Fabrication of Nanowire Arrays CuO-Al₂O₃-TiO₂ as p-Insulator-n Heterojunction for Photochemical Water Splitting

CuO@TiO2 nanowires were prepared with the use of a porous alumina membrane (PAM). The conventional thermal chemical vapor deposition (CVD) method was used for the deposition of TiO2 by decomposing titanium isopropoxide (Ti(OiPr)4). The multilayer heterojunction is tested for possible photochemical water splitting application. The photo conversion properties of the CuO-Al2O3-TiO2 (p-insulator-n) heterojunction along with the microstructures and composition were characterized by Potentiostat, SEM and TEM, respectively. The shape of CuO nanowire arrays were hexagonal honeycombs and size was about 90 nm which depends on the uniform pore size of the PAM. The microstructural characterization showed that the nanosized CuO-Al2O3-TiO2 is a p-insulator-n heterojunction. The maximum photoconversion efficiency of 1.13 and 1.61% is obtained for CuO and CuO-Al2O3-TiO2 nanowire arrays junctions. An energy band diagram was introduced to explain the change in current during water splitting due to electron tunneling through the insulating layer