Ultrathin Graphitic Carbon Nitride Nanosheets for Photocatalytic Hydrogen Evolution

Among semiconductor
photocatalysts, graphite carbon nitride (g-C3N4) has caused great concern in terms of water
splitting. Here, we prepared ultrathin g-C3N4 nanosheets with high photocatalytic activity by recrystallization
of urea from N,N-dimethylformamide
(DMF) to form a hydrogen-bonding network (named as UDF) and then utilized
the as-prepared complex for the synthesis of carbon nitride. Single-crystal
X-ray diffraction showed that urea and DMF form a 3:1 solvate in the
UDF precursor, which manifests an extended three-dimensional hydrogen-bonding
network. Then one-step thermal polycondensation of the UDF yields
a nanosheet morphology with a reduced thickness of 4.0 nm, an enlarged
surface area, and improved optical absorption, which results in a
high rate of photocatalytic hydrogen evolution (2.5 × 10–4 mol h–1) under the irradiation
of visible light. It is foreseen that the facile method herein provides
an alternative research approach for the synthesis of carbon nitride
materials with versatile morphologies and structures for solar energy
conversion.