Eu modified Cu2O thin films: Significant enhancement in efficiency of photoelectrochemical processes through suppression of charge carrier recombination (original) (raw)
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physica status solidi (a), 2017
The synthesization of Cu 2 O thin films by electrodeposition for photoelectrochemical water splitting is reported. The synthesized Cu 2 O samples are annealed at different temperatures between 300 and 500 C. The XRD analysis and SEM images indicate that the sample without annealing includes Cu 2 O grains with pyramid shape. With annealing to more than 300 C, due to the oxidization of the sample, a thin layer of CuO appears on the original Cu 2 O film and the crystalline signatures of such CuO structure increase with annealing at higher temperatures. The photoelectrochemical measurements indicate that annealing pure Cu 2 O by more than 300 C, remarkably increases the photocurrent achieved from this photocathode. The effect is accompanied with considerable improvement of chemical stability of the original Cu 2 O electrode during water splitting. Such protection effect, which is originated from generation of CuO on the samples, increases with the annealing temperature up to 500 C. However, the best photocurrent from the Cu 2 O/CuO composite is obtained from the annealing temperature of about 400 C. The results of impedance analysis of various annealed samples indicate that annealing at a higher temperature, better charge transfer occurs both at the interface of photocathode/electrolyte and inside the photocathode.
Electrodeposited Cu2O doped with Cl: Electrical and optical properties
Journal of Applied Physics
For understanding the electrical and optical properties of electrodeposited Cl-doped Cu 2 O thin films, we have studied layers with increasing thickness and Cl concentrations of 0.8 and 1.2 at. %. The deposits were characterized by measuring the charge transport, the optical reflectance, and the photoluminescence. No significant decrease of electrical resistivity was observed in doped samples compared to undoped ones. A decrease of about five orders of magnitude was measured and ascribed to the presence of pinholes, as confirmed by scanning electron microscopy analyses. From optical measurements, we concluded that the Cl atoms are incorporated into substitutional sites of Cu 2 O lattices in agreement with photoluminescence results showing a strong reduction in the peak intensity of V O þ2 defects in comparison to undoped layers. Computational calculation using density functional theory has pointed out high formation energy for single Cl related defects, but low formation energy for Cl-defect complexes, such as Cl O þ V Cu , that strongly compensate the carriers generated by the Cl doping.
Materials Science in Semiconductor Processing, 2020
Low cost electrodeposition method was employed to grow Cu 2 O nanostructure thin films on different conductive substrates (Au, ITO, and FTO). Here for first time, influence of substrate on morphology, structural, and optical properties of electrodeposited thin films as active layer for solar cell applications were investigated employing scanning electron microscopy, X-ray diffraction, Uv-vis spectroscopy, and photoluminescence. The results indicate single-phase formation of polycrystalline cubic structure of Cu 2 O thin film on the three substrates. Only the (111) diffraction plane was appeared on ITO and Au substrates demonstrating a good crystal quality. The formed Cu 2 O on Au substrate have the smallest grain sizes and highest surface area. Optical results show that the fabricated Cu 2 O films have band gap of 2.03, 2.03 and 1.93 eV for Au, ITO, and FTO substrates respectively. The grown Cu 2 O crystals on Au substrate have the lowest PL intensity that indicate the higher performance to separate the photogenerated carriers and lowest recombination rate as well as high crystal quality. I-V characteristic curves of the fabricated thin films showed that samples have a non-linear rectification behavior while Cu 2 O deposited on Au substrate has the highest forward current. I-V results confirmed and supported all the other obtained results from XRD, SEM, and PL techniques. Therefore, the results designate that the electrodeposited Cu 2 O thin film on Au substrate is the most favorable for solar cell applications.
Zeitschrift für Physikalische Chemie, 2018
Here, we report the enhanced photoelectrochemical performance of surface modified hematite thin films with n-type copper oxide nanostructures (Cu2O/Fe2O3) obtained through simple electrochemical deposition method. The thickness and amount of cuprous oxide layer were varied by simply changing the number of electrodeposition cycles (viz. 5, 10, 25, 50 and 100) in order to understand its thermodynamic and kinetic influence on the photoelectrochemical activity of the resultant nano-heterostructures. Structural and morphological characteristics of the obtained Cu2O/Fe2O3 films have been studied by absorption spectroscopy, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy analysis. Electrochemical investigations such as linear sweep voltammetry, Mott–Schottky analysis, and electrochemical impedance spectroscopy suggested the formation of n-type Cu2O layers over the hematite films with varying charge-carrier densities, ranging from 0.56×1019 to 3.94×...
Photoelectrochemistry of p-type Cu2O semiconductor electrode in ionic liquid
Research on Chemical Intermediates, 2006
We investigated the photoelectrochemical characteristics and photo-stability of Cu 2 O layered on a copper plate using a hydrophobic ionic liquid. Our findings revealed that Cu 2 O is stable under white light irradiation, provided water is removed from the electrolyte. Methyl viologen derivative, a well-established electron acceptor, was introduced to the ionic liquid electrolyte, allowing the photo-induced electron transfer reaction at the Cu 2 O/electrolyte interface to be characterized. The methyl viologen derivative exhibited two distinct redox reactions at −0.56 V and −0.98 V vs. Ag/AgCl, clearly indicating that no dimer formation or co-proportionation reaction occurred. The excessive photocurrents being continuously generated resulted from a viable photo-induced electron transfer reaction from the Cu 2 O to the acceptor. However, in contrast, the reduction of the Cu 2 O by water in the aqueous solution causes this electron transfer to be inhibited. We further demonstrate that these findings are vital to understanding the role of the Cu 2 O and its photoelectrochemical applications.
The Journal of Physical Chemistry C, 2012
We present a systematic study on the effects of electrodeposition parameters on the photoelectrochemical properties of Cu 2 O. The influence of deposition variables (temperature, pH, and deposition current density) on conductivity has been widely explored in the past for this semiconductor, but the optimization of the electrodeposition process for the photoelectrochemical response in aqueous solutions under AM 1.5 illumination has received far less attention. In this work, we analyze the photoactivity of Cu 2 O films deposited at different conditions and correlate the photoresponse to morphology, film orientation, and electrical properties. The photoelectrochemical response was measured by linear sweep voltammetry under chopped simulated AM 1.5 illumination. The highest photocurrent obtained was −2.4 mA cm −2 at 0.25 V vs RHE for a film thickness of 1.3 μm. This is the highest reported value reached so far for this material in an aqueous electrolyte under AM 1.5 illumination. The optical and electrical properties of the most photoactive electrode were investigated by UV−vis spectroscopy and electrochemical impedance, while the minority carrier lifetime and diffusion length were measured by optical-pump THz-probe spectroscopy.
Journal of The Electrochemical Society, 2005
The p-type semiconductor cuprous oxide ͑Cu 2 O͒ film has been of considerable interest as a component of solar cells and photodiodes due to its bandgap energy of 2.1 eV and high optical absorption coefficient. We prepared Cu 2 O films on a conductive substrate by electrodeposition at 318 K from an aqueous solution containing copper sulfate and lactic acid. The structural and electrical characterizations of the resulting films were examined by X-ray diffraction, X-ray photoelectron spectroscopy, and X-ray absorption measurements, and the Hall effect measurement, respectively. The resistivity varied from 2.7 ϫ 10 4 to 3.3 ϫ 10 6 ⍀ cm, while the carrier density was from 10 12 to 10 14 cm −3 and the mobility from 0.4 to 1.8 cm 2 V −1 s −1 , depending on the preparation conditions, i.e., solution pH and deposition potential. The carrier density was sensitive to the atomic ratio of Cu to O in the films and the mobility to the grain size.
2023
This study examines the influence of electrolyte parameters on the synthesis of Cu2O semiconductor nanostructures. Cu2O nanostructures were synthesized using the electrodeposition method for application in photoelectrochemical water splitting. The study focused on investigating the effects of electrolyte pH and temperature during the synthesis process. Cuprous oxide is considered a promising p-type semiconductor due to its excellent light absorption in the solar spectrum window. It is an attractive semiconductor for photoelectrochemical water splitting, given its high theoretical efficiency for this process. Various characterizations including X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), and UV-Visible spectroscopy (UV-Vis) were used to analyze the structural properties of the synthesized Cu2O. The photoelectrochemical activity of the synthesized samples was evaluated using current-voltage measurements. The results suggest that the optimal electrolyte conditions for Cu2O synthesis were achieved at pH 13 and electrolyte temperature of 60°C.
Electrodeposition of Cu2O: growth, properties, and applications
Journal of Solid State Electrochemistry
For a long time, the world has been waiting for a sustainable, inexpensive, and efficient material for application in electronic and energy conversion purposes. Cu 2 O thin films made by electrodeposition clearly fulfill the sustainability and cost prerequisites , and are broadly believed that they could lead to the fabrication of highly efficient devices if well prepared and designed. Here, we review the fundamentals for electrochemical synthesis and the electrodeposition aspects and procedures for growing Cu 2 O. The properties of electrodeposited Cu 2 O in thin films and nanostructures will be discussed in view of the literature, with emphasis on the electrical and optical properties and applications in photocatalysis and photovoltaics.