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.