Interfacial Hydrogen Spillover on Pd-TiO<sub>2</sub> with Oxygen Vacancies Promotes Formate Electrooxidation
Zheng Tang, Yongjia Li, Kaixin Zhang, Xiaoxuan Wang, Shiyu Wang, Yanfei Sun, Huiying Zhang, Shuyuan Li, Jinrui Wang, Xueying Gao, Zishan Hou, Lanlan Shi, Zhi Hao Yuan, Kaiqi Nie, Jiangzhou Xie, Zhiyu Yang, Yi‐Ming Yan
Abstract
Pd-based catalysts are crucial in direct formate fuel cells owing to their high stability and selectivity for the formate oxidation reaction (FOR) to CO 2, avoiding carbonaceous poisoning species (e.g., CO ad, CH x ) in alkaline media. However, the kinetics of Pd-based electrocatalysts are considerably impeded by the unfavorable adsorption of hydrogen species (H ad ), which serve as the primary intermediators and occlude the active sites. Herein, we crafted electron-rich Pd nanoparticles on a TiO 2 support with oxygen vacancies (Pd/O v -TiO 2 ) to improve H ad desorption. The as-prepared Pd/O v -TiO 2 exhibited a high mass activity of 4.16 A mg Pd –1, outperforming Pd/TiO 2 without oxygen vacancies and commercial Pd/C by 1.41 and 2.72 times, respectively. Experimental characterizations and density functional theory calculations revealed that the oxygen-vacant TiO 2 can concurrently downshift the d-band center of Pd and facilitate hydrogen spillover, thereby accelerating H ad desorption and FOR kinetics. Our findings provide a strategy to refine Pd-based catalysts for broader electrochemical uses.