Improved photocatalytic activity of TiO2 modified with unique O–Zn–Cl surface species

• The introduced Zn exist as O–Zn–Cl surface species.
• The O–Zn–Cl species result in an enhanced photocatalytic activity on reduction of CO2 into CH4.
• The band structure and photocatalytic mechanism of the samples are discussed.

TiO2 modified with unique surface O–Zn–Cl species is prepared by a simple sol-gel method. The Zn modified TiO2 samples exhibit improved photocatalytic activity on photo-reduction of CO2 into CH4, compared with pure TiO2. The surface structure and photocatalytic properties are investigated by Raman, XRD, XPS, UV–vis absorption spectra, PL and time-resolved PL decay curves techniques. It is revealed that the existence of O–Zn–Cl species can extend the absorption into visible region, inhibit the recombination of charge carriers and prolong the lifetime of photogenerated electrons. Therefore the O–Zn–Cl modified TiO2 samples represent an improved photocatalytic performance on photo-reduction of CO2 into CH4.

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