Fabrication of highly dispersed Ti/ZnO–Cr2O3 composite as highly efficient photocatalyst for naphthalene degradation

Abstract

In this paper, Ti-contained Schiff base complex was intercalated into the interlayer of the ZnCr layered double hydroxides (LDHs) to form a novel layered organic–inorganic nanoscale material. And then, the hybrid material was further calcined to make metal oxides composite contained Zn, Cr and Ti (Ti/ZnO–Cr2O3). This composite was used to study the performance and mechanism for naphthalene (l-acid) photodegradation under visible light. The characterization results showed that Ti/ZnO–Cr2O3 composite has higher specific area, more uniform pores size distribution and narrower band gap than that of original ZnCr–LDHs. Both physico-chemical property and photocatalytic performance for l-acid degradation by Ti/ZnO–Cr2O3 were greatly improved with the increasing of calcination temperature, due to the highly crystalline structures with appearance of spinel ingredients of Zn, Cr and Ti. In addition, the molar ratio of Ti/Cr would also influence the photocatalytic property of the materials. Ti/ZnO–Cr2O3 composite with Ti/Cr=1 and calcined at 800°C not only has narrow bang gap (2.11eV) and high surface area (227m2), but also shows highest photocatalytic performance for l-acid degradation (90.2% within 240min). Furthermore, the types and amounts of active radicals of photo oxidation reaction were also tested. The photocatalytic mechanism of the Ti/ZnO–Cr2O3 composite was also discussed. Moreover, based on the results from HPLC–MS, GC–MS, FT–IT and DFT analysis, the decomposition intermediates and reaction pathway for l-acid were investigated in detail.