Heterogeneity in a metal–organic framework in situ guides engineering Co@CoO heterojunction for electrocatalytic H2 production in tandem with glucose oxidation

Abstract

Herein, defective heterogeneity in a metal–organic framework (MOF) is pioneered as a flexible tactic in generating structural heterojunctions for hydrogen evolution reaction (HER). Competing pillared 4,4′-bipyridine ligand induced linker defects and thereby guided different oxidization effects in ZIF-67 anchored on graphene during pyrolysis. As a result, engineered Co@CoO heterojunctions with different structural features were obtained. Experimental and DFT results elucidated that the prominent spontaneous electron transfer from Co to CoO induced an up-shifted d-band center of core–shell Co@CoO catalyst towards a Volmer–Heyrovsky pathway for HER. Coupling glucose oxidation reaction with HER led to excellent performance in H₂ production and value-added chemicals compared with an overall water-splitting electrolyzer. This work may regulate Mott–Schottky heterojunctions through defective MOF precursors, which could serve as electrocatalysts for H₂ production with lowering voltage input and bolstering biomass conversion.