One-step hydrothermal synthesis of CaWO4/α-Ag2WO4 heterojunction: An efficient photocatalyst for removal of organic contaminants

• Published in: Materials science in semiconductor processing 2019-12, Vol.104, p.104693, Article 104693
• Main Authors: Ayappan, Chinnadurai, Palanivel, Baskaran, Jayaraman, Venkatesan, Maiyalagan, Thandavarayan, Mani, Alagiri
• Format: Article
• Language: English
• Subjects: CaWO4/α-Ag2WO4; Heterojunction; Organic pollutants; Photocatalysis
• ISSN: 1369-8001; 1873-4081
• DOI: 10.1016/j.mssp.2019.104693

A new class of CaWO4/α-Ag2WO4 heterojunction composites was synthesized by one-step hydrothermal method without adding any templates or surfactants. The XRD results indicate that the composite consists of CaWO4 and α-Ag2WO4 crystal phases. The FE-SEM and TEM studies confirm the CaWO4 nanoparticles are deposited on the rod-like α-Ag2WO4. The RAMAN and XPS analysis has used to analyze the vibrational properties, chemical composition and oxidation states of the prepared catalysts. The composite heterostructure holds the sufficient contact between the CaWO4 and α-Ag2WO4 nanoparticles which favor for adsorbed the organic molecules for photocatalytic process and also beneficial for the sediment of the catalyst particles. The CaWO4/α-Ag2WO4 (1CA) composite shows the highest photocatalytic activity (MB dye 85%, 105 min) and reaction rate constant compared to all other photocatalysts under the light irradiation. The highest degradation efficiency of 1CA composite ascribed to the effective separation of photogenerated e− and h+ pairs and lower recombination rate. The recycling results reveal that 1CA photocatalyst possess good degradation ability after four cycle tests. Moreover, the photocatalytic mechanism revealed that the h+ and OH are the key reactive species for the photodegradation of organic dyes over CaWO4/α-Ag2WO4 photocatalyst. [Display omitted] •Spherical-like CaWO4 nanoparticles are anchored on the rod-like α−Ag2WO4 crystal surface.•Optimal heterojunction photocatalyst 1CA composite (CaWO4/α−Ag2WO4) exhibits highest degradation efficiency (MB dye 85% within 105 min).•Unique heterojunction (CaWO4/α−Ag2WO4) reveals efficient flow of photogenerated electron/hole.•Holes (h+) and hydroxyl (OH) are the key reactive species for the photodegradation over CaWO4/α-Ag2WO4 heterojunction catalyst.