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

Abstract

• Solar light-driven dual Z-scheme Bi 2 MoO 6 /Bi 2 WO 6 \AgI\Ag photocatalyst was prepared. • The photocatalyst realizes degradation and conversion of nitrogenous organic pollutants. • The introduction of Ag as co-catalyst promotes selective conversions of NO 3 − and NO 2 − . • High-activity of •CO 2 − is conductive to the conversions of NO 3 − and NO 2 − to N 2 . • The photocatalyst shows good stability and reusability in degradation of 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 Bi 2 MoO 6 /Bi 2 WO 6 \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 (NO 3 − ) and nitrite (NO 2 − ) ions into nitrogen (N 2 ). The results reveal that the Z-scheme Bi 2 MoO 6 /Bi 2 WO 6 \AgI\Ag photocatalyst possesses high degradation ratio of MG and generation ratio of N 2 under solar light irradiating for 180 min at pH = 5.0. It can be attributed to the fabrication of dual Z-scheme Bi 2 MoO 6 /Bi 2 WO 6 \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 NO 3 − and NO 2 − into N 2 . 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 (•CO 2 − ) are in charge of the conversions of NO 3 − and NO 2 − ions. Furthermore, a probable mechanism on degradation of the nitrogenous organic pollutants and conversions of the generated NO 3 − and NO 2 − ions induced by Z-scheme Bi 2 MoO 6 /Bi 2 WO 6 \AgI\Ag photocatalyst is put forward.