Electrochemical template synthesis of copper hollow microtubes with dendritic surface and advanced HER performance

• Hollow copper microtubes were synthesized by electrochemical template synthesis. • The two-stage process “annealing-electroreduction” increased the ECSA of microtubes by 10 times. • The overpotential of HER on hollow copper microtubes are improved to 215 mV. This study is devoted to the electrochemical template synthesis of Cu-based electrode materials for the efficient hydrogen evolution reaction (HER). Hollow copper tubes with an inner diameter of 23 μm and a wall thickness of 2.5 μm were synthesized by the three-step method: electrodeposition of copper on the carbon felt (template), annealing of the composite in the air toward copper oxides with hollow tube (HT) morphology, and their electrochemical post-reduction to copper HT with the dendritic surface. The electrocatalytic test of the resulting material showed that the overpotential of HER is 215 mV, and the Tafel slope is 177 mV/dec. The electrochemical active surface area of the copper HT increased almost 10 times – from 300 cm 2 to 2850 cm 2 – relative to the electrodeposited sample. The stability test of the electrode material confirmed its high activity within 24 h at a current density of 10 mA∙cm −2 and an overpotential of −280 mV.