Ti₃C₂ MXene nanosheets integrated cobalt-doped nickel hydroxide heterostructured composite: An efficient electrocatalyst for overall water-splitting

Developing an efficient electrocatalyst for superior electrochemical water splitting (EWS) is crucial for achieving comprehensive hydrogen production. A heterostructured electrocatalyst, free of noble metals, Ti₃C₂ MXene nanosheet-integrated cobalt-doped nickel hydroxide (NHCoMX) composite was synthesized via a hydrothermal method. The abundant pores in the Ti₃C₂ MXene nanosheet (MX)-integrated microarchitecture increased the number of active sites and facilitated charge transfer, thus enhancing electrocatalysis. Specifically, the MX- enhanced charge transfer considerably transformed the microelectronic structure of cobalt-doped Ni(OH)₂ (NHCo), which promoted its hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Hence, as an EWS catalyst, NHCoMX exhibited an exceptional electrocatalytic activity, demonstrating OER and HER overpotentials of 310 mV and 73 mV, respectively, with low Tafel slopes of 65 mV dec^-1 and 85 mV dec^-1, respectively; it exhibited a current density of 10 mV cm^-2 in 1.0 mol L^-1 KOH, representing the closest efficiency to the noble state-of-the-art RuO₂ and Pt/C catalyst. Furthermore, the developed electrocatalyst improved the activities of both HER and OER, leading to an overall EWS current density of 10 mA cm^-2 at 1.72 V in an alkaline electrolyte with two electrodes. This study describes an efficient heterostructured NHCoMX composite electrocatalyst. It is significantly comparable to the noble state-of-the-art electrocatalysts and can be extended to fabricate resourceful catalysts for large-scale EWS applications.