Amorphous-crystalline heterostructure: Efficient catalyst for biomass oxidation coupled with hydrogen evolution.

An amorphous-crystalline heterostructure (Ni/NiMoO 4 /NiCo(OH) x) is prepared by wet chemical etching method for HMFOR and HER. The interaction between NiCo(OH) x and Ni/NiMoO 4 heterointerface regulates the electronic structure of catalyst to facilitate the adsorption behavior of reaction intermediates, thereby showing good performance for HMFOR-assisted H 2 production. [Display omitted] • Coupling of crystalline and amorphous materials provides abundant active sites. • Interactions between heterointerfaces optimize the adsorption of intermediates. • High FDCA selectivity (99.8%) and stability (40 cycles) for HMF oxidation. • Only 1.34 V is required to reach 10 mA cm−2 for HMFOR-assisted H 2 production. The development of catalysts with high activity, selectivity, and stability is critical for biomass upgrading coupled with hydrogen evolution. In this study, we present a simple method for fabricating crystalline-amorphous phase heterostructures using the etching effect of the acidic medium generated during cobalt salt hydrolysis, resulting in the formation of NiCo(OH) x -modified Ni/NiMoO 4 nanosheets electrode (NiCo(OH) x /Ni/NiMoO 4 /NF). The nanosheets array formed during the synthesis process enlarges the surface area of the prepared catalyst, which facilitates the exposure of electrochemically active sites and improves mass transfer. Unexpectedly, the strong coupling interactions between the amorphous-crystalline heterointerface optimize the adsorption of reaction molecules and the corresponding charge transfer process, consequently boosting the catalytic activity for the 5-hydroxymethylfurfural oxidation reaction (HMFOR) and hydrogen evolution reaction (HER). Specifically, NiCo(OH) x /Ni/NiMoO 4 /NF catalyst requires only 1.34 V to obtain a current density of 10 mA cm−2 for HMFOR-coupled H 2 evolution, and operates stably for 13 consecutive cycles with good product selectivity. This work thus provides insights into the design of efficient and robust catalysts for HMFOR-assisted H 2 evolution. [ABSTRACT FROM AUTHOR]