Photocatalytic reduction of carbon dioxide with water on InVO4 with NiO cocatalysts

• NiO/InVO4 was active for photoreduction of CO2 undervisible light irradiation. The quantum efficiency was 2.8%.
• Some pinholes were created on the InVO4 surface after loading with NiO cocatalyst.
• The pin hole creates defect sites which are the active sites for reaction.
• The band gap of NiO/InVO4 was lower than that of InVO4 due to the formation of subband in valence band by creating more defect sites on the surface of InVO4.

InVO4 was synthesized by solid-state reaction method using In2O3 and V3O4 as the starting materials. NiO was added as the cocatalyst. The catalysts were characterized by powder X-ray diffraction, scanning electron microscope, and ultraviolet–visible spectroscopy. The photocatalytic reduction of CO2 with water was carried out in a Pyrex reactor with KHCO3 aqueous solution bubbled with CO2 gas under visible light illumination. Many pinholes were observed on the InVO4 particles after loading with NiO cocatalyst. The band gap of NiO/InVO4 was lower than that of InVO4 due to the formation of subband in valence band by creating more defect sites on the surface of InVO4. Both NiO/InVO4 and InVO4 can reduce CO2 to methanol under visible light irradiation. The reaction rate increased with an increase of the loading of NiO cocatalysts.

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