Cationic vacancies accelerate the generation of CoOOH in perovskite hydroxides for the electrooxidation of biomass

Abstract

The electrocatalytic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid is an environmentally friendly strategy for enhancing biomass energy. Defect engineering has been demonstrated as a promising strategy for increasing the catalytic activity of the HMF oxidation reaction (HMFOR). However, the exact function of cationic vacancies has been rarely studied due to the higher formation energy. Herein, Co-based perovskite hydroxide [SnCo(OH)₆] was used as a mode material to investigate the critical role of cationic vacancies in HMFOR. A simple plasma-engraving strategy was applied to prepare Co-based perovskite hydroxides with abundant Sn cation vacancies [SnCo(OH)₆-V_Sn]. Compared to SnCo(OH)₆, the advanced potential of SnCo(OH)₆-V_Sn is 200 mV, indicating that cationic vacancies are a promising strategy for enhancing the performance of the HMFOR. Operando characterization and theoretical calculations revealed that the short-range ordered amorphous structure broke the periodicity of the crystalline lattice to produce a large number of cation vacancies. Subsequently, these vacancies facilitated the transfer of electrons, the oxidation of transition metal Co at the B site to a higher valence state, and the formation of deprotonated Co(OH)₂ active species, thereby promoting the adsorption of HMF on the catalyst surface. Thus, the current study provided significant insights into the critical role of cationic vacancies in enhancing the electrocatalytic performance of biomass upgrading via Co-based catalysts.