BN/GdxTi(1-x)O(4-x)/2 nanofibers for enhanced photocatalytic hydrogen production under visible light

Abstract

Abstract BN/GdxTi(1-x)O(4-x)/2 nanofibers were elaborated via electrospinning technique. The properties of the prepared nanofibers were controlled using different ratios of gadolinium. All the prepared nanofibers exhibit the tetragonal structure of anatase TiO2 phase. An increase in the unit cell volume and a decrease in the crystallite size were observed with increasing the doping amount of Gd3+ as revealed by Rietveld refinement analysis. The defect in TiO2 lattice was observed by Raman. The Gd3+ incorporation inside TiO2 lattice, which is accompanied by the creation of Ti-O-Gd bond, was characterized by the X-ray photoelectron spectra. Scanning electron microscopy demonstrates that the average diameter of BN/GdxTi(1-x)O(4-x)/2 nanofibers decreased by 0.1\u2009μm in comparison to nanofibers without doping. The d-spacing raised by 0.01\u2009nm after doping as demonstrated by high-resolution transmission electron microscopy. The distribution of BN and Gd3+ was homogenous and uniform on nanofibers as depicted by EDX. The incorporation of many impurity levels between valence band and conduction band enhanced absorptivity under visible light as revealed by UV–vis spectrophotometry. Moreover, the surface area of nanofibers was improved by 5 times after Gd3+ doping as demonstrated by BET which is favorable for the increase of photocatalytic activity. The electrons transfer rate (recorded by the electrochemical impedance spectroscopy analysis) was improved by gadolinium doping as well. The photocatalytic results indicate that the BN/GdxTi(1-x)O(4-x)/2 nanofibers improve hydrogen production up to 192,602\u2009±\u20091500 μmole/g during 6\u2009h under visible light. The BN/GdxTi(1-x)O(4-x)/2 nanofibers produced 7 times more hydrogen than nanofibers without BN. This improvement could be attributed to the e−/h+ stability that reached 63.69\u2009ms average time before recombination due to the beneficial effect of BN nanosheets.