Visible-light-driven photoreduction of CO₂ to CO over porous nitrogen-deficient carbon nitride nanotubes

The solar energy-driven photoreduction of CO₂ with H₂O to hydrocarbon fuels is an interesting but challenging topic. Herein, we report porous nitrogen-deficient carbon nitride nanotubes with tunable nitrogen vacancies (NCN-T) for visible-light-driven photoreduction of CO₂ to CO in the absence of any cocatalyst and sacrificial reagent. The NCN-T series were prepared via the thermal etching approach, which showed a specific surface area of up to 207 m² g^-1 and a CO₂ uptake capacity of 4.06 wt%. It was indicated that the nitrogen vacancies in NCN-T not only promoted the utilization of visible-light by extending the spectral response range, but also served as centres for capturing photoexcited electrons, hence, efficiently inhibiting the recombination of radiative electron-hole pairs. As a consequence, the NCN-T catalysts achieved the highest CO formation rate of 43.9 μmol g^-1 h^-1, which was >9 times higher than that obtained over the bulk counterpart.