Visible Light-Driven Highly Selective CO 2 Reduction to CH 4 Using Potassium-Doped g-C 3 N 5 .

Establishment of an efficient and robust artificial photocatalytic system to convert solar energy into chemical fuels through CO 2 conversion is a cherished goal in the fields of clean energy and environmental protection. In this work, we have explored an emergent low- Z nitrogen-rich carbon nitride material g-C 3 N 5 (analogue of g-C 3 N 4 ) for CO 2 conversion under visible light illumination. A significant enhancement of the CH 4 production rate was detected for g-C 3 N 5 in comparison to that of g-C 3 N 4 . Notably, g-C 3 N 5 also showed a very impressive selectivity of 100% toward CH 4 as compared to 21% for g-C 3 N 4 . The photocatalytic CO 2 conversion was performed without using sacrificial reagents. We found that 1% K doping in g-C 3 N 5 enhanced its performance even further without compromising the selectivity. Moreover, 1% K-doped g-C 3 N 5 also exhibited better photostability than undoped g-C 3 N 5. We have also employed density functional theory calculation-based analyses to understand and elucidate the possible reasons for the better photocatalytic performance of K-doped g-C 3 N 5 .