Uracil derivative-assisted universal synthesis of defective 2-dimensional porous flaky carbon nitride for efficient photocatalytic CO2 reduction

Abstract

In this paper, three novel defective two-dimensional lamellar carbon nitride were successfully synthesized by molecular self-assembly using melamine and cyanuric acid as supramolecular aggregates and introducing three different uracil derivatives (5-formyluracil, 5-acetyluracil, uracil-5-carboxylic acid). In our previous work, we found that the introduction of thymine into supramolecular precursors has good photocatalytic oxidation ability for NO. On this basis, we discovered that by introducing uracil derivatives as ligands for supramolecular aggregates, not only two-dimensional porous sheet nanostructures can be constructed, but also abundant nitrogen and oxygen defects can be introduced, which is supported by various characterizations. These defects can effectively modulate the electronic structure of carbon nitride and thus improve the separation of photogenerated carriers. In addition, the introduction of uracil derivatives affects the energy band structure of the catalyst, and these are important factors affecting the catalytic activity. Compared with bulk carbon nitride, the synthesized materials exhibited significantly enhanced photocatalytic CO2 reduction activity under mild conditions, with CO yields of 10.34, 28.65, 32.28, and 36.48 μmol g−1h−1 for BCN, CNU2.5, CNF2.5, and CNY2.5, respectively. More importantly, with the support of in situ DRIFTS, we proposed the reaction mechanism of photocatalytic reduction of CO.