Activity and Selectivity of Cu and Ni Doped TiO2 in the Photocatalytic Reduction of CO2 with H2O Under UV-light Irradiation

Improving the photo‐reduction of CO2 to fuels with catalysts synthesized under high pressure: Cu/TiO2

“…The size distribution of Cu size is relatively narrow for both catalysts, being the average particle size diameter 6.6 nm for Cu 1 wt% and 10.1 nm for Cu 3 wt%. Metal sizes are bigger than Pt and Pd nanoparticles obtained in previous work,, although they are consistent with those reported for Cu/TiO 2 catalysts synthesized by traditional methods , , …”

“…Table shows that synthesized catalysts have smaller crystallite sizes than commercial catalyst, with the exception of the TTIP‐isopropyl alcohol‐Cu combination . This decrease of crystallite size with metal introduction has also been observed in traditional syntheses …”

“…Thus, as seen in SEM measurements, the agglomeration degree of catalyst particles increases when metal concentration rises, increasing in size and decreasing in BET area. First, the decrease in surface area reduces the number of CO 2 adsorption sites . Moreover, excess Cu species cover illuminated TiO 2 , decreasing light absorption and electron/hole photogeneration .…”

“…6 Moreover, as occurred with other metals, 4,6 BET area decreases as metal concentration increases. Although some authors 17,24 suggest that increasing copper concentration promotes sintering process, increasing crystallite size and decreasing BET area, in view of the XRD results described below (no change in crystallinity with metal loading), we prefer to explain this trend in terms of a partial coverage of TiO 2 by metal species. 40 Some works dealing with traditional synthesis of Cu/TiO 2 (solvo-thermal) do not report any change in BET area with variable metal concentrations.…”

“…Metal sizes are bigger than Pt and Pd nanoparticles obtained in previous work, 4,6 although they are consistent with those reported for Cu/TiO 2 catalysts synthesized by traditional methods. 24,27,41 Figure 4 shows a HR-TEM image of TTIP-isopropyl alcohol-Cu 1 wt% catalyst. It shows clear lattice fringes of TiO 2 nanoparticles and confirms the crystallinity of TiO 2 .…”