Enhanced photo-catalytic activity of Sr and Ag co-doped TiO2 nanoparticles for the degradation of Direct Green-6 and Reactive Blue-160 under UV & visible light

Saraschandra Naraginti; T V L Thejaswini; D Prabhakaran; A Sivakumar; V S V Satyanarayana; A S Arun Prasad

doi:10.1016/j.saa.2015.04.101

Enhanced photo-catalytic activity of Sr and Ag co-doped TiO2 nanoparticles for the degradation of Direct Green-6 and Reactive Blue-160 under UV & visible light

Spectrochim Acta A Mol Biomol Spectrosc. 2015 Oct 5:149:571-9. doi: 10.1016/j.saa.2015.04.101. Epub 2015 May 8.

Authors

Saraschandra Naraginti¹, T V L Thejaswini², D Prabhakaran², A Sivakumar³, V S V Satyanarayana⁴, A S Arun Prasad⁵

Affiliations

¹ Environmental and Analytical Chemistry Division, School of Advanced Sciences, VIT University, Vellore 632 014, India.
² Chemistry Division, School of Advanced Sciences, VIT University Chennai Campus, Chennai 600 127, India.
³ Environmental and Analytical Chemistry Division, School of Advanced Sciences, VIT University, Vellore 632 014, India. Electronic address: svkmr7627@gmail.com.
⁴ Chemistry Department, School of Basic Sciences, IIT Mandi, Himachal Pradesh, India.
⁵ Division of Environmental Biotechnology, School of Biosciences and Technology, VIT University, Vellore 632 014, India.

PMID: 25983059
DOI: 10.1016/j.saa.2015.04.101

Abstract

This work is focused on sol-gel synthesis of silver and strontium co-doped TiO2 nanoparticles and their utilization as photo-catalysts in degradation of two textile dyes. Effect of pH, intensity of light, amount of photo-catalyst, concentration of dye, sensitizers, etc., were studied to optimize conditions for obtaining enhanced photo-catalytic activity of synthesized nanoparticles. XRD, BET, HR-TEM, EDAX and UV-Vis (diffused reflectance mode) techniques were used to characterize the nanoparticles. Interestingly, band gap of Sr and Ag co-doped TiO2 nanoparticles showed considerable narrowing (2.6 eV) when compared to Ag doped TiO2 (2.7 eV) and undoped TiO2 (3.17 eV) nanoparticles. Incorporation of Ag and Sr in the lattice of TiO2 could bring isolated energy levels near conduction and valence bands thus narrowing band gap. The XRD analysis shows that both Ag and Sr nanoparticles are finely dispersed on the surface of titania framework, without disturbing its crystalline structure. TEM images indicate that representative grain sizes of Ag-doped TiO2 & Sr and Ag co-doped TiO2 nanoparticles are in the range of 8-20 nm and 11-25 nm, respectively. Effective degradation of Direct Green-6 (DG-6) and Reactive Blue-160 (RB-160) under UV and visible light has been achieved using the photo-catalysts. Sr and Ag co-doped TiO2 photo-catalysts showed higher catalytic activity during degradation process in visible region when compared to Ag-doped and undoped TiO2 nanoparticles which could be attributed to the interactive effect caused by band gap narrowing and enhancement in charge separation. For confirming degradation of the dyes, total organic carbon (TOC) content was monitored periodically.

Keywords: Co-doped nanoparticles; Degradation; Direct Green-6; Photo-catalyst; Reactive Blue-160.