Efficient photocatalytic reduction of CO2 by a rhenium-doped TiO2-x/SnO2 inverse opal S-scheme heterostructure assisted by the slow-phonon effect

[Display omitted] •Re-IO-TiO2-x/SnO2 inverse opal heterostructure with oxygen vacancy was prepared.•Inverse opal can significantly boost light harvesting due to slow photon effect.•Re-IO-TiO2-x/SnO2 possesses high carrier separation efficiency due to excellent electron migration rate of SnO2 and the presence of multivalent Re.•Re-IO-TiO2-x/SnO2 performs outstanding CO yield of 16.59 μmol·g−1·h−1. Light harvesting and carrier separation play significant roles in determining the efficiency of photocatalytic reduction reactions. In this work, rhenium was doped into inverse opal TiO2-x/SnO2 to construct heterojunction catalysts in which Ti3+ is combined with oxygen vacancies (OVs). The slow-photon-effect of the inverse opal (IO) structure and the oxygen deficiency enable the catalysts to have high light-harvesting efficiency. SnO2 was selected to construct the heterojunction, and its excellent electron migration rate was highly beneficial for boosting the separation efficacy of the photogenerated carriers. As a result, the yield of CO in photocatalytic reduction of CO2 using the final obtained catalyst was 16.59 μmol·g−1·h−1, which is approximately 1.21, 2.14 and 7.44 times of the yields obtained using IO-TiO2-x/SnO2, IO-TiO2-x and SnO2, respectively. This strategy, which integrates the slow-photon-effect, oxygen vacancies, and element doping, affords a new avenue for preparing highly active heterojunction photocatalysts and improving photocatalytic performance.