Fabrication of Zr-doped SnO2 nanoparticles with synergistic influence for improved visible-light photocatalytic action and antibacterial performance
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Zr-doped SnO2 (Zr:SnO2) nanostructures (NSs) were produced by simplistic and low-cost co-precipitation route. The FTIR spectra of bands on 523 and 583 cm−1 were witnessed though indorsed as the features of (Sn–OH) term which approves the incident of Sn–O in the synthesized samples. The Zr:SnO2 NSs were spherical-like and composed of numerous agglomerated particles. The decreased crystallite sizes of the pristine and Zr-doped SnO2 NPs were 41.9, 38.9 and 35.8 nm individually. Moreover, the achievable growth manner of acquired samples was deliberated through the source of the customs of nucleation and crystal growth. The photocatalytic performances of 4% of Zr-doped SnO2 nanoparticles (NPs) were thoroughly explored in the photodegradation of methyl orange (MO) dye, thus revealing higher photocatalytic activity in the degradation of MO than pristine and 2% of Zr-doped SnO2 under via visible-light exposure. Related to pristine SnO2, the 4% Zr-doped SnO2 NPs are accessible to greater photocatalytic capability, which could be essentially accredited to existing in the nominal defects of oxygen vacancies by the produced NPs. Eventually, founded on the self-assembly progression the possible development of photocatalytic mechanism was projected by means of reactive species in trapping tests as well. Also, the antibacterial action was attained against E. coli and S. aureus bacteria through agar well diffusion system.
KeywordsZr-doped SnO2 Nanoparticles Photocatalytic performance Methyl orange dye Visible-light exposure
Currently, the synthesis progression, reform and applications of semiconductive nanomaterials (NMs) by appropriate modules and architectural assemblies have become an investigation emphasis in numerous fields as the enlargement of nanoscience expertise and semiconductor proficiency (Hu et al. 2014). As one of the supreme prevalent metal oxide (n-type) semiconductors (SCs), tin oxide (SnO2) nanostructure with the optical bandgap of ~ 3.6 eV has attracted great interests these years (Chen et al. 2019). SnO2 nanostructured ingredients own countless distinctive optical, electrical and electrochemical properties (Bhuvaneswari et al. 2018a; Song et al. 2019), which create it favourable solid material for innumerable new applications (dye base solar cells, magnetic devices, gas sensors, optoelectronic devices, catalysts and electrode materials) including photocatalytic explore for their great photosensitivity and chemical steadiness. It is substance underscoring that SnO2 NMs have greatly advanced electron mobility than TiO2, while expressly constructive to the aforementioned applications (Arnold et al. 2003; Hendry et al. 2006). Nonetheless, the low quantum yield of SnO2 quiet occurs and confines its concrete application, which is mostly owing to the firm recombination rate of photoexcited charges and the squat solar energy transformation efficacy (Fu et al. 2019). Thus it is exterme concern to increase the seperation of photo-excited charges (electron/hole) and auxiliary improve the photocatalytic properties of as-obtained SnO2 nanomaterials. The amendment of SnO2 with metal ions, additional SCs or else noble metals could be moderately operative to hasten the separation efficacy of photoexcited (e−/h+), and thus, it enriches the photocatalytic assets (Vignesh et al. 2013).
Zirconium is a precise, strong, flexible, ductile transition metal ion consuming chemical and physical belongings to titanium nanomaterials (NMs). It is exceedingly resistant to warmth and oxidization and is used in steel alloys as a hardening mediator and also used to sort surgical appliances. Zr4+ ion takes the ionic radius of 0.74 Å which is slighter than that of Sn2+ (0.93 Å) ion (Manjula and Selvan 2017). While SnO2 is doped with Zr, additional Zr4+ ions could be quartered into its matrix, thus changing its physical things (Reddy et al. 2017). The Zr4+ performance as a dual contributor provides up to binary further free electrons per ion replaced for Sn2+, and therefore, it is invented that Zr doping could augment the optical and the photocatalytic stuff of SnO2 actual much. Hence the extant work, a series of zirconium-doped SnO2 (Zr:SnO2) by different concentrations of Zr (2 and 4%) NPs were excellently blended by a modest proficient hydrothermal co-precipitation manner and the physical belongings remained deliberate and described. The Zr:SnO2 NPs revealed highly improved photocatalytic possessions to methyl orange (MO) aqueous organic dye degradation. Meanwhile, the probable growth progression and photocatalytic mechanism were conversed to intricate the charge transfer alleyways of photoinduced charge carriers in a photocatalytic manner, individually. Likewise, the antibacterial activity was achieved in contradiction of E. coli and S. aureus microbes/bacteria by an agar well diffusion scheme to discover the aptness of Zr:SnO2 NPs towards biological applications.
Materials and reagents
Tin (IV) chloride pentahydrate (SnCl4·5H2O), zirconium nitrate Zr(NO3)4, sodium hydroxide (NaOH), isopropanol (IPA), ethylene diamine tetra-acetic acid (EDTA), benzoquinone (BQ), and absolute ethanol (CH3CH2OH) were obtained from SDFCL Chemical Reagent Co., Pvt. Ltd., India, and used as customary without bonus modification. Deionized water (D.I) was used into entire synthesis progressions.
The Zr:SnO2 NPs with altered concentrations of Zr (2 and 4%) were organized by facile hydrothermal co-precipitation mode. The 0.1 M of SnCl4·5H2O was used as a precursor for organizing the SnO2 NPs. The SnCl4·5H2O was dissolved in an HCl and D.I water mixture solution (1:4 with an overall of 50 mL). To this effect, NaOH solution (1 g NaOH was softened in 20 mL D.I water) was auxiliary by drops sage, under vital stirring to upswing the pH value as ~ 10. To realize Zr doping, Zr (NO3)4 (% of Sn source) attention was more auxiliary to the pioneer solution. The ensuing solution was well-stirred for 6 h and consequently progressed by Teflon-lined stainless-treated autoclave and preserved at 200 °C for 24 h. Thus, the white precipitate was conquered, and additional wash away for plentiful times by absolute ethanol and D.I water surveyed by drying at 60 °C. The consequent product was formerly crushed with an agate mortar to acquire (2 and 4%) Zr:SnO2 NPs.
Assessment of antibacterial activity
The antibacterial studies of Zr-doped SnO2 NPs were done by test organisms of E. coli (Escherichia coli; Gram − ve) and S. aureus (Staphylococcus aureus; Gram + ve) bacterial strains patterned via agar well diffusion way; similarly, the Muller Hinton agar was further used for bacteriological culture (Vignesh et al. 2019a). The plate organized for agar wells by hovering out the type with a hygienic tool was overloaded with diverse attentiveness of 50 and 100 µL of obtaining pristine and Zr:SnO2 solution; formerly, these cultures were positioned in the shaking incubator for 37 °C at 24 h for evolution. Likely, the negative control (dimethyl sulfoxide—DMSO) and positive control (ampicillin) ethics were restrained in the alike progression. When the cultivation period was done, the diameters of zone of inhibition ideals (ZOI) fashioned about the wells were inspected and noted. Both testings were finished in triplicate, and the ZOI are specified as the mean ± usual deviance.
Results and discussion
Optical properties of obtained NMs
Photocatalytic activity measurements
Additionally, the prevailing oxygen vacancies (Vo) and incapacitating Zr4+ centres could act as arrested hubs for photoexcited charge carriers/(e−/h+), however supportive to diminish the recombination evolution of the particulars. Similarly the remarkable doping considerations (6% of Zr) and crystallite sizes are favorable for the larger photocatalytic performances.
Photocatalytic mechanisms of obtained photocatalyst
Comparison of visible-light generated MO degradation rate (%) over previously reported nanomaterials
Irradiation time (min)
Degradation efficiency (%)
Hir et al. (2017)
Carbon-coated alumina Ni-doped titanium dioxide NPs
Mbuli et al. (2019)
Mn–C–codoped TiO2 nanoparticles
Xin et al. (2012)
Mg-doped TiO2 polyscales
Shivaraju et al. (2017)
Raliya et al. (2017)
4% Zr-doped SnO2 NPs
Assessment on zone of inhibition of antibacterial activity for as-prepared nanoparticles
Zone of inhibition range (mm)
4 ± 0.5
3 ± 1
2% Zr-doped SnO2 NPs
5 ± 1
3 ± 0.5
4% Zr-doped SnO2 NPs
7 ± 0.5
5 ± 0.5
Summary and conclusions
In summary, the 4% Zr:SnO2 nanoparticles (NPs) were effectively produced by a modest and cost-efficient hydrothermal co-precipitation procedure. The XRD outcomes propose that nanocrystalline pristine and Zr-doped SnO2 NPs by tetragonal rutile-type construction and the crystallite size are about ~ 41 to 36 nm. FESEM imageries expose that the 4% of Zr:SnO2 NPs were self-possessed nanostructured with the agglomerated distribution of NPs and the EDX elemental enquiry endorses the manifestation of Zr metals was unvaryingly circulated over the SnO2 outward. The optical bandgap values are considered as 3.49 eV and 2.87 eV for pristine and Zr-doped SnO2 NPs separately. PL spectra fallouts advised that Zr dopant familiarized novel impurity planes amongst the CB and VB of SnO2, prominent to slighter bandgap augmenting the visible-light fascination. The 4% of Zr-doped SnO2 PCs influenced and enhanced photocatalytic activity and the superior deprivation efficacy towards MO dye under visible light. The deprivation rate of MO dye through Zr:SnO2 was augmented from 34.4 to 89.6% in 180 min and hence 2.6 times greater than the association with the pristine SnO2 NPs. The recycling test was established that through 4% Zr–SnO2 catalyst has no reduction of catalytic activity in the four sequential series runs. This effect advises that Zr-doped SnO2 catalyst might have prospective for good bacterial links and high concert visible-light-driven photocatalyst for the applications of industrial wastewater remediation.
Compliance with ethical standards
Conflict of interest
The authors declare no conflict of interest in presenting this article.
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