Doping Mo Triggers Charge Distribution Optimization and P Vacancy of Ni₂P@Ni₁₂P₅ Heterojunction for Industrial Electrocatalytic Production of Adipic Acid and H₂.

Abstract

Synchronous electrosynthesis of value-added adipic acid (AA) and H₂ is extremely crucial for carbon neutrality. However, accomplishing the preparation of AA and H₂ at large current density with high selectivity is still challenging. Herein, a robust Mo-doped Ni₂P@Ni₁₂P₅ heterojunction with more P vacancies on Ni foam is proposed for accomplishing simultaneous electrooxidation of cyclohexanol (CHAOR) to AA and hydrogen evolution reaction (HER) at large current density. Combined X-ray photoelectron spectroscopy, X-ray absorption fine structure, and electron spin resonance confirm that Mo incorporation induces the charge redistribution of Ni₂P@Ni₁₂P₅, where Mo adjusts electrons from Ni to P, and triggers more P vacancies. Further experimental and theoretical investigations reveal that the d-band center is upshifted, optimizing adsorption energies of water and hydrogen on electron-rich P site for boosting HER activity. Besides, more Ni³⁺ generated from electron-deficient Ni induced by Mo, alongside more OH* triggered from more P vacancies concurrently promote CHA dehydrogenation and C─C bond cleavage, decreasing energy barrier of CHAOR. Consequently, a two-electrode flow electrolyzer achieves industrial current density (>230 mA cm^-2) with 85.7% AA yield, 100% Faradaic efficiency of H₂ production. This study showcases an industrial bifunctional electrocatalyst for AA and H₂ production with high productivity.