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

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 (V_o) and d-band filling (f_d) 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 V_o and f_d of electrocatalysts. Our results, based on the experimental and computational calculation analyses, show that LaNiO₃ (LNO) with the highest contents of V_o and f_d exhibits the most enhanced intrinsic kinetics of EGOR. This is because accelerated charge transfer between LNO and glycolate species by high contents of V_o and f_d weakens the strength of C[sbnd]C bond in glycolate. In particular, the contents of V_o and f_d have a proportional relationship with the specific electrocatalytic activity of LaMO₃, indicating that V_o and f_d can be used as descriptors to predict the specific activity of electrocatalysts. This work highlights the importance of controlling V_o and f_d of electrocatalysts to achieve high performance EGOR.