Electrochemical water oxidation enables the conversion of H₂O to H₂O₂. It holds distinct advantages to the O₂ reduction reaction, which is restricted by the inefficient mass transfer and limited solubility of O₂ in aqueous media. Nonetheless, most reported anodes suffer from high overpotentials (usually >1000 mV) and low selectivity. Electrolysis at high overpotentials often causes serious decomposition of peroxides and leads to declined selectivity. Herein, we report a ZnGa₂O₄ anode with dual active sites to improve the selectivity and resist the decomposition of peroxides. Its faradaic efficiency reaches 82% at 2.3 V versus RHE for H₂O₂ generation through both direct (via OH⁻) and indirect (via HCO₃⁻) pathways. The percarbonate is the critical species generated through the conversion of bicarbonate at Ga-Ga dual sites. The peroxy bond is stable on the surface of the ZnGa₂O₄ anode, significantly improving faradaic efficiency.

The severe degradation of Fe–N–C electrocatalysts during a long-term oxygen reduction reaction (ORR) has become a major obstacle for application in proton-exchange membrane fuel cells. Understanding the degradation mechanism and regeneration of aged Fe–N–C catalysts would be of particular interest for extending their service life. Herein, we show that the by-product hydrogen peroxide during the ORR not only results in the oxidation of the carbon surface but also causes the demetallation of Fe active sites. Quantitative analysis reveals that the Fe demetallation constitutes the main reason for catalyst degradation, while previously reported carbon surface oxidation plays a minor role. We further reveal that post thermal annealing of the aged catalysts can transform the oxygen functional groups on the carbon surface into micropores. These newly formed micropores not only help to increase the active-site density but also the intrinsic ORR activity of the neighbouring Fe–N₄ sites, both contributing to complete activity recovery of aged Fe–N–C catalysts.

Structurally ordered intermetallic structure is an efficient catalyst design strategy to significantly improve the catalytic performance of Pt alloy electrocatalysts for oxygen reduction reaction in fuel cells. However, a high structural ordering degree generally relies on high-temperature annealing, which results in detrimental catalyst particle sintering. Herein, we reveal that the incompatibility between high ordering degree and minimum particle sintering during thermal annealing can be resolved through rational development of structurally ordered Pt ternary alloys. Ordering transformation mediated by high-temperature annealing of three representative Pt ternary alloys (Pt–Fe–Co, Pt–Ni–Co and Pt–Fe–Ni) at a similar Pt composition was systematically studied. It was found that Fe can significantly promote the structural ordering due to a faster atomic diffusion, whereas Co can effectively inhibit the particle sintering. As a result of the synergy between Co and Fe, the ordered PtCoFe catalyst exhibited the highest ordering degree after thermal annealing at 600 °C with the minimum nanoparticle growth, leading to the highest catalytic activity (0.65 A/mg_Pt at 0.9 V, 4 times that of pure Pt catalyst) and best stability (16% drop after 10,000 potential cycles). This study provides important clues for the rational design of high-performance structurally ordered ternary Pt alloys.

Ancient artifacts like bronze often suffer corrosion from water and soil, requiring effective surface coatings to prevent further decay. Herein, we developed a vacuum-assisted method to prevent bronzes as a model from surface corrosion. The graphene oxide (GO)-based coatings can be toughly infiltrated into the rough bronze surfaces with freezing drying. Scanning transmission electron microscopy and energy dispersive X-ray spectroscopy demonstrate the advantages of this method in micro-nano coating protection, namely, the complete coating covering the crack channels. The coated bronze still has a lower corrosion rate than the uncoated sample, confirmed by electrochemical methods under 3 wt.% NaCl solutions. Focused ion beam cross-section imaging confirms a continuous protective layer in the coated sample, contrasting with the compact oxide layer on uncoated bronze. This method offers a promising solution for the sustainable preservation of bronze artifacts and other metal relics.

For actual working conditions of fuel cells, the local mixing potential of transient condition can be as high as 1.2 V or even 1.5 V due to the residual water vapor and air during start-up gas exchange, as well as reverse-current decay. Such high transient potential makes the fuel catalysts extremely susceptible to oxidation, resulting in severe performance degradation. In the past two decades, introducing a second metal element to form an alloy with Pt has been a common way to enhance the activity and stability of fuel cell cathode catalysts. However, elements such as Fe, Co and Ni suffer from dissolution under acidic conditions, which can seriously deactivate the catalysts at the cathode and poison the membrane. In this work, tin oxides-decorated Pt nanocatalysts (SnOx-Pt/C) are constructed by a two-step impregnation method and show much better stability owing to the chemical inertness of tin oxides in acidic media. The SnOx-Pt/C catalysts showed good performance in oxygen reduction reaction test, (specifically, <30% loss in mass activity and <20% in electrochemical activity area after 40,000 cycle scans from 0.6 to 1.2 V. On the one hand, the tin oxides on the Pt surface help to protect surface Pt atoms from oxidation and detachment; on the other hand, the tin oxides favor the adsorption of hydroxyl groups and, meanwhile, weaken the hydroxyl poison on Pt surface. More importantly, SnOx-Pt/C nanocatalysts achieve higher power density of fuel cells in comparison to Pt/C catalysts, and the Ostwald ripening of Pt nanoparticles is suppressed and the cycle life is significantly improved. The SnOx-Pt/C nanocatalysts show advantages including low cost and facile production, which provides a promising way for the development of stable catalysts for high power density fuel cells.