In Situ Probe of the Hydrogen Oxidation Reaction Intermediates on PtRu a Bimetallic Catalyst Surface by Core-Shell Nanoparticle-Enhanced Raman Spectroscopy.

In situ monitoring of the evolution of intermediates and catalysts during hydrogen oxidation reaction (HOR) processes and elucidating the reaction mechanism are crucial in catalysis and energy science. However, spectroscopic information on trace intermediates on catalyst surfaces is challenging to obtain due to the complexity of interfacial environments and lack of in situ techniques. Herein, core-shell nanoparticle-enhanced Raman spectroscopy was employed to probe alkaline HOR processes on representative PtRu surfaces. Direct spectroscopic evidence of an OH ad intermediate and RuO x (Ru(+3)/Ru(+4)) surface oxides is simultaneously obtained, verifying that Ru doping onto Pt promotes OH ad adsorption on the RuO x surface to react with H ad adsorption on the Pt surface to form H 2 O. In situ Raman, XPS, and DFT results reveal that RuO x coverage tunes the electronic structure of PtRuO x to optimize the adsorption energy of OH ad on catalyst surfaces, leading to an improvement in HOR activity. Our findings provide mechanistic guidelines for the rational design of HOR catalysts with high activity.