화학공학소재연구정보센터
Applied Catalysis B: Environmental, Vol.226, 324-336, 2018
Facile synthesis of highly efficient ZnO/ZnFe2O4 photocatalyst using earth-abundant sphalerite and its visible light photocatalytic activity
Micrometer-scale ZnO/ZnFe2O4 coupled photocatalyst is synthesized via a simple, one-step thermal treatment performing on natural Fe-bearing sphalerite ((Zn, Fe)S). In situ high-temperature X-ray diffraction (XRD), thermogravimetry, differential thermal analysis (TG/DTA) and scanning electron microscopy (SEM) results indicated that octahedral ZnFe2O4 (similar to 5 mu m) formed on the surface of substrate-like ZnO (tens of microns) derived from the oxidation of sulfides upon heating to 800 degrees C in air for 1 h, and the two components kept stable phase ratio at 3:7 (wt%) from 900 degrees C (sample M-900) to 1200 degrees C (sample M-1200). X-ray absorption spectroscopy (XAS) and Raman spectra revealed that more Zn atoms in ZnFe2O4 of M-1200 occupied tetrahedral sites than M-900, resulting in a sharper A(1g) mode (similar to 647 cm(-1)), more ordered spinel structure and less antisite defects. Compared with visible-light responsive sphalerite (Zn, Fe)S, M-1200 performed more 200 nm of red-shifted optical absorption, 2.5 times at most higher the incident photon-to-electron conversion efficiency (IPCE) and 2-3-fold photocatalytic efficiency towards degradation of methyl orange and inactivation of Escherichia coli K-12. Besides, the photocatalytic activities of M-1200 preponderate over M-900, typical visible-light catalyst ZnFe2O4 and ZnO/ZnFe2O4 mechanically mixed sample. The optimization of lattice structure and the establishment of special band alignment were suggested to be remarkably beneficial to the separation of photogenerated electrons-holes and promote the photocatalytic performance. This study would enlighten a feasible and efficient strategy to fabricate coupled photocatalyst by utilizing Earth-abundant and low-cost natural minerals for solving environmental problems.