To realize excellent selectivity of CH4 in CO2 photoreduction (CO2 PR) is highly desirable, yet which is challenging due to the limited active sites for CH4 generation and severe electron-hole recombination on photocatalysts. Herein, based on the theoretically calculated effects of vanadium incorporation into the laminate of layered double hydroxides (LDHs), V into NiAl-LDH to synthesize a series of LDHs with various V contents is introduced. NiV-LDH is revealed to afford a high CH4 selectivity (78.9%), and extremely low H2 selectivity (only 0.4%) under λ > 400 nm irradiation. By further tuning the molar ratio of Ni to V, a CH4 selectivity of as high as 90.1% is achieved on Ni4 V-LDH, and H2 is completely prohibited on Ni2 V-LDH. Fine structural characterizations and comprehensive optical and electrochemical studies uncover V incorporation creates the lower-valence Ni species as active sites for generating CH4 , and enhances the generation, separation, and transfer of photogenerated carriers.
Keywords: CH 4 production; CO 2 photoreduction; electronic structure modulation; layered double hydroxide; vanadium incorporation.
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