Super effective Zn-Fe-doped TiO2 nanofibers as photocatalyst for ammonia borane hydrolysis

Abstract

ABSTRACTIn this study, the photocatalytic activity of TiO2 nanofibers toward ammonia borane hydrolysis has been strongly modified by doping the nanostructure by ZnO and Fe2O3 oxides. Due to the differences in the work function and band gap energy among the three semiconductors (TiO2, ZnO and Fe2O3), illumination of TiO2 leads to accumulate the electrons and holes on the conduction and valance bands of Fe2O3 and ZnO, respectively. Accordingly, the experimental results indicated that the surface of the obtained nanofibers is very active which results in an instant hydrolysis of ammonia borane molecules reaching the active zone surrounding the nanofibers. Moreover, negative activation energy was determined as increasing the temperature led to decrease the photocatalytic performance. Furthermore, kinetic studies indicated that the heterogeneous catalytic reaction describing the ammonia borane hydrolysis process is zero order which additionally supports the super activity of the introduced nanofibers. It was also observed that Fe2O3 content in the introduced nanofibers has distinct influence as the best performance was obtained at 1 wt%. The modified TiO2 nanofibers were prepared by calcination of electrospun nanofibers composed of titanium isopropoxide, zinc acetate and iron acetate in air at 700 °C for 1 h. Overall, the present study opens a new avenue to overcome the fast electrons/holes recombination dilemma facing TiO2-based nanostructures.