Synergistic lactic acid dehydrogenation and hydrogen evolution catalyzed by an electrodeposited Ni–Co alloy on rGO-SWCNTs

Abstract

We investigated the synergistic coupling of lactic acid direct dehydrogenation (LAOR) and the hydrogen evolution reaction (HER) in acidic media using a Ni–Co alloy catalyst supported on reduced graphene oxide-single-walled carbon nanotubes (rGO-SWCNTs). Compared with pristine Ni or Co, the Ni–Co alloy exhibited superior activity for both the HER and LAOR. Specifically, the CoNi11 alloy (Co/Ni = 1) demonstrated exceptional HER performance, achieving a low overpotential of 162.2 mV (vs. RHE) at 10 mA cm⁻², a Tafel slope of 69.2 mV dec⁻¹, and a high electrochemically active surface area (ECSA) of 200.3 mF cm⁻². At the anode, the LAOR selectively produced pyruvic acid (PA) and hydrogen via direct dehydrogenation, dominating over the oxygen evolution reaction (OER). The PA selectivity was significantly enhanced to 90% with the addition of Br⁻. Crucially, the CoNi11 catalyst displayed excellent stability during three consecutive electrochemical cycles and a 12-hour chronopotentiometric operation. This work provides an efficient strategy for the co-production of renewable hydrogen and value-added pyruvic acid using Ni–Co alloy catalysts.