Gold-indium modified TiO2 nanocatalysts for photocatalytic CO2 reduction with H-2 as reductant in a monolith photoreactor

Abstract

In this study, CO2 photoreduction via reverse water gas shift (RWGS) reaction over gold (Au) and indium (In) modified TiO2 nanocatalysts in a monolith photoreactor has been investigated. Crystalline nanoparticles of anatase TiO2 were obtained in doped TiO2 samples with metals deposited over TiO2 as Au and In3+ ions. The catalytic performance of metal-doped/TiO2 catalysts was found to be considerably higher when compared to pure TiO2. The maximum production of CO as the main product was 8982 µmol g-catal-1 h-1 at selectivity 99% and CO2 conversion of 9.5% over 0.2 wt.% Au-3.5 wt.% In/TiO2, and CO2/H2 feed ratio 1.5. The CO production over co-metals (Au-In) doped TiO2 monolithic catalyst was 1.3 times higher than Au/TiO2, 4.39 times higher than In/TiO2 and 76 times higher than un-doped TiO2 catalysts. Significantly higher photoactivity of metal-doped TiO2 was obviously due to fast electron transfer with hindered recombination rates and larger illuminated surface area in monolith channels. The quantum efficiency of CO production through RWGS reaction using Au-In/TiO2 catalyst was considerably improved (0.79%) than Au/TiO2 (0.53%) and In/TiO2 (0.14%) monolithic catalysts. The stability of the reused catalysts for CO production sustained at cyclic runs. This development confirmed higher performance of metals-doped TiO2 nanocatalysts supported over monolith channels for CO2 photoreduction via RWGS reactio