Optimizing the Electronic Structure of IrO<sub><i>x</i></sub> Sub-2 nm Clusters via Tunable Metal Support Interaction for Acidic Oxygen Evolution Reaction
Qiuyan Chu, Yanpu Niu, Haolan Tao, Honglai Liu, Quan Li, Cheng Lian, Jingkun Li
Abstract
Iridium-based electrocatalysts are the most promising candidates for the acidic oxygen evolution reaction (OER). Considering their high cost and scarcity, it is imperative to maximize atom utilization and enhance the intrinsic activity of iridium. In this work, IrO x sub-2 nm clusters are stabilized on TiO 2 supports via metal support interaction (MSI) induced by vacancy defects in TiO 2 . The strength of MSI is readily tuned by the type of vacancies: oxygen vacancies in TiO 2 (V O -TiO 2 ) induce the adsorbed MSI with relatively weak strength, while titanium vacancies in TiO 2 (V Ti -TiO 2 ) lead to the strong embedded MSI. The tunable MSI further modulates the electronic structure of IrO x sub-2 nm clusters. IrO x /V O -TiO 2 with adsorbed MSI exhibits an optimized electronic structure with a downshifted d-band center of IrO x, resulting in a reduced binding energy with oxygen and a low energy barrier of the rate-determining step for OER. Consequently, IrO x /V O -TiO 2 delivers an activity twice that of commercial IrO 2 and a good stability for 120 h in a practical proton exchange membrane water electrolyzer. Our study provides a guideline for the rational design of acidic OER catalysts based on modulating the electronic structure of IrO x sub-2 nm clusters via tunable MSI.