Self-assembly construction of NiCo LDH/ultrathin g-C3N4 nanosheets photocatalyst for enhanced CO2 reduction and charge separation mechanism study

Graphite phase carbon nitride (g-C3N4) is a promising catalyst for artificial photocatalytic carbon dioxide (CO2) reduction. However, the fast carrier recombination and the inadequacy of the CO2 reduction active site in g-C3N4 block the escalation of the performance. In this work, NiCo layered double hydroxide (NiCo LDH) nanoflowers were self-assembled with ultrathin graphite phase carbon nitride (g-C3N4) by an ultrasonic stirring strategy utilizing the Zeta potential difference. The formed NiCo LDH/ultrathin g-C3N4 nanosheets (LDH-CN) photocatalysts own the merits of rich active sites and Z-scheme heterojunction, which lead to the enhanced CO2 reduction activity and selectivity. The highest yields of CO and CH4 were 114.24 and 26.48 μmol·h−1·g−1, which were much greater than those of g-C3N4 and LDH. Meanwhile, the enhanced selectivity for CO confirmed the strong redox ability in the LDH-CN caused by the Z-scheme. The heterojunction-induced built-in electrical field can promote the separation and migration of photoinduced electrons and holes. This study provides a theoretical basis for designing high-performance photocatalysts.