Construction of solar light-driven dual Z-scheme Bi2MoO6/Bi2WO6\AgI\Ag photocatalyst for enhanced simultaneous degradation and conversion of nitrogenous organic pollutants

Designing efficient photocatalyst for degradation and conversion of nitrogenous organic pollutants is meaningful to remediate the water environment. In this research, a dual Z-scheme Bi2MoO6/Bi2WO6\AgI\Ag photocatalyst is prepared via isoelectric point and continuous ion layer adsorption methods. The morphology, structure, composition and photoelectrical property of the acquired photocatalyst are investigated by multiple characterization techniques. The activity of the prepared photocatalyst is evaluated by degrading malachite green (MG) and converting the generated nitrate (NO3−) and nitrite (NO2−) ions into nitrogen (N2). The results reveal that the Z-scheme Bi2MoO6/Bi2WO6\AgI\Ag photocatalyst possesses high degradation ratio of MG and generation ratio of N2 under solar light irradiating for 180 min at pH = 5.0. It can be attributed to the fabrication of dual Z-scheme Bi2MoO6/Bi2WO6\AgI photocatalytic system and the deposition of Ag nanoparticle as co-catalyst, which enables the photocatalyst to have high separation efficiency of electrons and holes and strong selectivity for the conversions of NO3− and NO2− into N2. The cycle experiment and XRD test confirm the preeminent stability and reusability of the photocatalyst. The trapping and electron spin resonance (ESR) experiments verify that the hole plays a vital part in the degradation of MG, electron and carbon dioxide free radicals (•CO2−) are in charge of the conversions of NO3− and NO2− ions. Furthermore, a probable mechanism on degradation of the nitrogenous organic pollutants and conversions of the generated NO3− and NO2− ions induced by Z-scheme Bi2MoO6/Bi2WO6\AgI\Ag photocatalyst is put forward.