Role of ZnO in ZnO Nanoflake/Ti₃C₂ MXene Composites in Photocatalytic and Electrocatalytic Hydrogen Evolution

Herein, we report a simple hydrothermal synthesis of ZnO-Ti3C2 MXene nanocomposites with a varying wt % of ZnO to exploit the synergistic effect of 2D layer structured Ti3C2 and semiconductor ZnO for photocatalysis and electrocatalysis applications. A systematic study on the efficiency of ZnO-Ti3C2 nanocomposites toward the degradation of organic pollutants (dyes and pharmaceuticals) and the hydrogen evolution reaction (HER) is demonstrated. Among the developed nanohybrid catalysts, the ZnO-Ti3C2 composite with 10 wt % ZnO (MXZnO-10) showed the highest photodegradation efficiency of 76.4% within 10 min of the reaction and 99.2% in 60 min for methylene blue (MB) dye. The synergistic interactions between 2D layered Ti3C2 and ZnO improved the lifetime of electrons and holes by reducing the recombination rate. The uncombined electrons and holes facilitated the effective degradation of the MB dye. The ZnO-Ti3C2 nanocomposite with 5 wt % ZnO (MXZnO-5) showed excellent HER performance and exhibited an overpotential of 495 mV at 10 mA/cm2 with a Tafel slope of 108 mV/dec. This work widens the application range of transition metal oxide–MXene composites, providing potential substitute materials for photocatalysis and electrocatalysis applications.