Structural reorganization of ultrathin g-C3N4 nanosheets for significantly boosting wide-spectrum-driven CO2 photoreduction

Abstract

Graphitic carbon nitride (g-C3N4) exhibits moderate CO2 photoreduction due to fast recombination of photoexcited charges and low-grade visible light absorption. Herein, we synthesized highly polymerized ultrathin g-C3N4 nanosheets by structural reorganization. Both experimental and theoretical calculations indicate that amino groups stabilized by hydrogen bonding networks are the easiest to remove to form a more stable bridged N-(C)3. This procedure provides additional electron transfer channels with an extended conjugated π → π* system and buckled plane structure with activated n → π* electronic transitions. This new configuration significantly improves the separation efficiency of photoexcited charges and widens the light absorption range. As a result, the prepared g-C3N4 shows efficient CO2-to-CO conversion with a CO production rate of 12.95 μmol g-1 h−1 under λ ≥ 420 visible light and 2 μmol g-1 h−1 under λ ≥ 500 visible light, respectively. This work offers a new design idea for highly active visible-light-driven g-C3N4 for CO2 photoreduction.