Photocatalytic reduction of CO2 to methane over HNb3O8 nanobelts

KNb3O8 and HNb3O8 nanobelts were prepared by hydrothermal synthesis. The characteristics of samples were investigated by XRD, SEM, and UV–vis diffuse reflectance spectroscopy. The KNb3O8 and HNb3O8 nanobelts exhibited much higher activities for CO2 photoreduction to methane than commercial TiO2 (Degussa P25), and the KNb3O8 and HNb3O8 particles prepared by conventional solid state reaction. It was also found that either the HNb3O8 nanobelts or the HNb3O8 particles performed better than the corresponding KNb3O8 counterpart. It is proposed that the nanobelt-like morphology and the protonic acidity contribute to the higher photocatalytic activity of the HNb3O8 nanobelts.

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► HNb3O8 with nanobelt-like morphology was prepared by hydrothermal synthesis.
► HNb3O8 nanobelts exhibited high activity for CO2 photoreduction to methane.
► The photocatalytic activity of HNb3O8 is higher than that of KNb3O8.
► The protonic acidity contributes to the high activity of HNb3O8 nanobelts.
► The nano-structure contributes to the high activity of HNb3O8 nanobelts.