One-step synthesis of carbon-onion-supported PtCo alloy by underwater arc discharge for pH-universal hydrogen evolution reaction

Exploring low-cost and highly efficient electrocatalysts for pH-universal hydrogen evolution reaction (HER) is critical for the development of hydrogen energy conversion but challenging. In this study a novel catalyst of well-dispersed PtCo alloy nanoparticles with a size of ∼2 nm anchored on carbon nano onions (CNOs) has been constructed by a one-step underwater arc discharge method. The optimized Pt_0.91Co_0.09@CNOs catalyst with a Pt loading of 17.5 wt% and Co loading of 0.54 wt% exhibits excellent HER performances with overpotentials of 24 mV, 15 mV and 39 mV at the current density of 10 mA cm⁻², and 137 mV, 108 mV and 63 mV at 100 mA cm⁻² in alkaline, neutral, and acidic electrolytes, respectively, as well as superior continuous stability. Density functional theory calculations indicate the formation of PtCo nano alloy is beneficial for the modulation of the electron structure of catalysts, and thus presents a moderate H* adsorption energy and d-band center. This work provides a simple and economical strategy on constructing efficient alloy catalysts for pH-universal HER and offers an opportunity for the real-world application of hydrogen energy conversions.