Enhanced photocatalytic performance of the N-rGO/g-C3N4 nanocomposite for efficient solar-driven water remediation

Abstract

This paper describes the synthesis and analysis of a photocatalyst made from a combination of reduced graphene oxide (rGO) and graphitic carbon nitride (g-C₃N₄) through a simple hydrothermal process. The effectiveness of the N-rGO/g-C₃N₄ heterostructure in photocatalysis was examined by studying the breakdown of different types of organic pollutants, such as cationic and anionic dyes, as well as antibiotics, under simulated solar light irradiation. Due to the presence of Schottky junctions formed between rGO and g-C₃N₄, the electron transfer process is significantly enhanced, leading to a reduction in the recombination of photogenerated electrons and holes. As a result, the photocatalytic activity of the rGO/g-C₃N₄ photocatalyst is significantly higher compared to that of g-C₃N₄ alone. The photocatalytic performance was further augmented through the nitrogen doping of rGO, which led to an increase in conductivity due to electron doping and an enhancement in the charge separation process. The heterojunction of rGO/g-C₃N₄ with an optimum concentration of 60% rGO attained a degradation efficiency of 98.7% for rhodamine B (RhB) dye after 50 minutes of light irradiation. In comparison, the nitrogen-doped photocatalyst (N-rGO/g-C₃N₄) achieved a photodegradation efficiency of 99.99% within 30 minutes. The reaction rate constant of the N-rGO/g-C₃N₄ nanocomposite was found to be 0.11 min⁻¹ using pseudo first-order rate kinetics. This value is about 16 times more than that of pure g-C₃N₄ (0.007 min⁻¹) for the degradation of rhodamine B. Additionally, N-rGO/g-C₃N₄ effectively degraded various contaminants, such as methylene blue, methyl orange, and tetracycline hydrochloride. The paper also addresses the photocatalytic mechanism, which entails the facilitated movement of electrons and holes produced by light, owing to the alignment of energy bands at the interface of the N-rGO/g-C₃N₄ heterojunction. These findings contribute to the advancement of a metal-free and porous photocatalyst that is highly interconnected and can be used for waste water treatment and environmental remediation.