Manipulating Charge Distribution at Organic‐inorganic Interface via Optimizing Substituents for Sustainable Water Electrolysis

Abstract The space charge effect induced by high‐quality heterojunctions is essential for efficient electrocatalytic processes. Herein, we delicately manipulate intermolecular charge transfer by modifying substituents (−g=‐CH 3 , ‐H, ‐NO 2 ) with various electron donating/withdrawing capabilities in CoPc‐g/CoS organic–inorganic heterostructures. CoPc‐CH 3 , as a typical electron donor, transfers more electrons to CoS due to the presence of ‐CH 3 , forming the strongest space electric field and thus regulating the dual active sites at the interface. Furthermore, oxygen‐containing intermediates preferentially adsorb on the positively charged CoPc‐CH 3 side, and the rapid accumulation of electrons on the CoS side decelerates catalyst dissolution at the oxygen evolution reaction (OER) potential, ensuring the stable OER process under the optimized adsorbate evolution mechanism. As a result, CoPc‐CH 3 /CoS catalyst exhibits the lowest overpotential and remains stable for 150 h at 0.5 A cm −2 in the membrane electrode assembly electrolyzer. The method provides a novel strategy for accurately regulating the space electric field of heterojunctions.