Effect of Deposition Time on the Photoelectrochemical Properties of Cupric Oxide Thin Films Synthesized via Electrodeposition Method

Abstract

Abstract.The main aim of this study was to investigate the effect of deposition time on the physicochemical and photoelectrochemical properties of cupric oxide (CuO) thin films synthesized via electrodeposition method. Firstly, the electrodeposition of amorphous CuO films on fluorine-doped tin oxide (FTO) working electrodes with varying deposition time between 5 and 30 min was carried out, followed by annealing treatment at 500 ℃. Resultant nanocrystalline CuO thin films were characterised using field emission-scanning electron microscopy (FE-SEM), photocurrent density, and photoluminescence measurements. Through FE-SEM analysis, it was observed that the surface of thin films was composed of irregular-sized CuO nanocrystals. A smaller CuO nanocrystals size will lead to a higher photoactivity due to the increase in overall catalytic surface area. In addition, the smaller CuO nanocrystals size will prolongs the electron-hole recombination rate due to the increase in copious amount of surface defects. From this study, it was revealed that the relationship between deposition time and CuO film thickness was non-linear. This could be due to the detachment of CuO thin films from the FTO surface at an increasing amount of CuO mass being deposited. It was observed that the amount of light absorbed by CuO thin films increased with film thickness until a certain extent whereby, any further increase in the film thickness will result in a reduction of light photon penetration. Therefore, the CuO nanocrystals size and film thickness have to be compromised in order to yield a higher catalytic surface area and a lower rate of surface charge recombination. Finally, it was found that the deposition time of 15 min resulted in an average CuO nanocrystals size of 73.7 nm, optimum film thickness of 0.73 μm, and corresponding photocurrent density of 0.23 mA/cm 2 at the potential bias of -0.3 V (versus Ag/AgCl). The PL spectra for the deposition time of 15 min has the lowest rate of recombination of photogenerated electron-hole pairs by referring to its lowest PL intensity.

Photoelectrocatalytic Degradation of Methylene Blue on Electrodeposited Bismuth Ferrite Perovskite Films

“…The increase in the photocurrent response is an indication that thin film photoanodes could enhance interfacial charge transfer and consequently inhibit the recombination of electron–hole pairs [ 47 ]. This observation of an increase in current density in thin films with shorter electrodeposition time is in good agreement with the results reported by Yam et al [ 48 ] and Shafi et al [ 49 ] who attributed their observations to an increase in surface area and surface defects.…”

Nanoengineering of Thin Film V2O5 Cathode Interfaces via Atomic Layer Deposition for use with Polymer Gel Ionic Liquid Electrolytes

“…[35,36,37] The maximum capacities for each sample were 10, 15, 25, and 32 μAh for 10, 20, 40 and 90 s, respectively. [38] To investigate if the samples could be more completely crystallised yielding larger capacities, oven annealing at 450 °C for 7 hours in ambient air was employed on 10, 40 and 90 s deposited samples. The upper potential limit for 90 s was increased from 3.65 to 3.8 V still within the maximum range of 2.5-4 V recommended for the 1 e À reaction without decreasing the cycling stability.…”

“…The maximum capacities for each sample were 10, 15, 25, and 32 μAh for 10, 20, 40 and 90 s, respectively [38] . To investigate if the samples could be more completely crystallised yielding larger capacities, oven annealing at 450 °C for 7 hours in ambient air was employed on 10, 40 and 90 s deposited samples.…”