| This thesis uses photocatalytic hydrogen production as a clean energy solution to address the challenges of energy crises and environmental sustainability.Semiconductor photocatalysis technology has been recognized as a green approach to solve environmental and energy problems and is expected to play an important role in solving these problems.However,the rapid recombination of photogenerated electron-hole pair,reverse reaction and low visible light utilization limit the development of semiconductor materials.Since the discovery of two-dimensional(2D)transition metal carbides,nitrides and carbonitrides(MXene)in 2011,MXene has received increasing attention due to its unique electronic and structural properties,and is known as the next generation of nanomaterials in the field of energy and environmental technologies.The combination of MXene and semiconductor materials can increase the photogenerated electron transport rate,inhibit photogenerated electron-hole pair recombination,and effectively improve photocatalytic performance.The main research contents and results of this thesis are as follows:(1)Three-dimensional(3D)Ti3C2-TiO2 nanoflowcr composites were prepared by partial oxidation,alkalization,ion exchange and heat treatment with Ti3C2 as the titanium source.By changing the heat treatment temperature,3D Ti3C2-TiO2 nanoflower composites with different morphologies were obtained,and the hydrogen and oxygen production properties of photolysis water were studied,and the overall water splitting without sacrificial conditions was realized.The prepared 3D Ti3C2-TiO2 nano flower composites possess the best photocatalytic performance at the heat treatment temperature of 500℃,which is better than the TiO2 nanobelts loaded with platinum(Pt)at the same temperature.It indicates that Ti3C2 can be used as an effective substitute for noble metal in the field of photocatalytic water splitting to achieve high-efficiency photocatalytic water splitting without noble metal.(2)The Ti3C2@TiO2@MoS2 composite with 2D/2D/2D exposed(001)crystal plane was prepared by two-step hydrothermal method using Ti3C2 as the titanium source.In the as-prepared Ti3C2@TiO2@MoS2 composite,TiO2 nanosheets were interspersed and grown on layered Tij3C2,and ultrathin MoS2 nanosheets were selectively distributed on the(101)crystal plane of TiO2 nanosheets,exposing highly active(001)crystal facets.The prepared Ti3C2@TiO2@MOS2 composite possesses the highest hydrogen production efficiency when the loading ofMoS2 nanosheet is 15 wt%,reaching 6425.297 μmol g-1 h-1,which is 87 times that of pure TiO2 nanosheet.The high catalytic activity of Ti3C2@TiO2@MOS2 composites is mainly attributed to the presence of Ti3C2 and MoS2 double cocatalysts,as well as the exposure of high activity(001)crystal facets of TiO2 nanosheets,which enables efficient photocarrier transport.It promotes the activation of water molecules and achieves efficient photocatalytic hydrogen production efficiency.(3)A 2D/2D/2D 1T/2H MoS2@TiO2@Ti3C2 composite containing bimetallic cocatalysts Ti3C2 MXene and 1T-MoS2 nanopatches was prepared by a simple two-step hydrothermal method using Ti3C2 as the titanium source.When the loading of 1T/2H MoS2@TiO2@Ti3C2 composite material is 15 wt%,the photocatalytic hydrogen production efficiency is the highest,reaching 9738 μmol g-1 h-1 which is about 132 times of pure TiO2 nanosheets.Due to the presence of metallic Ti3C2 MXene and 1T-MoS2 nanopatches,the fast photogenerated electron transport rate is achieved,which effectively suppresses the photo-generated electron-hole pair recombination,greatly improves the photocatalytic hydrogen production performance,and realizes the preparation of cost-effective photocatalysts without noble metal catalysts. |
