Study On Preparation And Photocatalytic Activity For Hydrogen Evolution Of Graphene-based TiO₂Composites

Hydrogen is one of the most ideal clean energy.As the worsening energy crisis,the photocatalytic hydrogen production technology becomes a research focus.Wastewater treatment is another important application of the photocatalytic technique,Recently,researchers have begun to try to develop new catalyst to unite the twoapplications,and make use of the pollutants in wastewater for hydrogen evolutionresult in " turning waste into treasure."In this paper, graphite oxide was prepared by an improved Hummer method,and graphite oxide, P25, Cu(NO3)23H2O were used as raw materials,graphene/TiO2,graphene-TiO2nanotubes, graphene-CuO/TiO2composites were prepared bysolvothermal method. Pt loading of the composite materials surface by in situ opticalmethod,The surface morphology,crystal structures and optical properties of thesamples were characterized by SEM、TEM、XRD、FT-IR and DRS。First, Pt/graphene-TiO2was used for catalyst, the effects of loading of graphene,organics and so on on the activity for hydrogen production were studied.The resultsshow that the composites in which the graphene content is1wt%has the maximumhydrogen production acitivity. Ethanol was used as sacrificial agent and the reactionmechanism of hydrogen production was studied. The total hydrogen amount reached3444.36μmol under the sunlight irradition for5h which was2.16times of the P25(1598.25μmol) under the same conditions.In order to make TiO2with larger surfacearea and stronger adsorption capacity,the graphene-TiO2nanotube composite catalystswere prepared by hythermal method. In return,during hydrogen production process,the photocatalytic reactions of hydrogen production were promoted.The activity forhydrogen production of the sample in which the graphene content was5wt%washighest.The amount of evolved hydrogen was reached3712.79μmol under thesunlight irradation for5h. Its activityfor hydrogen production has been improved.Secondly,the graphene-CuO/TiO2composites which could effectively make useof visible light was prepared by the combination of CuO and TiO2.The sample inwhich the grapheme content was0.5wt%and CuO was2wt%has the highest photocatalytic activity.The co-existence of CuO and graphene could produce asynergistic effect, which could improve the utilization of visible light and furtherenhance the photocatalytic activity for hydrogen production. The amount of evolvedhydrogen were reached1083.54μmol under visible light and4374.51μmol underthe sunlight irradation for5h.Finally,graphene-CuO/TiO2was used for photocatalyst,and industrialpharmaceutical wastewater was studied. The photocatalytic hydrogen productiontechnology was introduced to the field of pharmaceutical wastewater treatment,thestudy on hydrogen production accompanied by photocatalytic degradation ofpharmaceutical wastewater was conducted. The experimental results showed that: thebest hydrogen production technology was0.10g, initial pH was11,2-fold dilution,the amount of hydrogen production reached358.96μmol under the sunlightirradiation for5h, while the wastewater was degradated, it achieved the dual goals ofboth hydrogen production and wastewater treatment, which provid a new referencefor organic wastewater treatment.