CuS/NiFe-LDH/NF as a Bifunctional Electrocatalyst for Hydrogen Evolution (HER) and Oxygen Evolution Reactions (OER)

Abstract

Increasing energy demands have motivated scientists to work out affordable, clean, and renewable energy technologies to replace conventional fossil fuels. Among different energy resources, hydrogen energy produced by electrochemical water splitting is gaining more attention. One electrocatalyst for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is the greatest challenge in the field of electrochemical water splitting. NiFe-LDH has been widely investigated for OER but shows poor performance for HER and overall water splitting (OWS). We have explored the enhanced electrochemical activities by depositing CuS particles on NiFe-LDH. The prepared CuS/NiFe-LDH/NF electrocatalyst requires an overpotential of only 55 mV to achieve the current density of 10 mA cm⁻² in case of hydrogen evolution reaction (HER) which is close to the ideal noble metal catalyst (Pt/C 33 mV for 10 mA cm⁻²). While in the case of OER, CuS/NiFe-LDH shows an overpotential of 170 mV to deliver a current density of 10 mA cm⁻². More importantly, CuS/NiFe-LDH/NF composite can act as an excellent bifunctional electrocatalyst for HER and OER. To achieve the current density of 10 mA cm⁻² in the overall water splitting process, CuS/NiFe-LDH/NF cell voltage is 1.517 V. The prepared electrocatalyst also showed good stability for 72 h’ time. The composite formation of CuS with NiFe-LDH opens a new way of boosting the electrochemical activity of water splitting.