Self-organized copper impregnation and doping in TiO2 with enhanced photocatalytic conversion of H2O and CO2 to fuel

Abstract

To utilize the full spectrum of solar light, we prepared a series of self-organized CuTiO2 photocatalysts via the sonothermal-hydrothermal route with high reactivity under both UV and visible region. The obtained catalysts were characterized by XRD, UV–Vis, BET surface area, SEM, TEM, XPS, and TPR. The Cu species were doped in the lattice of TiO2 and also present on the surface of TiO2 as revealed by TEM, XPS, and TPR. Catalytic potential of prepared catalysts was checked for photocatalytic reduction of CO2. The effects of the different base including K2CO3, Na2CO3, NaOH, KOH, the concentration of base, catalyst amount, copper doping amount, light source, reaction medium and reaction time were monitored to get optimum reaction conditions. The Cu2TiO2 catalyst performed the best; 6.6 μmol g−1 of methane, 472.5 μmol g−1 methanol, and 743.8 μmol g−1 of acetone were obtained in KOH/H2O medium in 24 h under UVA. While in acetonitrile (ACN)/Triethanolamine (TEOA)/H2O mixture, the Cu2TiO2 catalyst was able to selectively catalyze methanol formation (99.99%) 8469.6 μmol g−1 in 24 h under visible light. The formation of H• is also an intermediate step in the photocatalytic reduction of CO2. Therefore, the Cu2TiO2 catalyst was also tested for H2 production with or without CO2 at different reaction media such as H2O, KOH/H2O, ACN/H2O, ACN/TEOA/H2O under UVA light. The highest H2 production, i.e., 152.0 mmol g−1 was observed with ACN/TEOA/H2O in the presence of CO2 in 8 h. The prepared series of CuTiO2 catalysts are highly active for CO2 reduction and H2 production.