Bio-synthesis of BiVO 4 Nanorods Using Extracts of Callistemon viminalis
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MRS Advances © 2018 Materials Research Society DOI: 10.1557/adv.2018.318
Bio-synthesis of BiVO4 Nanorods Using Extracts of Callistemon viminalis H.E.A.Mohameda,b, B.T.Sonea,b, M.S.Dhlaminia,b, M.Maazaa,b a
UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria, South Africa b
Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset, South Africa
ABSTRACT In this contribution we report on the synthesis of n-type Bismuth vanadate (BiVO4) nanorods prepared via the use of aqueous extracts of Callistemon viminalis. X-ray diffraction analysis confirmed the formation of highly crystalline monoclinic BiVO4 nanorods post annealing of the Bismuth vanadate precursor powder at 500 °C. Scanning Electron Microscopy and High Resolution Transmission Electron Microscopy showed that BiVO4 nanorods have a high aspect ratio. Using UV-Vis absorption measurements the optical band gap of the nanorods is estimated to be 2.4 eV which makes the bio-synthesized BiVO4 powder a good candidate for sunlight driven photocatalysis.
1. INTRODUCTION Bismuth vanadate (BiVO4) has become a promising candidate material as a photocatalyst and has been proven to exhibit excellent photocatalytic performance under visible light irradiation due to its relatively narrow band gap. The preparation of monoclinic BiVO4 phase is of vital importance for the degradation of organic pollutants. BiVO 4 has been extensively investigated and has been proven to be a good photocatalyst for water splitting. In addition, it also acts as pollutant decomposing under visible light irradiation [1-2]. In respect to the three structure types of bismuth vanadate (BiVO 4); which are a) zircon tetragonal, b) scheelite monoclinic, and c) scheelite tetragonal, the monoclinic scheelite BiVO 4 exhibits a higher visible-light photocatalytic activity over the other forms. This has resulted in drawing much more researched based attention to Bismuth vanadate (BiVO4) as a photocatalyst. Bismuth Vanadate has received attention as a noted photocatalyst, especially in its application to water splitting and the decomposition of pollutants under visible light irradiation [3]. The study of visible light driven photocatalysts has become a vital point of research. Previously, TiO2 has been used as an effective photocatalyst where the photocatalytic activity has
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been widely studied. However, titanium oxide is only able to respond to UV light of only 4% of the whole solar energy, leaving a further 43% available for use. Methods that have been employed for the synthesis of monoclinic structure BiVO 4 crystallites include sol-gel method, hydrothermal method, chemical co-pre
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