Phosphorus Regulates Coordination Number and Electronegativity of Cobalt Atomic Sites Triggering Efficient Photocatalytic Water Splitting
Yuqi Zhao, Xi Wu, Hengliang Wang, Ming Ma, Jian Tian, Xin Wang
Abstract
High Resolution Image Download MS PowerPoint Slide Optimizing the local electronic structure of a single-atom catalyst (SAC) is crucial for efficient photocatalytic hydrogen evolution reactions. This study synthesized a Co-P 4 /g-C 3 N 4 heterostructure by selective phosphidation of the Co metal–organic framework/graphitic carbon nitride (Co-MOF/g-C 3 N 4 ), converting the Co-O 6 configuration into a highly electronegative, coordinatively unsaturated Co-P 4 configuration anchored to a carbon matrix. P-doping induces strong charge redistribution, shifting the d -band center toward the Fermi level, transforming the Co sites from an electron-deficient state to an electron-rich state, and resulting in a significant reduction in the free energy barrier for HER to −0.08 eV. The Co-P 4 / g -C 3 N 4 heterostructure demonstrated a HER rate of 13.51 mmol g –1 h –1, approximately 4.82–8.35 times greater than those of photocatalysts loaded with noble metals. The apparent quantum efficiency (AQE) was 28.45% at 380 nm. The synergistic effect of the low coordination number and high electronegativity metal sites significantly enhances the photocatalytic HER performance.