Synthesis and photocatalytic performance of CoMoO4/MoO3 composite for wastewater treatment

Abstract

Wastewater treatment is becoming severe issue owe to use of different dyes at commercial level in industries. In search of a suitable photocatalyst such as to degrade these dyes, we have developed CoMoO4/MoO3 composites by varying 1–4 wt% of CoMoO4 and adopting a facile hydrothermal synthesis route. The crystalline and structural investigations of as obtained products were done with the help of XRD spectroscopic tool. The morphological features along with elemental composition were probed by SEM and TEM microscopic tools. To observe the optical band gap structure, a UV–vis spectroscopy was employed, which has explored that the band gap of 3% CoMoO4/MoO3 composite was 2.50 eV which was lesser than pure and other composites. The emission properties and electrons-holes recombination kinetics were studied by PL spectroscopic tool and the as optimized 3 wt% composite sample has offered the lowest recombination rate. For the wastewater treatment, the photodegradation of a model dye i.e methyl orange was observed over the course of contact time with the catalyst and the photocatalytic efficiency of pure MoO3 was compared with 1–4 wt% CoMoO4/MoO3 nanocomposites. This photocatalytic efficiency of the 3% CoMoO4/MoO3 composite turn out to be 92%. Besides, this optimized composite material has exhibited a superior degradation stability i.e 83% even after 5 degradation rounds against methyl orange. Furthermore, the as optimized composite has offered 10 times enhanced rate constant (k) than pure MoO3. These characterizations have shown that this excellent increase in the photocatalytic degradation performance is owe to the formation of p-n junction heterostructure, which led to the successful separation of charge carriers and also owe to the increase in surface area hence increasing the active sites for the reduction of dye molecules. Results also have shown the extended visible light response of the catalyst, hence its performance has been further boosting in visible light region.