Deciphering oxygen vacancies and d-band structures as key descriptors for understanding electrocatalytic trend of glycerol oxidation reaction kinetics in alkaline media

Abstract

Despite the advantages of employing electrocatalytic glycerol oxidation reaction (EGOR) as the anode reaction for hydrogen production, the limited understanding of how electrocatalytic activity trends relate to the intrinsic properties of electrocatalysts leads to frequent trial and error in designing high-performance electrocatalyst materials. Herein, we report systematic studies to decipher the correlation between the kinetics of EGOR under alkaline conditions and the concentration of oxygen vacancy (Vo) and d-band filling (fd) of electrocatalysts using a perovskite-based model system. The modulation of transition metal species in the B-site of LaMO3 (M = transition metal species such as Mn, Fe, Co, and Ni) electrocatalysts allows the systematic control of the density of Vo and fd of electrocatalysts. Our results, based on the experimental and computational calculation analyses, show that LaNiO3 (LNO) with the highest contents of Vo and fd exhibits the most enhanced intrinsic kinetics of EGOR. This is because accelerated charge transfer between LNO and glycolate species by high contents of Vo and fd weakens the strength of C-C bond in glycolate. In particular, the contents of Vo and fd have a proportional relationship with the specific electrocatalytic activity of LaMO3, indicating that Vo and fd can be used as descriptors to predict the specific activity of electrocatalysts. This work highlights the importance of controlling Vo and fd of electrocatalysts to achieve high performance EGOR.