Preparation And Properties Based On Cu₂O And Their Heterostructure Nanomaterials

As an important P-type metal oxide semiconductor material,Cu₂O has a wide range of applications in photocatalysis,solar cells,and light-emitting diodes due to its environmental protection and abundant resources.Meanwhile,as an important photocatalytic material,Cu₂O is also used for photocatalytic hydrogen production,photocatalytic degradation of organic dyes.It's shown that the photocatalytic properties of the Cu₂O largely depend on the morphology,size,and itsstructure.Therefore,the synthesis of special morphology and proper size was a significate measure to improve photocatalytic properties.The monodisperse Cu₂O-cubes,Cu₂O-concaved cubes and Cu₂O-octapodssupercrystals have been synthesized using a self-assembly approach.The characterizations of XRD and XPS showed that the material was composed of Cu₂O and a small amount of CuO.The morphology of the material was investigated by FESEM and TEM.The mechanism of the formation of Cu₂O evolution fromcubes,concave cubes to octapods was systematically investigatedand the facet etching mechanism was developed and confirmed.During the experiment of the synthesis of Cu₂O-cubes and Cu₂O-concave cubes,due to the increasing amount of Cu?Ac?₂,more OH^-was combining with Cu²⁺to form[Cu?OH?₄]^2-.The{100}facets are most easily etched by carefully injecting ascorbic acid.Precise control of the amount of Cu?Ac?₂ enables this facet etching,novel Cu₂O with concave{100}facets can be fabricated.For samples with different morphologies,the photocatalytic hydrogenproduction was investigated.The best efficiency of photocatalytichydrogen evolution is Cu₂O-octapods and a steady H₂ evolutionrate.The amount of hydrogen could reach 870.6?mol,the Cu₂O-concaved cubes were 423?mol,and the Cu₂O-cubes were 148.2?mol.Core-shell Cu₂O@ZnO composites were synthesized successfully based on a one-p ot hydrothermal method.The Cu₂O can be converted to rough core-shellCu₂O@ZnO st ructure by adjusting the amount of zinc powder added.In the process of the synthesis,th e Zn powders were reacting with the NaOH to form much Zn O by introducing the Zn powder s.By adjusting the sequence of the zinc powders and NaOH solution,the OH^-was combinin g with Cu²⁺to form[Cu?OH?₄]^2-and less amount of OH^-was remained in the solution.The c haracterizations of FESEM and TEM showed that the ZnO was finally formed and co ated on the Cu₂O.The characterizations of XRD and XPS showed that the the compo sites were composed of Cu₂O and ZnO.The core-shell Cu₂O@ZnO composite was obta ined.The photocatalytic properties of Cu₂O and Cu₂O@Zn O composites were studied systematically.The as-synthesized Cu₂O@ZnO compositesexhibited excellent photocatal ytic hydrogen production and the amount of H₂ generated using these composites was4.5-foldmore than that produced with Cu₂O cubes.The amount of hydrogen could re ach 236.3?mol.Cu₂O,TiO₂ and Cu₂O-TiO₂ composites were synthesized successfully based on a one-pot hydrothermal method.The characterizations of FESEM and TEM of Cu₂O and TiO₂showed that thesize of the particle were about 1.2?m and about 10 nm,respectively.The Cu₂O-TiO₂ composites were synthesized successfully by adding the Ti O₂ nanoparticles.The characterizations of XRD,TEM and XPS showed that the TiO₂ nanoparticles had been successfully loaded on the surface of the Cu₂O.The photocatalytic hydrogen production performance of the Cu₂O,TiO₂ and Cu₂O-TiO₂ composites has been tested,respectively.The results showed that with the increaseing amount of the TiO₂,the photocatalytic hydrogen production performance of the Cu₂O-TiO₂ composites is gradually improved.The amount of hydrogen generated by pure Cu₂O-cubes and TiO₂ nanoparticles in 6 hours could reach 56.1?mol and 436.6?mol,respectively.With the increasing amount of TiO₂ nanoparticles,the increase of H₂ generation was 775.7?mol,960.3?mol and 2827.4?mol,respectively.The results showed that the photocatalytic hydrogen production performance of the Cu₂O-TiO₂composite can reach 53 times more than Cu₂O and 6 times more than TiO₂.Therefore,TiO₂nanoparticles play an important role in improving the photocatalytic hydrogen production performance of Cu₂O.