Accelerating carrier separation to boost the photocatalytic CO2 reduction performance of ternary heterojunction Ag–Ti3C2Tx/ZnO catalysts

Abstract

Developing low-cost and efficient photocatalyst/co-catalyst systems that promote CO₂ reduction remains a challenge. In this work, Ag–Ti₃C₂T_x composites were made using a self-reduction technique, and unique Ag–Ti₃C₂T_x/ZnO ternary heterojunction structure photocatalysts were created using an electrostatic self-assembly process. The photocatalyst's close-contact heterogeneous interface increases photogenerated carrier migration efficiency. The combination of Ti₃C₂T_x and Ag improves the adsorption active sites and reaction centers for ZnO, making it a key site for CO₂ adsorption and activation. The best photocatalysts had CO and CH₄ reduction efficiencies of 11.985 and 0.768 μmol g⁻¹ h⁻¹, respectively. The CO₂ conversion was 3.35 times better than that of pure ZnO, which demonstrated remarkable stability even after four cycle trials with no sacrificial agent. Furthermore, in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) and valence band spectroscopy were utilized to propose the photocatalytic reaction mechanism and electron transfer channels of the Ag–Ti₃C₂T_x/ZnO system, confirming that CHO* and CO* are the important intermediates in the generation of CH₄ and CO. This study introduces a novel method for the development of new and efficient photocatalysts and reveals that Ti₃C₂T_x MXene is a viable co-catalyst for applications.