Chemical states of metal-loaded titania in the photoreduction of CO2

Copper-doped titania photocatalysts for simultaneous reduction of CO2 and production of H2 from aqueous sulfide

“…These yields are higher than some of the most efficient systems reported [19,20,37]. In addition, the activity of the newly prepared Cu-TiO 2 photocatalysts took place in the presence of small amounts of sulfide as the only sacrificial electron donor, without the need for additional reducing agents, as observed elsewhere for ZnS photocatalysts [38].…”

“…Its use for the production of chemicals is doubly beneficial, since in addition to its availability, it would represent a decrease in the carbon footprint for the manufacturing of the particular chemical. Other researchers have reported lower but noticeable methanol yields using similarly prepared photocatalysts and Hg lamp irradiation (10-23 µmol g cat −1 h −1 ) [19,20]. In gas-phase reactions, the formation of methanol was also reported, but in considerably lower yields (2 nmol g cat −1 h −1 ), being methane the major product formed by Cu/TiO 2 photocatalysis [21].…”

Design and fabrication of semiconductor photocatalyst for photocatalytic reduction of CO2 to solar fuel

“…The copper cluster is an effective electron trapper, and able to reduce the recombination of electron-hole pairs [55,133]. However, higher Cu loading gave a lower rate of methanol yield because of the masking effect of Cu 2 O clusters on the TiO 2 surface [132,133]. Consequently, it is generally believed that CO 2 can be selectively reduced to methanol in an aqueous solution under light irradiation due to the Cu 2 O or CuO species on the TiO 2 surface [54,55,131,133,218,308,328].…”

“…Furthermore, the doped metal ion can also perform as electron traps and active sites for highly selective CO 2 photoreduction. It is well known that TiO 2 doped with copper shows good selectivity for CH 3 OH from the reduction of CO 2 , which will be discussed below [55,[131][132][133] is also an effective strategy to enhance the photocatalytic activity of TiO 2 under visible light, which deserves more attention in photocatalytic reduction of CO 2 [140]. It should be noted that the excess amount of dopants as recombination centers can also lead to a greatly decreased activity for CO 2 photoreduction.…”

“…It is well known that TiO 2 doped with copper shows good selectivity for CH 3 OH from the reduction of CO 2 , which will be discussed below [55,[131][132][133]. Besides Cu, other metal-ion doping such as Ce [134], Mn [135], Ru [83,136], Ni [96,137], In [105], Fe [89], Ag [89,132], Au [136,138], Mg [139] and their co-doping with Cu or N have also been reported for photocatalytic reduction of CO 2 and exhibit enhanced photocatalytic activities for the reduction of CO 2 . Generally, a metal cation doping of TiO 2 not only creates oxygen vacancies and new active sites for the reaction, but also introduces localized mid-gap states which contribute to charge separation and the absorption of visible light [39].…”