Structure And Photocatalytic Properties Of In(Oh)(3)/Inooh Natural Heterojunction Nanocrystals Prepared By Hydrothermal Synthesis

In(OH)(3)/InOOH nanocrystals are synthesized using InCl3 center dot 4H(2)O as the indium source in the presence of ethylenediamine by a one-step hydrothermal process, and the effect of synthesis temperature on the morphology, crystallization, structure, and photocatalytic properties of the photocatalysts is investigated. The results show that all the synthesized In(OH)(3)/InOOH samples have granular nanoparticles with a size of 20-30 nm. When the synthesis temperature is lower than 150 degrees C, only the In(OH)(3) phase exists. With increasing synthesis temperature, In(OH)(3) gradually dehydrates to form InOOH to achieve a phase equilibrium between InOOH and In(OH)(3). The concentration of InOOH is the maximum at 180 degrees C and decreases at 210 degrees C. The photocatalytic activity is evaluated from the degradation of a Rhodamine B solution under ultraviolet light irradiation, which follows the first-order reaction kinetics. The increase in synthesis temperature can significantly improve the photocatalytic performance of In(OH)(3)/InOOH because of the formation of a large number of natural heterojunctions in the nanocrystals, which can enhance ultraviolet light absorption and facilitate charge transfer and separation. The first-order kinetic constant of the nanocrystals synthesized at 180 degrees C is almost 2.5 times that of the nanocrystals synthesized at 150 degrees C. The active species capture experiments demonstrate that holes and superoxide radicals are the main active species in the photocatalytic systems.