Fabrication And Doping Of CuMnO₂ By Hydrothermal Method And Characterization Of CuMnO₂/TiO₂ Photocatalysts

In the past few decades,increasing attentions have been focused on semiconductor photocatalytic technique due to the serious environment and energy problems.Semiconductor photocatalyst shows much potential applications in environment protection for its performance of direct capture and application of solar energy.At present,the TiO₂ crystal still plays an important role in the photocatalyst owing to its chemical stability and low cost.However,the photocatalytic performance of TiO₂ is limited because of its wind bandgap.Nowadays,p-type delafossite oxides have attracted much attention for their several applications such as transparent diodes,photocatalysts,photovoltaics,ferroelectrics and so on.Compared to a large number of works have been focused on the p-type delafossite oxides CuAlO₂,CuFeO₂ and CuCrO₂,a few reports have paid attention to CuMnO₂.Herein,we successfully fabricated delafossite oxides CuMnO₂ crystals and Mg doped CuMnO₂ nanocrystals through low temperature hydrothermal method in this work and developed a novel p–n heterostructure photocatalyst which is consisting of CuMnO₂ nanoparticles and TiO₂ nanorods to enhance the photocatalytic performance.The conclusions are as follows.Firstly,nano-sized C2/m-CuMnO₂ crystals with 70 nm were successfully prepared through hydrothermal reaction at low-temperature of 80°C.CuO and Mn₃O₄ could be obtained at a low dosage of NaOH.When the NaOH dosage was high,the XRD patterns could be indexed as crednerite CuMnO₂.During the hydrothermal reaction,the Cu²⁺were reduced to Cu⁺and Mn²⁺were oxidized to Mn³⁺,and finally formed CuMnO₂ nanocrystals.Moreover,the Mott-schottky plots results show that CuMnO₂ nanocrystals have a p-type semiconductor behaviours and carrier density of CuMnO₂ nanocrystals are 2.46×10¹⁸cm^-3.Secondly,Mg doped CuMnO₂ nanocrystals were synthesized by a facile hydrothermal method.Experimental study found that Mg dopants concentration had a great influence on the crystal structure of CuMnO₂,resulting in the formation of CuMn_1-xMg_xO₂.It can be seen from the XRD results and SEM images that the diffraction peaks and morphology of product changed.Furthermore,the Mg-doped CuMnO₂ powder had more strong absorption ability and carrier density than the pure CuMnO₂,which is beneficial for its applications in optoelectronics devices.Thirdly,rutile TiO₂ nanorod-array film with different thickness were synthesized by adjusting the growth time and temperature in a facile hydrothermal method.CuMnO₂/TiO₂ photocatalysts were fabricated by simple spin-coating method andcharacterized by different tests.The photocatalytic activity of CuMnO₂/TiO₂ for degradation of methylene blue?MB?aqueous solution was much higher than pure TiO₂ and the deposit amount of CuMnO₂ plays important roles on the photocatalytic performance.