Visible light driven Ni–BaMo3O10 photocatalyst for Indigo Carmine degradation: Mechanism and pathways

Abstract

The microwave hydrothermal method was employed for the synthesis of Ni doped Barium trimolybdate (Ni–BaMo3O10) tripod microcrystals. The photocatalyst, BaMo3O10 and Ni–BaMo3O10 have tendency to degrade the Indigo Carmine (IC) about 40 and 98% under visible light irradiation, respectively in 180 min. The photocatalyst revealed the excellent photodegradation stability up to five cycles. The active species (OH•, O2•-, and h+) were responsible for IC degradation on the basis of scavenger test. Effect of pH on IC degradation was also investigated. The enhancement of photocatalytic efficiency for IC degradation is related to increase in visible light absorption/oxygen vacancy and efficient separation of electron-hole pairs on the surface of photocatalyst. The suppression of charge recombination explained by transient photocurrent response and EIS measurements. The IC degradation was analyzed by ultra-performance liquid chromatography-photodiode array (UPLC-PDA) and high resolution-quadruple time of flight electrospray ionization mass spectroscopy (HR-QTOF ESI/MS). The four degradation pathways of IC in water were proposed on the basis of degraded products. Hydroxylation, oxidation, methylation, decarboxylation, and desulfonation reactions were observed during IC degradation. The efficient mineralization of IC occurred according to total organic carbon (TOC) investigation. Therefore, this research article presents removal of dyes pollutants from polluted water and in-depth analysis of IC pathways.