Synthesis of novel ZnO/carbon xerogel composites: Effect of carbon content and calcination temperature on their structural and photocatalytic properties

Author(s)

de Moraes, Nicolas Perciani ^[1] ; Bacetto, Leticia Araujo ^[1] ; dos Santos, Gabriela Spirandelli ^[1] ; Caetano Pinto da Silva, Maria Lucia ^[1] ; Barros Machado, Joao Paulo ^[2] ; Bastos Campos, Tiago Moreira ^[3] ; Thim, Gilmar Patrocinio ^[3] ; Rodrigues, Liana Alvares ^[1]

Affiliation

^[1] Univ Sao Paulo, EEL, Dept Engn Quim, Estr Municipal Campinho S-N, BR-12602810 Lorena, SP - Brazil

^[2] Inst Nacl Pesquisas Espaciais, Av Astronautas 1-758, BR-12227010 Sao Jose Dos Campos, SP - Brazil

^[3] CTA, ITA, Praca Mal Eduardo Gomes 50, BR-12228900 Sao Jose Dos Campos, SP - Brazil

• Document type: Journal article
• Source: CERAMICS INTERNATIONAL; v. 45, n. 3, p. 3657-3667, FEB 15 2019.
• Web of Science Citations: 1

Abstract

This paper reports the development of new ZnO/carbon xerogel composites (XZn w) for photocatalytic applications. The use of black wattle tannin as a precursor to the carbon xerogel aimed at reducing costs and environmental impacts. The composites were characterized by diffuse reflectance spectroscopy (DRS), BET surface area, scanning electron microscopy (FEG-SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), infrared spectroscopy (IR), and X-ray diffraction (XRD). The photocatalytic performance of the materials was evaluated in the decomposition process of methylene blue, a known toxic pollutant. The impacts of the catalyst dosage and calcination temperature on the photocatalytic process were also examined systematically. The X-ray profiles of the XZn w evidenced the existence of the hexagonal structure of the zinc oxide (wurtzite) in the composites. The XPS and XRD analyses confirmed the incorporation of carbon in the zinc oxide crystalline structure. The higher carbon content resulted in a larger surface area. All composites presented the ability to absorb radiation in less energetic wavelengths, contrary to pure zinc oxide that only absorbs radiation of wavelengths below 420 nm. The optimal dosage and calcination temperature were found to be 0.2 g L-1 and 300 degrees C. All the developed composites displayed significant photocatalytic activities in the decomposition of methylene blue under both visible and solar light. The composites had superior photocatalytic efficiency under visible light when compared to pure zinc oxide. The XZn 0.5 presented the best degradation efficiency under visible radiation. All materials presented similar photocatalytic responses under solar light, evidencing the synergy between the carbon xerogel and the zinc oxide. The photocatalytic mechanism was evaluated by trapping experiments to be mainly controlled by the electron vacancies that are generated during the photoexcitation of the composites. (AU)

• FAPESP's process: 18/10492-1 - Photocatalytic evaluation of heterojunctions semiconductor/ZnO/carbon xerogel in the photodegradation of 4-chlorophenol in both fluidized bed and batch reactors
• Grantee: Liana Alvares Rodrigues
• Support Opportunities: Regular Research Grants
• FAPESP's process: 16/04244-0 - Preparation, modification and catalytic evaluation of TiO2-based photocatalysts
• Grantee: Nicolas Perciani de Moraes
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• FAPESP's process: 15/08995-7 - Preparation, modification and catalytic evaluation of Nb2O5-based photocatalysts
• Grantee: Liana Alvares Rodrigues
• Support Opportunities: Regular Research Grants
• FAPESP's process: 16/20920-5 - Heterogeneous photocatalysis applied in the degradation of organic pollutants using a hybrid zinc oxide-carbon xerogel as catalyst
• Grantee: Nicolas Perciani de Moraes
• Support Opportunities: Scholarships in Brazil - Master