Fabrication of pebble stone-like PbMoO₄ nanostructure: Focus on photocatalysis, photoluminescence and electron density distribution analysis

Highlights

• PbMoO₄ nanomaterial is fabricated via simple hydrothermal route.

• The SEM reveals the good morphology (Pebble stone structure) structure of PbMoO₄.

• The photocatalyst PbMoO₄ enhancing the degradation rate of above 92% for CIP degradation.

• The optimum parameters like the effects of different catalyst dosage, pollutant concentration and recycle ability were studied.

• Rietveld refinement and charge density distribution analysis of PbMoO₄ through JANA – 2006 and dysnomia software’s.

Abstract

In this work, the PbMoO₄ nanocatalyst is synthesized by the hydrothermal way. The as-prepared PbMoO₄ nanomaterial was confirmed by powder X-ray diffraction (P-XRD), UV–visible diffuse reflectance spectroscopy (UV-DRS), photoluminescence (PL), scanning electron microscopy (SEM) and Transmission electron microscopy techniques (TEM). The scanning Electron Microscope result indicates the pebble stone morphology structure of PbMoO₄ nanomaterials. The catalytic performance for as-synthesized PbMoO₄ nanomaterial was analyzed by the ciprofloxacin (CIP) degradation process. More interestingly, the as-prepared PbMoO₄ material is having higher catalytic performance compared to the other previous PbMoO₄ nanoparticles reports with an efficiency of above 92%. A photodegradation mechanism and the reaction kinetics of PbMoO₄ nanomaterial were also investigated. The aforesaid results are strong enough to suggest the PbMoO₄ nanomaterial may be an effective catalyst for environmental application. In addition, the electron density distributions studies were carried out for this PbMoO₄ nanomaterial to explain the bond length value between the atoms.

Introduction

Ecotoxicity is the main issue for people's day to day life; In particular, water is one of the common issues threatening human existence [1]. Every annum raised the pollution level due to industrialization which is affecting the surrounding. The discharged waste from industrial effluents is into the surrounding with improper treatment, it is highly poisonous for aquatic organisms and the environment [2,3]. Furthermore, the higher usage of antibiotics poses a major menace to the aquatic system [[4], [5], [6]]. In particular, fluoroquinolone is the most crucial antibiotic for the treatment of Gram (+ve) and Gram (-ve) bacteria affects [7]. In a fluoroquinolone family, the ciprofloxacin (CIP) is mainly used in medicine for bacterial infections and lungs illness in both humans and animals [[8], [9], [10], [11]]. The proper environmental rescue method like wastewater treatment is a very intricate process due to very expensive. To overcome this problem, the researchers can improve the advanced oxidation process (AOPs), to develop the treatment of the waste effluents. In the process of AOPs, the photocatalytic method is very useful for the rescue of the environment. This photocatalysis method has been more effective and inexpensive; also it is an eco-friendly method for the mineralization of hazardous materials [[12], [13], [14]]. Recently, many semiconductor materials are used to decompose the poisonous pollutants in the degradation method [[15], [16], [17], [18], [19]]. These highly efficient processes are eco-friendly into the surrounding.

A collection of higher efficacy and innovative catalyst products has been improved and recently it is gained more importance. Semiconductor materials are used to mineralize harmful organic pollutants into harmless moieties and are a technology that benefits the environment [2,20,21]. The semiconductors like TiO₂ [[22], [23], [24]], PbMoO₄ [[25], [26], [27]] and ZnO [[28], [29], [30]] have been studied extensively by many researchers.

In this present work, the PbMoO₄ nanomaterial was synthesized by hydrothermal route. The PbMoO₄ is a very important material for the molybdate family in addition to scheelite structure; it is raised the interest as a photocatalyst for the decomposition of organic pollutants [31]. By the large bandgap (eV) value of lead molybdate (Eg = 3.26 eV), it was reacted as a catalyst for the degradation process under UV light illumination. In recent, the lead molybdate was prepared under different processes, such as solvothermal, hydrothermal, microwave irradiation, and chemical precipitation, sonochemical techniques [[32], [33], [34], [35], [36], [37]]. However, the PbMoO₄ photocatalyst compiled by solid-state method, solvothermal and co-precipitation methods, etc., [[38], [32], [37]].

Among the decomposition technique, the PbMoO₄ nanomaterial is a highly effective catalyst for the degradation of CIP by UV irradiation. In these report, the CIP is decomposed under PbMoO₄ material from water to reduce surrounding endangers. Using this semiconductor photocatalytic method, the hazardous pollutant is mineralized fully in harmful hazardous into CO₂, H₂O and some mineral acids. The CIP structure is portrayed in Fig. 1.