Doping Modification Of Semiconductors With Enhanced Photocatalytic Activity

As the important material basis for human being survival and development,fossil energy,like coal,oil and natural gas,which supported the rapid development of human civilization and progress of economy in the last 200 years.Yet,these fossil energy are irrevocably exhausted,owing to the artificial over-development and their own non-renewable characteristic,most of fossil fuels in this century would be depleted.Therefore,it is imminent to study and develop green renewable energy for mankind progress.Hydrogen is a clean energy with high calorific value and good stability in combustion,which can be preserved in gaseous,liquid or solid metal hydride forms and also could meet the requirements in different applied environment.Meanwhile,the by-product of hydrogen energy is merely water that is friendly to the environment,so the hydrogen is deemed as an ideal renewable resource.Since 1970,the energy issues in studying and developing hydrogen energy for the sake of the sustainable development of mankind has been widely concerned.Among many new technologies,photocatalytic technology has great potential in directly transforming low-density solar energy into storable high-density hydrogen energy,which makes photocatalysis the most ideal technology for developing hydrogen energy.In many semiconductor meterials such as bismuth vanadium and cadmium sulfide can be excited by visible light,showing outstanding visible-light absorption characteristics and excellent water spilitting efficiency.In this paper,the doping modification of a series of semiconductor materials and their visible-light water spilitting performance were studied.The main contents include the following parts:1.Preparation of porous BiVO4 nanoshuttles by Fe and Mo co-doping for efficient photocatalytic water oxidationIn this chapter,a homogeneous porous Fe/Mo co-doped BiVO4 nanoshuttles was firstly prepared through a simple solvothermal method combined with a subsequent thermal treatment.It has been discovered that the incorporation of Fe and Mo into the BVO lattice not only influences the shuttle-like morphology and porous structure but also modifies the band structure of the pristine BVO;this consequently boosts the photocatalytic performance of BVO.The as-prepared Fe/Mo-BVO PNSs exhibit significantly enhanced photoactivity for water oxidation under visible-light irradiation,and an average O2 evolution rate of up to 191.5 ?mol·h-1·g-1 is obtained,which is nearly 1.5 and 17 times higher than the rates obtained for Mo-doped BVO and pristine BVO,respectively.Density functional theory(DFT)calculations were also employed to further investigate the electronic structure of the co-doped products.2.One-pot solvothermal synthesis of Mo doped CdS nanowires with enhanced visible-light photocatalytic activityIn this work,homogeneous Mo doped CdS nanowires were obtained through a facial solvothermal process,in which cadmium acetate was acted as cadmium source while the sulfur source and molybdenum source were merely ammonium tetrathiomolybddate for the typical reaction.The as-obtained Mo doped CdS nanowires show excellent photoactivity for hydrogen evolution under visible-light irradiation,its average H2 evolution rate up to 14.6mmol·h-1·g-1,which is nearly 5.8 times higher than the rates obtained for pristine CdS.Meanwhile,Pt loaded Mo doped CdS nano wires has been obtained via a photo-reduction process,the photocatalytic performance for H2 production has been elevated 2.4 times than the Mo doped CdS sample and its H2 evolution rate was up to 35.2 mmol·g-1·h-1,also the photocatalytic stability has been enhanced significantly,the H2 evolution rate never decaied any more,even after 12 h photocatalytic reaction.3.Facile synthesis of carbon-coated BiVO4 nanobelts with enhanced photoactivity.In this section,the carbon-coated BiVO4 nanobelets were obtained from pregrown Na2V6O16 nanowires.The cation exchange process involved and the carbon coated process all took place via facile solvothermal method.As demonstration,the as-prepared carbon-coated BiVO4 nanobelts exhibit enhanced photocatalytic activity and favorable recycle ability for O2 evolution under visible-light irradiation.