An in Situ Deposited Covalent Triazine Framework Photocathode for Electric Bias‐Free Solar‐to‐Hydrogen Peroxide Conversion in a Photoelectrochemical Cell

Abstract

ABSTRACT Innovative technology for sustainable hydrogen peroxide (H 2 O 2 ) production in neutral aqueous media using solar energy displaces the current industrial production of H 2 O 2 , which primarily relies on the Riedel‐Pfleiderer process involving critical issues on the use of organic solvents and high energy consumption to supply H 2 gas. Photoelectrochemical (PEC) O 2 reduction to produce H 2 O 2 by visible light irradiation was approached by a new covalent triazine framework photocathode with carbazole donor moieties (Cz‐CTF) in situ‐deposited on a mesoporous indium tin oxide (meso‐ITO) film (Cz‐CTF/meso‐ITO). The Cz‐CTF/meso‐ITO photocathode exhibited outstanding performances with IPCE of 4.7 and 2.9% (at 420 nm and 1.05 V versus reversible hydrogen electrode (RHE)), Faraday efficiency (FE H2O2 ) of 96 and 95% for H 2 O 2 production at pH 3.0 and 7.0, respectively, and the high onset potential of ≈1.4 V for PEC O 2 reduction among the state‐of‐the‐art organic polymer photocathodes. The visible light‐driven overall H 2 O 2 production using water as an electron source was first achieved without electric bias in a two‐electrode system in a neutral aqueous medium (pH 7.0) by coupling the Cz‐CTF/meso‐ITO photocathode with a BiVO 4 ‐based photoanode for water oxidation. This sheds light on the sustainable method for solar‐driven overall H 2 O 2 production in neutral aqueous media in the future industry.