Synthesis of Graphene Oxide Interspersed in Hexagonal WO(3) Nanorods for High-Efficiency Visible-Light Driven Photocatalysis and NH(3) Gas Sensing

WO(3) nanorods and GO (at 1 wt% loading) doped WO(3) were synthesized using a template free deposition-hydrothermal route and thoroughly characterized by various techniques including XRD, FTIR, Raman, TEM-SAED, PL, UV-Vis, XPS, and N(2) adsorption. The nano-materials performance was investigated toward photocatalytic degradation of methylene blue dye (20 ppm) under visible light illumination (160 W, λ> 420) and gas sensing ability for ammonia gas (10–100 ppm) at 200°C. HRTEM investigation of the 1%GO.WO(3) composite revealed WO(3) nanorods of a major d-spacing value of 0.16 nm indexed to the crystal plane (221). That relevant plane was absent in pure WO(3) establishing the intercalation with GO. The MB degradation activity was considerably enhanced over the 1%GO.WO(3) catalyst with a rate constant of 0.0154 min(−1) exceeding that of WO(3) by 15 times. The reaction mechanism was justified dependent on electrons, holes and •OH reactive species as determined via scavenger examination tests and characterization techniques. The drop in both band gap (2.49 eV) and PL intensity was the main reason responsible for enhancing the photo-degradation activity of the 1%GO.WO(3) catalyst. The later catalyst initiated the two electron O(2) reduction forming H(2)O(2), that contributed in the photoactivity improvement via forming •OH moieties. The hexagonal structure of 1%GO.WO(3) showed a better gas sensing performance for ammonia gas at 100 ppm (R(a)-R(g)/R(g) = 17.6) exceeding that of pure WO(3) nanorods (1.27). The superiority of the gas-sensing property of the 1%GO.WO(3) catalyst was mainly ascribed to the high dispersity of GO onto WO(3) surfaces by which different carbon species served as mediators to hinder the recombination rate of photo-generated electron-hole pairs and therefore facilitated the electron transition. The dominancy of the lattice plane (221) in 1%GO.WO(3) formed between GO and WO(3) improved the electron transport in the gas-sensing process.