Studies On The Preparation And Photocatalytic Performance Of MoS₂-La₂Ti₂O₇ And NiS-La₂Ti₂O₇

With the rapid development of world economy,environment pollution and energy crisis are becoming more and more serious,as a result,how to seek a new technology to solve the two problems mentioned above has become a common focus.Hydrogen is a kind of clean energy and releases high heat when it burns,all these make it a ideal fuel and energy carrier,however,hydrogen is mainly produced by steam reforming of hydrocarbons such as methane which would causes more pollution and waste of energy.The semiconductor photocatalytic technique has attracted much more attention for its great prospect in the field of new energy development and pollution control.Hence,it is becoming a popular topic to develop novel photocatalysts with high efficiency.In this paper,layered structure La2Ti2O7 has been chosen as the research object and to be modified by MoS2 and NiS.Photocatalytsts including MoS2-La2Ti2O7 and NiS-La2Ti2O7 are prepared and their photocatalytic performance is evaluated through photocatalytic hydrogen evolution reaction under UV-Light illumination.A series of characterization of the as-prepared samples are performed and the possible reasons for the increase of the photocatalytic performance has been preliminary discussed.The main conclusions are shown as follows:(1)MoS2-La2Ti2O7 photocatalysts are synthsized and showing higher photocatalytic efficency than La2Ti2O7.The highest photocatalytic activity of the composite photocatalyst was obtained when the mass percent of MoS2 reached 50 wt%,with the hydrogen production rate as high as 162.7 ?mol/h,about 2.7 times as that over pure La2Ti2O7.The compsite materials show transient photocurrent enhancement,decrease of impedance,and its hydrogen evolution overvoltage is also decreased obviously.All these prove that the MoS2 effectively promote the photoproduction electrons and holes separation and cause the improving of photocatalytic hydrogen production.(2)NiS-La2Ti2O7 photocatalysts are prepared and show superior photocatalytic hydrogen evolution performance in methanol aqueous solution than pure La2Ti2O7.When the mass percent of NiS was 20 wt%,the sample exhibits the highest photocatalytic hydrogen evolution performance.The compsite photocatalyst shows stronger transient photocurrent as well as lower impedance and smaller hydrogen evolution overvoltage,and the recombination of NiS had obviously promoted the photocatalytic hydrogen production of La2Ti2O7.The novelty of this study are shown as follows:It is the first time that MoS2 and NiS are composited with La2Ti2O7 as co-catalysts,which can give a new idea for the non-noble-metal co-catalyst application to photocatalytic hydrogen generation.