Effective CH4 production from CO2 photoreduction using TiO2/x mol% Cu–TiO2 double-layered films

•Photoreduction of CO2 to CH4 on TiO2/x mol% Cu–TiO2 double layered films.•CH4 gas generated from the photoreduction of CO2 increased on TiO2/Cu–TiO2 films.•CH4 gas on TiO2/5.0 mol% Cu–TiO2 film was twice higher than on the TiO2/TiO2 film.•Recombination of photogenerated electron–hole pairs inhibited on TiO2/Cu–TiO2 film.

This study examined the photoreduction of CO2 to CH4 over TiO2/x mol% Cu–TiO2 double layered films. x mol% Cu-incorporated TiO2 nano-sized powders were prepared using a conventional solvothermal method. The prepared powders were fabricated as TiO2 (bottom)/Cu–TiO2 (top) double layered films for applications to the photoreduction of CO2. The amount of CH4 generated from the photoreduction of CO2 with H2O increased remarkably over the TiO2/Cu–TiO2 double layered films compared to the TiO2/TiO2 double-layered films. In particular, the amount of CH4 gas evolved over the TiO2/5.0 mol% Cu–TiO2 doubled layered film was twice as high as that produced over the TiO2/TiO2 double layered film. A proposed model suggested that the photoactivity over the TiO2/Cu–TiO2 double layered films can be enhanced by effective charge separation and inhibited recombination of the photogenerated electron–hole (e−/h+) pairs during interfacial transfer between TiO2 and Cu–TiO2.

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