Scalable Binder-Free Supersonic Cold Spraying of Nanotextured Cupric Oxide (CuO) Films as Efficient Photocathodes

Jong Gun Lee, Do Yeon Kim, Jong Hyuk Lee, Min Woo Kim, Seongpil An, Hong Seok Jo, Carlo Nervi, Salem S. Al-Deyab, Mark T. Swihart, Suk Goo Yoon

Research output: Contribution to journalArticlepeer-review

46 Citations (Scopus)


We demonstrate production of nanotextured p-type cupric oxide (CuO) films via a low-cost scalable supersonic cold spray method in open air conditions. Simply sweeping the spray nozzle across a substrate produced a large-scale CuO film. When used as hydrogen evolution photocathodes, these films produced photocurrent densities (PCD) of up to 3.1 mA/cm2 under AM1.5 illumination, without the use of a cocatalyst or any additional heterojunction layers. Cu2O particles were supersonically sprayed onto an indium tin oxide (ITO) coated soda lime glass (SLG) substrate, without any solvent or binder. Annealing in air converted the Cu2O films to CuO, with a corresponding decrease in the bandgap and increase in the fraction of the solar spectrum absorbed. Annealing at 600 °C maximized the PCD. Increasing the supersonic gas velocity from ∼450 to ∼700 m/s produced denser films with greater surface roughness, in turn producing higher PCD. The nanoscale texture of the films, which resembles the skin of a dinosaur, enhanced their performance, leading to one of the highest PCD values in the literature. We characterized the films by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, and transmission electron microscopy to elucidate the origins of their outstanding performance. This supersonic cold spraying deposition has the potential to be used on a commercial scale for low cost mass production.

Original languageEnglish
Pages (from-to)15406-15414
Number of pages9
JournalACS Applied Materials and Interfaces
Issue number24
Publication statusPublished - 2016 Jun 22

Bibliographical note

Publisher Copyright:
© 2016 American Chemical Society.


  • cupric oxide (CuO)
  • cuprous oxide (CuO)
  • nanotextured surface
  • supersonic cold spray
  • water splitting

ASJC Scopus subject areas

  • General Materials Science


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