Ligand modulation of active center to promote lead-free Cs2AgInCl6 photocatalytic CO2 reduction

Metal halide perovskites (MHP) are potential candidates for the photocatalytic reduction of CO2 due to their long photogenerated carrier lifetime and charge diffusion length. However, the conventional long-chain ligand impedes the adsorption and activation of CO2 molecules in practical applications. Here, a ligand modulation technology is employed to enhance the photocatalytic CO2 reduction activity of lead-free Cs2AgInCl6 microcrystals (MCs). The Cs2AgInCl6 MCs passivated by Oleic acid (OLA) and Octanoic acid (OCA) are used for photocatalytic CO2 reduction. The results show that the surface defects and electronic properties of Cs2AgInCl6 MCs can be adjusted through ligand modulation. Compared with the OLA-Cs2AgInCl6, the OCA-Cs2AgInCl6 catalyst demonstrated a significant improvement in the catalytic yield of CO and CH4. The CO and CH4 catalytic yields of OCA-Cs2AgInCl6 reached 171.88 and 34.15 µmol g−1 h−1 which were 2.03 and 12.98 times higher than those of OLA- Cs2AgInCl6, and the total electron consumption rate of OCA-Cs2AgInCl6 was 615.2 µmol g−1 h−1 which was 3.25 times higher than that of OLA-Cs2AgInCl6. Furthermore, in situ diffuse reflectance infrared Fourier transform spectra revealed the enhancement of photocatalytic activity in Cs2AgInCl6 MCs induced by ligand modulation. This study illustrates the potential of lead-free Cs2AgInCl6 MCs for efficient photocatalytic CO2 reduction and provides a ligand modulation strategy for the active promotion of MHP photocatalysts.