Delocalization of π‐Electron in Graphitic Carbon Nitride to Promote its Photocatalytic Activity for Hydrogen Evolution

Abstract

Polymers with a large π‐electron conjugated system have aroused extensive concern in photocatalysis due to their appropriate bandgap and high stability. In order to overcome such drawbacks as its inadequate visible light absorption and rapid recombination of the photogenerated electron‐hole pairs of graphic carbon nitride (g‐C3N4), a facile strategy is proposed to tune its electronic structure by grafting small molecules. The conjugated photocatalysts were prepared by attaching 3‐Aminobenzoic acid (AB) and 6‐Aminopyridine‐2‐carboxylic acid (APy) to the framework of g‐C3N4 via low‐temperature condensation. The obtained catalysts UCN‐AB and UCN‐APy possess higher visible light absorption that results from the modified band structure by extending π‐electron delocalization. Additionally, AB and APy worked as the electron acceptors which further enhance transport of the photogenerated electrons. The optimal UCN‐AB and UCN‐APy accomplished remarkable photocatalytic hydrogen evolution rates of 104.0 and 133.2 μmol/h, respectively, which are nearly four or five times of that over g‐C3N4. This work provides a simple and feasible modification approach to extend π‐electron delocalization in g‐C3N4 with a stronger visible light response and accelerated charge transfer for high photocatalytic hydrogen evolution.

The Influence of Metal-Doped Graphitic Carbon Nitride on Photocatalytic Conversion of Acetic Acid to Carbon Dioxide

“…Such correlations are applicable for classifying these materials as high-performance photocatalysts in terms of CO 2 evolution rate, i.e., Fe-doped CN (Fe_CN, FeCu_CN, and FeZn_CN) and Cu_CN materials, corresponding to the relatively ESR intensity ( g = 2.003) of 1.3 and above. The presence of delocalized π-electrons in CN materials described herein, and their relationship with photocatalytic activity for chemical conversion, is in excellent agreement with previous work ( Guan and Zhang, 2019 ; Lin et al, 2021 ).…”

Boosting photocatalytic H2generation by assembling a copper complex and carbon nanotubes onto a carbon nitride polymer

“…45,46 Moreover, CN possesses very abundant terminal amine groups that could be modified by various organic reactions to incorporate low-cost copper complexes for H 2 evolution. [47][48][49] The present work, for the first time, reports a CuL/CNTs/ CN photocatalyst for H 2 generation without any metal cocatalysts. The low-cost complex CuL was covalently anchored onto CN by S N 2 reaction, serving as a cocatalyst to decrease the overpotential for H 2 generation.…”

Boron–pnictogen monolayers with a negative Poisson's ratio and excellent band edge positions for photocatalytic water splitting

“…Generally, an efficient photocatalyst is furnished with spatially well-separated holes and electrons, which in turn leads to a low recombination rate of the charge carriers and a higher efficiency in the overall water-splitting reaction. 62,63 Observably, the partial charge density corresponding to the CB is localized on the B atom, while that of VB is localized on the respective pnictogen (X) atom of each 2D bp-BX sheet (X = N, P, As and Sb), as depicted in Fig. 9.…”