Ultrathin PtNiW@WOx core-shell nanowires for enhanced CO-tolerant hydrogen oxidation: three-in-one catalyst design

Platinum (Pt) is the state-of-the-art electrocatalyst for anodic hydrogen oxidation reaction (HOR) in proton exchange membrane fuel cells (PEMFCs). However, a critical drawback of PEMFCs is the extreme sensitivity of Pt catalyst to CO (impurity in industrial hydrogen), which markedly damages the device's performance. Therefore, enhancing the CO-tolerant performance of Pt catalysts is crucial for the commercialization of PEMFCs. Herein, we constructed PtNiW@amorphous WOx core-shell nanowires to improve the CO-tolerance of Pt. Mechanistically, it is demonstrated that the surface amorphous WOx shell can kinetically hinder the accessibility of CO over Pt sites by acting as a selective molecular-sieving layer. Besides, thermodynamically, the electronic effect from the alloying of Ni and W elements could weaken the CO adsorption on Pt sites by downshifting the d-band center. In addition, the oxyphilic W elements can accelerate the dissociation of water to provide more OH species, promoting the oxidation of CO. As a consequence, the as-designed PtNiW@WOx NWs can maintain over 90% HOR current density after 4000 s in 1000 ppm CO/H2, exceeding most of the Pt-based catalysts reported ever.