Successive Ionic Layer Adsorption Reaction Research Articles

Mitigation on self-discharge behaviors via morphological control of hierarchical Ni-sulfides/Ni-oxides electrodes for long-life-supercapacitors

To cope up with the sustainable energy storage goals for supercapacitors (SCs), the self-discharge in SC electrodes is a significant hurdle, and thereby, nickel sulfide (NS) with high conductivity is adopted as a test vehicle for understanding the morphological evolution effects for long-life SCs. Herein, honeycomb-like NS is hierarchically formed over hydrothermally grown nickel oxide (NO) via successive ionic layer adsorption reaction (SILAR) method. Their heterostructure shows a fivefold improvement in specific capacitance from 348 F g−1 to 2077 F g−1 at 1 mV s−1 over bare NO. Furthermore, the remarkable upliftment of capacitance retention is achieved from 60.7% to 92.3% even after 3000 cycles via morphological control of NS/NO hetero-structure with the help of highly conductive NS. More importantly, the self-discharge behaviors and synergistic role of leakage current associated with morphological evolution via NS overcoating are studied in detail. In particular, the self-discharge mitigation from 45% (NO) to 35% (NS20/NO) due to the NS/NO heterostructure and the behind mechanism are ascribed to the activated-controlled Faradaic reaction coupled with a charge redistribution. This study emphasizes the potential importance of composite heterostructure by tuning the electrical conductivity and morphological adjustment NO via consecutive overcoating of NS through SILAR as a novel strategy. This enhances charge storage, redox kinetics, and the mitigation of self-discharge properties of the active electrode materials. For practical validation on sustainable energy storage, NS20/NO supercapacitors illuminate the LED for 35% longer than NO after one-time charging, potentially beneficial for the next generation SCs.

Facile preparation of MnO2–TiO2 nanotube arrays composite electrode for electrochemical detection of hydrogen peroxide

The MnO2-TNTA composite electrodes were obtained through depositing MnO2 into TiO2 nanotube arrays (TNTA) by successive ionic layer adsorption reaction (SILAR) and subsequent hydrothermal method. The MnO2-TNTA nanocomposites were used as electrochemical sensors for the detection of hydrogen peroxide (H2O2). The preparation conditions of MnO2-TNTA electrodes and test conditions affect the electrochemical detection performance significantly. The optimal conditions are listed as follows: the number of SILAR cycles, 6 times; KMnO4 solution temperature, 50 °C; supporting electrolyte, 0.5 M NaOH. Under these conditions, the MnO2-TNTA electrode exhibits the best performance for detecting H2O2. The optimized MnO2-TNTA electrode has a minimum detection limit of 0.6 μM (S/N = 3) and a linear range of 5 μM ∼ 13 mM, which is much superior to the previously-reported electrodes. Moreover, the optimized MnO2-TNTA electrode possesses high selectivity, excellent stability and good reproducibility in the detection of H2O2. When used in the determination of H2O2 content in actual samples including disinfectant and milk, it also shows good accuracy, ideal recovery (96.00% ∼ 102.67%) and high precision (RSD < 4.0%).

Preparation and photoelectric properties of holmium-doped bismuth sulfide film

Ho-doped Bi2S3 film (Ho/Bi2S3) was prepared on the FTO substrate by successive ionic layer adsorption reaction (SILAR) and hydrothermal method. The as-prepared films were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), UV–Vis diffuse reflection spectroscopy (DRS), and X-ray Photoelectron Spectroscopy (XPS). EDS and XPS have confirmed the existence of Ho. The Ho3+ ions enter the crystal lattice of Bi2S3 and occupy the Bi3+ sites making some crystals vertical flake-like. The photovoltage of Ho/Bi2S3 increases from 0.203 V to 0.265 V by 30% and the photocurrent density increases from 0.366 mA/cm−2 to 1.09 mA/cm−2 by 1.97 times when the Ho-doping concentration is 0.5 mmol L−1. Moreover, the impurity level introduced by Ho-doping reduces the energy of the electronic transition making Ho/Bi2S3 generate more photo-generated carriers to improve the photoelectric performance.

Mixed phase FeTe: Fe2TeO5 nanopebbles through solution chemistry: Electrochemical supercapacitor application

Mixed phase of iron telluride based thin films consisting of nanopebbles has been grown successfully over conducting stainless steel (SS) substrate through successive ionic layer adsorption reaction (SILAR) process. Crystal structural and elemental states through XPS revealed clear indication of FeTe: Fe 2 TeO 5 mixed phase growth and well supported through FTIR studies. Agglomeration of embedded quantum dots forming nanopebbles like surface architecture resulting in enhanced hydrophilic nature evident through contact angle and higher surface roughness by atomic force micrographs found beneficial as more electroactive surface area for electrolyte ions to interact. This helped to achieve a significant specific capacitance of 591 F/g (166 mF/cm 2 ) @3 mV/s potential scan rate and, 107 F/g (30 mF/cm 2 ) @0.4 mA/cm 2 in NaCl electrolyte. Performed electrochemical impedance spectroscopy (EIS) studies explored clear insight of the solution and charge transfer resistances, and relaxation time constant. Iron telluride based thin film clearly demonstrates very high value of pseudo capacitive contribution than the electric double layer due to the intrinsic pseudocapacitive behavior of mixed phase. • First report on iron telluride based (FeTe: Fe 2 TeO 5 ) thin film synthesis using simple SILAR method and successfully employed as supercapacitor electrode. • Nanopebbles embedded with quantum dots agglomeration responsible for more electrochemical active sites. • Notable specific capacitance of 591 F/g (426 C/g or 166 mF/g) at 3 mV/s by CV and 107 F/g (30 mF/cm 2 ) at 0.4 mA/cm 2 by GCD studies. • Enhanced inner (pseudo q p ) charge storage contributions than outer (EDLC q d l ).

In situ formed CuInS2/SnS2 hybrid on foam-like nickel as bifunctional electrode for water splitting

Developing low-cost, efficient and robust non-noble electrocatalysts for overall water splitting is of primary importance in the future of energy solutions. In this paper, the CuInS2/SnS2 composite nanosheets array on foam-like nickel (CuInS2/SnS2/NF) was synthesized in situ via a facile hydrothermal approach and the successive ionic layer adsorption reaction method (SILAR). The as-obtained heterostructure array exhibits high electrocatalytic activity toward HER with a small overpotential of 78, 191 and 337 mV at 10, 20, and 100 mA/cm2, and remarkably enhanced OER activities with the overpotential of 258, 286 and 382 mV at 10, 20, and 100 mA/cm2 in an alkaline electrolyte. Meanwhile, the CuInS2/SnS2/NF electrode shows a lower tafel slope and outstanding electrochemical stability in both the HER and OER, displaying an excellent application foreground in the field of electrocatalytic water splitting. Moreover, the overall water splitting performance of CuInS2/SnS2/NF electrode was studied, in which the electrode serves as both the anode and cathode, and at a comparatively low voltage of 1.79 V, the current density achieves 100 mA/cm2. This study establishes a primitive strategy for obtaining mixed multimetal sulfides on self-supporting porous metal substrate, which can be used as an efficient bifunctional electrocatalyst, and is of great practical significance in future energy application.

Promoting photoelectrochemical hydrogen production performance by fabrication of Co1-XS decorating BiVO4 photoanode

Photoelectrochemical (PEC) water splitting is an effective way of converting solar energy into hydrogen (H2) energy. However, the carriers’ transmission and the reaction kinetics of the photoelectrode are dilatory, which will influence the conversion efficiency of solar energy to H2. In this work, a novel of BiVO4/Co1-XS photoanode was successfully fabricated through the successive ionic layer adsorption reaction. The photocurrent density of optimal sample BiVO4/Co1-XS (2.9 mA cm−2 at 1.23 VRHE) has reached up to 5 times that of pure BiVO4, and the applied bias photon to current conversion efficiency increased from 0.04% (BiVO4) to 0.4% (BiVO4/Co1-XS). The superior PEC performance of the BiVO4/Co1-XS photoanode is mainly related to the improved conductivities and reaction kinetics. The charge injection efficiency of BiVO4/Co1-XS grew to about 80%, and the charge separation efficiency was up to 34%, revealing that the decoration of Co1-XS could significantly accelerate the transfer speed of photogenerated carriers from the electrode surface to the electrolyte. This work provided an efficient and simple scheme for improving the PEC performance of photoanode, through reasonable design and research.

Tungsten Disulfide Heterostructure for Boosting Charge Carriers and for Enhancing Photoanodic Performance in Water Splitting

Photoelectrochemical water splitting (PEC) is a compelling approach to convert solar energy to chemical energy by liberating hydrogen, making it a possible solution to the worldwide energy crisis by eliminating all carbon dioxide emissions. In practice, no single electrode material can meet all PEC water splitting requirements. The major challenges for PEC are electron-hole pair recombination, stability and reduced absorption of visible light. Transition Metal dichalcogenides (TMD) based heterostructures are being envisioned as novel electrode materials because of their exceptional electrical, chemical, mechanical and thermal stability which include high electron mobility, highly exposed active sites, layer dependent band gap, and higher ionic conductivity etc. TMDs have higher electro conductivity resulting in significant enhancement of the electrochemical performance in PEC. Further, it also exhibits desirable electrochemical behaviour through its oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) as a photoelectrode for water splitting. However, due to poor absorbance and significant reflection at the grain boundaries, the light harvesting ability of bulk or nanosized TMD materials is often limited. The charge carriers produced by light illumination will also reach the surface faster than bulk materials in the semiconductor, because of the lesser transport distance.In the present work, heterostructures consisting of Tungsten disulfide (WS2) and cadmium sulphide (CdS) were synthesized using a hydrothermal method and Successive Ionic Layer Adsorption Reaction (SILAR) deposition method. The presence of these nanostructures was confirmed by XRD, Raman, UV-Visible spectroscopy, SEM, TEM and PL spectroscopy. The morphological study clearly indicates a homogeneous distribution of CdS nanospheres on WS2 nanostructures, indicating close contact between them which helps in efficient charge separation and migration. Further, the continuous nature of the heterostructures of the two materials is not limited to any visible discrete entities. The porosity of the pristine WS2 nanostructures allows CdS nanospheres to deposit inside the pores along the entire thickness of the nanosphere, and hence, the highly homogeneous nature of the heterostructures is obtained as indicated by the physical characterization.Due to this unique structure, the obtained heterostructures showed excellent performance as photoanode. The CdS@WS2 photoanode demonstrated a photocurrent density of 0.15 mA cm−2 at 1.23 V vs. RHE, which is over 20 times higher than that of the pure pristine materials. Further, CdS@WS2 heterostructures, as compared to pure materials, have demonstrated longer emission-decay-life times and dramatically quenched the emission of fluorescence compared to pristine materials. In CdS@WS2 heterostructures, the absorption edge of the WS2 nanostructures also exhibit a considerable increase in light absorption in the total visible spectrum. This results in enhanced charge separation with proper band alignment leading to improvements in electrochemical performance of CdS@WS2 photoelectrodes. Further, the low onset potential further eliminates the need for voltage bias in practical applications.

Fabrication of multilayer 1D TiO2/CdS/ZnS with high photoelectrochemical performance and enhanced stability

Nano TiO2 is a basic photoanode material in the application of new type solar cell for its appropriate bandgap and photoemission. However, traditionally TiO2-based photoanode films are limited in weak photoresponse and effortless recombination. Herein, we increase light absorption range through combined the uniform CdS quantum dots (QDs) by successive ionic layer adsorption reaction (SILAR) method and decrease the recombination of photo-generated electrons/holes through ZnS passivation layer overlaying on TiO2/CdS. Photocurrent response (i-t), photocurrent density-voltage (J-V) curves of TiO2/CdS/ZnS demonstrated the photovoltaic conversion efficiency (η) has been reaching 3.43%, which has 230% and 33% improvement than pure TiO2 and TiO2/CdS.

Fe doping effects in MgO thin films grown with SILAR technique

Magnesium oxide (MgO) thin films were grown by successive ionic layer adsorption reaction (SILAR). As a result of Fe doping, modifications of the morphological, structural and optical properties of MgO thin films were reported. UV–Vis spectroscopy, photoluminescence (PL), X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses were performed to investigate the consequences of Fe doping. The energy band gap for the un-doped MgO and Fe doped MgO thin films were obtained to be between 3.57 and 4.00 eV. The density of PL spectrum peaks were observed to decrease with the addition of Fe which shifted to the UV region of the spectrum. The XRD measurement of MgO thin films were of nanostructures which possess a cubic structure with order of planes (200) and (220). The SEM measurements of the thin films were of nano structure. All in all, pure MgO and Fe doped MgO nanostructures were successfully produced in the light of variable characterization techniques.

A comparative study of CuO deposition methods on titania nanotube arrays for photoelectrocatalytic ammonia degradation and hydrogen production

In this study, the deposition of CuO nanoparticles into titania nanotube arrays (TiNTAs) was prepared via two methods, i.e an in-situ anodization (AND) and a successive ionic layer adsorption reaction (SILAR). The two methods were compared in terms of their properties as efficient photoanodes in photoelectrocatalytic processes. FESEM and TEM imaging showed that the nanotubular structure was successfully generated. The bandgap energy was probed by UV-DRS analysis, revealing that CuO-TiNTAs SILAR had a lower bandgap than other samples. The photoelectrochemical responses of CuO-TiNTAs SILAR exhibit better activity compared to its counterpart. The maximum ammonia removal was achieved at 50.1% while as high as 235.7 μmol of hydrogen was generated over 120 min under Hg lamp illumination, by the use of CuO-TiNTAs SILAR. We thereby conclude that, for the given experimental conditions, CuO-TiNTAs SILAR is a better photoanode than CuO-TiNTAs AND concurrently eliminate ammonia and produce hydrogen in a photoelectrochemical setup.

Chemical synthesis and supercapacitive evaluation of polyaniline nanofibers (PANINFs)

The aim of the present work is the morphological evaluation of PANINFs synthesized by easy and economical Successive Ionic Layer Adsorption Reaction (SILAR) method by varying deposition cycles for supercapacitor application. The semi-crystalline nature is confirmed by X-ray diffraction (XRD) patterns. From XRD analysis, it is observed that increasing deposition cycles caused decrement in the crystallite size. On the contrary micro-strain, dislocation density, and distortion parameter were increased with deposition cycles. The Fourier infrared spectroscopy (FT-IR) and Raman analysis confirmed the formation of PANI. The surface morphological analysis reveals that the nanofibers appeared with greater interconnectivity and increased porosity with increasing deposition cycles. These observations are supported by an electrochemical analysis which demonstrated that the electrochemical performance of PANINFs is improved. The obtained highest specific capacitance (Cs) of PANINFs is 196 F/g in 1 M H2SO4 electrolyte at 0.5 mA/cm2 current density with 17.46 Wh/kg and 181.81 W/kg energy and power density, respectively. The synthesis of PANINFs via a simple, cost-effective and eco-friendly chemical route, i.e., the SILAR method with enhanced supercapacitive properties promoting its applications in energy storage technology.

Fabrication of heterostructured CdS/TiO2 nanotube arrays composites for photoreduction of U(VI) under visible light

Heterostructured CdS/TiO2 nanotube arrays composites (CdS/TNTAs) were synthesized by the successive ionic layer adsorption (SILAR) reaction with vacuum freeze-drying-assisted method. The CdS nanoparticles were anchored on the inner wall of the anodic TNTAs via strong electronic interaction rather than occupied the nanotubes. The CdS/TNTAs-10 with 27.28 ​wt% CdS exhibited shows the best photocatalytic activity for reduction of U(VI) (97% at 240 ​min) and the photocatalytic activity was still 83.6% after 5 cycles. These improvements probably stem from the porous tubular structure of TNTAs acts as the protective shell which can effectively inhibit the photocorrosion of CdS and promote the photoinduced interfacial electron-hole pairs separation. Furthermore, the possible the photocatalytic electron transfer path was proposed, and the photogenerated electrons (e-) and the superoxide radicals (·O2-) were the predominant active free radicals. This work highlighted a simple synthesis of CdS/TNTAs heterojunction with potential application in radioactive wastewater remediation.

Fabrication, characterization and photoelectrochemical properties of CdS/CdSe nanofilm co-sensitized ZnO nanorod arrays on Zn foil substrate

The photoelectrochemical (PEC) performance of ZnO is restricted by its low light absorption ability and high recombination rate of photogenerated carriers. In order to overcome these drawbacks, ZnO/CdS/CdSe heterostructures are prepared on Zn foil substrate using facile three-step methods containing hydrothermal growth, successive ionic layer adsorption reaction (SILAR) and modified chemical bath deposition (CBD). The effects of process parameters containing the number of SILAR cycles of CdS, sensitization sequence of CdS and CdSe, and precursors of CdSe on PEC performance of ZnO/CdS/CdSe heterostructures, and ZnO NRAs on PEC performance of CdS/CdSe co-sensitizer have been scrutinized. Through CdS and CdSe co-sensitization, a layer of CdS/CdSe nanofilm is conformally deposited on ZnO nanorod arrays (NRAs) observed by transmission electron microscopy (TEM). Both the visible-light absorption ability and separation efficiency of photogenerated carriers of ZnO NRAs are significantly enhanced evidenced by UV–vis diffuse reflectance absorption spectra, photoluminescence (PL) spectra and electrochemical impedance spectra. Due to the synergistic effect of ZnO NRAs and CdS/CdSe co-sensitizer, the ZnO/CdS/CdSe heterostructures with five SILAR cycles and one modified CBD cycle (ZnO-CdS5-CdSe) show efficient PEC properties with photocurrent density of 6.244 mA/cm2 at −0.2 V vs Ag/AgCl under light illumination of 100 mW/cm2, which are 57.28 and 4.73 times higher than those of pristine ZnO NRAs and CdS/CdSe clusters, respectively. Moreover, the photoconversion efficiency and incident photon to current conversion efficiency (IPCE) of the ZnO-CdS5-CdSe photoanode reach 4.381% and 80.92%, respectively. The heterostructures based on Zn foil substrate in this study can be a promising candidate for practical PEC application and other applications such as photocatalytic degradation and solar cell due to its low manufacturing cost, large-scale production and efficient PEC ability.

Voltage-assisted SILAR deposition of CdSe quantum dots to construct a high performance of ZnS/CdSe/ZnS quantum dot-sensitized solar cells

The charge recombination on the interfaces of TiO2/quantum dots (QDs)/electrolyte is a key factor limiting the efficiency of quantum dot-sensitized solar cells (QDSSCs). Construction of double-layer barrier structure of ZnS/QDs/ZnS is a vital strategy to suppress the interfacial charge recombination. However, a large lattice mismatch (12%) at CdSe/ZnS interfaces causes CdSe to grow slowly on TiO2/ZnS mesoporous film, weakening the interaction between QDs and mesoporous film, which reducing the efficiency of CdSe QDSSCs with double ZnS barrier layers. Applying a voltage of 2 V in successive ionic layer adsorption reaction (VASILAR) to create an electric field, which assists Cd2+ and SeSO32− ions rapidly diffuse into the TiO2/ZnS mesoporous film to react forming CdSe QDs at room temperature. Optimizing the number of CdSe QDs deposition layers and combine with ZnS double-layer barrier structure, a best PCE of 4.34% for ZnS/CdSe/ZnS QDSSCs is achieved. This study gives a fast and simple approach to inhibit interfacial charge recombination to construct high performance CdSe QDSSCs.

Ag-Pi/BiVO4 heterojunction with efficient interface carrier transport for photoelectrochemical water splitting

The limitation of pristine BiVO4 photoanode severely causes the high carrier recombination efficiency and low energy conversion efficiency in the photoelectrochemical (PEC) system. In this work, the Ag-Pi/BiVO4n-n heterojunction has been rationally designed and fabricated for efficient PEC water splitting, through successive ionic layer adsorption reaction method. The built-in field of Ag-Pi/BiVO4 significantly promotes the separation efficiency of photogenerated carriers, benefiting for the participation of abundant holes in water oxidation. The photocurrent density of 40-Ag-Pi/BiVO4 has been enhanced to 2.32 mA/cm2, which is 4.5 times than that of the pristine BiVO4. Compared with the pristine BiVO4 (6.5%), the IPCE value of 40-Ag-Pi/BiVO4 achieves 22% (410 nm, 1.23VRHE). In addition, the charge injection efficiency (ηinjection) and charge separation efficiency (ηseparation) of 40-Ag-Pi/BiVO4 have been achieved to 74.36% (1.23 VRHE) and 31.57% (1.23 VRHE), respectively, revealing the excellent carriers’ transfer behavior in the both bulk and interface. The desirable stability endows Ag-Pi/BiVO4 system with a great potential in the practical application in PEC water splitting, and the corresponding mechanism for in-depth understanding the process of carriers’ transfer in Ag-Pi/BiVO4 structure has been also proposed. Therefore, the construction of Ag-Pi/BiVO4 heterojunction will provide a new insight for the configuration of efficient PEC system.

Facile synthesis and photoelectrochemical properties of novel TiN/C3N4/CdS nanotube core/shell arrays

Recently, the g-C3N4-based heterojunctions have been widely investigated for their greatly enhanced photogenerated carrier separation efficiency. However, most studies are based on the study of g-C3N4 powders. In this study, a novel TiN/C3N4/CdS nanotube arrays core/shell structure is designed to improve the photoelectrochemical catalytic performance of the g-C3N4-based heterojunctions. Among them, TiN nanotube arrays do not respond to simulated solar light, and thus only serve as an excellently conductive nanotube arrays backbone for supporting g-C3N4/CdS heterojunctions. g-C3N4 prepared by simple liquid atomic layer deposition, which possesses appropriate energy band position, mainly acts as the electron acceptor to transport and separate electrons. Deposited CdS quantum dots obtained by successive ionic layer adsorption reaction can effectively absorb visible light and thus act as a light absorber. The TiN/C3N4/CdS nanotube arrays core/shell structure could be verified by X-ray diffractions, Raman spectra, scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy elemental mappings and X-ray photoelectron spectroscopy. Compared with TiN/C3N4 nanotube arrays, the TiN/C3N4/CdS samples greatly improve the photoelectrochemical performance, which can be evaluated by photoelectrochemical tests and photoelectrochemical catalytic degradation. Especially, the optimized photocurrent density of TiN/C3N4/CdS has almost 120 times improvement on TiN/C3N4 at 0 V bias under simulated sunlight, which can be ascribed to the effective expansion of the light absorption range and separation of electron-hole pairs.

Gas Response of SILAR Fabricated Zinc Oxide Thin Film to Ammonia and Methane Gas at Room Temperature

Abstract The study aimed to determine the gas response of unsensitized, Pd-sensitized, Mn-sensitized ZnO thin films to ammonia and methane gas. The films are successfully fabricated using Successive Ionic Layer Adsorption Reaction (SILAR) method. One of the films is left unsensitized and the other two were sensitized with 0.01M of Pd and Mn via dipping technique. Each film was exposed to ammonia (NH3) and methane (CH4) with concentrations of 667pm, 1333ppm and 2000 ppm. The sensitivity of the unsensitized film to methane gas was 2.46 10 , 000 p p m while its sensitivity to ammonia gas was 0.49 10 , 000 p p m . Results show that the unsensitized film was more sensitive to methane compared to ammonia gas

Synthesis and Functionalization of Copper-Doped Indium Phosphate Quantum Dots with Ratiometric Fluorescence

The doped quantum dots (QDs) that feature dual emission in one nanocrystal and long fluorescence lifetime have gained great interest in biosensing and bioimaging applications. In this work, we report the synthesis and functionalization of copper ion-doped indium phosphate (Cu:InP) QDs that exhibit simultaneous green InP emission and red Cu[Formula: see text] emission. The oil-soluble QDs were synthesized by adsorbing Cu[Formula: see text] onto InP core, followed by growing zinc selenide (ZnSe) shell via the successive ion layer adsorption reaction. During the synthesis, fluorescence ratiometry (and resultant multiple fluorescence colors) can be generated by changing either the dopant amount or the shell-growth time, but they act in a different manner: increasing the Cu[Formula: see text] amount results in quenched InP emission and oppositely improved Cu[Formula: see text] emission; the increase of shell-growth time leads to continuously improved Cu[Formula: see text] emission relative to constant InP emission. Further, functionalization of the oil-soluble Cu:InP QDs with dihydrolipoic acid-polyethylene glycol (DHLA-PEG) via ligand exchange produces the water-soluble and biocompatible dual-emission QDs. The PEGylated Cu:InP QDs present desirable charge neutrality and excellent thermal stability and photostability, thereby holding high potential in a diversity of biomedical applications.

Capacitive property studies of inexpensive SILAR synthesized polyaniline thin films for supercapacitor application

The polyaniline (PANI) is an eco-friendly conductive polymer which has been considered for diverse applications. The partially oxidized phase of the PANI is useful for the charge storage application. Here, a unique nanograin/nanofiber structured PANI was grown on inexpensive stainless steel (SS) current collector by the simple oxidative polymerization process and its charge storage properties were systematically investigated. For that, the inexpensive successive ionic layer adsorption reaction method was used to grow a uniform nanostructured PANI on the SS conductor. This evolution of the nanostructure was studied with the Field emission scanning electron microscope. Furthermore, the as-prepared PANI was confirmed by the X-ray diffraction and the Fourier-transform infrared spectroscopy. In the half cell electrochemical testing, the prepared PANI exhibited a maximum specific capacitance of 710 F g−1 with a specific discharge capacity of 119 mAh−1 at 0.2 mA cm−2 in 1 M H2SO4 for the supercapacitor application. Also, by using the power-law relation it was observed that, in a charging and a discharging current, initially a contribution of the diffusive faradaic reactions is more as compared with the surface capacitive non-faradaic reactions.

Voltage-assisted SILAR deposition of CdSe quantum dots into mesoporous TiO2 film for quantum dot-sensitized solar cells

CdSe quantum dots (QDs) grows slowly in mesoporous TiO2 film deriving from a large lattice mismatch (11%) and poor interaction between the two, which resulting the low power conversion efficiency (PCE) of quantum dot-sensitized solar cells (QDSSCs). An external voltage is applied in the successive ionic layer adsorption reaction (SILAR) process, which drives the Cd2+ and SeSO32− ions quickly diffused into the mesoporous TiO2 film and reacted to form CdSe QDs at room temperature. The CdSe QDSSCs yields a PCE of 3.27%. This work provides an efficient strategy to assemble QDs for enhancing the performance of QDSSCs.