Carbon dots/PtW6O24 composite as efficient and stable electrocatalyst for hydrogen oxidation reaction in PEMFCs

CDs/PtW6O24 composite with excellent catalytic activity for hydrogen oxidation reaction in acidic environment. [Display omitted] •CDs/POMs exhibit excellent catalytic activity of HOR in acid with low Pt loading.•POMs can be used as an ideal model system to construct Pt single-atom catalyst.•CDs can effectively improve the mass transfer rate of HOR.•TPV tests, Butler-Volmer formulation and in situ XAS were used to explore the dynamics process of charge transfer.•CDs/POMs show higher power density and stability than 20% Pt/C in PEMFCs. Platinum (Pt) is practical available candidate for satisfying the requirements of anode catalysts in the proton exchange membrane fuel cells (PEMFCs). Totally dispersed Pt is an ideal way to minimize Pt use, and the develop of Pt-single-atom based hydrogen oxidation reaction (HOR) catalysts should be carried out in a multi-component/-function model system with a clear active site (Pt-single-atom) geometric structure. This work combines the well-defined Na6[H2PtW6O24] clusters and multi-function carbon dots (CDs) to show the highly efficient Pt-single-atom catalyst design for HOR in acid. The mass activity and exchange current density of POMs/CDs (2.18 wt% Pt) achieved 86.72 A mgpt−1 and 3.78 A mgpt−1, respectively, which were 9.5 and 14 times that of 20% Pt/C. Also, this catalyst exhibits better performance than 20% Pt/C in the test of single cell, including higher open circuit potential (OCP), higher power density and better long-time stability. In particular, CDs can effectively improve the catalytic performance of POMs by enhancing the electron acquisition ability of Pt in POMs, the conductivity of composites, the structure stability, the ability to resist toxicity and accelerating the transfer of H+ produced on POMs.