Electroreduction-Driven Distorted Nanotwins to Activate Pure Cu for Efficient Hydrogen Evolution

Precious metals like Pt have been favored as catalysts due to their excellent catalytic activity for hydrogen evolution reaction (HER). However, the scarcity and high cost of precious metals have prompted researchers to explore alternative, non-precious metal catalysts. Cu is an attractive candidate for HER due to its plentiful reserves, affordability, and good electrical conductivity. However, Cu shows poor catalytic performance due to its weak binding with intermediates and is generally used as a current collector instead of a catalyst. Herein, the catalytic activity of pure Cu is greatly activated by electroreduction-driven local structure regulation, showing superior HER catalytic performance over commercial Pt/C catalysts at the working current densities greater than 100 mA cm^-2 in acid electrolyte. The activation process involved two steps. First, polycrystalline Cu₂O were prepared by pulsed laser ablation, resulting in abundant grain boundaries within Cu₂O particles. Next, the Cu₂O particles were electroreduced to nano pure Cu, inducing the formation of distorted nanotwins and edge dislocations. These local structure regulations introduce strong lattice strain and decrease the Cu coordination number, which enhance the interaction between Cu and intermediates, leading to excellent catalytic activity and durability of pure Cu catalyst. The transformation of non-active nature into high catalytic activity, coupled with the intrinsic low cost, makes pure Cu a promising HER catalyst for large-scale industrial applications.