Preparationand Performance Investigation Of Highlyactive Cu2O Photocatalyst

As an important P type semiconductor materials, cuprous oxide has uniquecatalytic, optical, electrical and gas-sensitive properties and has been widelyused in the fields of solar energy conversion, electronics, catalysts and gassensors, etc.. It is of great significance to study the performance by controlingthe growth process of Cu2O to form controllable morphologies and structuresaccording to the human’s will.In this paper, highly symmetrical Cu2O polyhedron, Cu2O concave andladder-like Cu2O polyhedron were prepared by liquid phase reduction methodcombining with chemical etching method. Besides, their formation mechanismswere also investigated. Whereafter their photocatalytic properties were studied.The photocatalytic performance of Cu2O crystal was improved by controllingthe surfaces exposed outside.Firstly, based on the PVP’s selective adsorption of different facets, shapeevolutions of Cu2O crystal from cubes, truncated cubes, truncated octahedronsto octahedrons were realized by delicately controlling the polyvinylpyrrolidone(PVP) concentration to change the area ratio of {111} facets and {100} facets.The average length was about1.2μm. According the reducing differences between the ascorbic acid and glucose and the molecular weight differences ofPVP, truncated cubes and truncated octahedrons in nano order of magnitudeswere also prepared to improve their specific surface areas.Secondly, based the runcated cubes and truncated octahedrons obtained in thefirst step, Cu2O concave with only {111} facets exposed was prepared via anoxygen etching method. It demonstrated that PVP in the precursor solutionpreferential adsorbed on the {111} facets. As a result, the {111} facets wereprotected while the {100} facets were etching. And then {111} facets-exposedCu2O concaves were obtained.Then, based the truncated cubes and truncated octahedrons obtained in thefirst step, ladder-like Cu2O polyhedrons were developed successfully by sodiumcitrate corrosion liquid. In the absence of PVP,{111} facets were easily to reactwith the O2in the air. Meanwhile the sodium citrate could also accelerate thedisappearance of {111} planes to form a triangular pyramid structure, whichowned both {110} edges and {111} corners. Besides, as the etching timeextended, denser ladder structures were formed.Finally, the photocatalytic performance of the products above were studied.The photocatalytic results were as follows: nano structures> micro structures;octahedrons> truncated octahedrons> truncated cubes> cubes. It is becausethat different sizes of crystals have different specific surface areas. In addition,different parts and different facets of crystals exhibited different surface energies:Ecorners>Eedges>Efacets,E{110}>E{111}>E{100}. The results indicate that the bigger the specific surface area was and the lager proportion of highly active surfaceexposed was, the better the photocatalytic performance of the product was.