Preparation Of New Ternary Metal Nitride And Properties In Photocatalytic Water Splitting Hydrogen Production

The problems of air pollution as well as the energy shortage,caused by excessive use of fossil fuels are becoming more and more serious.People need to find green alternative energies instead of non-renewable fossil energies.Hydrogen has been considered as an important renewable energy source in recent years,aiming to solve the current energy crisis and global warming problems.Among many hydrogen production methods,Photocatalytic water-splitting hydrogen evolution has always been considered as the most ideal hydrogen production method.Noble metals like Pt-based materials are normally used for photocatalysts electrodes due to their good conductive properties.However,the high price and rarity of noble metal materials limit their application.Therefore,people are constantly looking for suitable replacing alloys for these precious metals.Transition metal nitrides have high similarity with Pt-based materials,so they have attracted much attention in the field of catalysis.In this thesis,Ni3FeN photocatalyst is successfully synthesized and is applied to the dye-sensitized photocatalytic H2 generation system.Then the Ni0.2Mo0.8N(Ni)ternary nitride is synthesized,and loaded it onto the In2S3,resulted in In2S3-Ni0.2Mo0.8N(Ni)composites.The composite is used for photocatalytic water-splitting hydrogen evolution and the effects of Ni0.2Mo0.8N(Ni)and Ni in ternary nitride on the photocatalytic properties of composites are investigated.The specific studies are as follows:(1)Ni3FeN sample is obtained by a simple oxidation-fast nitridation method and tested for dye-sensitized photocatalytic hydrogen evolution.The porous ternary Ni3FeN nanocubes exhibit relatively good photocatalytic performance with the H2 evolution rate of 3073?mol·g-1·h-1,about 2.5 times higher than that of NiFeOx.To explore the reaction mechanism,a series of characterization on the samples are conducted,including electrochemical impedance test,polarization curve test and so on.Meanwhile,in the dye-sensitized photocatalytic system,the effect of eosin concentration and pH on Ni3FeN hydrogen production activity are also studyed.The final results show,when the added eosin mass is 40 mg,pH 11,the sample has the best hydrogen production activity.(2)The green solid ammonium ni-molybdate is successively calcined in hydrogen-argon mixture and ammonia to obtain the grey-black sample Ni0.2Mo0.8N(Ni).The blank In2S3 is prepared by simple reflux method,using the same process mentioned above,different proportions of In2S3-Ni0.2Mo0.8N(Ni)composite samples with different Ni0.2Mo0.8N(Ni)loading are prepared and the photocatalytic H2 evolution rate is tested,1wt%In2S3-Ni0.2Mo0.8N(Ni)shows the best photocatalytic performance,the H2 evolution rate is 614.2 ?mol·g-1·h-1,about 10 times higher than that of the blank In2S3.Finally,the possible mechanism of Ni0.2Mo0.8N(Ni)is proposed by a series of characterization tests.Moreover,in order to have further investigations on the effect of Ni0.2Mo0.8N and metal Ni on photocatalytic hydrogen production,the comparative experiments are conducted,which shows that metal Ni and related species reduce the co-catalytic effect of ternary nitrides.