| In the course of the rapid development of industry and economy,some issues on energy crunch and environmental pollution became extremely urgent,which have limited the sustainable and steady development of society.Hydrogen,a non-pollution and sustainable energy source,which widely applied in petrochemical industry,electronic industry,aerospace industry and other fields.Photocatalytic hydrogen production from alcohols or water using renewable solar energy is a promising strategy to help ease the crisis.Up to now,a wide variety of materials expored for photocatalytic hydrogen evolution and photocatalytic degradation,especially semiconductors have been widely applied.Amount numerous semiconductors,Graphitic carbon nitride(g-C3N4)is environmentally benign,thermostability,chemical stability,wide absorption spectral range,is gaining increasing attention.However,pristine g-C3N4 still shows some key issues,which restricted the photocatalytic activity of g-C3N4,due to the low surface area and the rapid recombination rate of photo-generated electron-hole pairs.So it is urgent to modify the materials with various methods to improve the photocatalytic activity.Cadmium sulfide(CdS),a representative semiconductor,has been attached much attention in water splitting because of the narrow band gap width(Eg=2.4 eV).But the serious photocorrosion and fast recombination of photon-generated carrier astricted the practical application of CdS.Compared to CdS,zinic sulfide(ZnS)shows outstanding photostability but the undesirable band gap width(Eg=3.6-3.8 eV).On this basis Zn-doped CdS composite materials(Zn1-xCdxS),not only photostability but also photocatalytic activity,have been widely studied in recent years.In view of the slow electron mobility,it is necessary to optimize the materials to improve the photocatalytic evolution rate.In spite of the extensive application of TiO2 in water splitting,CO2 reduction and pollutant degradation,the small response of visible light and large amount of recombination of photo-generated electron-holes reduced quantum efficiency,which affected the photocatalytic activity of TiO2.On the basis of those problems of semiconduntor,this paper based on the in-situ synthesis method and complexometry modified materials by doping noble metals.On account of the surface plasmon resonance effect of noble metals,which is the electron capture trap,broaden the absorption range of visible light and inhibit the recombination of electron-holes to improve the photocatalytic activity.The preliminary conclusions are as follows.(1)The fibrous AgNPs/g-C3N4 aerogel was successfully manufactured via in situ synthesis method and two-step annealing.It was proved that AgNPs were successfully doped on the surface of g-C3N4 by analyzing light absorption,electrochemical analysis and photocatalytic analysis AgNPs/g-C3N4 composite material exhibited efficient photocayalytic activity for splitting of methanol under the irradiation of visible light.Whats more,due to the moderate redox feature of silver,hydrogen was constantly generated while neither CO nor CO2 was detected in the products.(2)The hierarchical AuNPs/Zn0.5Cd0.5S composite material was directly fabricated via a facile one-step in-situ hydrothermal method,which exhibited superior photocatalytic performance toward hydrogen production under visible light irradiation.The hydrogen evolution rate of the 5 wt%-AuNPs/Zn0.5Cd0.5S synthesized with in situ hydrothermal method can be 7.1 times greater than that of pure Zno.5Cdo.5S and as much as 2.5 times of 5 wt%-AuNPs loaded Zn0.5Cd0.5S synthesized with photodeposition method.Systematical investigations reveal that the enhanced photocatalytic performance of the one-step in situ prepared AuNPs/Zn0.5Cd0.5S can be attributed to the inherent SPR effect and favorable electron transfer properties of AuNPs,as well as the rational hierarchical nanoarchitectures that allow AuNPs to be uniformly incorporated into Zno.5Cdo.5S matrix.This one-step in situ fabrication method provides a simple and efficient route to synthesize well-defined heterocatalysts.(3)The Ag/AgCl/TiO2 nano-composite material,assembled via complexometry and thermal treatment,which showed superior photocatalytic performance toward hydrogen evolution by splitting pure ethonal.Compared with Ag/TiO2 and AgCl/TiO2,Ag/AgCl/TiO2 hybrid exhibited controllable in size and size distribution,which photocatalytic hydrogen evolution rate was improved 10 times than that of pure TiO2.The combination of Ag/AgCl and TiO2 was more coherent under complexometry and thennal treatment.On account of the SPR effect of Ag nano-composite,the migration rate of electron was improved to inhibit the recombination of photo-generated electron-holes,which increased the photocatalytic activity of Ag/AgCl/TiO2.This meathod provided an efficient route to synthesize new-style photocatalytic material for photocatalytic hydrogen production. |
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