Fabrication of Nanostructured Copper Oxide via Anodization in Organic Electrolytes

Open Access
Author:
Scopelianos, George Evan
Graduate Program:
Materials Science and Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
July 13, 2011
Committee Members:
  • Joan Marie Redwing, Thesis Advisor
Keywords:
  • foil
  • copper oxide
  • potentiostatic
  • anodization
  • anodic oxidation
  • electrochemistry
  • nanotube
  • nanowire
  • nanostructure
  • photoelectrochemical
  • photocurrent
  • solar cell
  • water splitting
  • metal oxide
  • electrolyte
  • ethylene glycol
  • dimethyl sulfoxide
  • aqueous
Abstract:
Copper oxide is a material that has attracted interest for a wide range of applications. Due to its relatively low cost, non-toxicity, and its nature as a p-type semiconductor material with narrow band gap of 1.2 eV for CuO, it has the potential for use as a photoactive material in the visible-light region. However, given its rather weak absorption profile that suffers from recombination in the bulk, reducing the photogenerated carrier diffusion distance by introducing high surface-area nanoarchitectures is one route to circumvent this problem. Thin films of copper oxide nanoarchitectures were synthesized via anodic oxidation of copper foil in organic electrolytes with fluoride-bearing ions. Ethylene glycol (EG) and dimethyl sulfoxide (DMSO) were the solvents studied. The obtained structures were found to depend on the pH of the anodizing electrolyte, water content, temperature, voltage, and acid concentration. Nanoporous structures were formed under certain conditions in NH4F + EG electrolytes, while nanowire structures were present in HF + DSMO electrolytes. Annealing the films in O2 gas achieved full conversion to CuO composition. Photocurrent measurements indicated the p-type nature of the CuO device and a photoresponse to broad-wavelength visible light.