates the formation of H2O in ORR, thus demonstrating superior ORR performance comparable to Pt/C. For EGOR, the presence of amorphous MnO2 promotes the formation of adsorbed OH species, which accelerates the desorption of intermediate CO from Pd sites, and thus exhibits excellent EGOR activity and stability. [ABSTRACT FROM AUTHOR]

Atomically dispersed 3D transitional metal active sites with nitrogen coordination anchored on carbon support have emerged as a kind of promising electrocatalyst toward oxygen reduction reaction (ORR) in the field of fuel cells and metal–air cells. However, it is still a challenge to accurately modulate the coordination structure of single‐atom metal sites, especially first‐shell coordination, as well as identify the relationship between the geometric/electronic structure and ORR performance. Herein, a carbon‐supported single‐atom nickel catalyst is fabricated with boron and nitrogen dual coordination (denoted as Ni‐B/N‐C). The hard X‐ray absorption spectrum result reveals that atomically dispersed Ni active sites are coordinated with one B atom and three N atoms in the first shell (denoted as Ni‐B1N3). The Ni‐B/N‐C catalyst exhibits a half‐wave potential (E1/2) of 0.87 V versus RHE, along with a distinguished long‐term durability in alkaline media, which is superior to commercial Pt/C. Density functional theory calculations indicate that the Ni‐B1N3 active sites are more favorable for the adsorption of ORR intermediates relative to Ni‐N4, leading to the reduction of thermodynamic barrier and the acceleration of reaction kinetics, which accounts for the increased intrinsic activity. [ABSTRACT FROM AUTHOR]

Cobalt‐rich materials have generally been recognized as the prevailing candidates of cathodes for low‐temperature solid oxide fuel cells (LT‐SOFCs, 400–600 °C). Regrettably, their instability and high cost are the major concerns for future commercialization. In response to these drawbacks, here, an A‐site‐deficient low‐cobalt‐containing perovskite‐type oxide, Ba0.95Fe0.7Co0.2Sc0.1O3‐δ (BFCS0.95), as an efficient bifunctional electrode with triple‐conducting (H+|O2−|e−) nature for oxygen‐ion conducting SOFCs (O‐SOFCs) and proton conducting SOFCs (H‐SOFCs) is proposed. BFCS0.95 electrode exhibits impressive versatility in catalyzing oxygen reduction reaction, i.e., ultralow area‐specific resistances (0.072 Ω cm2 for O‐SOFCs and 0.4 Ω cm2 for H‐SOFCs at 550 °C, respectively), extraordinarily high power outputs (1092 mW cm−2 for O‐SOFCs and 419 mW cm−2 for H‐SOFCs at 550 °C, respectively), excellent long‐term durability (>100 h for O‐SOFCs and H‐SOFCs at 600 °C), remarkable reversibility between pure air and CO2‐containing air, and superior resistance against temperature fluctuations. The combined experimental and computational studies elucidate the roles of A‐site deficient state and triple‐conducting behavior, both of which are essential to overall electrochemical performance. Low‐cobalt‐containing feature also makes BFCS0.95 cathode economically competitive among all cobalt‐containing analogues. Overall, the finding paves a highly efficient route to develop bifunctional electrodes for LT‐SOFCs toward a sustainable energy future. [ABSTRACT FROM AUTHOR]

Immobilizing ultrafine high‐entropy Pt alloy nanocrystals (HENs) in porous carbon (PC) with strong interface interaction, which is crucial to efficient and durable oxygen reduction reaction (ORR), remains a challenge. In this study, an anchoring‐carbonization strategy for strongly bonding sub‐3 nm HENs in ordered mesoporous carbon is reported. When heating the orderly assembled composites containing hydrophobic organometallic precursors, structure directing agent F127, and hydrophilic resol, F127 is first removed at moderate temperature region, leading to reduced metallic species directly anchored on partially carbonized resol framework. Then along further temperature increase, in situ carbonization of resol around the HENs, enables more effective plane bonding rather than a single point contact of HENs with carbon. It not only enhances the anchor strength, but also inhibits migration and size growth of HENs along the subsequent high‐temperature carbonization. As a result, senary, septenary, octonary, and denary Pt‐based HENs with average nanocrystal sizes of 2.2, 2.6, 2.9, and 2.8 nm, respectively, are successfully imbedded into porous carbon. In electrocatalytic ORR, porous carbon‐supported senary Pt‐based HENs (6‐HENs/PC) exhibit superior activity and durability, representing a promising electrocatalyst. This strategy allows for the preparation of a range of ultrafine HENs strongly loaded on porous carbon for wide applications. [ABSTRACT FROM AUTHOR]

The surface structure and lattice strain necessary to optimize oxygen reduction reaction (ORR) in a cost‐effective electrocatalyst still requires systematic exploration. Here, by means of oxidative etching of surface confinement stacking faults, a comparative study of the influence of defects on the growth and lattice strain of PtAgPb core‐shell nanoplates for ORR is conducted. Stacking faults are key to forming the core–shell structure and induce tensile and compressive strains to improve catalytic performance of nanoplates. In particular, the compressive strain arising from the optimal composition of nanoplates enhances the ORR activity. The findings show how compressive strain in core–shell nanoplates shift the electronic band structure of platinum (Pt) and weakens chemisorption of oxygenated species. As a result, the obtained PtAgPb‐IV/C nanoplates display superior specific and mass activities (5.06 mA cm−2 and 2.24 A mgPt−1) for ORR that are ≈18 and ≈13 times higher than that of commercial Pt/C, placing it among the best reported Pt based ORR electrocatalysts. Furthermore, the PtAgPb‐IV/C catalyst exhibits substantially improved durability relative to commercial Pt/C catalysts. This work represents a major step toward the deterministic synthesis of Pt‐based multimetallic nanocrystals with specific structure and surface strain for efficient ORR performance. [ABSTRACT FROM AUTHOR]

Photocatalytic hydrogen peroxide (H2O2) production from dioxygen and water is regarded as a promising technology since it can achieve sustainable and green solar‐to‐chemical energy conversion. Herein, oxygen and potassium dual‐heteroatom incorporated polymeric carbon nitride (O/KCN) is rationally designed for H2O2 generation with an ultrahigh rate of 309.44 µM h−1 mg−1, which surpasses that of other C3N4‐based photocatalysts. The enhanced performance can be ascribed to the effective light absorption, fast charge transfer/separation, strong oxygen adsorption, and highly selective two‐electron oxygen reduction reaction (ORR). Density functional theory calculations further confirm that the obtained O/KCN is more favorable than others for electrons migrating from β spin‐orbital to π* orbitals of O2 molecule, thus optimizing O2 molecule activation to promote the formation of intermediate species *OOH and decrease the energy barrier of H2O2 production. This work not only provides in‐depth insights for the photocatalytic H2O2 generation mechanism, but also lays the foundation for further development of highly active photocatalysts for environmental remediation and energy conversion. [ABSTRACT FROM AUTHOR]

Exploiting efficient and stable electrocatalysts with trifunctional catalytic activity toward hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) act has a crucial role with sustainable energy development. Therefore, this study fabricates Co3O4‐RuO2 hollow spheres using a facile and eco‐friendly solvothermal and low temperature oxidation procedure followed by ice water treatment (IW‐Co3O4‐RuO2‐HS). The specific hollow nanostructure could provide sufficient active sites and channels in the electrocatalytic procedure. Then, the IW‐Co3O4‐RuO2‐HS presents small overpotentials toward HER (40 mV@ 10 mA cm−2) and OER (250 mV@ 10 mA cm−2), and high half‐wave potential for ORR (E1/2@ 0.79 V). Remarkably, the IW‐Co3O4‐RuO2‐HS also presents superior catalytic performances toward water‐splitting and flexible rechargeable Zn–air batteries. Furthermore, the water electrolysis can be driven by sustainable energy, including solar, wind, thermal energy, and the assembled flexible rechargeable Zn–air battery. This study provides a valid path to synthesize multifunctional electrocatalysts on energy‐related devices. [ABSTRACT FROM AUTHOR]

Direct electrosynthesis of hydrogen peroxide (H2O2) via two‐electron pathway oxygen reduction reaction (2e− ORR) is crucially essential for a sustainable green economy. However, catalysts inevitably undergo four‐electron pathway oxygen reduction reaction (4e− ORR), resulting in low selectivity and economic benefits. The current challenge is to provide a feasible design strategy for obtaining satisfactory 2e− ORR catalysts with high selectivity. In this work, carbon dots (CDs) act as a cocatalyst to regulate the electron transport kinetics of In2O3/CDs, and the influence of CDs on the ORR pathways of In2O3/CDs is also studied. The electron transfer kinetics on In2O3/CDs composites are studied and analyzed using the transient photo‐induced voltage (TPV) technology. Combining the TPV results and kinetics analysis, it is shown that the electron transport on the In2O3 interface is obviously weakened after the addition of CDs, resulting in a high H2O2 selectivity. It is also demonstrated that CDs can effectively enhance the selectivity of H2O2, and the H2O2 selectivity of In2O3/CDs–10 is in close proximity to 100%, which is much higher than that of pure In2O3 (72%). This work will provide a new understanding and insight into addressing the challenge of low H2O2 selectivity for 2e− ORR catalysts. [ABSTRACT FROM AUTHOR]

Dual–single‐atom catalysts with synergistic effect of adjacent atomic metal sites show a great potential for oxygen reduction reaction (ORR). Herein, a dynamical synthetic strategy is demonstrated for the rational design of dual‐atom catalyst ((Zn, Cu)−NC) with non‐covalent Cu and Zn sites as nitrogen‐doped carbon as support. Owing to the non‐covalent interaction of Zn and Cu atomic pair sites, (Zn, Cu)−NC exhibits significant performances for ORR, surpassing the catalysts with individual Zn or Cu site. The theoretical calculations reveal that (Zn, Cu)−NC can highly activate the linear O2 molecule via the non‐covalent interaction between Zn and Cu pairs, providing the more effective overlap between the metal 3d orbitals and O 2p orbital. Therefore, the ORR activity is optimized with the improvement of the adsorption configuration and adsorption energy of O2. Further, both liquid and quasi‐solid zinc−air batteries with (Zn, Cu)−NC as air cathodes achieve remarkable energy density and stability. This research proposes a facile synthetic strategy to construct single‐atom catalysts and presents an insightful understanding of the non‐covalent interplay between heteronuclear metal atoms in dual‐atom catalysts. [ABSTRACT FROM AUTHOR]

Nitrogen‐doped carbons are among the fastest‐growing class of materials used for oxygen electrocatalysis, namely, the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), thanks to their low cost, environmental friendliness, excellent electrical conductivity, and scalable synthesis. The perspective of replacing precious metal‐based electrocatalysts with nitrogen‐doped carbon is highly desirable for reducing costs in energy conversion and storage systems. In this review, the role of nitrogen and N‐induced structural defects on the enhanced performance of N‐doped carbon electrocatalysts toward the OER and the ORR as well as their applications for energy conversion and storage technologies is summarized. The synthesis of N‐doped carbon electrocatalysts and the characterization of their nitrogen functional groups and active sites for the conversion of oxygen are also reviewed. The electrocatalytic performance of the main types of N‐doped carbon materials for OER/ORR electrocatalysis are then discussed. Finally, major challenges and future opportunities of N‐doped carbons as advanced oxygen electrocatalysts are highlighted. [ABSTRACT FROM AUTHOR]

Surging interests exist in double‐atom catalysts (DACs), which not only inherit the advantages of single‐atom catalysts (SACs) (e.g., ultimate atomic utilization, high activity, and selectivity) but also overcome the drawbacks of SACs (e.g., low loading and isolated active site). The design of DACs, however, remains cost‐prohibitive for both experimental and computational studies, due to their huge design space. Herein, by means of density functional theory (DFT) and topological information‐based machine‐learning (ML) algorithms, we present a data‐driven high‐throughput design principle to evaluate the stability and activity of 16 767 DACs for oxygen evolution (OER) and oxygen reduction (ORR) reactions. The rational design reveals 511 types of DACs with OER activity superior to IrO2 (110), 855 types of DACs with ORR activity superior to Pt (111), and 248 bifunctional DACs with high catalytic performance for both OER and ORR. An intrinsic descriptor is revealed to correlate the catalytic activity of a DAC with the electronic structures of the DAC and its bonding carbon surface structure. This data‐driven high‐throughput approach not only yields remarkable prediction precision (>0.926 R‐squared) but also enables a notable 144 000‐fold reduction of screening time compared with pure DFT calculations, holding promise to drastically accelerate the design of high‐performance DACs. [ABSTRACT FROM AUTHOR]

In sodium–air batteries (SABs), achieving the regulation of the electron transfer number during oxygen reduction reactions (ORRs) in the same electrolyte system remains a significant challenge. In this work, a promising strategy is proposed to dynamically modulate 2e−/4e− transfer in ORRs by regulating the electrolyte structures to realize the different performances of SABs. The 4e− ORR can be realized by decreasing the electrolyte concentration. The solvation sheath of Na+ at dilute concentrations consists mainly of water molecules that hinder the access of Na+ to the cathode surface due to the high solvation energies indicated by theoretical calculations, thereby impeding the 2e− reaction. In contrast, excess free water can easily access the cathode surface and trigger the 4e− ORR. The solvation energies of Na+ can be remarkably reduced by increasing the electrolyte concentration, forming a water‐in‐salt unit, in which the Na+ mainly coordinates with the bis(fluorosulfonyl)imide anion and can be easily released from the solvation sheath. Hence, the 2e− ORR is significantly promoted and becomes the dominant reaction. The SAB based on the 2e− reaction exhibits excellent energy density (15980 Wh kg−1) and good cycle performance (300 times), and the 4e− reaction exhibits excellent power density (12.09 mW cm−2). [ABSTRACT FROM AUTHOR]

Developing efficient Pt‐based alloy as oxygen reduction reaction (ORR) electrocatalysts is critical for practical applications of fuel cells. High‐temperature reduction technology can improve the alloy atoms ordering but inevitably accelerate metal sintering. Here, Pt–Ni nanoparticles (<5 nm) embedded into ordered mesoporous carbon (OMC) matrix are developed, and its confinement effect suppresses nanoparticles sintering up to 900 °C. After an elaborative dealloying process, the surface structure of Pt–Ni nanoparticles changes from a Ni‐rich to Pt‐rich layer (the thickness is about 0.15 nm). The optimized sample (PtNi3@OMC‐A) displays outstanding mass and specific activities of 2.11 A mgPt–1 and 3.23 mA cmPt–2, more than one order of magnitude higher than commercial Pt/C (20 wt%). PtNi3@OMC‐A also exhibits long‐term stability with a negligible activity loss after 10 000 potential cycles. Both experimental results and density functional theory calculations reveal that alloying effect as well as strain effect weaken Pt–O binding strength, thus resulting in an outstanding ORR activity. Furthermore, the high long‐term stability can be attributed to the confinement of OMC, inhibiting the detachment or agglomeration of the embedded alloy nanoparticles. [ABSTRACT FROM AUTHOR]

Single‐atom catalysts (SACs) have shown great potential in the electrochemical oxygen reduction reaction (ORR) toward hydrogen peroxide (H2O2) production. However, current studies are mainly focused on 3d transition‐metal SACs, and very little attention has been paid to 5d SACs. Here, a new kind of W SAC anchored on a porous O, N‐doped carbon nanosheet (W1/NO‐C) is designed and prepared via a simple coordination polymer‐pyrolysis method. A unique local structure of W SAC, terdentate W1N1O2 with the coordination of two O atoms and one N atom, is identified by the combination of aberration‐corrected scanning transmission electron microscopy, X‐ray photoelectron spectroscopy and X‐ray absorption fine structure spectroscopy. Remarkably, the as‐prepared W1/NO‐C catalyzes the ORR via a 2e– pathway with high onset potential, high H2O2 selectivity in the wide potential range, and excellent operation durability in 0.1 m KOH solution, superior to most of state‐of‐the‐art H2O2 electrocatalysts ever reported. Theoretical calculations reveal that the C atoms adjacent to O in the W1N1O2‐C moiety are the most active sites for the 2e– ORR to H2O2 with the optimal binding energy of the HOO* intermediate. This work opens up a new opportunity for the development of high‐performance W‐based catalysts for electrochemical H2O2 production. [ABSTRACT FROM AUTHOR]