Built‐in Electric Field in Yolk Shell CuO‐Co 3 O 4 @Co 3 O 4 with Modulated Interfacial Charge to Facilitate Hydrogen Production from Ammonia Borane Methanolysis Under Visible Light

Abstract Developing highly efficient and low‐cost catalysts is an endless challenge in the field of producing H 2 from ammonia borane (AB). Herein, the manufacture of yolk‐shell CuO‐Co 3 O 4 @Co 3 O 4 nanocomposites are reported by using Cu 2 O@CuO as a template, in which CuO‐Co 3 O 4 is encapsulated into the Co 3 O 4 hollow nanocubes. Due to the unique morphology and built‐in electric field (BIEF) induced by the CuO‐Co 3 O 4 interface, the CuO‐Co 3 O 4 @Co 3 O 4 nanocomposites display remarkable catalytic activity in AB methanolysis. The turnover frequency (TOF) is 24.8 min ‐1 in the absence of light and significantly increases to 33.9 min ‐1 when exposed to visible light. The experimental and theoretical calculations demonstrate that charge migration from CuO to Co 3 O 4 results in the formation of dual active sites (Cu and Co sites) in charge of adsorption and activation of CH 3 OH and AB, respectively. Visible light‐induced acceleration is likely caused by type‐II heterojunction, which allows a large number of photogenerated electrons to accumulate in the CuO conduction band. This effectively activates the adsorbed CH 3 OH on the Cu site, rendering it easier to break the O−H bond. A plausible reaction mechanism involved the activation of the O−H bond of CH 3 OH, as the RDS is proposed according to the FT‐IR and kinetic isotope effect (KIE) experiments. This work offers an avenue to rationally design high‐performance yolk‐shell catalyst for rapid hydrogen production from AB methanolysis reaction under visible light.