A novel dual and synergetic effect of NH3 and CO2 atmospheric gases in the synthesis of a low-energy LED light-activated g-C3N4 photocatalyst for efficient organic pollutant degradation

Abstract

This study presents a novel synthesis route for graphitic carbon nitride (g-C₃N₄) using simultaneous NH₃ and CO₂ gas flow to enhance surface area and photocatalytic efficiency. NH₃ functions as both an exfoliating and a templating agent, while CO₂ provides a protective atmosphere during synthesis. The resulting materials were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), field emission scanning electron microscopy (FE-SEM)/energy dispersive X-ray spectroscopy (EDS), UV-vis diffuse reflectance spectrometry (DRS), photoluminescence (PL), nitrogen adsorption–desorption and Brunauer–Emmett–Teller (BET) analyses. The photocatalytic performance was evaluated using rhodamine B (RhB) as a model pollutant under various conditions. Among the synthesized samples, the one prepared with melamine and ammonium chloride under a CO₂ atmosphere (MACO₂) demonstrated superior performance, achieving complete dye degradation within 120 minutes under LED and natural sunlight. The sample also exhibited high stability and reusability over five cycles. The active species involved in the degradation process were investigated, confirming the dominant role of superoxide radicals. Due to its ease of synthesis, high efficiency, and sustainability, MACO₂ has emerged as a promising green photocatalyst for environmental remediation.