High photocatalytic activity of C-ZnSn(OH)6 catalysts prepared by hydrothermal method

Enhanced photocatalytic activity of cubic ZnSn(OH)6 by in-situ partial phase transformation via rapid thermal annealing

In this study, a mixed phase ZnSn(OH)₆/ZnSnO₃ photocatalyst was synthesized by calcining ZHS nanostructures via rapid thermal annealing (RTA) process. The composition ratio of ZnSn(OH)₆/ZnSnO₃ was controlled by changing the duration of the RTA process. The obtained mixed-phase photocatalyst was characterized by X-ray diffraction, field emission scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy, ultraviolet photoelectron spectroscopy, photoluminescence, and physisorption analysis. Results showed that ZnSn(OH)₆/ZnSnO₃ photocatalyst obtained by calcining ZHS at 300 °C for 20 s displayed the best photocatalytic performance under UVC light illumination. Under optimized reaction conditions, ZHS-20 (0.125 g) demonstrated nearly complete removal (>99%) of MO dye in 150 min. Scavenger study revealed the predominant role of OH^• in photocatalysis. The enhanced photocatalytic activity of the ZnSn(OH)₆/ZnSnO₃ composites was mainly ascribed to the photosensitization of ZHS by ZTO and effective electron-hole separation at the ZnSn(OH)₆/ZnSnO₃ heterojunction interface. It is expected that this study will provide new research input for the development of photocatalyst through thermal annealing-induced partial phase transformation.

Photodegradation of Methylene Blue Using Carbon-Doped ZnSn(OH)6 Composite Coated on Membrane

The dye contamination of water is a global concern in the environment. In this study, the photocatalytic technology and membrane module were combined to improve the surface distribution of the active species of the catalyst for better degradation of the methylene blue (MB) dye under visible light. ZnSn(OH)6 was chosen due to carbon’s complex metal oxide doped to facilitate the application under visible light. The numerous characterizations were analyzed in the composites to verify the consistency of the optimum degradation of MB over the catalyst coated on the membrane. During the preparation of the ZnSn(OH)6 composite, the results confirmed that different reaction times and amounts of sodium hydroxide significantly affected the pollutant’s degradation. The carbon-doped composite denoted the largest surface area and increased the catalyst’s reactive sites on the membrane. The photocatalytic activity test showed that 1% carbon doped on ZnSn(OH)6 prepared at 160°C by hydrothermal method coated on the membrane had the optimal degradation of 89.74% of MB. This study contributes to the ongoing study and development of photocatalytic membranes for the photodegradation of wastewater treatment.

The hydrothermal synthesis of ZnSn(OH)6 and Zn2SnO4 and their photocatalytic performances

The pH value and hydrothermal temperature played an important part in the transition between ZnSn(OH)₆ and Zn₂SnO₄.

Facile synthesis and enhanced visible-light photocatalysis of graphitic carbon nitride composite semiconductors

The semiconductor heterojunction has been an effective architecture to enhance photocatalytic activity by promoting photogenerated charge separation. Here, graphitic carbon nitride (CN) and B-modified graphitic carbon nitride (CNB) composite semiconductors were fabricated by a facile calcination process using cheap, sustainable, and easily available sodium tetraphenylboron and urea as precursors. The synthetic CN-CNB-25 semiconductor with a suitable CNB content showed the highest visible-light activity. Its degradation ratio for methyl orange and phenol was more than twice that of CN and CNB and its H2 evolution rate was ∼3.4 and ∼1.8 times higher than that of CN and CNB, respectively. It also displayed excellent stability and reusability. The enhanced activity of CN-CNB-25 was attributed predominantly to the efficient separation of photoinduced electrons and holes. This paper describes a visible-light-responsive CN composite semiconductor with great potential in environmental and energy applications.