Epitaxial growth of nano-interconnected catalysts on Cu dendrites with fast gas bubble delivery for highly efficient oxygen evolution reaction.

The water electrolysis process, involving multiple electron transfer steps, is inherently hindered by sluggish reaction kinetics and inefficient mass transport, highlighting the need for advanced electrocatalysts with enhanced activity and durability. In this study, a rapid epitaxial solution combustion method combined with a displacement reaction on iron foam (IF) enabled the fabrication of pine-leaf-shaped dendritic electrodes (PLS-TMOs/CuO/Cu/IF) featuring a hierarchical porous surface. The arrangement of the pine-leaf-shaped dendrites, with their high hydrophilicity, reduces bubble aggregation and facilitates efficient gas release and transport through directional channels. Additionally, the hierarchical structure increases the number of active sites for water splitting reaction. Theoretical calculations reveal that the CoO/CuO heterointerface facilitates favorable charge redistribution, which concurrently reduces the energy barrier for intermediate formation while significantly enhancing oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance. The bifunctional PLS-CoO/CuO/Cu/IF electrode exhibits outstanding performance, with low overpotentials of 221 and 64 mV at 10 mA cm for OER and HER respectively, along with long-term stability. Furthermore, a PLS-CoO/CuO/Cu/IF||PLS-CoO/CuO/Cu/IF two-electrode system for overall water splitting maintains stability for over 100 h at a current density of 1000 mA cm, with a low cell voltage of 2.41 V. This work introduces an electronic engineering approach to optimize the electrocatalytic properties of Cu-based materials and elucidates their mass transport behavior within a complex architecture.