Z-scheme g-C3N4/ZnO heterojunction decorated by Au nanoparticles for enhanced photocatalytic hydrogen production

Abstract

The construction of heterojunction photocatalysts is an effective and widespread approach to solving global environmental issues. Herein, we designed and fabricated a Z-scheme g-C3N4/ZnO/Au heterojunction using a simple chemical method for photocatalytic H2 production under UV–Visible light irradiation. The g-C3N4/ZnO/Au-2 composite has an optimal photocatalytic H2 production rate of 46.46 μmol∙g−1∙h−1, representing 25.2-fold and 30.4-fold enhancements compared with a g-C3N4/ZnO-2 composite and bare g-C3N4, respectively. The decorated Au nanoparticles not only enhance the absorption of visible light by the LSPR effect, but also act as an electron mediator to accelerate the electrons transfer from ZnO to g-C3N4. The improved photocatalytic activity of the g-C3N4/ZnO/Au-2 composite can be attributed to the effectively suppressed recombination of photogenerated electron and hole pairs. The mechanism of the photocatalytic hydrogen evolution process had been studied by UV–vis diffuse reflectance spectroscopy (UV–vis DRS), Ultraviolet photoemission spectroscopy (UPS), photoluminescence (PL), transient photocurrent responses, electrochemical impedance spectroscopy (EIS), and electron spin resonance (ESR). This work provides a strategy for the design and synthesis of an environmentally friendly Z-scheme heterojunction for photocatalytic H2 evolution applications.