Controlled Synthesis And Photocatalytic Properties Of Nanostructured Tungsten Oxide-Based Oxides

In the recent decades,application of photocatalysis in the field of energy and environment has been regarding as a global research hotspot.It is well-known to all that 90%of solar energy is distributed in the range of visible and near infrared.However,at present,few broad spectrum responsive photocatalysts with efficient utilization of solar energy are available,especially such issues as harsh synthetic conditions and low yield have become a bottleneck for large scale actual application of the photocatalysts.Aim at exploring advanced photocatalysts responding to broader solar spectrum and their efficient and environmentally-benign synthetic approaches,in this dissertation,the ultrathin 2D WO₃·2H₂O nanosheets with superior UV-vis responsive photocatalytic activity were innovatively prepared by a mechanochemical method,and the novel W₁₈O₄₉9 supported on N-doped reduced graphene oxide(W₁₈O₄₉@N-rGO)nanocomposite with full-spectrum-driven photocatalytic properties was fabricated via solution combustion process combined with subsequent thermal reduction for the first time.The controlled synthesis of the two photocatalysts and photocatalytic activity for degrading Rd B were systematically investigated.The results revealed that the large scale and efficient preparation of uniform ultrathin WO₃·2H₂O nanosheets can achieved by the mechanochemical reaction between Na₂WO₄·2H₂O and H₂C₂O₄·2H₂O,where H₂C₂O₄·2H₂O served as both reactants and templates for formation of 2D nanosheets.88.0%RhB in the solution could be degraded by WO₃·2H₂O nanosheets under 90-min UV irradiation,80.4%under 140-min visible light irradiation,85.2%under 120-min irradiation of simulated sunlight.88.0%RhB in the solution could be degraded by WO₃·2H₂O nanosheets after five cycles of simulated-sunlight-driven photocatalytic degradation,indicating that superior UV-vis-driven photocatalytic activity and desirable stability.High yield fabrication of W₁₈O₄₉@N-rGO could be realized via 700 ^oC thermal reduction of precursor under the atmosphere of 5%H₂/N₂,which was derived from solution combustion process using ammonium metatungstate as tungsten source,ammonium nitrate as oxidant,glycine as fuel,proper amount of graphene oxide as supporting material.98.4%RhB in the solution could be removed by W₁₈O₄₉@N-rGO under 60-min UV irradiation,97.2%under 80-min visible light irradiation,90.9%under 90-min irradiation of near infrared light.83.6%RhB in the solution could be removed by W₁₈O₄₉@N-rGO after five cycles of near-infrared-driven photocatalytic degradation,suggesting that ultrahigh UV-vis-NIR-driven photocatalytic activity and desirable stability.In summary,this work not only provides two novel broad-spectrum-driven tungsten-oxide-based photocatalysts but also proposes two facile and efficient synthetic approaches for them.