Effective separation and transfer of carriers into the redox sites on Ta3N5/Bi photocatalyst for promoting conversion of CO2 into CH4

Abstract Improving separation efficiency of carriers and inhibiting the inverse reaction are key challenges for achieving efficient sunlight driven conversion of CO 2 by H 2 O as reducing agent into CH 4 . Here, we proposed using metal Bi with low work function to modify n -type Ta 3 N 5 , thus building an ohmic junction photocatalyst of Ta 3 N 5 /Bi. It achieved an about 5 times increase in CH 4 yield compared with Ta 3 N 5 . The enhanced photocatalytic activity was ascribed to the following two effects: (1) The junction electric field drove the injection of conduction-band electrons of Ta 3 N 5 to Bi, greatly improving separation efficiency of carriers; (2) The oxidation and reduction reaction sites were respectively constructed over Ta 3 N 5 and Bi, effectively separating the oxidation reaction of H 2 O and the reduction reaction of CO 2 , which distinctly suppressed the reverse reaction during CH 4 generation.