Highly Photoactive and Photo-Stable Spray Pyrolyzed Tenorite CuO Thin Films for Photoelectrochemical Energy Conversion

Tenorite CuO thin films have been synthesized via spray pyrolysis of aqueous copper(II) chloride solution followed by heat-treatment, exhibited a photocurrent density of 24 mA cm −2 at 0.25 V vs. RHE under AM 1.5G solar irradiation in alkaline electrolyte. This large photocurrent density has been attributed to a drift assisted transport of photo-generated electrons across the semiconductor/electrolyte interface in the annealed films. The tendency of photo-corrosion from the surface of CuO has been reduced substantially without any extra protective layer, simply by adding K 3 Fe(CN) 6 in the electrolyte, which acts as a sacrificial excess-electron scavenging agent. The fabricated electrode exhibited a positive onset potential at 0.25 V vs. RHE even after the electrolyte modification and a stable photocurrent density of more than 40% has been retained after 20 minutes of continuous illumination. The processed photo-cathode showed a solar to chemical conversion efficiency of 7.85% and 21.5% with and without using an electron scavenging agent, respectively. It holds the promise of using this photocathode in PEC energy conversion, photocatalysis and solar water splitting.