Cobalt–platinum intermetallic composite loaded on pyridinic N-enriched carbon for acidic hydrogen evolution catalysis with ultralow overpotential

Abstract

Platinum is a highly efficient catalyst for the hydrogen evolution reaction (HER) in acidic media, but its widespread use has been seriously impeded by its scarcity and high cost. Herein, we report the preparation of CoPt₃ nanoparticles loaded on N-doped carbon nanosheets (NCS-CoPt) via a simple mixing-calcination strategy. This strategy could simultaneously achieve metal nanosize controlling, heteroatom synergy, and support stabilization. Ar calcination of NCS-CoPt could form intermetallic compound CoPt₃, which could be the highly active HER catalytic site, while the H₂/Ar atmosphere with higher reducing ability could decompose the Co–Pt intermetallic compound into non-valent metal nanoparticles at a high temperature (750 °C). Meanwhile, for NCS-CoPt, the high content of pyridinic N on the carbon substrate could benefit the strong interaction of the support and CoPt₃ nanoparticles and contribute to its robust HER activity and stability. Consequently, NCS-CoPt exhibits an outstanding HER activity in acidic media, requiring an ultralow overpotential of 41 mV to achieve a current density of 10 mA cm⁻². Moreover, its mass activity reaches up to 3.17 A mg_Pt⁻¹ at an overpotential of 50 mV, which is 7.9 times that of commercial 20 wt% Pt/C.