Suppressed Hydrogen Peroxide Generation and Enhanced Electrochemical Hydrogen Oxidation Activity for Tungsten-Oxide-Modified Platinum Surface Model Catalyst System

Abstract

Suppressed hydrogen peroxide (H 2 O 2 ) generation and practical H 2 oxidation reaction (HOR) activity of the anode catalyst surface is crucial to improve proton exchange membrane fuel cells (PEMFCs) performance. Here, the influence of surface modification on H 2 O 2 generation and HOR activity by introducing tungsten suboxides (WO x ) was investigated for platinum catalyst surfaces. A Pt(111) single-crystal substrate surface was used as the model of Pt-nanoparticle anode catalyst surface and modified with WO x through the reactive arc plasma deposition (APD) of W under an O 2 partial pressure ( p(O 2 ) = 1 © 10 ¹1 or 10 ¹3 Pa). The oxidation states of WO x were estimated by X-ray photoelectron spectroscopy, and the resulting electrocatalytic properties of H 2 O 2 generation and HOR activity were investigated using a scanning electrochemical microscope. The as-prepared oxidation states of WO x were modified depending on p(O 2 ) during the APD. Contrarily, potential cycle (PC) loadings resulted in a similar oxidation state of WO x : substoichiometric oxides containing W 4+ or W 5+ , irrespective of the as-prepared oxidation states of the deposited tungsten. Regardless of the WO x oxidation state, the WO x /Pt(111) surfaces exhibited suppressed H 2 O 2 generation, even accompanied by enhanced HOR activity compared with the clean Pt(111). Therefore, the WO x surface modification can improve the properties of Pt-based anode catalysts and contribute to high-performance catalyst developments.