Function of TiO_𝟐 Lattice Defects toward Photocatalytic Processes: View of Electronic Driven Force

Table 2

Possible reaction pathways for defective TiO₂.

Phase	CO2 photoreduction with H2O vapor
Defective TiO2 anatase and brookite	H2O+h^+→H^++OH• (1)	CO2+Ti^3+→Ti^4++CO2^− (2)
	OH•+CO2^+→HCO3^− (3)	CO2^−+H^++𝑒^−→CO+OH^− (4)
	CO2^−+CO2^−→CO+CO3^2− (5)	CO2^−+Ti^3+−Vo−Ti^4+↔CO+Ti^4+−O^2−−Ti^4+ (6)
	CO,HCO3^−,HCOOH−−→^𝑒−C(ads)⋅−−→^H•CH3⋅−−→^H•CH4 (7)
Defective TiO2 brookite	CO2+2H^++2𝑒^−→HCOOH (8)	CO2^−+2H^++𝑒^−→HCOOH (9)
	HCOOH→CO+H2O (10)	CO,HCOOH−−−−→^𝑒−,H+CH4 (11)