Tandem paired electrodes for efficient hydrogen evolution coupled with biomass valorization

It is desirable that catalysts preparation and subsequent application can be driven by only one set of equipment, enabling efficient system integration, hydrogen generation and value-added chemicals acquisition. Here we demonstrate a strategy of tandem paired electrodes, which contain a deeply foaming electrode with vacancy as cathode (DF/cNF) for electroreductive water splitting, and a wrinkled NiMoO 4 -Ni(OH) 2 heterojunction electrode serving for anode (NiMo-Ni/aNF) to electrooxidize biomass conversion. For integrally paired electrodes, DF/cNF shows excellent HER performance with 43 mV overpotential at 10 mA cm −2 , and NiMo-Ni/aNF exhibits good biomass oxidation activity, such as almost 100 % 5-hydroxymethylfurfural conversion and 96.4 % 2,5-furandicarboxylic acid selectivity. Remarkably, in situ Raman spectra and operando scanning electrochemical microscopy (SECM) analysis indicate NiMoO 4 -Ni(OH) 2 heterojunctions stabilize the vital Ni III intermediate role in oxidation reaction. Density functional theory (DFT) results further prove the advantage of Ni vacancy for enhanced HER activity and interface for improving biomass oxidation performance. This work delivers a novel system of tandem paired electrodes and highlights precise control for catalysts by geometric and electronic structural engineering.