Ultrathin Graphitic Carbon Nitride Nanosheets for Photocatalytic Hydrogen Evolution

Abstract

Among semiconductor photocatalysts, graphite carbon nitride (g-C 3 N 4 ) has caused great concern in terms of water splitting. Here, we prepared ultrathin g-C 3 N 4 nanosheets with high photocatalytic activity by recrystallization of urea from N,Ndimethylformamide (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 Xray 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 onestep 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.

Carbon Nitride-Perovskite Composites: Evaluation and Optimization of Photocatalytic Hydrogen Evolution in Saccharides Aqueous Solution

“…Notice that appreciable HER was gained also with no metal, underlining the potentiality of such photoactive material. This evidence corroborates a photoreaction mechanism typical of the photocatalytic systems for H 2 production from water [1,3,23], wherein:…”

“…Since Pt is in situ photodeposited on the catalyst surface, after Ar bubbling, a small volume from an H 2 PtCl 6 aqueous solution (0.15, 3 or 15 g L −1 ) was added using a 10-100 µL micropipette to the catalyst suspension, directly in the photoreactor. This was closed with sleeve stopper septa and was irradiated, as described in the following, achieving simultaneous Pt deposition and H 2 production [23,[28][29][30]. Irradiation was done under simulated solar light using a Solar Box 1500e (CO.FO.ME.GRA S.r.l., Milan, Italy) set at a power factor of 500 W m -2 , and equipped with UV outdoor filter made of IR-treated soda lime glass.…”

Panchromatic Ternary Polymer Dots Involving Sub-Picosecond Energy and Charge Transfer for Efficient and Stable Photocatalytic Hydrogen Evolution

“…Recently, reports have shown that ultrathin g-C 3 N 4 nanolayers are able to greatly enhance photocatalytic hydrogen evolution. 13 , 14 Porous conjugated polymers as photocatalysts have been rapidly developed in recent years, and the structures of the polymer have been proven to be one of the key factors for obtaining good performance. 12 − 25 Making the linear conjugated polymer particles as small as possible can shorten the required distance for exciton diffusion to suppress the unwanted annihilation of excitons as well as increase the catalytic surface area, therefore enhancing the photocatalytic performance.…”

Urea-induced supramolecular self-assembly strategy to synthesize wrinkled porous carbon nitride nanosheets for highly-efficient visible-light photocatalytic degradation

“…[17][18][19] Modied g-C 3 N 4 with nanotubes, nanosheets and porous structures have been successfully prepared by methods including the hard template method, so template method, acid treatment method and thermal etching method. 20,21 However, these methods suffer from drawbacks such as template removal, residual impurities, consumption of strong acids and low efficiency. 22,23 Therefore, it is still an urgent task to explore facile and highly-efficient methods for the nanostructure engineering of g-C 3 N 4.…”