Effect of calcination temperature on the photodegradation efficiency of Ni/ZnO composite in removal of organic dye

• Main Authors: Thein, Myo Thuya, Pung, Swee-Yong, Aziz, Azizan, Lockman, Zainovia, Itoh, Mitsuru
• Format: Conference Proceeding
• Language: English
• Subjects: Chemical precipitation; Chemical synthesis; Composite materials; Dyes; Efficiency; Emission analysis; Energy dispersive X ray spectroscopy; Field emission microscopy; Organic compounds; Photocatalysts; Photodegradation; Photoluminescence; Photovoltaic cells; Roasting; Rods; Tips; Ultraviolet radiation; Wurtzite; X-ray diffraction; Zinc oxide
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/1.4993331

ZnO based composite is an attractive UV light driven semiconductor photocatalyst to degrade organic compounds attributed to its wide bandgap (3.37 eV). In this study, Ni/ZnO composites were synthesized via solution precipitation method. The composites were calcinated at various temperature, i.e. from 250 °C to 700 °C and subsequently annealed at 500°C in reductive environment (hydrogen atmosphere). The diffraction peaks of all samples could be indexed to the hexagonal wurtzite ZnO. No diffraction peaks from Ni could be observed in all samples, suggesting that the amount of Ni in the composites were below the detection limit of X-ray diffraction (XRD). The field emission scanning electron microscope (FESEM) images confirm that all samples were rod-like structure with hexagonal tips. In addition, small Ni particles were homogeneously deposited on the surface of ZnO rods. This observation is supported by energy dispersive X-ray spectroscopy (EDX) analysis, showing present of Zn, O and Ni elements. It is noted that ZnO rods coupled with Ni experienced quenching of visible emission and enhancing of UV emission in room temperature photoluminescence (RTPL) analysis. The photodegradation efficiency of Ni/ZnO rods was improved when a higher calcination temperature was used. The removal of RhB dye under UV light (352 nm) by these photocatalysts followed pseudo first-order kinetic reaction. The Ni/ZnO composites synthesized at calcination temperature of 500 °C demonstrated the highest photodegradation efficiency of 37 % and the largest rate constant of 0.0053 min−1 after 75 min UV irradiation.