Se-doped and polyaniline interface modified cobalt phosphide for enhanced water splitting

Regulating the electronic structure and d-band center of metal atoms to develop efficient water-splitting catalysts remains an urgent challenge. Herein, a novel Se-doped and polyaniline (PANI) interface-modified CoP mesoporous composite (Se-CoP/PANI) is prepared via hydrothermal and calcination processes. Compared to CoP, Se-CoP, and CoP/PANI, the OER and HER properties of this catalyst are significantly improved. For OER, the required overpotentials to achieve current densities of 10, 50, and 100 mA cm-2 are 194 mV, 210 mV, and 255 mV, respectively. For HER, the overpotentials needed to maintain current densities of 10, 50, and 100 mA cm-2 are 72 mV, 145 mV, and 202 mV, respectively. Moreover, only 1.507 V cell voltage is required to reach 10 mA cm-2. DFT calculations reveal that through PANI interface coupling and Se doping, the d-orbital electrons of Co on the crystal plane are rearranged and the d-band center is optimized. Crystal orbital Hamilton population (COHP) analysis shows that the anti-bonding state shifts to the unoccupied region, reducing the anti-bonding state, promoting the adsorption for reaction intermediates, resulting in higher intrinsic activity. This work demonstrates the agreement between DFT calculations and experimental results, revealing the effectiveness of the synthesis method and calculation strategy for improving electrochemical performance.