International Journal of Hydrogen Energy, Vol.43, No.43, 19873-19884, 2018
In situ preparation of N doped orthorhombic Nb2O5 nanoplates /rGO composites for photocatalytic hydrogen generation under sunlight
The synthesis of nitrogen doped orthorhombic niobium oxide nanoplates/reduced graphene oxide composites (N-Nb2O5/rGO) and their photocatalytic activity towards hydrogen generation from water and H2S under natural sunlight has been demonstrated, uniquely. Nanostructured N-Nb2O5/rGO is synthesized by in situ wet chemical method using urea as a source of nitrogen and optimized by varying percentage of graphene oxide (GO). X-ray diffraction (XRD) study reveals that N-Nb2O5 have orthorhombic crystal structure with crystalline size, 35 nm. Further, X-ray photoelectron spectroscopy (XPS) confirm the presence of nitrogen and rGO in N-Nb2O5/rGO nanocomposite. Morphological features of (N-Nb2O5/rGO) were examined by FE-SEM and FE-TEM showed Nb2O5 nanoplates of diameter 25-40 nm anchored on 2D rGO. Diffuse reflectance spectra depicts the extended absorbance in the visible region with band gap of 2.2 eV. Considering the band gap in the visible region, the photocatalytic hydrogen generation from water and H2S has been performed. The 1 wt % rGO hybridized N-Nb2O5 (S2) exhibited superior photocatalytic hydrogen generation (537 mu mol/h) from water and (1385 mu mol/h) from H2S under sunlight. The improved photocatalytic activity is attributed due to an extended absorbance in the visible region, modified electronic structure upon doping and formation of well defined N-Nb2O5/rGO interface, provides large surface area, accelerates the supression of electron and hole pairs recombination rate. In our opinion, this works may provides facile route for energy efficient and economic approach for fabrication of N-Nb2O5/rGO nanocomposites as a visible light active photocatalyst. (C) 2018 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.