Synergistic enhancement of Pt electrocatalyst stability and activity in hydrogen oxidation reaction by polyoxometalate and carbon dot co-boosting

Abstract

Pt-based catalysts are prone to oxidation and CO poisoning during the hydrogen oxidation reaction (HOR), leading to deactivation, which has presented significant challenges for the application of proton exchange membrane fuel cells (PEMFC). Here, we propose a dual-protection strategy with the advantages of Pt-polyoxometalates (POMs) and carbon dots (CDs) to synthesize an advanced POMs-CDs based electrocatalyst, Pt-SiW₁₂-CDs, with Pt clusters dispersed on SiW₁₂-CDs substrates. It exhibited exceptional HOR performance, achieving a mass activity of 10.36 A mg_Pt⁻¹ at an overpotential of 50 mV, which is over 54 times greater than that of Pt/C (0.19 A mg_Pt^–1). These catalysts also display impressive stability and CO tolerance. By employing X-ray absorption fine structure (XAFS) spectra, transient photovoltage (TPV), transient potential scanning (TPS), and density functional theory (DFT) calculation, the in-depth investigation suggested the muti-roles of SiW₁₂ and CDs for synergistic enhancement of Pt electrocatalyst stability and activity in HOR process. CDs act as bridges, effectively and rapidly transferring protons and electrons to SiW₁₂ from Pt clusters. CDs can effectively coordinate with Pt, regulating its electronic structure while pre-occupying Pt sites, thus hindering CO adsorption on Pt. The reduced SiW₁₂ efficiently transfers electrons to Pt, inhibiting the oxidation of Pt. Additionally, SiW₁₂ also serves as the driving force, maintaining the rapid progression of the HOR process. The dual-protection strategy provides new ideas and directions for design of efficient and stable heterogeneous catalyst.