Electrostatically directed assembly of two-dimensional ultrathin Co2Ni-MOF/TiCT nanosheets for electrocatalytic oxygen evolution.

Hydrogen production from water electrolysis is severely restricted by the poor reaction kinetics of oxygen evolution reaction (OER). In this work, a series of two-dimensional (2D) composites MOF/TiCT (the MXene phase) were fabricated by electrostatically directed assembly and used as catalysts for OER. The obtained composite materials exhibit enhanced electrocatalytic properties, thanks to the ultrathin 2D/2D heterostructure with abundant active sites in Co2Ni-MOF and the high electronic conductivity of TiCT. Among all the catalysts, Co2Ni-MOF@MX-1 achieved the best oxygen evolution performance with the lowest Tafel slope (51.7 mV dec) and the lowest overpotential (265 mV on carbon paper) at the current density of 10 mA cm. These results demonstrated that the synthesis of 2D composite materials by electrostatically directed assembly could be a feasible and promising method for the preparation of 2D heterostructure catalysts.