Substitution and oxygen vacancy double defects on Bi2MoO6 induced efficient conversion of CO2 and highly selective production of CH4

A series of novel iodine substitution and oxygen vacancy double defects Bi 2 MoO 6 nanosheets for enhanced photocatalytic reduction of CO 2 is reported, which exhibited superior CO 2 photocatalytic activity and CH 4 selectivity under full solar spectrum illumination. Bi 2 MoO 6 -I2 (the molar ratio of I to Mo is 0.13) has the highest photocatalytic activity, its CO yield is 2.0 times that of pure Bi 2 MoO 6 , the CH 4 yield is 12.2 times that of pure Bi 2 MoO 6 , and the CH 4 selectivity reaches 5.3 times that of pure Bi 2 MoO 6 . Its structure and physicochemical properties were investigated by material characterizations, photoelectrochemical tests and DFT calculations. The enhancement in CO 2 conversion and CH 4 selectivity benefit from: (1) Larger specific surface areas and smaller nanosheets thicknesses facilitate carrier migration; (2) More suitable band structure promotes the reduction of CO 2 ; (3) Insertion of impurity energy levels in the band gap enables efficient jumping of photogenerated electrons; (4) Double defects contribute to efficient CO 2 adsorption and activation; (5) Promoting highly selective conversion of CO 2 to CH 4 by optimising the formation energy of reaction intermediates.