Enhanced photodegradation of toxic volatile organic pollutants using Ni-doped graphitic carbon nitride under natural solar light

In this study, nickel-doped graphitic carbon nitride (Ni-gC3N4) was synthesized via facile thermal condensation and explored as a visible-light responsive photocatalyst for degrading volatile organic compounds (VOCs). Remarkably, Ni-gC3N4 with 2.5 wt% of Ni loading was capable of removing 98.6% of VOCs within 120 min under solar light. Moreover, the pseudo-first-order kinetic rate for Ni-gC3N4 was found to be approximately twice as high as that of an undoped sample. The Ni doping promoted visible light harvesting and charge separation efficiency, and endowed photoexcited electrons (e-) with an enhanced reduction capacity, as demonstrated by X-ray photoelectron spectroscopy analysis, the photoluminescence (PL), the photocurrent (PC) and UV–Vis optical characterization. In addition, recycling test results showed that Ni-gC3N4 exhibited excellent stability and recyclability. The influencing factors such as solution pH, the initial concentration of VOCs, and co-existing inorganic anions were investigated in detail. Results from radical scavenger experiments revealed that O2−, OH and h+ were involved in the photocatalytic degradation process by using Ni-gC3N4/solar-light system. This study can contribute to the development of high-performance catalysts for removing toxic organic pollutants from wastewaters.