Morphological Changes in Cu2O Nanoshells During Photocatalysis

Background: It is meaningful to use semiconductor nanomaterials for degradation of organic compounds under irradiation of solar light. Introduction: Nano Cu2O is suitable for visible-light photocatalysis for the narrow band gap (~2.17 eV). However, few focus on the morphology changes of Cu2O in the process of photocatalysis. Methods: By two-step addition of reducer, porous Cu2O nanoshells (NSs) with almost 100% hollow structure were synthesized, characterized and used to photocatalyze MO in neutral solution at 30 C in air. Results: Cu2O NSs have high adsorption and good photocatalysis rates for MO. After photocatalysis, some new results were observed. Most chemical bonds of MO were broken, but part of sulfur containing group of MO left on the NSs. The morphology of Cu2O NSs was changed and lots of nanodebris was produced. Further experimental results showed some nanodebris was also observed after adsorption-desorption equilibrium (ADE). Without MO and only light irradiation of Cu2O suspension, little nanodebris appeared. The results of X-ray diffraction (XRD), scanning transmittance electron microscope (STEM) and high-resolution transmittance electron microscope (HRTEM) proved the composite of the nanodebris is Cu2O. The nanodebris are the nanosheets dropped off from the Cu2O NSs. Conclusion: For the porous Cu2O NSs are composed of Cu2O nanosheets with exposed 111 facets, which have strongest adsorption ability for MO and strongest catalysis performance. Light irradiation sped up this interaction and led to the Cu2O nanosheets dropping off from the Cu2O NSs. For the strong interaction between Cu+ and S, part of sulfur containing group of MO left on the NSs after photocatalysis.