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

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 Ru-complex photosensitizer. 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.