ABSTRACT
Graphitic carbon nitride nanosheet (CNS) represents an attractive candidate for solar fuel production. However, the abundant defects in CNS lead to serious charge recombination and limit the photocatalytic performance. Herein, the synthesis of a CNS-covalent organic framework (CNS-COF) nanosheet composite is presented for the first time. CNS with significantly reduced defects is first obtained by rationally tuning the thermal exfoliation conditions of bulk carbon nitride. Subsequent modification of the CNS with trace COF nanosheet through chemical imine bonding can not only passivate the surface termination of carbon nitride in the boundary region, but also establish strong electronic coupling between these two components. As a consequence, enhanced charge separation and photocatalytic activity are realized on the resulting CNS-COF nanosheet composite. Under optimum conditions, hydrogen is evolved at a rate of 46.4 mmol g-1 h-1 . This corresponds to an apparent quantum efficiency of 31.8% at 425 nm, which is among the best values ever reported for carbon nitride-based materials.
ABSTRACT
Modifying g-C3N4 with covalent organic frameworks (COFs) through imine linkage results in a dramatically enhanced visible-light-driven photocatalytic hydrogen evolution, which reached 10.1 mmol g-1 h-1 when 2 wt% Pt and triethanolamine were used as co-catalyst and sacrificial agent, respectively, corresponding to an apparent quantum efficiency (AQE) of 20.7% at 425 nm.
ABSTRACT
A composite of single-crystalline Bi2WO6 and polycrystalline BiOCl with a high percentage of exposed (00l) facets was fabricated by the molten salt method (MSM) in the presence of polytetrafluoroethylene (PTFE). The photocatalytic activity of the composite was 17 and 70 times that of Bi2WO6 prepared by the MSM without PTFE and the traditional solid state reaction method, respectively.
