Anion modulation enhances the internal electric field of CuCo2O4 to improve the catalysis in ammonia borane hydrolysis

Ammonia borane (NH 3 BH 3 , AB) is considered a promising chemical hydrogen storage material. The development of efficient, stable, and economical catalysts for AB hydrolysis is essential for realizing the hydrogen energy economy. In this study, a series of p-p heterojunction catalysts, labeled M (P/S/Cl)-CuCo 2 O 4 , were fabricated using the high-temperature vapor phase method to achieve anionic interface gradient doping. Due to the differences in electronegativity among the anions P/S/Cl–O, electron-rich and electron-deficient regions are generated at the interface, inducing the formation of local p-p heterojunctions with built-in electric fields (BIEF). The difference in work function (ΔW f ) at the interface enhances the strength of the BIEF. Because of the positive influence of the BIEF on the adsorption of intermediates and interfacial behavior, the catalytic performance of P-CuCo 2 O 4 , characterized by a hydrogen evolution rate (HER) of 1125 mL H2 (g cat ·min) −1 , is significantly higher than that of intrinsic CuCo 2 O 4 , which has an HER of 705 mL H2 (g cat ·min) −1 . Its apparent activation energy of only 32.25 kJ/mol is superior to that of previous non-precious metal catalysts. Density functional theory (DFT) further confirms that the construction and enhancement of the BIEF can reduce the band gap, accelerate electron transfer, regulate the metal d-band center, and enhance the adsorption of AB and H 2 O molecules. This process facilitates the elongation and breakage of the O–H bond length in H 2 O and the B–H bond length in AB, thereby promoting the release of H 2 .