Modulation of copper (I) oxide reduction/oxidation in atmospheric pressure plasma jet

We describe the controlled reduction of copper(I) oxide films to metallic copper in a non-thermal, atmospheric pressure, helium plasma jet. Thin layers (≈0.1 μm) of Cu2O are electrochemically deposited onto Pt electrodes and placed in capacitively coupled helium plasma doped with H2, O2 or CH4 gases. Ex situ Raman spectroscopy was used to probe the effect of plasma treatment on the deposited copper oxide layer. We show that application of a static bias voltage to the Pt substrate during plasma exposure can control the rate of reduction of the copper(I) oxide film. We propose that the reduction process is mediated by plasma electrons and controlling the electron flux to the surface can be used as a means to modulate the reduction process.