Single-Crystalline Branched CuO Nanowires for Photoelectrochemistry Performance

Abstract

We report a simple solution process to fabricate single-crystalline branched CuO nanowires (CuO b-NWs) on copper (Cu) foil. A CuO backbone was grown by a wet chem-ical oxidation, then nanostructured CuO branches were grown by chemical precipitation. The CuO backbone was poly-crystalline, composed of (002) and (111) planes, whereas, the branches were single-crystalline CuO with (001) preferred orientation. The single-crystalline branches are free from grain boundaries, so they have good conductivity, which results in enhancement of photoelectrochemical (PEC) performance. CuO b-NWs with single-crystalline branches provided larger surface area, superior crystallinity, and higher light absorption in near-surface region than the conventional CuO NWs. When CuO b-NWs were used as a photocathode for photoelectrochemical water splitting, carrier re-combination was suppressed, thereby resulting in the enhancement of photocurrent from -1.0 to -2.6 mA/cm2 at 0 VRHE.