Elsevier

Applied Surface Science

Volume 463, 1 January 2019, Pages 1019-1027
Applied Surface Science

Full Length Article
Synthesis, characterization and photocatalytic activity of LaNdZr2O7 supported SnSe nanocomposites for the degradation of Foron blue dye

https://doi.org/10.1016/j.apsusc.2018.09.023Get rights and content

Highlights

  • LaNdZr2O7-SnSe composite was synthesized successfully.

  • The synthesized materials have been employed as photocatalysts for Foron blue degradation under visible-light.

  • The higher photocatalytic activities are ascribed to efficient charge separation.

Abstract

The present investigation reports a facile strategy for the synthesis of stable as well as visible-light active LaNdZr2O7/SnSe composite photocatalysts for applications in the degradation of Foron Blue azo dye. The as-synthesized photocatalysts have been characterized via several characterization techniques including x-ray diffraction (XRD) to confirm the phase of materials, scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS) to investigate the surface morphology as well as composition of synthesized materials, particle size distribution (PSD) and UV–vis diffuse reflectance spectroscopy (DRS) along with x-ray photoelectron spectroscopy (XPS) in order to draw the alignment of energy levels from the bandgap and valence band positions of photocatalysts, respectively. Foron Blue was degraded with a maximum efficiency up to 86.3% under visible-light illumination in 60 min by composite photocatalyst which is much higher as compared to SnSe and LaNdZr2O7 photocatalysts. The higher photocatalytic activity over the composite might be attributed to efficient charge separation.

Introduction

Environmental related problems are the global concerns which need to be addressed for a sustainable future. In the past few years, enormous scientific research has been conducted on the applications of photocatalysts for water and air decontamination with a major focus on dyestuff removal from water [1]. It has already been evaluated that only 10% of the total dyestuff is used for dyeing, while the remaining amount is discharged in the environment. Attributed to toxic as well as non-biodegradable nature and slow decoloration rate associated with the release of dye effluent, these are very harmful for the aquatic environment. Various chemical and physical techniques has been used for the removal of poisonous dyestuff from wastewater include adsorption, coagulation, flocculation, precipitation, ultrafiltration, air striping, ozonation and photocatalytic oxidation [2]. Among all these techniques, photocatalytic oxidation has been proved to be an excellent strategy for the wastewater treatment. The organic pollutants present in dyes are degraded into harmless substances i.e. carbon dioxide, water and mineral ions [3].

Ever since the pioneering work of Honda and Fujishima, a large number of novel photocatalysts such as titanates, tantalates and various metal oxide materials have already been developed for targeted applications using different methods [4]. However, there still exists plenty of room to explore novel photocatalysts for energy production as well as water purification. However, in commonly employed photocatalysts such as TiO2, their wide band gap (i.e. 3.2 eV) and rapid recombination of the photogenerated charge carriers (valence band holes and conduction band electrons) hamper the photocatlytic activity by only absorbing a small fraction of light of solar spectrum (∼4–5%) and hence are not suitable for large scale practical applications [5].

For the effective utilization of solar energy, significant work has also been carried out during the past decade for the development of various visible-light active photocatalysts for energy production and environmental applications [1], [6], [7], [8], [9], [10]. The visible-light photocatalytic activity of the semiconductors based photocatalysts has been improved by using different strategies such as sensitization of various transition metals and rare earth metals, doping of non-metal ions, development of single as well as multi-metal oxides [11] and fabrication of composite photocatalysts due to their exclusive properties [12]. These composite materials effectively suppress the recombination between the charge carriers by accommodating charge transfer from one component to the other component [13], [14], [15], [16], [17].

In the present investigation, we report the preparation and overall visible-light photocatalytic activity of LaNdZr2O7-SnSe composite. This work focuses on the overall photocatalytic activity of LaNdZr2O7, SnSe and their composite (LaNdZr2O7-SnSe) under visible-light i.e. degradation of the Foron Blue dye (Table 1) in aqueous medium. The structural, compositional, morphological, and photocatalytic properties are investigated in detail. A comparative study is carried out in order to reveal the structure-activity relationship among the photocatalytic properties of LaNdZr2O7, SnSe and their composite LaNdZr2O7-SnSe.

Section snippets

Chemicals

Lanthanum (III) nitrate hexahydrate (La(NO3)3·6H2O, Aldrich-99.99%), neodymium (III) nitrate hexahydrate (Nd(NO3)3·6H2O, Aldrich- 99.99%), zirconyl chloride octahydrate (ZrOCl2·8H2O, Aldrich-98%), ethanol (Analar, 99.8%), cetyltrimethyl ammonium bromide (CTAB, Merck-97%), selenium powder (Se, Aldrich-99.9%), potassium hydroxide (KOH, Merck-99%), tin(II) chloride (SnCl2, Aldrich- 99%), ethylene glycol (EG, Merck-99%) and hydrazine hydrate (N2H4·H2O Panreac-80%) were used for the synthesis of

Dye degradation

Foron Blue dye was selected as the target molecule to evaluate the photocatalytic activity of the LaNdZr2O7, SnSe and LaNdZr2O7–SnSe composite under ultraviolet (UV) and visible-light irradiation depending upon band gap energy of the synthesized photocatalysts at room temperature. The light source used in the photodegradation experiments of Foron dye was a 300 W Xe arc lamp (PLS-SXE300, Beijing Trusttech Co. Ltd.) with a UV cut-off filter of 420 nm in case of visible-light. The visible-light

XRD analysis

Fig. 1a shows the XRD pattern of the synthesized samples. One can clearly observe that all peaks of the sample (LaNdZr2O7) are identical to the standard pattern (00-017-0458) with the Fd-3m space group and a cubic unit cell (a = 1.06 nm) reflected in Fig. 1b. No other impurity phases were detected indicating the obtained product is in single phase and the sharp peaks indicate good crystallinity.

The crystal structure clearly indicates that the synthesized LaNdZr2O7 belongs to the cubic

Conclusion

Novel LaNdZr2O7/SnSe composite photocatalysts synthesized via hydrothermal method are efficiently employed as visible-light active photocatalyst for the photodegradation of Foron Blue (FB). The composite materials exhibited efficient degradation activity which was significantly higher than their individual counterparts. The enhanced photocatalytic activity over LaNdZr2O7/SnSe photocatalysts is due to minimized charge recombination which is attributed to the formation of a strong interface.

Acknowledgement

Nazia Karamat thanks the Higher Education Commission (HEC) of Pakistan for financial support under Indegeneous-5000 Phase II fellowship. Muhammad Naeem Ashiq is also thankful to Bahauddin Zakariya University, Multan for financial support.

References (33)

Cited by (21)

  • Sn-based materials in photocatalysis: A review

    2023, Advances in Colloid and Interface Science
  • Novel 0D/2D ZnSe/SnSe heterojunction photocatalysts exhibiting enhanced photocatalytic and photoelectrochemical activities

    2022, Journal of Alloys and Compounds
    Citation Excerpt :

    In Fig. 4A, it can be seen that SnSe is a 100 nm thick nanosheet of about 1–5 µm. Fig. 4B shows a further enlarged image, which shows some very small fragments on the surface of the nanosheet [43]. In Fig. 4C and D, it is observed that ZnSe is composed of homogeneous nanoparticles, and the morphology of ZnSe can be more clearly observed by TEM.

View all citing articles on Scopus
View full text