Electrochemical reconstitution of Prussian blue analogue for coupling furfural electro-oxidation with photo-assisted hydrogen evolution reaction

Prussian blue (PB) and its analogues (PBAs) have served as effective electrocatalysts for the oxidation of biomass. However, the PBA-based catalyst is prone to structural changes in the electrochemical process under alkaline medium, which may alter the mechanism and kinetics of the electrocatalytic reaction. Herein, a PBA-based catalytic electrode (NiFe/Ni) is obtained by depositing Ni2[Fe(CN)6] on Ni foam through a wet chemistry method. It is found that Ni2[Fe(CN)6] converts to high-valence NiOOH during the electrochemical process in alkaline medium. Meanwhile, the polarons generated by lattice deformation in Ni2[Fe(CN)6] can transform into NiOOH with oxygen vacancies (v-NiOOH). The obtained v-NiOOH endows the catalytic electrode with superior performance for the electro-oxidation of furfural compounds to furoic acids. The in-situ ATR-FTIR and furfural temperature-programmed desorption further prove that the fast furfural electro-oxidation kinetics can be ascribed to the high-flux furfural adsorption ability of the v-NiOOH. In addition, the electrocatalytic oxidation of furfural and photo-assisted hydrogen evolution reaction are integrated into a water-splitting electrolyzer. Compared with the conventional water-splitting electrolyzer, the integrated electrolyzer can reduce the cell voltage by 480 mV at 100 mA cm−2. This work proves the electrochemical reconstitution of the PBA-based catalysts for biomass oxidation under alkaline electrolyte, which provides a new way for the design of PBA-based electrocatalysts.