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An efficient and facile water dissociation process plays a crucial role in enhancing the activity of alkaline hydrogen evolution reaction (HER). Considering the intricate influence between interfacial water and intermediates in typical catalytic systems, meticulously engineered catalysts should be developed by modulating electron configurations and optimizing surface chemical bonds. Here, a high‐entropy double perovskite (HEDP) electrocatalyst La2(Co1/6Ni1/6Mg1/6Zn1/6Na1/6Li1/6)RuO6, achieving a reduced overpotential of 40.7 mV at 10 mA cm−2 and maintaining exemplary stability over 82 h in a 1 m KOH electrolyte is reported. Advanced spectral characterization and first‐principles calculations elucidate the electron transfer from Ru to Co and Ni positions, facilitated by alkali metal‐induced super‐exchange interaction in high‐entropy crystals. This significantly optimizes hydrogen adsorption energy and lowers the water decomposition barrier. Concurrently, the super‐exchange interaction enhances orbital hybridization and narrows the bandgap, thus improving catalytic efficiency and adsorption capacity while mitigating hysteresis‐driven proton transfer. The high‐entropy framework also ensures structural stability and longevity in alkaline environments. The work provides further insights into the formation mechanisms of HEDP and offers guidelines for discovering advanced, efficient hydrogen evolution catalysts through super‐exchange interaction. [ABSTRACT FROM AUTHOR]

Developing efficient electrocatalysts for acidic electrosynthesis of hydrogen peroxide (H2O2) holds considerable significance, while the selectivity and stability of most materials are compromised under acidic conditions. Herein, we demonstrate that constructing amorphous platinum–selenium (Pt–Se) shells on crystalline Pt cores can manipulate the oxygen reduction reaction (ORR) pathway to efficiently catalyze the electrosynthesis of H2O2 in acids. The Se2‒Pt nanoparticles, with optimized shell thickness, exhibit over 95% selectivity for H2O2 production, while suppressing its decomposition. In flow cell reactor, Se2‒Pt nanoparticles maintain current density of 250 mA cm−2 for 400 h, yielding a H2O2 concentration of 113.2 g L−1 with productivity of 4160.3 mmol gcat−1 h−1 for effective organic dye degradation. The constructed amorphous Pt–Se shell leads to desirable O2 adsorption mode for increased selectivity and induces strain for optimized OOH* binding, accelerating the reaction kinetics. This selenization approach is generalizable to other noble metals for tuning 2e‒ ORR pathway. Developing efficient catalysts for acidic electrosynthesis of H2O2 is desirable, while most materials are compromised in acidic conditions. Here, the authors report that constructing amorphous Pt–Se shells on crystalline Pt cores can regulate the reaction pathway to efficiently produce H2O2 in acid. [ABSTRACT FROM AUTHOR]

Anionic redox allows the direct formation of O─O bonds from lattice oxygens and provides higher catalytic in the oxygen evolution reaction (OER) than does the conventional metal ion mechanism. While previous theories have predicted and experiments have suggested the possible O─O bond, it has not yet been directly observed in the OER process. In this study, operando soft X‐ray absorption spectroscopy (sXAS) at the O K‐edge and the operando Raman spectra is performed on layered double CoFe hydroxides (LDHs) after intercalation with [Cr(C2O4)3]3−, and revealed a three‐step oxidation process, staring from Co2+ to Co3+, further to Co4+ (3d6L), and ultimately leading to the formation of O─O bonds and O2 evolution above a threshold voltage (1.4 V). In contrast, a gradual oxidation of Fe is observed in CoFe LDHs. The OER activity exhibits a significant enhancement, with the overpotential decreasing from 300 to 248 mV at 10 mA cm−2, following the intercalation of [Cr(C2O4)3]3− into CoFe LDHs, underscoring a crucial role of anionic redox in facilitating water splitting. [ABSTRACT FROM AUTHOR]

Anionic redox chemistry can surpass theoretical limits of conventional layered oxide cathodes in energy density. A recent model system of sodium‐ion batteries, O3‐NaLi1/3Mn2/3O2, demonstrated full anionic redox capacity but is limited in reversibility and kinetics due to irreversible structural rearrangement and oxygen loss. Solutions to these issues are missing due to the challenging synthesis. Here, we harness the unique structural richness of sodium layered oxides and realize a controlled ratio of P2 structural intergrowth in this model compound with the overall composition maintained. The resulted O3 with 27 % P2 intergrowth structure delivers an excellent initial Coulombic efficiency of 87 %, comparable to the state‐of‐the‐art Li‐rich NMCs. This improvement is attributed to the effective suppression of irreversible oxygen release and structural changes, evidenced by operando Differential Electrochemical Mass Spectroscopy and X‐ray Diffraction. The as‐prepared intergrowth material, based on the environmentally benign Mn, exhibits a reversible capacity of 226 mAh g−1 at C/20 rate with excellent cycling stability stemming from the redox reactions of oxygen and manganese. Our work isolates the role of P2 structural intergrowth and thereby introduces a novel strategy to enhance the reversibility and kinetics of anionic redox reactions in sodium layered cathodes without compromising capacity. [ABSTRACT FROM AUTHOR]

Surface reconstruction or elemental leaching is generally involved in the oxygen evolution reaction (OER) process on transition metal-based oxides during alkaline water electrolysis, which gives rise to both opportunities and challenges for the development of OER electrocatalysts. Reaction-derived metal (oxy)hydroxides have been proven to be the actual active species for many metal oxides but have suffered from the dissolution of active elements. Here, the construction of a dynamically stable CoFe (oxy)hydroxide OER nanocatalyst is proposed, which delivers a low overpotential of 253 mV at 10 mA cm−2 and high mass activity (3.78 A mg−1 at an overpotential of 300 mV), among the highest of all the hydroxides reported previously. The in situ synthesized nanocatalyst acts as a stable CoOxHy host for Fe adsorption and facilitates active Co–O–Fe motif formation. The weak metal–O coordination environment and hydrophilic surface morphology lead to superficial mass transfer. The drawbacks of Fe depletion for conventional CoFe (oxy)hydroxides are overcome, attributed to tardy lattice oxygen ion diffusion and dynamic Fe-saturated dual metal active sites, which lead to a stable performance for over 100 h. This study provides a design strategy for OER electrocatalysts with both high mass activity and durability, which shows application prospects for large-scale electrochemical water splitting. [ABSTRACT FROM AUTHOR]

This study unveils a novel concept of symmetric protonic ceramic fuel cells (symm‐PCFCs) with the introduction of a self‐recoverable electrode design, employing the innovative material BaCo0.4Fe0.4Zr0.1Y0.1O3‐δ (BCFZY). This research marks a significant milestone as it demonstrates the bi‐functional electrocatalytic activity of BCFZY for the first time. Utilizing density functional theory simulations, the molecular orbital interactions and defect chemistry of BCFZY are explored, uncovering its unique capability for the reversible exsolution and dissolution of Co‐Fe nanoparticles under redox conditions. This feature is pivotal in promoting both hydrogen oxidation and oxygen reduction reactions. Leveraging this insight, a cell is fabricated exhibiting high electrocatalytic activity and fuel flexibility as evidenced by the peak power densities of ≈350, 287, and 221 mW cm−2 (at 600 °C) with hydrogen, methanol, and methane as fuels, respectively. Experiments also show that the reversible exsolution/dissolution mitigates performance degradation, enabling prolonged operational life through self‐recovery. This approach paves the way for novel, advanced, durable, and commercially viable symm‐PCFCs. [ABSTRACT FROM AUTHOR]

Protonic ceramic cells show great promises for electrochemical energy conversion and storage, while one of the key challenges lies in fabricating dense electrolytes. Generally, the poor sinterability of most protonic ceramic electrolytes, such as BaZr0.1Ce0.7Y0.1Yb0.1O3‐δ, is attributed to the Ba evaporation at high temperatures. In a systematic and comparative study of BaCeO3 and BaZrO3, the results demonstrated that Ba tends to segregate to grain boundaries rather than evaporate. Additionally, thermal reduction of Ce4+ to Ce3+ promotes the displacement of Ce to the Ba‐site or the exsolution of CeO2 phase, leading to an abnormal lattice shrinkage of perovskite phase and hindering the electrolyte densification. Contrary to previous beliefs that Ba deficiency inhibits the electrolyte sintering, the findings indicate that it surprisingly promotes the sintering of BaZrO3 perovskites, while excess Ba negatively affects its sintering behavior due to the accumulation of Ba species at grain boundaries. As to BaCeO3, excess Ba improves electrolyte sintering by suppressing the Ce exsolution at high temperatures. Meanwhile, Co‐doping Zr and Ce in the B‐site of protonic perovskite can optimize the sintering characteristic. These findings offer new insights into sintering of protonic perovskites and provide guidance for the development of new protonic devices. [ABSTRACT FROM AUTHOR]

The structural tailoring of Pt‐based catalysts into 1D nanowires for oxygen reduction reactions (ORR) has been a focus of research. Mo(CO)6 is commonly used as a morphological modifier to form nanowires, but it is found that it inevitably leads to Mo doping. This doping introduces unique electrochemical signals not seen in other Pt‐based catalysts, which can directly reflect the stability of the catalyst. Through experiments, it is demonstrated that Mo doping is detrimental to ORR performance, and theoretical calculations have shown that Mo sites that are inherently inactive also poison the ORR activity of the surrounding Pt. Therefore, a novel gas‐assisted technique is proposed to replace Mo(CO)6 with CO, which forms ultrafine nanowires with an order of magnitude increase in length, ruling out the effect of Mo. The catalyst performs at 1.24 A mgPt−1, 7.45 times greater than Pt/C, demonstrating significant ORR mass activity, and a substantial improvement in stability. The proton exchange membrane fuel cell using this catalyst provides a higher power density (0.7 W cm−2). This study presents a new method for the preparation of ultra‐long nanowires, which opens up new avenues for future practical applications of low‐Pt catalysts in PEMFC. [ABSTRACT FROM AUTHOR]

Electric-field control of magnetism requires deterministic control of the magnetic order and understanding of the magnetoelectric coupling in multiferroics like BiFeO3 and EuTiO3. Despite this critical need, there are few studies on the strain evolution of magnetic order in BiFeO3 films. Here, in (110)-oriented BiFeO3 films, we reveal that while the polarization structure remains relatively unaffected, strain can continuously tune the orientation of the antiferromagnetic-spin axis across a wide angular space, resulting in an unexpected deviation of the classical perpendicular relationship between the antiferromagnetic axis and the polarization. Calculations suggest that this evolution arises from a competition between the Dzyaloshinskii-Moriya interaction and single-ion anisotropy wherein the former dominates at small strains and the two are comparable at large strains. Finally, strong coupling between the BiFeO3 and the ferromagnet Co0.9Fe0.1 exists such that the magnetic anisotropy of the ferromagnet can be effectively controlled by engineering the orientation of the antiferromagnetic-spin axis.