Photocatalytic activity of ZnO-MnO₂ core shell nanocomposite in degradation of RhB dye

Abstract

Purpose The purpose of this study is to synthesize a semiconductor photocatalyst which responds to both UV light and visible light in removal of organic dyes. Design/methodology/approach ZnO nanoparticles were pre-synthesised via sol-gel method using zinc nitrate tetrahydrate and methanamine at 90°C for 20 h. Subsequently, the as-synthesised ZnO nanoparticles were filtered, washed and dried. To synthesize ZnO-MnO2 core shell nanocomposites (CSNs), 2:3 M ratio of KMnO4 and MnSO4 solution was stirred for an hour. Next, ZnO nanoparticles were added into the solution. The solution was heated at 160°C for 3 h for the formation of ZnO-MnO2 CSNs. The structural, optical and photocatalytic properties of ZnO-MnO2 CSNs were characterised by field emission scanning electron microscope, transmission electron microscopy (TEM), X-ray diffractometer and PL spectroscopy, respectively. Findings The photodegradation efficiencies of rhodamine B (RhB) dye by ZnO-MnO2 CSNs as photocatalysts are 87.1 per cent under UV irradiation and 76.6 per cent under visible light irradiation, respectively. Their corresponding rate constants are 0.016 min−1 under UV irradiation and 0.013 min−1 under visible light irradiation. It can be concluded that N-deethylation was the dominant step during the photodegradation of RhB dye as compared to cycloreversion. The ZnO-MnO2 CSNs demonstrated good photostability after three consecutive runs. Originality/value ZnO-MnO2 CSN photocatalyst which could response to UV and visible light in degradation of RhB dye was synthesised using sol-gel method. The analysis shows that N-deethylation was the key photodegradation mechanism of RhB by ZnO-MnO2 CSN.

Synthesis, characterisation, and antimicrobial activity of ZnO‐based nanocomposites

“…The peak at 502 cm −1 in S 1 , S 2 , and S 3 is attributed to the characteristic absorption peak of the Zn-O bond and also confirms the presence of ZnO in all samples [20]. The peaks at 622 cm −1 and around 1010-1122 cm −1 in S 2 and S 3 illustrate the stretching of O-Mn-O lattice vibrations [1,38]. The wideband at 3000-3600 cm −1 assigned to the -OH band [39,40].…”

Photocatalytic Activity of ZnxMn3−xO4 Oxides and ZnO Prepared From Spent Alkaline Batteries

“…Both the XRD and microscopic characterizations indicate that, in the case of the Zn x Mn 3−x O 4 oxides, real mixed oxides were formed with only one type of morphology. This was not the case for the studies carried out by Pung et al ( 2016 ), in which a ZnO–MnO 2 core–shell nanocomposite was formed, or by Wang et al ( 2019 ), in which both oxides were mixed to form a composite material that maintained both structures. In the study reported by Li et al ( 2008a ), the effects of the presence of MnO 2 on the photocatalytic degradation of phenol by TiO 2 and ZnO were investigated.…”

“…Thus, the design and development of low-cost, high-performance catalysts that are preferably sustainable and active across the entire solar spectrum should be key objectives. Several researchers have evaluated the photocatalytic activities of MnO 2 -TiO 2 (Li et al, 2008a ) and MnO 2 -ZnO (Pung et al, 2016 ) mixtures. However, lower photocatalytic activity was observed for ZnO and TiO 2 in the presence of MnO.…”

Adsorptive removal of Rhodamine B dye from aqueous solution by using graphene–based nickel nanocomposite

“…In order to improve the adsorption and dye degradation efficiency by using graphene-based nanomaterials, along with co-catalysts, noble metal particles, metallic, non-metallic doping and with hydrogels have been used [ 18 ]. Even though many researchers reported on the dye degradation of RhB, our work using graphene based nickel nanocomposite (RGO–Ni) showed better adsorption efficiency than adsorption for removing RhB dye compared to that of other adsorbents like TiO 2 and graphene TiO 2 [ 19 ], CuS/PVA nanocomposite [ 20 ], ZnO–MnO 2 [ 21 ], and other self-assembled GO nanostructures from various styles [ 22 , 23 , 24 , 25 ].…”