Amrish Chandra

Facile Green Synthesis of BiOBr Nanostructures with Superior Visible-Light-Driven Photocatalytic Activity

Novel green bismuth oxybromide (BiOBr-G) nanoflowers were successfully synthesized via facile hydrolysis route using an Azadirachta indica (Neem plant) leaf extract and concurrently, without the leaf extract (BiOBr-C). The Azadirachta indica leaf extract was employed as a sensitizer and stabilizer for BiOBr-G, which significantly expanded the optical window and boosted the formation of photogenerated charge carriers and transfer over the BiOBr-G surface. The photocatalytic performance of both samples was investigated for the degradation of methyl orange (MO) and phenol (Ph) under the irradiation of visible light. The leaf extract mediated BiOBr-G photocatalyst displayed significantly higher photocatalytic activity when compared to BiOBr-C for the degradation of both pollutants. The degradation rate of MO and Ph by BiOBr-G was found to be nearly 23% and 16% more when compared to BiOBr-C under visible light irradiation, respectively. The substantial increase in the photocatalytic performance of BiOBr-G was ascribed to the multiple synergistic effects between the efficient solar energy harvesting, narrower band gap, high specific surface area, porosity, and effective charge separation. Furthermore, BiOBr-G displayed high stability for five cycles of photocatalytic activity, which endows its practical application as a green photocatalyst in the long run.

Biofabricated BiOI with enhanced photocatalytic activity under visible light irradiation

In the recent past, there has been a large-scale utilization of plant extracts for the synthesis of various photocatalysts. The biofabrication technology eliminates the usage of harmful chemicals and serves as an eco-friendly approach for environmental remediation. Herein, a comparative analysis between bismuth oxyiodide synthesized via Azadirachta indica (neem) leaf extract (BiOI-G) and without leaf extract (BiOI-C) has been envisaged. The BiOI-G and BiOI-C samples were characterized by spectral and microscopic techniques, which revealed that the Azadirachta indica assisted BiOI-G attained enhanced features over BiOI-C such as narrower band gap, large surface area, porosity, increased absorption range of visible light and effectual splitting of the photogenerated e−–h+ pairs. Benefiting from these enhanced features, BiOI-G degraded methyl orange (MO), rhodamine B (RhB), and benzotriazole (BT) at a significantly higher rate in comparison to BiOI-C. The degradation rate of MO, RhB and BT by BiOI-G was observed to be 1.3, 1.25 and 1.29 times higher in comparison to BiOI-C. Moreover, BiOI-G displayed high stability upto five cycles of the photocatalytic activity, which endow its effectiveness as a highly-efficient green photocatalyst.

A Review on BiOX (X= Cl, Br and I) Nano-/Microstructures for Their Photocatalytic Applications

In the recent past, bismuth oxyhalides (BiOX) have been widely used for the photocatalytic degradation of the organic pollutants and other environmental remediation because of their higher stability, economic viability, nontoxicity and effective charge separation. We begin with the review of the different approaches adopted so far for BiOX (X = Cl, Br, and I) synthesis and a study of their photocatalytic performances under UV and visible light towards the various organic as well as inorganic pollutants. Later on, a study on further enhancement of the efficiency of BiOX under UV and visible light irradiation using recent advancements would be presented. The new approaches involve controlled morphology by forming composite and hybrid materials with other semiconductors and also doping with other metals and nonmetals that would undoubtedly be beneficial in the interfacial charge transfer and efficient inhibition of the photo-generated species. Herein, we would also exploit the recent developments in the research strategies for enhancing photocatalytic activity of BiOX.

Plant leaf extracts as photocatalytic activity tailoring agents for BiOCl towards environmental remediation

The inducement of plant leaf extracts for the synthesis of various nanostructures has intrigued researchers across the earth to explore the mechanisms of biologically active compounds present in the plants. Herein, a green modified hydrolysis route has been employed for the synthesis of bismuth oxychloride i.e. BiOCl-N, BiOCl-T and BiOCl-A using plant extracts of Azadirachta indica (Neem), Ocimum sanctum (Tulsi), and Saraca indica (Ashoka), and; simultaneously, without plant extract (BiOCl-C), respectively. The as-prepared samples were examined by several microscopic and spectroscopic techniques which revealed that the biosynthesized BiOCl attained certain favorable features such as hierarchical nano-flower morphology, higher porosity, higher specific surface area and narrower band gap compared to BiOCl-C. The degradation of methyl orange (MO) and bisphenol A (BPA) using biosynthesized BiOCl were improved by 21.5% within 90 min and 18.2% within 600 min under visible light irradiation, respectively. The photocurrent response, electrochemical impedance spectroscopy (EIS) and photoluminescence (PL) studies indicated the effective inhibition of the electron-hole pair recombination and enhanced photocatalytic activity of the biosynthesized BiOCl.