Now, Bruce Koel, Jose Mendoza-Cortes and co-workers report a highly efficient and stable PtSe2-based ORR catalyst that is synthesized through restructuring defective platinum diselenide (DEF-PtSe2) via electrochemical cycling in an O2-saturated electrolyte. Impressively, DEF-PtSe2, activated by 42,000 accelerated durability test (ADT) cycles (DEF-PtSe2 (42,000)), exhibits 1.3 times higher specific activity and 2.6 times higher mass activity compared with a commercial Pt/C electrocatalyst. The reaction mechanism is investigated with a combination of characterization techniques and quantum mechanical calculations that attribute the superior performance of DEF-PtSe2 to the synergistic contributions from the Pt apical active sites on the DEF-PtSe2 surface.
The synthesis of the DEF-PtSe2 (42,000) catalyst commences with the electron-beam evaporation of an Al-supported Pt foil, followed by selenization at 500 °C to generate PtSe2 crystals on the Al foil. Subsequent etching of Al in strong alkaline and acid solutions sequentially yields DEF-PtSe2 with a rough surface and disordered layer structure at the edges. The optimal catalyst, DEF-PtSe2 (42,000), is further optimized by an ADT with 42,000 ORR cycles. Notably, DEF-PtSe2 (42,000) achieves a half-wave potential (E1/2) at 0.85 V versus a reversible hydrogen electrode (RHE) and maintains stability after 126,000 cycles at E1/2 = 0.83 V versus RHE in a 0.1 M HClO4 electrolyte. The specific activity and mass activity current densities of DEF-PtSe2 (42,000) are 0.089 mA cm−2 and 0.100 A mg−1 of Pt, respectively, surpassing those of commercial Pt/C. More importantly, DEF-PtSe2 (42,000) exhibits exceptional methanol and CO tolerance, as evidenced by the linear sweep voltammetry measurements conducted both in the presence and absence of methanol and CO.
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