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 Cu TiO 2 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 TiO 2 and also present on the surface of TiO 2 as revealed by TEM, XPS, and TPR. Catalytic potential of prepared catalysts was checked for photocatalytic reduction of CO 2 . The effects of the different base including K 2 CO 3 , Na 2 CO 3 , 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 Cu 2 TiO 2 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/H 2 O medium in 24 h under UVA. While in acetonitrile (ACN)/Triethanolamine (TEOA)/H 2 O mixture, the Cu 2 TiO 2 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 CO 2 . Therefore, the Cu 2 TiO 2 catalyst was also tested for H 2 production with or without CO 2 at different reaction media such as H 2 O, KOH/H 2 O, ACN/H 2 O, ACN/TEOA/H 2 O under UVA light. The highest H 2 production, i.e., 152.0 mmol g −1 was observed with ACN/TEOA/H 2 O in the presence of CO 2 in 8 h. The prepared series of Cu TiO 2 catalysts are highly active for CO 2 reduction and H 2 production.