n-Type Cu2O/α-Fe2O3 Heterojunctions by Electrochemical Deposition: Tuning of Cu2O Thickness for Maximum Photoelectrochemical Performance

2018 ◽  
Vol 232 (9-11) ◽  
pp. 1551-1566 ◽  
Author(s):  
Soniya Gahlawat ◽  
Nusrat Rashid ◽  
Pravin P. Ingole
Keyword(s):  
Oxide Layer ◽  
Electrochemical Deposition ◽  
Cuprous Oxide ◽  
Electrochemical Impedance ◽  
Base Material ◽  
Morphological Characteristics ◽  
Linear Sweep Voltammetry ◽  
Photoelectrochemical Performance ◽  
Photoelectrochemical Activity ◽  
X Ray

Abstract 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 3.94×1019 cm−3, that varies with the number of cycles of electrochemical deposition. Besides, the thickness of deposited cuprous oxide layer is noted to alter the net electrochemical and photo-electrochemical response of the base material. An interesting, peak event was recorded for a particular thickness of the cuprous oxide layer (obtained after 25 cycles of electrochemical deposition) below and above which the efficiency of catalyst was impaired. The heterojunction obtained thus, followed well known Z-scheme and gave appreciable increment in the photocurrent response.

Enhanced Photoelectrocatalytic Activity of Oriented Rutile TiO2 Nanorod Array Film through Nb Doping

2014 ◽  
Vol 1010-1012 ◽  
pp. 195-201
Author(s):  
Meng Lei Chang ◽  
Dong Chu Chen ◽  
Xiu Fang Ye ◽  
Xin Jun Li ◽  
Liang Peng Wu ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Linear Sweep Voltammetry ◽  
Nanorod Array ◽  
Rutile Phase ◽  
Electrode System ◽  
X Ray Diffraction ◽  
X Ray ◽  
Conductive Glass ◽  
Nb Doping ◽  
Oxidation Of Glucose

TiO2 nanorod array films with or without Nb doping grown directly on transparent conductive glass (FTO) were prepared by a facile hydrothermal method. The films were characterized by means of field emission scanning electron microscopy (FE-SEM) with energy-dispersive x-ray spectra (EDS), X-ray diffraction (XRD) and the X-ray photoelectron spectroscoy (XPS). The electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV) and transient photocurrent were investigated in a three-electrode system with TiO2 nanorod array film served as the photoanode. The photoelectrocatalytic activity of the films was evaluated by the oxidation of glucose under UV irradiation. The results show that both the pure and Nb-doped TiO2 nanorods perpendicularly grown on FTO substrate are rutile phase. The resistance of the TiO2 nanorod array photoanode is decreased significantly by Nb doping. The steady-state photocurrent (iss) for glucose oxidation at Nb-doped TiO2 nanorod array film is much higher than that at the pure one. The enhanced photoelectrocatalytic activity of the Nb-doped TiO2 nanorods could be attributed to the enhanced charge transport ability.

scholarly journals Effect of Morphology on the Photoelectrochemical Activity of TiO2 Self-Organized Nanotube Arrays

Catalysts ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 279 ◽  
Author(s):  
Houda Ennaceri ◽  
Kristina Fischer ◽  
Kevin Hanus ◽  
Abdelkrim Chemseddine ◽  
Andrea Prager ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Tube Wall ◽  
Linear Sweep Voltammetry ◽  
Photocurrent Density ◽  
Tio2 Nanotube ◽  
Geometrical Parameters ◽  
Linear Sweep ◽  
Photoelectrochemical Activity ◽  
Self Organized ◽  
Anodization Process

In the present work, highly ordered titanium dioxide (TiO2) nanotube anodes were grown using a rapid anodization process. The photoelectrochemical performances of these electrodes strongly depend on the anodization conditions. Parameters such as electrolyte composition, anodization potential and anodization time are shown to affect the geometrical parameters of TiO2 nanotubes. The optimal anodization parameters are determined by photocurrent measurements, linear sweep voltammetry and electrochemical impedance spectroscopy. The thickness of the tube wall and its homogeneity is shown to strongly depend on the anodization potential, and the formation mechanism is discussed. This study permits the optimization of the photocurrent density and contributes to further improvement of the photoelectrochemical water-splitting performance of TiO2 nanotube photoelectrodes.

scholarly journals A Selective Synthesis of TaON Nanoparticles and Their Comparative Study of Photoelectrochemical Properties

Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1128
Author(s):  
Vijay Khanal ◽  
Eric Soto-Harrison ◽  
Dhanesh Chandra ◽  
Narmina O. Balayeva ◽  
Detlef W. Bahnemann ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Linear Sweep Voltammetry ◽  
Morphological Characterization ◽  
Photoelectrochemical Properties ◽  
Photoelectrochemical Performance ◽  
Chemical Safety ◽  
Xenon Light ◽  
Eis Measurements ◽  
Significant Increment

A simplified ammonolysis method for synthesizing single phase TaON nanoparticles is presented and the resulting photoelectrochemical properties are compared and contrasted with as-synthesized Ta2O5 and Ta3N5. The protocol for partial nitridation of Ta2O5 (synthesis of TaON) offers a straightforward simplification over existing methods. Moreover, the present protocol offers extreme reproducibility and enhanced chemical safety. The morphological characterization of the as-synthesized photocatalysts indicate spherical nanoparticles with sizes 30, 40, and 30 nm Ta2O5, TaON, and Ta3N5 with the absorbance onset at ~320 nm, 580 nm, and 630 nm respectively. The photoactivity of the catalysts has been examined for the degradation of a representative cationic dye methylene blue (MB) using xenon light. Subsequent nitridation of Ta2O5 yields significant increment in the conversion (ζ: Ta2O5 < TaON < Ta3N5) mainly attributable to the defect-facilitated adsorption of MB on the catalyst surface and bandgap lowering of catalysts with Ta3N5 showing > 95% ζ for a lower (0.1 g) loading and with a lamp with lower Ultraviolet (UV) content. Improved Photoelectrochemical performance is noted after a series of chronoamperometry (J/t), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS) measurements. Finally, stability experiments performed using recovered and treated photocatalyst show no loss of photoactivity, suggesting the photocatalysts can be successfully recycled.

scholarly journals Iridium and Ruthenium Modified Polyaniline Polymer Leads to Nanostructured Electrocatalysts with High Performance Regarding Water Splitting

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 190
Author(s):  
Razik Djara ◽  
Marie-Agnès Lacour ◽  
Abdelhafid Merzouki ◽  
Julien Cambedouzou ◽  
David Cornu ◽  
...  
Keyword(s):  
Water Splitting ◽  
High Performance ◽  
Electrochemical Impedance ◽  
Cell Voltage ◽  
Linear Sweep Voltammetry ◽  
Water Electrolysis ◽  
Linear Sweep ◽  
X Ray ◽  
On Demand ◽  
New Strategy

The breakthrough in water electrolysis technology for the sustainable production of H2, considered as a future fuel, is currently hampered by the development of tough electrocatalytic materials. We report a new strategy of fabricating conducting polymer-derived nanostructured materials to accelerate the electrocatalytic hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and water splitting. Extended physical (XRD, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX)) and electrochemical (cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS)) methods were merged to precisely characterize the as-synthesized iridium and ruthenium modified polyaniline (PANI) materials and interrogate their efficiency. The presence of Ir(+III) cations during polymerization leads to the formation of Ir metal nanoparticles, while Ru(+III) induces the formation of RuO2 oxide nanoparticles by thermal treatment; they are therefore methods for the on-demand production of oxide or metal nanostructured electrocatalysts. The findings from using 0.5 M H2SO4 highlight an ultrafast electrochemical kinetic of the material PANI-Ir for HER (36 − 0 = 36 mV overpotential to reach 10 mA cm−2 at 21 mV dec−1), and of PANI-Ru for OER (1.47 − 1.23 = 240 mV overpotential to reach 10 mA cm−2 at 47 mV dec−1), resulting in an efficient water splitting exactly at its thermoneutral cell voltage of 1.45 V, and satisfactory durability (96 h).

scholarly journals Fabrication, characterization, and photocatalytic performance of ternary cadmium chalcogenides CdIn2S4 and Cd7.23Zn2.77S10-ZnS thin films

2020 ◽  
Vol 44 (1) ◽  
pp. 39-50
Author(s):  
Umar Daraz ◽  
Tariq Mahmood Ansari ◽  
Shafique Ahmad Arain ◽  
Muhammad Adil Mansoor ◽  
Muhammad Mazhar ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Chemical Vapor ◽  
Linear Sweep Voltammetry ◽  
Photocurrent Density ◽  
Charge Transfer Resistance ◽  
Single Step ◽  
Transfer Resistance ◽  
X Ray ◽  
Dual Source

Abstract Dithiocarbamate complexes [Cd(S2CNCy2)2(py)] (1), [In(S2CNCy2)3]·2py (2) and [Zn(S2CNCy2)2(py)] (3) were synthesized and toluene solution of (1) and (2) was used as dual source precursor for the synthesis of CdIn2S4 (CIS), while that of (1) and (3) was applied for the deposition of Cd7.23Zn2.77S10–ZnS composite (CZS-ZS) thin film photoan-odes by employing single step aerosol assisted chemical vapor deposition (AACVD) technique. Deposition experiments were performed at 500°C under an inert ambient of argon gas. The structural properties of deposited films were evaluated by using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The field emission scanning electron microscopy (FESEM) exposed surface morphologies while UV-Visible spectrophotometry revealed that CIS is low band gap photoanode in comparison to CZS-ZS. The comparison of photoelectrochemical (PEC) responses measured in identical conditions in terms of linear sweep voltammetry (LSV) depicts photocurrent density of 4.4 mA /cm2 and 2.9 mA/cm2 at applied potential of 0.7 V under solar light intensity of 100 mW/cm2 for CIS and CZS-ZS respectively. Further, electrochemical impedance spectroscopy (EIS) confirms that PEC properties of CIS are superior to CZS-ZS photoanode as the former offer less charge transfer resistance (Rct) 0.03 MΩ in comparison to CZS-ZS having Rct value of 0.06 MΩ.

scholarly journals Electrochemical Deposition and Formation Mechanism of Single-Crystalline Cu2O Octahedra on Aluminum

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Q. T. Du ◽  
J. S. Tan ◽  
Q. T. Wang ◽  
C. Y. Li ◽  
X. H. Liu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Formation Mechanism ◽  
Electrochemical Deposition ◽  
Cuprous Oxide ◽  
Edge Length ◽  
X Ray ◽  
Transmission Electron ◽  
Average Edge Length ◽  
Electron Energy Loss

A simple electrochemical deposition was developed to synthesize the cuprous oxide (Cu2O) octahedra on aluminum foils. The average edge length of the octahedra is about 300 nm. The chemical composition of the octahedra was determined using energy dispersive X-ray spectroscopy and electron energy-loss spectroscopy. The microstructure of the octahedra was investigated using transmission electron microscopy. The formation mechanism of the octahedra is proposed.

S-C3N4 Quantum Dot Decorated ZnO Nanorods to Improve Their Photoelectrochemical Performance

NANO ◽  
2017 ◽  
Vol 12 (05) ◽  
pp. 1750064 ◽  
Author(s):  
Haizhou He ◽  
Jie Li ◽  
Yang Liu ◽  
Qiong Liu ◽  
Faqi Zhan ◽  
...  
Keyword(s):  
Light Absorption ◽  
Photoelectron Spectroscopy ◽  
Seed Layer ◽  
Electrochemical Impedance ◽  
Solid Phase ◽  
Zno Nanorods ◽  
Phase Method ◽  
Photoelectrochemical Performance ◽  
Electrochemical Impedance Spectra ◽  
X Ray

S-doped C3N4 quantum dots (SCNQDs) were synthesized successfully by a low-temperature solid-phase method. The as-synthesised SCNQDs were decorated on ZnO nanorods by a dipping method. The ZnO nanorod films were prepared through a two-stage method, including pulse electrodeposition for depositing ZnO seed layer on fluorine doping SnO2 glass (FTO) and chemical bath for growing ZnO nanorods on the ZnO seed layer. The prepared samples were characterized via scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-vis absorption spectroscopy, X-ray photoelectron spectroscopy (XPS). The photoelectrochemical performances of the prepared samples were estimated using linear sweep voltammograms, electrochemical impedance spectra (EIS), Mott–Schottky, transient photocurrent and incident photon-to-current conversion efficiency (IPCE). The results show that the light absorption edge of the prepared SCNQDs increases from 326[Formula: see text]nm (CNQDs) to 349[Formula: see text]nm after S doping. The CNQD decorated ZnO photoanode film exhibits 1.34 times as high photocurrent as bare ZnO photoanode film. Importantly, the photocurrent increased to 1.79 times than bare ZnO photoanode film by S doping at 1.0[Formula: see text]V (versus Ag/AgCl), which is attributed to a wider light absorption of SCNQDs and a better efficiency of electron transfer in the interface between SCNQDs and ZnO.

Electrodeposition of Ni-W and Ni-W-P films using a pulse current technique and their application for hydrogen evolution in an acidic solution

2020 ◽  
Vol 67 (1) ◽  
pp. 38-47
Author(s):  
Zeinab Abdel Hamid ◽  
H.B. Hassan ◽  
Mohamed Sultan
Keyword(s):  
Hydrogen Evolution ◽  
Acidic Solution ◽  
Pulse Current ◽  
Electrochemical Impedance ◽  
Linear Sweep Voltammetry ◽  
Chemical Compositions ◽  
Electrodeposition Technique ◽  
High Hydrogen ◽  
Content Type ◽  
X Ray

Purpose The improvement of the hydrogen evolution reaction (HER) performance requires more efficient and inexpensive electrocatalysts. The purpose of this study is to prepare Ni-W and Ni-W-P thin films using the electrodeposition technique using a pulse current and investigate their behaviors toward HER in an acidic solution. Design/methodology/approach The aim is to prepare Ni-W and Ni-W-P films by the electrodeposition technique using a pulse current and estimate their performance for the HER. The surface morphologies and chemical compositions of the deposited films were assessed using scanning electron microscopy, energy-dispersive X-ray analysis and X-ray diffraction. Linear sweep voltammetry, chronoamperometry, Tafel plots and electrochemical impedance spectroscopy were used to evaluate the prepared electrodes toward the hydrogen evolution process. Findings The main conclusion is that the surface morphology of Ni–W deposited film is a crystalline structure, while that of Ni-W-P deposit is an amorphous structure. HER activity on Ni-W electrodes increases with decreasing the Wt.% of W to 7.83 Wt.% in the prepared electrodes. In addition, the presence of P enhances HER activity, which increases with increasing the Wt.% of P in the prepared Ni-W-P electrodes. Both Ni-W (7.83 Wt.% W) and Ni-W-P (20.34 Wt.% P), which have been prepared at 8 A dm−2 display the best performance toward HER compared to the other prepared electrodes. They exhibit high catalytic activities toward HER, which is evidenced by high hydrogen evolution current density values of 9.52 and 33.98 mA cm−2, low onset potentials of −0.73 and −0.63 V, low Tafel slopes of −125 mV/dec, high exchange current densities of 0.058 and 0.20 mA cm−2, low charge transfer resistances (Rct) of 226.28 and 75.8 ohm·cm2 for Ni-W (7.83  Wt.% W) and Ni-W-P (20.34  Wt.% P), respectively; moreover, they exhibited considerable stabilities too. Originality/value The results presented in this work are an insight into understanding the performance of the prepared Cu electrodes coated by Ni-W and Ni-W-P films toward HER. In this work, a consistent assessment of the results achieved on laboratory scale has been conducted.

scholarly journals Thermal And Kinetic Study of Electrochemical Deposition of Lead On FTO Substrate

2021 ◽  
Author(s):  
Ridha Hamdi ◽  
Amani Rached ◽  
Amor Saidi BEN Ali
Keyword(s):  
Electrochemical Deposition ◽  
Tin Oxide ◽  
Morphological Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fixed Concentration ◽  
Constant Potential ◽  
Nitrate Bath ◽  
Potential Conditions

Abstract We report the electrochemical deposition of lead (Pb) onto fluorine-doped tin oxide (FTO) electrodes in a sodium nitrate bath (0.4M NaNO3) at constant potential conditions. The kinetics electrodeposition processes have been in situ monitored for advanced nucleation stages by chronoamperometry for various temperature at fixed concentration of Pb2+, that is 0.1M. The microstructure and morphological characteristics of the deposit layers were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-Ray EDX techniques. The results show that the current density as well as the deposits density strongly depend on the temperature. The correlation between the experimental results and the theoretical process of the lead deposits was discussed and verified.

Interactions of Ge Atoms with High- ê Oxide Dielectric Surfaces

2005 ◽  
Vol 879 ◽  
Author(s):  
Scott K. Stanley ◽  
John G. Ekerdt
Keyword(s):  
Oxide Layer ◽  
Photoelectron Spectroscopy ◽  
Chemical Vapor ◽  
Temperature Programmed Desorption ◽  
Tungsten Filament ◽  
X Ray ◽  
Dielectric Surfaces ◽  
Temperature Programmed ◽  
The Stability ◽  
Ge Nanocrystals

AbstractGe is deposited on HfO2 surfaces by chemical vapor deposition (CVD) with GeH4. 0.7-1.0 ML GeHx (x = 0-3) is deposited by thermally cracking GeH4 on a hot tungsten filament. Ge oxidation and bonding are studied at 300-1000 K with X-ray photoelectron spectroscopy (XPS). Ge, GeH, GeO, and GeO2 desorption are measured with temperature programmed desorption (TPD) at 400-1000 K. Ge initially reacts with the dielectric forming an oxide layer followed by Ge deposition and formation of nanocrystals in CVD at 870 K. 0.7-1.0 ML GeHx deposited by cracking rapidly forms a contacting oxide layer on HfO2 that is stable from 300-800 K. Ge is fully removed from the HfO2 surface after annealing to 1000 K. These results help explain the stability of Ge nanocrystals in contact with HfO2.

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