Interest in research on semiconductor based photocatalysts has attracted much attention in the fields of photochemistry, catalysis, electrochemistry, and owing to their high chemical stability and photocatalytic activity [1]. Several semiconductor photocatalysts like ZnO, TiO2, WO3, CdO, Fe2O3, ZnS, MoS2 and CdS etc. have been more apt for the elimination of organic pollutants contaminate in the waste water which release from the paper, leather and textile industries [2]. Among this, ZnS act as a considerable II–VI compound semiconductor material with wide band gap (3.6 eV) and large exciton binding energy (40 meV), has been studied widely as an excellent photocatalyst due to its quick photoexcited electron (e−) -hole (h+) pairs and highly negative reduction potentials of excited electrons [3, 4]. Numerous methods have been utilized to develop ZnS nanoparticles (NPs) like electrochemical deposition, sol-gel, solvothermal, hydrothermal, co-precipitation, pyrolysis, microemulsion, laser ablation, combustion synthesis, and vapor deposition [5]. Among them, co-precipitation technique has various reaction time, temperature, and parameters like pH. As well as, initial concentration of the solution and material, have played a crucial role on receiving ceramic powders with preferred shape and size [6].
In current decade, transition metal ferrite (ZnFe2O4, CdFe2O4, MgFe2O4, NiFe2O4, CoFe2O4, CuFe2O4, SrFe12O19 etc.) has been widely researched as photocatalysts due to their easy magnetic separation, photocorrosion in aqueous solutions, low cost and biocompatibility [7]. Among ferrites, magnesium ferrite (MgFe2O4, MFO) is an n-type semiconductor with a spinel structure, which endows the absorption of visible light owing to their narrow band gap of 2.0 eV [8]. Fascinatingly, earlier literatures revealed p-n (or) n-n type heterojunction structure for enhance the photocatalytic activity by their charge separation efficiency between photo-induced electron and hole pair’s [9]. In this aspect, Su et al. has developed MgFe2O4–-ZnO heterojunction photocatalyst for degradation of Rhodamine B organic dye. The excellent photocatalytic activity has been achieved via interconnected heterojunction of n-MgFe2O4 and n-ZnO nanoparticles [10].
Therefore, in the present investigation focus to form a novel n-MgFe2O4/n-ZnS heterojunction for improve the photocatalytic activity owing to their efficient separation of photo-exited electron and hole pairs. The photocatalytic activity was investigated by prepared samples of MgFe2O4, ZnS and MgFe2O4/ZnS NCs under visible-light illumination by the photodegradation of methylene blue (MB) and crystal violet (CV) and reported for the first time.