Solar-driven triple photocatalytic action of defective S-doped g-C3N4 for 1,4 NADH regeneration and simultaneous benzylamine conversion along with CO2 fixation into HCOOH†

Abstract

Incorporating defects through intrinsic defect engineering has emerged as a versatile strategy for finely tuning the key properties of materials, particularly the redox capacity. Defects are fundamentally important in enhancement of the electronic, optical, and structural properties, thereby improving the photocatalytic effectiveness of a material. In this study, defects were induced in sulphur-doped graphitic carbon nitride through treatment with NaBH₄. This process notably enhanced the material's capacity to capture light, demonstrating the effectiveness of introducing defects to improve its performance. This work describes the photocatalytic action of defective S-doped g-C₃N₄ (DSGN), where the surface electrons from the DSGN photocatalyst were directed to selectively reduce CO₂ to formic acid while the holes assisted in the coupling of benzylamines. Notably, this process occured under the illumination of solar light without the need for any external sacrificial agent or bio-enzyme. The simultaneous conversion of benzylamines to their corresponding imines (94%) and CO₂ transformation into HCOOH (203.46 mol g_cat⁻¹) carried out under ordinary environmental conditions promoted by the DSGN photocatalyst make this a remarkable process. In addition to this, the DSGN photocatalyst showed a significant 1,4 NADH regeneration yield (75.40%) in 1 h. The recyclability and physico-chemical stability tests for DSGN demonstrated its high stability and suitability for repeated use. This work on photocatalysis utilizing the DSGN photocatalyst for both environmental remediation (CO₂ reduction) and organic transformations (benzylamine coupling) in one step and exceptional 1,4 NADH regeneration capabaility has potential to contribute to the fields of green chemistry and sustainable energy.