Visible-Light-Responsive Graphitic Carbon Nitride: Rational Design and Photocatalytic Applications for Water Treatment

Abstract

Graphitic carbon nitride (g-CN) has recently emerged as a promising visible-light-responsive polymeric photocatalyst; however, a molecular-level understanding of material properties and its application for water purification were underexplored. In this study, we rationally designed nonmetal doped, supramolecule-based g-CN with improved surface area and charge separation. Density functional theory (DFT) simulations indicated that carbon-doped g-CN showed a thermodynamically stable structure, promoted charge separation, and had suitable energy levels of conduction and valence bands for photocatalytic oxidation compared to phosphorus-doped g-CN. The optimized carbon-doped, supramolecule-based g-CN showed a reaction rate enhancement of 2.3-10.5-fold for the degradation of phenol and persistent organic micropollutants compared to that of conventional, melamine-based g-CN in a model buffer system under the irradiation of simulated visible sunlight. Carbon-doping but not phosphorus-doping improved reactivity for contaminant degradation in agreement with DFT simulation results. Selective contaminant degradation was observed on g-CN, likely due to differences in reactive oxygen species production and/or contaminant-photocatalyst interfacial interactions on different g-CN samples. Moreover, g-CN is a robust photocatalyst for contaminant degradation in raw natural water and (partially) treated water and wastewater. In summary, DFT simulations are a viable tool to predict photocatalyst properties and oxidation performance for contaminant removal, and they guide the rational design, fabrication, and implementation of visible-light-responsive g-CN for efficient, robust, and sustainable water treatment.

Extremely Compressible Hydrogel via Incorporation of Modified Graphitic Carbon Nitride

“…Graphitic carbon nitride (g‐CN) is a metal‐free visible light active photocatalyst with tunable properties, which is composed of repeating tri‐s‐triazine units . It is synthesized from low cost precursors and possesses high activity in applications such as water splitting, CO 2 reduction, emulsion stabilization, and designed organic reactions .…”

g‐C3N4‐Based Heterostructured Photocatalysts

“…[288][289][290] Photocatalysis has been demonstrated effective for the deg radation of environmental pollutants, including organic and inorganic air pollutants, [168,212] toxic dyes, [50,89,220,291] phenol and persistent organic micropollutants in water. Photocatalysis has proven to be a promising strategy for environmental decontamination due to its high efficiency and low cost.…”

Facile and Versatile Functionalization of Two‐Dimensional Carbon Nitrides by Design: Magnetism/Multiferroicity, Valleytronics, and Photovoltaics

“…[3,4] Another member of graphitic carbon nitrides, CN, has also been widely studied [5] owing to its potential applications in energy storage and catalysis. For instance, C 3 N 4 is known as a promising photocatalyst for water splitting and for degradation of organic pollutants under sunlight irradiation.…”