Crystalline nitrogen-doped-carbon anchored well-dispersed Fe3O4 nanoparticles for real-time scalable neutral H2O2 electrosynthesis†

Abstract

Salt-free neutral H₂O₂ electrosynthesis via a 2-electron oxygen reduction reaction (2e⁻-ORR) remains challenging owing to the absence of efficient electrocatalysts and well-matched practical processes. Herein, we report an important progress and understanding of neutral H₂O₂ electrosynthesis of 2e⁻-ORR at a scalable rate using crystalline nitrogen-doped-carbon anchored Fe₃O₄ nanoparticles (NPs, Fe₃O₄@TNC) as efficient electrocatalysts, which were derived from the pyrolysis of a mixture of g-C₃N₄ and Fe@Tpy, achieving a salt-free, real-time and continuous H₂O₂ production process. Based on rotating ring-disk electrodes, Fe₃O₄@TNC achieved nearly 100% selectivity from 0 to 0.75 V vs. RHE and a limiting diffusion current density up to 5.2 mA cm⁻² at 0 V vs. RHE. It was revealed that the exposed (220) facet of Fe₃O₄ NPs obtained a thermodynamically optimal binding of *OOH and rapid *OOH-mediated kinetic pathway. The integration of Fe₃O₄@TNC into scalable cells exhibited superior performance and techno-economic potential for neutral H₂O₂ electrosynthesis as industrially relevant current densities were achieved with remarkable real-time continuous production while maintaining relatively large faradaic efficiency. This work provides in-depth mechanistic insights into neutral H₂O₂ electrosynthesis and offers an advanced and economical process for integrating efficient electrocatalysts and scalable electrolyzer for industrially relevant neutral H₂O₂ production.