Copper(II)‐Assisted Ammonia Borane Dehydrogenation: An Insight

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

Ammonia borane (NH3BH3, 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)-CuCo2O4, 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 (ΔWf) 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-CuCo2O4, characterized by a hydrogen evolution rate (HER) of 1125 mLH2(gcat·min)-1, is significantly higher than that of intrinsic CuCo2O4, which has an HER of 705 mLH2(gcat·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 H2O molecules. This process facilitates the elongation and breakage of the O-H bond length in H2O and the B-H bond length in AB, thereby promoting the release of H2.