Defects And Interface Regulation Of 2D-ReS₂/2D-TiO₂ Composites And Their Photocatalytic Hydrogen Evolution Performance

Solar-driven photocatalytic hydrogen evolution technology has the characteristics of low cost,low energy consumption and no pollution,which is in line with the development goals under the background of reaching carbon peak by 2030and achieving carbon neutrality by 2060.Titanium dioxide（TiO₂）is considered to be an ideal photocatalytic material due to its strong redox ability,eco-friendliness,good chemical stability,and low cost.However,its narrow solar spectral response range and high charge recombination efficiency limit its application to a certain extent.Rhenium disulfide（ReS₂）,as a new type of transition metal sulfide,has light carrier mass,weak interlayer coupling,high charge transport ability,and an energy band structure independent of the number of layers,making it as a co-catalyst have received much attention.In this work,2D/2D ReS₂/TiO₂ composites were obtained by chemical vapor deposition method.The coexistence of homojunction and heterojunction were realized.The role of vacancy defects in the photocatalytic hydrogen production process was studied.The effects of different phase interfaces of composites on the growth and carrier transport of ReS₂ were elucidated.The growth mechanism of ReS₂was revealed.The main findings are as follows:（1）The growth mechanism of ReS₂ is parallel growth first and then vertical growth.Oxygen vacancies were introduced on the surface of TiO₂ by hydrogen calcination.The effects of oxygen vacancy defects on the growth of ReS₂ and the microstructure of the composites were systematically studied.The essential relationship between oxygen vacancy defects and photocatalytic hydrogen production performance was revealed,and the relationship model between oxygen vacancy defects and ReS₂ growth mode was constructed by combining density functional theory（DFT）.Studies have shown that the oxygen vacancy defect of TiO₂ is beneficial to form stable chemical bonds with sulfur atoms,while capturing photogenerated carriers and improving the rate of charge transfer.The photocatalytic hydrogen production rate of ReS₂/TiO₂（100%H₂-1h）was 490.2μmol g^-1 h^-1,which is1.7 times higher than that of the composites without oxygen vacancy.（2）Different TiO₂ is obtained by air calcination.ReS₂ was grown on the anatase,rutile and mixed phases,respectively.The growth mode of ReS₂ on different TiO₂ and the microstructure of different composites were systematically studied.The intrinsic mechanism of enhanced photocatalytic hydrogen production performance was revealed under the coexistence of homojunction and heterojunction.Studies have shown that ReS₂ easily forms a stable structure with rutile.The TiO₂ homojunction inhibits the recombination of TiO₂ photogenerated electron-hole pairs,and forms a heterointerface with ReS₂ to accelerate the transport of photogenerated carriers,thereby improving the photocatalytic activity of the ReS₂/TiO₂ composite.The hydrogen production rate of ReS₂/800TiO₂ composite is the highest,reaching 762.3μmol g^-1 h^-1,in which the ratio of anatase phase to rutile phase of 800TiO₂ is 9:1.In conclusion,the 2D/2D ReS₂/TiO₂ composites provide a good research platform for structural design and modification strategies.Meanwhile,broaden the ideas for the development of new composite materials in the field of catalysis.