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

Abstract

The desired salt-free neutral H2O2 electrosynthesis via a 2-electron oxygen reduction reaction (2e−-ORR) remains challenging due to the absence of efficient electrocatalysts and its well-matched practical process. Herein we report an important progress and understanding of neutral H2O2 electrosynthesis of 2e−-ORR at a scalable rate through combining crystalline nitrogen-doped carbon-anchored Fe3O4 nanoparticles (NPs, Fe3O4@TNC), derived from the pyrolysis of the mixture of g-C3N4 and Fe@Tpy, with the 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 the limiting diffusion current density up to 5.2 mA cm−2 at 0 V vs RHE, respectively. It is first revealed that the exposed (220) facet of Fe3O4 NPs obtains a thermodynamically optimal binding of *OOH and rapid *OOH-mediated kinetic pathway. Integration of Fe3O4@TNC into scalable cells that exhibited superior performance and techno-economic potential of neutral H2O2 electrosynthesis, where the industrial-relevant current densities are achieved at the remarkable real-time continuous production while maintaining relatively large Faradaic efficiency. This work with in-depth mechanistic insights into neutral H2O2 electrosynthesis and provides an advanced and economical process for integrating efficient electrocatalysts and scalable electrolyzer for industrial-relevant neutral H2O2 production.