Bimetallic Cu-Co-Se Nanotube Arrays Assembled on 3D Framework: an Efficient Bifunctional Electrocatalyst for Overall Water Splitting.

Highly active bifunctional electrocatalysts for water splitting are of particular importance for the widespread usage of renewable energy, which require synergistic effect of ingenious architecture and intrinsic catalytic activity. Herein, a novel Cu-Co-Se nanotube array supported on 3D copper skeleton was synthesized as high-efficiency bifunctional electrocatalyst for overall water splitting via a facile two-step hydrothermal method. The rationally designed Cu-Co-Se nanotube electrocatalyst exhibited good electrocatalytic performance, with overpotential of only 152 mV to generate 10 mA cm-2 for the hydrogen evolution reaction and a small overpotential of 332 mV to drive a current density of 50 mA cm-2 for the oxygen evolution reaction. The good electrocatalytic performance was mainly due to the large electrochemical surface area and electronic coupling synergies triggered by the self-supported bimetallic nanotube architecture. The water splitting system assembled using Cu-Co-Se nanotube as cathode and anode only needed a cell voltage of 1.65 V to drive a current density of 10 mA cm-2 with long durability of 50 h for overall water splitting. Furthermore, density functional theory calculations proved that the existence of electron exchange between the neighboring bimetals as well as the coupling between Cu, Co, and Se contributed to the improvement of the water splitting performance. This work provides a general strategy to develop cost-efficient and geometrically superior bimetallic electrocatalysts toward water splitting for large-scale hydrogen production.