Porous Carbon Nitride Thin Strip: Precise Carbon Doping Regulating Delocalized π‐Electron Induces Elevated Photocatalytic Hydrogen Evolution

Abstract

The photocatalytic efficiency of polymeric carbon nitride is hampered by high carrier recombination rate and low charge transfer. Herein, these issues are addressed by constructing 1D strip-like carbon nitride with a large π-electron conjugated system from carbon-doping, realizing the synchronization control of its electronic structure and morphology. Nicotinic acid, a monomer with the carboxyl group and pyridine ring, and melamine are selected for assembling the strip-like supramolecular via hydrogen bond under hydrothermal process. Both peripheral pyridine unit and hydrogen bond have significant effect on self-assembly process of nicotinic acid and melamine along one dimension to form a strip-like precursor. Subsequently, 1D thin porous strip-like carbon nitride is obtained by calcination treatment of precursor. The as-prepared 1D strip-like carbon nitride with effective π delocalization from carbon-doping and porous structure can accelerate charges and mass transfer and provide extra active sites. Both theoretical and experimental results demonstrate that carbon doping (pyridine heterocycle) narrows the bandgap via manipulating the band position and increases the π electron density. Thus, the 1D porous thin strip-like carbon nitride realizes compelling hydrogen evolution rate (126.2 µmol h −1), far beyond (≈18 fold) the value of polymeric carbon nitride (PCN) (7.2 µmol h −1) under visible light irradiation.

K/O co-doping and introduction of cyano groups in polymeric carbon nitride towards efficient simultaneous solar photocatalytic water splitting and biorefineries

“…As shown in Table S1, † the photocatalytic hydrogen production rate of K/O@CN-CuN is higher than those of other catalysts (Table S1, † entries 1-5). 18,25,36,48 Furthermore, K/O@CN-CuN is a highly efficient photocatalyst for lactic acid production from xylose (Table S2, † entry 1) and glucose (Table S2, † entry 7). As compared with the CuO@CS-H and B@mCN systems, the K/O@CN-CuN system gives better yields at low reaction temperature (Table S2, † entries 1-3).…”

“…As a promising metal-free photocatalyst, polymeric carbon nitride has attracted tremendous attention for its visible-light responsiveness, easy preparation, excellent chemical/thermal stability, suitable band structure and low cost. 16,17 Currently, carbon nitride-based photocatalysts are used widely in photocatalytic water-splitting, 18 CO 2 reduction, 19 pollutant degradation, 20 organic synthesis, 21 and biorefineries. 11,12,22 However, primary carbon nitride has some shortcomings, such as limited light absorption and a slow migration/separation rate of charge carriers, resulting in poor photocatalytic performance.…”

Dopant and Defect Doubly Modified CeO2/g-C3N4 Nanosheets as 0D/2D Z-Scheme Heterojunctions for Photocatalytic Hydrogen Evolution: Experimental and Density Functional Theory Studies

“…In the past few years, carbon-based materials have shown great capabilities in promoting the PHE activities of semiconductor photocatalysts. , Carbon-based materials exhibited extensive π–π conjugation, which improved the circulation of photogenerated carriers, high surface area for multiple reactive sites, and a flexible framework that is easy to structure modification. Graphite carbon nitride (g-C 3 N 4 ), as a representative of 2D carbon nanomaterials, has attracted much attention due to its many advantages in photocatalysis. − Nevertheless, the photocatalytic efficiency of pristine g-C 3 N 4 has been unsatisfactory by now due to its small surface area, insufficient light absorption, and serious charge recombination. To date, extensive efforts have been exploited to enhance the photocatalytic activity of g-C 3 N 4 by elements doping, defect engineering, morphology control and constructing heterostructure, etc. , Among these modification methods, a g-C 3 N 4 -based heterojunction has been considered an effective strategy to significantly improve the separation efficiency of photogenerated carriers and photocatalytic activity.…”

Uracil-mediated supramolecular assembly for C-enriched porous carbon nitrides with enhanced photocatalytic hydrogen evolution

“…24,29 After calcination, the C-CQC structure from uracil can be introduced into the carbon nitride skeleton, resulting in a novel porous carbon-doped graphitic carbonitride (MCA-U). 30 The morphology and microstructure of the catalysts were studied through field emission scanning electron microscopy (SEM). The SEM image of g-C 3 N 4 (Fig.…”