Green light (550 nm) driven tunable syngas synthesis from CO2 photoreduction using heterostructured layered double hydroxide/TiC photocatalysts

Abstract

Synthesis of syngas (CO, H₂) by photocatalytic reduction of CO₂ and H₂O represents an eco-friendly pathway for large-scale CO₂ utilization for the production of chemical raw materials with high added value. However, the precise control of the CO : H₂ ratio from 1 : 1 to the stoichiometric ratio of 1 : 3 is a major challenge in the process of photocatalytic CO₂ reduction, especially under long-wavelength irradiation (like green light of 550 nm). Herein, under visible light (λ > 400 nm), a heterostructured layered double hydroxide nanosheets/TiC (denoted as LDH/TiC) photocatalyst was prepared and exhibited tunable syngas synthesis with different CO/H₂ ratios (from 1 : 1–1 : 3). More importantly, such performance can be well controlled even under green light irradiation (550 nm) in conjunction with a Ru-complex photosensitizer and triethanolamine (TEOA) as a sacrificial agent. Theory calculations revealed that the excellent performance came from the assembly between LDH and TiC, which could not only improve the charge transfer efficiency but also change the desorption energy of H₂, resulting in the precise tunable ratio of syngas. This work offers an excellent strategy to design photocatalysts for reducing CO₂ to syngas for potential applications.