Photocatalytic CO2 reduction with H2 as reductant over copper and indium co-doped TiO2 nanocatalysts in a monolith photoreactor

Abstract:

The photocatalytic CO₂ reduction with H₂ over copper (Cu) and indium (In) co-doped TiO₂ nanocatalysts in a monolith photoreactor has been investigated. The catalysts, prepared via modified sol–gel method, were dip-coated onto the monolith channels. The structure and properties of nanocatalysts with various metal and co-metal doping levels were characterized by XRD, SEM, TEM, N₂ adsorption–desorption, XPS, and UV–vis spectroscopy. The anatase-phase mesoporous TiO₂, with Cu and In deposited as Cu⁺ and In³⁺ ions over TiO₂, suppressed photogenerated electron–hole pair recombination. CO was the major photoreduction product with a maximum yield rate of 6540 μmol g⁻¹ h⁻¹ at 99.27% selectivity and 9.57% CO₂ conversion over 1.0 wt% Cu–3.5 wt% In co-doped TiO₂ at 120 °C and CO₂/H₂ ratio of 1.5. The photoactivity of Cu–In co-doped TiO₂ monolithic catalyst for CO production was 3.23 times higher than a single ion (In)-doped TiO₂ and 113 times higher than un-doped TiO₂. The performance of the monolith photoreactor for CO production over Cu–In co-doped TiO₂ catalyst was 12-fold higher than the cell-type photoreactor. More importantly, the quantum efficiency of the monolith photoreactor was significantly improved over Cu–In co-doped TiO₂ nanocatalyst using H₂ as a reductant. The stability of the monolithic Cu–In co-doped TiO₂ catalyst for CO partially reduced after the third run, but retained for hydrocarbons.

1. Muhammad Tahir and Nor Aishah Saidina Amin (2015) Photocatalytic CO2 reduction with H2 as reductant over copper and indium co-doped TiO2 nanocatalysts in a monolith photoreactor Applied Catalysis A: General, 493, 90-102. DOI: https://doi.org/10.1016/j.apcata.2014.12.053