Tailoring the electronic structure of cobalt phthalocyanine on BiVO4via substituent effects for enhancing photoelectrochemical water splitting

Abstract

Tailoring the electronic structure of oxygen evolution catalysts (OECs) integrated on BiVO₄ is essential for achieving efficient photoelectrochemical (PEC) water splitting, yet remains challenging. Herein, we demonstrate that the substitution of sulfonic acid, due to its strong electron-withdrawing properties, could effectively tailor the electronic structure of cobalt phthalocyanine (CoPc) on BiVO₄. This electronic structure regulation enhances the interface coupling between CoPc and BiVO₄, promotes the adsorption and activation of OH⁻ intermediates at the central Co active site, and simultaneously enhances the hydrophilicity of the photoanode surface, leading to improved PEC performance. Compared to CoPc/BiVO₄ (2.9 mA cm⁻² at 1.23 V_RHE), the sulfonic acid-functionalized derivative (CoPcTs)/BiVO₄ achieves a significantly higher photocurrent density of 3.9 mA cm⁻² at 1.23 V_RHE. This work not only provides an efficient molecular electronic structure engineering strategy for designing high-performance metal complex OECs, but also significantly contributes to overcoming key kinetic and interfacial challenges in practical PEC water splitting.