Synthesis And Electrocatalytic Performance Of Three-dimensional Flower-like NiCo-LDH Grown On MXene/NF

Hydrogen has attracted much attention due to its high energy density and environment friendly characteristics.Water-splitting electrolyzers is one of the cleanest and most efficient ways to produce high-purity hydrogen.The high overpotential of the oxygen evolution reaction（OER）means it is generally considered to be the critical bottleneck.Layered double hydroxides（LDHs）has been proven to have excellent catalytic activity for OER,but the disadvantages of poor conductivity and easy agglomeration restrict the release of LDHs catalytic activity.In this work,MXene/NF was used as the carrier to improve the dispersibility and conductivity of LDHs and obtain a composite catalyst with higher catalytic activity.As follows:（1）NiCo-LDH/MXene hybrid electrocatalyst was obtained by growth of NiCo-LDH on MXene（Ti₃C₂T_x）with hydrothermal method.NiCo-LDH/MXene hybrid electrocatalyst had a lower overpotential of 358 m V and a small Tafel slope of30.86 m V dec^-1 than that of NiCo-LDH(overpotential of 391 m V and Tafel slope of81.6 m V dec^-1)at the current density of 50 m A/cm².The results showed that MXene could effectively promote the dispersion of NiCo-LDH and improve its OER catalytic activity.（2）The three-dimensional flower-like NiCo-LDH was grew on nickel foam（NF）to get NiCo-LDH/NF,the mixed metal oxides（MMOs）on NF was obtained by calcination of NiCo-LDH/NF under nitrogen protection.MMOs inherited the large specific surface area layered structure and promoted charge separation and electron transfer.The overpotential of NiCo-MMO/NF-300 was 320 m V and Tafel slope of30.86 m V dec^-1 at current density of 100 m A cm^-2.（3）Using the nickel foam（NF）as the skeleton and MXene（Ti₃C₂T_x）as the intermediate,NiCo-LDH/MXene/NF hybrid structure was synthesized by two-step method.The Ti₃C₂T_x MXene coating layer on the NF skeleton was obtained by natural deposition firstly and then the three-dimensional flower-like NiCo-LDH was grown on the surface of Ti₃C₂T_x MXene by hydrothermal method.Benefiting from the interfacial interaction and electrons transfer between NiCo-LDH,NF and MXene,a low overpotential of 223 m V and a small Tafel slope of 47.2 m V dec^-1 of the NiCo-LDH/MXene/NF can be achieved at the current density of 100 m A cm^-2.