Copper-promoted growth of hierarchical Cu–Co–Ni alloys on copper nanodendrites for enhanced hydrogen evolution in a wide pH range

Abstract

Efficient and sustainable electrocatalysts for the hydrogen evolution reaction (HER) using earth-abundant elements are crucial for eco-friendly hydrogen production, particularly under neutral and acidic conditions. In metallic alloys, careful selection of alloying elements and control over the composition, morphology, electronic structure, and structural defects are expected to tune electrocatalytic activities. In this work, we introduce a two-step electrodeposition approach to create a 3D porous trimetallic alloy, Cu@Cu–Ni–Co, exhibiting excellent catalytic activity and stability for HER in neutral and acidic environments. The process begins with the electrodeposition of 3D copper dendrites, which was found to be crucial for the catalyst's mechanical stability, followed by the deposition of the trimetallic alloy, where copper's inclusion promotes the controlled growth of the alloy's 3D structure. The Cu@Cu–Ni–Co catalyst outperforms Cu@Ni, Cu@Co, Cu@Ni–Co, and GC@Cu–Ni–Co electrocatalysts in neutral and acidic conditions, highlighting the importance of the developed electrodeposition approach. In 1.0 M phosphate-buffer solution (PBS), Cu@Cu–Ni–Co achieves a current density of 10 mA cm−2 at an overpotential of 275 mV with a Tafel slope of 134 mV dec−1, maintaining remarkable stability in both acidic and neutral conditions at high current densities (48–165 mA cm−2) for up to 50 h without any decline in activity.