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Abstract:
Direct synthesis of hydrogen peroxide (H2O2) through electrochemical oxygen reduction has gained close attention yet remains a great challenge due to the slow kinetics. Herein, combining with the virtues of the native high energy state and fascinating surface environment of metastable materials and doping strategy, an efficient phosphorus-optimized metastable hexagonal-close-packed phase nickel catalyst (P-hcp Ni), belonging to the space group (P63/mmc, 194), with P doping is demonstrated. Significantly, it achieves high selectivity of 97 and a high intrinsic turnover frequency of 2.34 s−1, much better than those of the stable face-centered-cubic Ni catalyst. It also displays high stability with remaining in the metastable phase after the stability test. More importantly, P-hcp Ni also achieves a productivity of 4917.2 mmol gNi−1 h−1 and an accumulated concentration of (H2O2) of 2.38 mol L−1 after 130 h stability test in pure water with a solid electrolyte. Further investigation reveals that the P doping not only greatly enhances the stability of metastable phase, but also weakens the *OOH adsorption on the active site, promoting the high production of H2O2 in the neutral media. © 2023 Wiley-VCH GmbH.
