2D CuO materials with superior photoelectrochemical performances for water splitting

Photoelectrochemical (PEC) water splitting have emerged as promising methods for achieving solar-to-chemical conversion. Therefore, we develop a facile one-pot thermal synthetic method for controllable synthesis of CuO plates, CuO sheets and CuO particles for preparing photoelectrochemical systems. Interestingly, CuO sheets and CuO plates display better activity than CuO particles in electrocatalytic water oxidation, as the required overpotential for 10 mA/cm² is 170 mV, 200 mV and 470 mV, respectively. Their superior catalytic performances are due to lower bandgap energy, higher conductivity, and larger active surface area. Further investigations suggest that CuO sheets and CuO plates possess more numbers of carriers, which can lead to improvement of charge transport, a faster carrier transfer rate and higher efficiency of charge separation. Then, three photoelectrochemical systems based on these three CuO materials and TiO₂ film have been designed for photocatalytic water splitting. The photocurrent and the generation rate of oxygen for CuO sheets and CuO plates systems are relative higher than that of CuO particles. Deep studies reveal that, their superior photoelectrochemical performances are attributed to the following factors: higher efficiency of hole-electron separation, enhanced charge transfer rate, higher concentration of carriers and conductivity, reduced defect, and decreased electron-hole recombination rate.