Design Of Semiconductor Photocatalyst And Their Activity For Hydrogen Production

It is important to seek clean and new-type energy resources to solve the problem of increasing consumption of traditional fossil fuels and environmental issues.Hydrogen has attracted much attention due to its broad application prospect and environmentally friendliness.Currently,the frequently-used steam methane reforming to produce hydrogen in industry will consume vast energy and produce lots of carbon dioxide.However,photocatalytic water splitting can direactly convert solar energy into chemical energy stored in hydrogen.Generally,the photocatalytic perform,ances are determined by light absorption,charge separation and transfer,surface reaction kinetics.In this article,we mainly design and optimize the photocatalytic system according to the above mentioned aspects.The following are the specific research contents.(1)Graphited nanocarbon-conjugated g-C3N4 was developed as an efficient photocatalyst for water splitting.Firstly,the light absortion ability was prominently enhanced as a result of the conjugation extension.In addition,this unique structure benefits the separation of photogenerated carriers and promotes the transportation of the photoelectron through the local ?-conjugated electric field.Finally,the photocatalytic hydrogen production rate in this system is 15 times higher than that of the pristine g-C3N4.(2)Ni-decorated Zn0.5Cd0.5S solid solution was employed in photocatalytic dehydrogenation of benzyl alcohol for simultaneous hydrogen and benzaldehyde production.This photocatalytic system shows an excellent hydrogen production rate of 666.3 ?mol h-1,which is much higher than that of the pure Zn0.5Cd0.5S and Pt-loaded Zn0.5Cd0.5S solid solution.The optimal apparent quantum yield of 52.5%is obtained at 420 nm.Further studies reveal that the metallic Ni nanocrystals play an important role in accelerating the separation of photogenerated charge carriers and the subsequent cleavage of a-C-H bond during dehydrogenation of benzyl alcohol.(3)We demonstrate the use of CoP nanoparticles for facile surface modification of nanoporous BiVO4 photoanode,which can generate a tremendous cathodic shift of?430 mV in the onset potential for photoelectrochemical water oxidation.In addition,a remarkable photocurrent density of 4.1 mA cm-2 is achieved at 1.23 V vs.RHE under AM 1.5G illumination.The photoelectrochemical measurement using sodium sulfite as a hole scavenger clearly shows that the greatly improved performances are attributed to the efficient suppression of interfacial charge recombination through loading of CoP catalyst.