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 μmol/h) from water and (1385 μmol/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.