Effect of oxygen vacancy on electrochemical performance of NiCo-layered double oxides as water splitting electrocatalyst

It is of importance for the design of cost-effective bifunctional electrocatalysts with good durability to decrease the energy rampart of total water decomposition. However, few electrocatalysts simultaneously exhibits excellent catalytic property and durability for both oxygen evolution reaction (OER) as well as hydrogen evolution reaction (HER). Herein, we adopt strategies toward defect engineering coupled with metal organic framework (MOF) to synthesize oxygen vacancy abundant NiCo-layered double oxides with hollow nanotube arrays structures supported on Ni foam (Ov-NiCo-LDO HNTAs/NF) via etching of ZnO template, which is considered as an efficient electrocatalyst for water splitting. The optimal Ov-NiCo-LDO HNTAs/NF reveals an ultra-low overpotential of 149 and 30 mV to afford a current density of 10 mA·cm-2 for OER and HER in alkaline solution, respectively. Moreover, the catalyst also displays significant stability for 24 h with no significant decrease when a stable current density of 100 mA·cm-2 is applied. A full water splitting system coupled with Ov-NiCo-LDO HNTAs/NF as both poles of hydrolysis tank can drive of 20 mA·cm-2 current density at a potential of 1.68 V, along with steady operation for over 24 h, indicating that Ov-NiCo-LDO HNTAs/NF is a promising bifunctional electrocatalyst.