Surface hydroxylation engineering to boost oxygen evolution reaction on IrO2/TiO2 for PEM water electrolyzer

CL Yang and WH Ling and YP Zhu and YX Yang and S Dong and CY Wu and ZR Wang and S Yang and J Li and GL Wang and YF Huang and B Yang and QQ Cheng and Z Liu and H Yang, APPLIED CATALYSIS B-ENVIRONMENT AND ENERGY, 358, 124462 (2024).

DOI: 10.1016/j.apcatb.2024.124462

Dynamic evolutionary hypervalent Irx+ species (HVI) plays a decisive role in promoting the catalytic activity towards acidic oxygen evolution reaction (OER) on Ir-based electrocatalysts, but regulating the efficient formation of HVI remains a big challenge. Herein we propose surface hydroxylation engineering to accelerate the formation of HVI along the OER process on the OH-rich IrO2/TiO2 electrocatalyst. In- situ/operando spectroscopies demonstrate that the high concentration OH ligand accelerates the formation of HVI. DFT calculation clarifies that the dynamically evolved HVI benefits to weakening the adsorption free energy and thus boosting the OER kinetics. Differential electrochemical mass spectrometry with O-18 isotope labelling experiment further unveils that the OH ligand directly participates in the OER cycle, facilitating the rapid oxidation of Ir3+ to Ir5+ and the O-O bond formation. PEM water electrolyzer with the optimized IrO2/TiO2 electrocatalyst delivers a low cell voltage of 1.787 V at 2 Acm(-2) with an inaccessible low Ir usage of ca. 0.08 g/kW, while maintaining a good stability over 350 h, with an estimated cost of US$0.88 kg(-1) of H-2, much lower than 2026 US-DOE target.

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