Cu2O/CuO composite for efficient performance in photoelectrochemical and optoelectronics applications

This study introduces a highly active photoelectrode, comprising a Cu2O/CuO composite, synthesized through annealing Cu2O thin film under controlled conditions to induce partial oxidation. Through systematic investigation of annealing conditions, including temperature and duration, an optimal synthesis condition of 400 degrees C for 1 h was identified, resulting in superior photoelectrochemical and optoelectronic properties. It yielded the most favorable outcomes, exhibiting the largest charge carrier density of 1.09 x 10(21) cm(-3), lowest charge transfer resistance of 18.8 Omega, and highest photocurrent density of -2.97 mA cm(-2) with stability of 81%. This performance enhancement, which surpassed the initial photocurrent by 7 times under AM 1.5 simulated sunlight illumination at 0 V versus the reversible hydrogen electrode (RHE), is attributed to the formation of the Cu2O/CuO composite. This composite facilitates improved electron-hole pair separation efficiency, while the narrow bandgap of CuO enables enhanced light absorption. Additionally, the stability of the photocurrent is significantly improved by 2.3 times, attributed to the protective function of the CuO layer on Cu2O. Thus, the Cu2O/CuO composite emerges as a highly efficient and promising photocathode, offering a facile and cost-effective route for photoelectrochemical and optoelectronics applications.