Effect of La as Promoter in the Photoreduction of CO2 Over TiO2 Catalysts

Mechanistic View of the Main Current Issues in Photocatalytic CO2 Reduction

“…However, on working systems, CO 2 * dissociation to form CO has only been observed for TiO 2 with metal NP systems (as no dissociation was observed for only TiO 2 ). − In conclusion, it seems like the activation of CO 2 molecules to CO 2 * requires the confluence of several factors such as adsorption conformation and the presence of coadsorbed reactants and co-catalysts in order to occur. For example, the CO 2 chemisorption capacity of TiO 2 has been improved by the addition of a second oxide like MgO or La 2 O 3 . − Moreover, CO 2 reduction products have been observed under photocatalytic conditions using bare TiO 2 systems, and further investigations are needed in order to fully identify the factors behind CO 2 activation or alternative multielectronic processes behind these observed reactions.…”

Towards the Improvement of Methane Production in Co2 Photoreduction Using Bi2wo6/Tio2 Heterostructures

“…S3b) also allowed to distinguish bands corresponding to Bi 2 WO 6 and TiO 2 within the BiW/Ti heterostructures. The characteristic bands of TiO 2 anatase appear at 147 (E g ), 394 (B 1 g ), 515 (A 1 g + B 1 g ) and 637 (E g ) cm − 1 [22]. The rest of the bands in the range 200-1000 cm − 1 are assigned to Raman actives modes for Aurivillius Bi 2 WO 6 (2A 1 + B 1 + 3E g ) [23].…”

Improved Methane Production by Photocatalytic CO2 Conversion over Ag/In2O3/TiO2 Heterojunctions

“…Furthermore, the use of heterojunctions can also enhance the light harvesting and extend the light absorption toward the visible range by means of a sensitization mechanism [16,[19][20][21][22][23][24]. There are some kinds of heterojunctions, based on the use of inorganic semiconductors, which present higher activity than bare TiO 2 in different photocatalytic applications, such as La 2 O 3 /TiO 2 , In 2 O 3 /TiO 2 , Fe 2 O 3 /TiO 2 , SnO 2 /TiO 2 , and V 2 O 5 /TiO 2, which promote charge separation and transfer, improve the light harvesting, or modify the surface chemistry of the system [25,26]. In addition, there is the possibility of creating three-component or ternary systems based on the union of oxides with a metal, thus allowing more efficient charge transfer and adding additional catalytically active sites [27][28][29][30][31].…”