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 Na 6 [H 2 PtW 6 O 24 ] 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 mg pt −1 and 3.78 A mg pt −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.
The oxidized platinum (Pt) can exhibit better electrocatalytic activity than metallic Pt 0 in the hydrogen evolution reaction (HER), which has aroused great interest in exploring the role of oxygen in Pt-based catalysts. Herein, we select two structurally well-defined polyoxometalates Na 5 [H 3 Pt (IV) W 6 O 24 ] (PtW 6 O 24 ) and Na 3 K 5 [Pt (II) 2 (W 5 O 18 ) 2 ] (Pt 2 (W 5 O 18 ) 2 ) as the platinum oxide model to investigate the HER performance. Electrocatalytic experiments show the mass activities of PtW 6 O 24 /C and Pt 2 (W 5 O 18 ) 2 /C are 20.175 A mg −1 and 10.976 A mg −1 at 77 mV, respectively, which are better than that of commercial 20% Pt/C (0.398 A mg −1 ). The in situ synchrotron radiation experiments and DFT calculations suggest that the elongated Pt-O bond acts as the active site during the HER process, which can accelerate the coupling of proton and electron and the rapid release of H 2 . This work complements the knowledge boundary of Pt-based electrocatalytic HER, and suggests another way to update the state-of-the-art electrocatalyst.
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