LAUSR

CuO as a catalyst has shown promising application prospects in photocatalytic splitting of water into hydrogen (H2). However, the instability of CuO in amine aqueous solution limits the applications of CuO‐based photocatalysts in the photocatalytic H2 evolution. In this work, a novel dodecahedral nitrogen (N)‐doped carbon (C) coated CuO‐In2O3 p–n heterojunction (DNCPH) is designed and synthesized by directly pyrolyzing benzimidazole‐modified dodecahedral Cu/In‐based metal‐organic frameworks, showing long‐term stability in triethanolamine (TEOA) aqueous solution and excellent photocatalytic H2 production efficiency. The improved stability of DNCPH in TEOA solution is ascribed to the alleviation of electron deficiency in CuO by forming the p–n heterojunction and the protection with coated N‐doped C layer. Based on detailed theoretical calculations and experimental studies, it is found that the improved separation efficiency of photogenerated electron/hole pairs and the mediated adsorption behavior (|∆GH*|→0) by coupling N‐doped C layer with CuO‐In2O3 p–n heterojunction lead to the excellent photocatalytic H2 production efficiency of DNCPH. This work provides a feasible strategy for effectively applying CuO‐based photocatalysts in photocatalytic H2 production.