Research Article pubs.acs.org/journal/ascecg
Biotemplating Synthesis of Graphitic Carbon-Coated TiO2 and Its Application as Efficient Visible-Light-Driven Photocatalyst for Cr6+ Remove Qing Cai,† Chenglu Liu,† Chaochuang Yin,† Wei Huang,‡ Lifeng Cui,† Huancong Shi,† Xueyou Fang,† Lu Zhang,† Shifei Kang,*,† and Yangang Wang*,† †
Department of Environmental Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, P. R. China ‡ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, P. R. China ABSTRACT: TiO2 and graphitic carbon (GC) composites with hierarchical pore structures were synthesized using Staphylococcus aureus (ATCC6538) as the biotemplate to modify Degussa P25 TiO2 powder. Then, the composites were applied as photocatalysts for Cr6+ reduction under visible light irradiation. X-ray diffraction, Raman spectroscopy, transmission electron microscopy, nitrogen adsorption−desorption analysis, and X-ray photoelectron spectroscopy demonstrated the presence of a GC coating layer and a unique anatase/rutile mixed crystal phase of TiO2 even after heating at 800 °C. The novel TiO2@GC composites, especially the S-P25-800 sample, which possessed abundant hierarchical mesoporous structures, exhibited strong catalytic activities in Cr6+ photoreduction under visible light. This work provides light to overcome the challenge on synthesis of GC modified TiO2 photocatalysts with the highly reactive but heat-labile anatase main crystal phase at high temperature. Furthermore, the present results demonstrated that TiO2@GC heterojunctions has a great potential to be used as efficient and economical photocatalysts for environmental contaminants remove. KEYWORDS: TiO2, Graphitic carbon, Visible-light-driven photocatalyst, Cr6+ reduction
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INTRODUCTION TiO2 as an n-type semiconductor photocatalyst has received much attention because it is able to address the worldwide energy and environmental problems due to its optical stability, low cost, and nontoxicity.1 Nowadays, owing to their high photocatalytic activity under ultraviolet light, many commercial TiO2 products are widely used as photocatalysts in photochemical reactions. It is well known that TiO2 has a wide band gap energy of 3.2 eV, so when illuminated by photons at proper energy (
