NH4Cl assisted gC3N4 nanosheets for improved photodegradation of dyes in pure water under visible light

Abstract

ABSTRACT Porous gCNNCl nanosheets were synthesised using a simple bottom-up chemical route with varying NH4Cl: melamine ratios (2:1, 1:1, 1:2). FTIR, XRD, TRPL, PL spectra, ESR, BET, and UV-DRS techniques investigated the inherent properties of the catalysts. Notably, gCNNCl (2:1) nanosheets exhibited an enhanced surface area (26.68 m2/g) and bandgap value (2.65 eV), both favourable for photocatalysis. Their exceptional properties extended to a longer lifetime, coupled with enhanced crystallinity and improved optical characteristics compared to other ratios. The NH3 gas released during gCNNCl nanosheet formation likely contributes to these enhanced properties. These gCNNCl nanosheets were employed for photodegradation of Rhodamine B (REB), Methylene Blue (MEB), and Methyl Orange (MEO). Remarkably, gCNNCl (2:1) achieved complete MEB degradation (98%) within 25 minutes, significantly faster than gCNNCl (1:1) (40 minutes) and gCNNCl (1:2) (60 minutes, respectively). Similarly, gCNNCl (2:1) displayed superior performance for REB degradation, reaching 92% removal in 40 minutes compared to 85% for both gCNNCl (1:1) (45 minutes) and gCNNCl (1:2) (60 minutes, respectively). For MEO, gCNNCl (2:1) achieved a maximum removal of 60% in 75 minutes, outperforming gCNNCl (1:1) (46% in 110 minutes) and gCNNCl (1:2) (42% in 110 minutes, respectively). Further, five repeated trials with fresh catalyst confirmed the reusability of gCNNCl (2:1) for MEB degradation, although a 10% reduction in activity was observed.