Composite Tin and Zinc oxide nanocrystalline particles for enhanced charge separation in sensitized degradation of dyes

• Published in: Chemosphere (Oxford) 2002-10, Vol.49 (4), p.439-445
• Main Authors: Bandara, J., Tennakone, K., Jayatilaka, P.P.B.
• Format: Article
• Language: English
• Subjects: Applied sciences; Catalysis; Charge separation; Chemistry; Coloring Agents - chemistry; Coloring Agents - isolation & purification; Crystallization; Exact sciences and technology; General and physical chemistry; General purification processes; Light; Nanotechnology - methods; Particle Size; Photochemistry; Photochemistry - methods; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); Pollution; Sensitized degradation; Tin Compounds - chemistry; Tin oxide; Wastewaters; Water treatment and pollution; Zinc oxide; Zinc Oxide - chemistry
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/S0045-6535(02)00306-5

Composite ZnO/SnO 2 catalyst has been studied for the sensitized degradation of dyes e.g. Eosin Y (2 ′,4 ′,5 ′,7 ′-tetrabromofluorescein disodium salt) in relation to efficient charge separation properties of the catalyst. Improved photocatalytic activity was observed in the case of ZnO/SnO 2 composite catalyst compared to the catalytic activity of ZnO, SnO 2 or TiO 2 powder. The suppression of charge recombination in the composite ZnO/SnO 2 catalyst led to higher catalytic activity for the degradation of Eosin Y. Degradation of Eosin follows concomitant formation of CO 2 and formation of CO 2 followed a pseudo-first-order rate. Photoelectrochemical cells constructed using SnO 2, ZnO, ZnO/SnO 2 sensitized with Eosin Y showed V oc of 175, 306, 512 mV/cm 2 and I sc of 50, 70, 200 μA/cm 2 respectively. A higher irreversible degradation of Eosin Y and higher V oc observed on composite ZnO/SnO 2 than ZnO and SnO 2 separately can be considered as a proof of enhanced charge separation of ZnO/SnO 2 catalyst. Eosin Y showed a higher emission decreases on ZnO/SnO 2 composite than on individual ZnO, SnO 2 or TiO 2 indicating dominance of the charge injection process. Photoinjected electrons are tunneled from ZnO to SnO 2 particles accumulating injected electrons in the conduction bands allowing wider separation of excited carriers.