Scalable synthesis and photoelectrochemical properties of copper oxide nanowire arrays and films

Here, we present a scalable method based on both atmospheric plasma and wet chemical oxidation methods to synthesize thin films and nanowire arrays of both cupric and cuprous oxides. In terms of nanowire arrays, the wet chemical oxidation is shown to produce copper hydroxide nanowire arrays on copper foils using hydrogen peroxide as the oxidant similar to ammonium persulfate. Experiments using different concentrations of hydrogen peroxide at constant pH resulted in higher nucleation density and smaller diameter of copper hydroxide nanowires. A scheme involving a short period of wet oxidation followed by plasma annealing resulted in high number density of Cu2O nanowire arrays. The overall process is rapid on the order of 1 min reaction time scale. Photoelectrochemical characterization of titania coated copper oxide nanowire and thin film electrodes showed that the nanowire array electrodes exhibited significantly higher photoactivity than the thin film electrodes. The performance of resulting Cu2O NW array electrodes can be optimized further with other protective coatings.

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► A scalable method for synthesizing high number density of cupric oxide and cuprous oxide nanowire arrays on different substrates using a combination of wet chemical oxidation and plasma oxidation techniques is presented.
► A mechanism for the growth of metal hydroxide nanowires by wet chemical oxidation is proposed.
► Photoelectrochemical characterization of titania coated copper oxide nanowire arrays was performed.
► Challenges in achieving high photocurrent densities with copper oxide nanowires are discussed.