One-pot synthesis of octahedral NiSe2 as a co-catalyst for enhanced CO2 photoreduction performance

•We have grown the first octahedral NiSe2 on one-dimensional NiTiO3 NFs using a one-pot solvothermal method.•The composite NiTiO3 NFs/NiSe2 presented an improved CO2 photoreduction efficiency compared to the pristine NiTiO3 NFs photocatalyst.•The optimal sample (0.09 wt% NTNs) can perform UV–vis light-driven CO2 reduction to CO and CH4 with a selectivity of 88.8% at a rate of 459.96, 269.02 μmol g−1h−1 respectively.•The high CO2 photoreduction is attributed to the improved light absorbance and prolonged lifetime of photogenerated carriers due to metallic NiSe2.•In situ FT-IR (DRIFT) revealed the selective CO2→COOH∗→CO∗/CO→CHO∗→CH3O∗→CH4 conversion on the optimal sample.