Photoelectrochemical, Structural, and Optical Investigations of Silver-Doped Cupric Oxide Films Fabricated via Electrodeposition

In this work, we report for the first-time the impact of silver doping on the structural, electrical, and optical properties of CuO thin films synthesized through a low-energy electrodeposition method. Both pure and Ag-doped CuO films were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy, UV–visible spectroscopy, and electrochemical impedance spectroscopy (EIS). The photocurrent response was examined in a photo-electrochemical cell. FE-SEM revealed a significant morphology shift from rod-like grains to compact globular structures upon Ag doping. XRD confirmed a monoclinic phase, with preferred orientations along (002) and (111) planes. The intensity ratio I(111)/I(002) decreased from 1.169 for pure CuO to 1.060 with 2% Ag doping, then increased to 1.289 for 5% Ag, indicating changes in growth orientation. The crystallite size decreased from 29.8 nm (pure) to 27.8 nm with 2%Ag doping. A band gap narrowing was observed of from 2.25 eV (undoped) to 1.62 eV at 5%Ag. EIS shows a decrease in charge transfer resistance R ct from 49.86 Ω to 30.77 Ω, confirming enhanced conductivity and photo-response. These results demonstrate that Ag doping via low-energy electrodeposition effectively tunes the properties of CuO thin films, offering a novel and promising route for optoelectronic applications.