Ultrathin metal−organic layers/carbon nitride nanosheet composites as 2D/2D heterojunctions for efficient CO2 photoreduction

Abstract

Metal–organic layers (MOLs), a new class of 2D photocatalysts with abundant readily accessible active sites, have emerged as a new 2D catalysis platform. Most pristine MOLs possess large band gaps and merely harvest ultraviolet light, which restricts their application in solar-driven CO₂ reduction. If MOLs are combined with visible-light-active semiconductors, it may overcome the shortage and construct efficient CO₂ reduction photocatalysts. Herein, a series of 2D/2D TM-MOLs/CN (TM = transition metal; CN = g-C₃N₄) heterogeneous composites were assembled by an in situ ultrasonic-assisted synthesis method. The resultant Co-MOL/CN(400) exhibited excellent photocatalytic CO₂ reduction performance, with a CO formation rate of 539 μmol h⁻¹ g⁻¹ and a selectivity of 79.8%. The proximity of the interfacial contact between Co-MOL and CN facilitates charge carrier separation/transfer from the photosensitizer to catalytic centers, which affords a superior photoactivity performance compared to most MOFs/CN (MOF = metal–organic frameworks) analogous hybrid photocatalysts. This heterogeneous composite thus represents a remarkable stepping stone in 2D/2D assembled multifunctional materials for studying the artificial photocatalytic reduction of CO₂ to solar chemicals and fuels.