Successive Ionic Layer Adsorption And Reaction Research Articles

Interface-modulated kinetic differentials in electron and hole transfer rates as a key design principle for redox photocatalysis by Sb2VO5/QD heterostructures.

The efficient conversion of solar energy to chemical energy represents a critical bottleneck to the energy transition. Photocatalytic splitting of water to generate solar fuels is a promising solution. Semiconductor quantum dots (QDs) are prime candidates for light-harvesting components of photocatalytic heterostructures, given their size-dependent photophysical properties and band-edge energies. A promising series of heterostructured photocatalysts interface QDs with transition-metal oxides which embed midgap electronic states derived from the stereochemically active electron lone pairs of p-block cations. Here, we examine the thermodynamic driving forces and dynamics of charge separation in Sb2VO5/CdSe QD heterostructures, wherein a high density of Sb 5s2-derived midgap states are prospective acceptors for photogenerated holes. Hard-x-ray valence band photoemission spectroscopy measurements of Sb2VO5/CdSe QD heterostructures were used to deduce thermodynamic driving forces for charge separation. Interfacial charge transfer dynamics in the heterostructures were examined as a function of the mode of interfacial connectivity, contrasting heterostructures with direct interfaces assembled by successive ion layer adsorption and reaction (SILAR) and interfaces comprising molecular bridges assembled by linker-assisted assembly (LAA). Transient absorption spectroscopy measurements indicate ultrafast (<2ps) electron and hole transfer in SILAR-derived heterostructures, whereas LAA-derived heterostructures show orders of magnitude differentials in the kinetics of hole (<100ps) and electron (∼1ns) transfer. The interface-modulated kinetic differentials in electron and hole transfer rates underpin the more effective charge separation, reduced charge recombination, and greater photocatalytic efficiency observed for the LAA-derived Sb2VO5/CdSe QD heterostructures.

(Invited) CdS/Ti-Si-O Composite Photoanode for Photoelectrochemical Hydrogen Generation

Advancements in clean energy drive socio-economic development and foster a sustainable future by restructuring energy systems and promoting low-carbon development. In this paper, we presented a comprehensive investigation on the design and performance characterization of CdS/Ti-Si-O composite photoanodes for photoelectrochemical (PEC) hydrogen generation. Silicon-doped TiO2 nanotube arrays were fabricated through anodization of Ti-5Si alloy, followed by the deposition of CdS using the SILAR (successive ionic layer adsorption and reaction) process, resulting in nanostructured Ti-Si-O photoanodes modified with CdS. The composite photoanodes were characterized in terms of their composition, microstructure, optical properties and photoelectrochemical hydrogen production performance. The composite photoanodes revealed a notable enhancement in PEC hydrogen generation properties with a photocurrent density of 7.86 mA/cm2，which was 19.15 times and 9.59 times to those of the undoped TiO2 photoanode and Ti-Si-O photoanode, respectively. The Si-doping mechanism of the photoanodes was elucidated through Density Functional Theory (DFT) calculations. The synergistic combination of Si-doping and CdS modification represents a novel and promising approach for the design of efficient nanostructured photoanodes.

Formation of a potential barrier by a ZnSXSe1−X electron-blocking layer to improve the efficiency of CdSe0.3S0.7/CdSe quantum dot sensitized solar cells

We designed and fabricated multilayer quantum dots sensitized solar cells (QDSCs) with TiO2 NPs/CdSe0.3S0.7/CdSe/ZnSXSe1−X, X = S/S + Se = 0, 0.7, 0.8, 0.9, and 1 photoelectrodes to achieve optimum power conversion efficiency (PCE). In the corresponding structure, incoming light is absorbed by the CdSe0.3S0.7 and CdSe quantum dots (QDs), while the ZnSXSe1−X QDs act as an electron blocking layer or passivation layer, forming an energy barrier that restricts electron mobility from the light absorbers to the polysulfide electrolyte. The beneficial effect of the alloyed ZnSXSe1−X layer is the adjustability of its nanoparticle size/bandgap energy proportional to variations in the concentration of anionic precursors X, according to optical results. The PCE value of the reference cell with the TiO2 NPs/CdSe0.3S0.7/CdSe photoanode is 4.15 %. Following the coating of ZnSe, ZnS0.7Se0.3, ZnS0.8Se0.2, ZnS0.9Se0.1, and ZnS QDs via two successive ionic layer adsorption and reaction (SILAR) cycles (2Sc) on the CdSe0.3S0.7/CdSe co-sensitized photoelectrode increasing stability and improving the PCE value to 4.9 %, 5.40 %, 5.70, 5.25 %, and 5.05 %, respectively. Next, by modifying the thickness of the champion cell's passivation layer, the QDSCs with TiO2 NPs/CdSe0.3S0.7/CdSe/ZnS0.8Se0.2 (3Sc) photoelectrode exhibit maximum photovoltaic performance parameters of short circuit current density (JSC) = 26.25 mA/cm2, open circuit voltage (VOC) = 560 mV, fill factor (FF) = 0.42 % and PCE = 6.15 %. This improvement in performance is the result of decreased internal energy loss and recombination of charge carriers at the interface between the electrolyte and photoelectrode, which increases electron collection efficiency and electron injection efficiency in the visible region according to the external and internal quantum efficiency curves.

Modified successive ionic layer adsorption and reaction for interconnected bismuth vanadate nanograins: Highly active visible light harvesting photoanodes

A modified successive ionic layer adsorption and reaction (SILAR) method is developed for depositing interconnected bismuth vanadate (BiVO4) nanoparticles with improved visible light harvesting activity. Facile control of preparative parameters like deposition cycles, anionic precursor, pH and deposition temperature significantly altered BiVO4 surface morphology. BiVO4 thin films prepared with Na3VO4 anionic precursor show dispersed nanoparticles type morphology and that deposited with NaVO3 precursor displays 3D interconnected nanoparticles morphology. The BiVO4 photoanodes with 3D interconnected nanoparticles morphology exhibits an excellent photocurrent density of 5.19 mA cm−2 at 1.23 V vs. RHE with superior photostability and improved applied bias photon to current efficiency (ABPE) (1.50 %) compared to dispersed nanostructured BiVO4 photoanodes. The excellent photoelectrochemical (PEC) characteristics of BiVO4 photoanodes with 3D interconnected nanoparticle morphology can be ascribed to porous morphology, optimum thickness, narrow band gap energy and favorable electronic band structure for water splitting. The current study illustrates the usefulness of the modified SILAR approach for depositing 3D interconnected BiVO4 nanoparticle morphology in a single step that is superior and efficient to previously reported multistep processes.

Coating effect of metal organic complex (Co-DTPMP) layer on enhancing PEC water oxidation performance of BiVO4 photoanode

Photoelectrochemical (PEC) water splitting is a promising method for transforming solar energy into clean and sustainable energy. However, PEC is severely limited, and they cannot achieve the predicted photocurrent density owing to the severe photochemical deterioration of the electrode and the recombination of photogenerated carriers. In this study, BiVO4/Co-diethylenetriamine Penta (methylene phosphonic acid) (BVO/Co-DTPMP) co-catalyst was successfully prepared as a nanoporous photoanode. Diethylenetriamine Penta (methylene phosphonic acid) was crosslinked with Co ions and coated on the BiVO4 surface by successive ionic layer adsorption and reaction (SILAR) to reduce fast recombination, which correlated with the BiVO4 photoanode. Various characterization and PEC measurements were conducted, revealing that the co-catalyst thin layer enhanced the charge separation and electrons transfer which significantly affected on the PEC performance of BiVO4, and the current density by BVO/Co-DTPMP was 4 mA cm−2 at 1.23 V vs. RHE. Furthermore, the co-catalyst exhibited improved charge transport and long-term stability.

A core/shell Bi2S3/BiVO4 nanoarchitecture for efficient photoelectrochemical water oxidation.

The construction of nanostructured heterostructure is a potent strategy for achieving high-performance photoelectrochemical (PEC) water splitting. Among these, constructing BiVO4-based heterostructure stands out as a promising method for optimizing light-harvesting efficiency and reducing severe charge recombination. Herein, we present a novel approach to fabricate a type II heterostructure of core/shell Bi2S3/BiVO4 using electrolytic deposition and successive ionic layer adsorption and reaction (SILAR) methods. We identify the type II heterostructure and the difference in fermi energy using UV-Vis spectroscopy, X-ray photoelectron spectroscopy, and PEC measurements. This redistribution of charges due to the fermi energy difference induces an interfacial built-in electric field from BiVO4 to Bi2S3, reinforcing the photogenerated hole transfer kinetics from BiVO4 to Bi2S3. The Bi2S3/BiVO4 heterostructure exhibits a superior photocurrent (6.0 mA cm-2), enhanced charge separation efficiency (85%), and higher open-circuit photovoltage (350 mV). Additionally, the heterostructure displays a prolonged average lifetime of charge (1.63 ns), verifying this heterojunction could boost interfacial carriers' migration via an additional nonradiative quenching pathway. Furthermore, the lower photoluminescence (PL) intensity demonstrates the interfacial built-in electric field is beneficial for boosting charge migration.

Highly stable flexible ozone gas sensors using Mn3O4 nanoparticles-decorated IGZO thin films through the SILAR method

Metal or semiconductor nanoparticles (NPs) can enhance the device performance of gas sensors due to their high surface area and unique electronic properties. However, this method requires additional thermal bonding with high temperatures to secure the NPs, making it unsuitable for flexible substrates. In this study, we develop a room-temperature flexible ozone (O3) gas sensor using Mn3O4 NPs on an amorphous InGaZnO (a-IGZO) film. The Mn3O4 NPs are synthesized by a successive ionic layer adsorption and reaction (SILAR) method at low temperatures. The sensor with Mn3O4 NPs exhibits a gas response of 4.06 against 5 ppm O3 gas at room temperature, which is much higher than that of its pristine counterpart. It also shows excellent selectivity for O3 over toxic gases and maintains stability over 60 days, with reproducible folding even after 500 bending cycles. Thus, the combination of SILAR-synthesized Mn3O4 NPs and a-IGZO films provides an effective way to fabricate flexible O3 gas sensors.

Fabrication and Characterization of ZnWO4/CoWO4 Heterojunction for Multispectral Photodetection on Flexible Substrate

Flexible photodetectors hold significant interest across diverse applications, such as imaging, communication, healthcare, and environmental monitoring. This work reports a broad-band photodetector comprising Zinc tungstate (ZW) and Cobalt tungstate (CW) on a flexible paper substrate. CW thin film was fabricated by a facile successive ionic layer adsorption and reaction(SILAR) technique and the ZW nanoparticles, synthesised via simple co-precipitation method, were drop casted on it to form a heterojunction. Structural characterization of the materials was conducted using X-ray diffraction (XRD), Raman spectroscopy, and Fourier-transform infrared spectroscopy (FTIR), while scanning electron microscopy was employed for detailed morphology analysis. CW is a p type semiconductor with its bandgap of 2.6eV, exhibits impressive sensitivity across both visible and infrared segments of the electromagnetic spectrum. In contrast, ZW which is n type contributes UV-responsive, attributes effectively broadening the overall spectral sensitivity from Ultraviolet (UV) to Infrared (IR) spectra within a single compact device. The photodetector demonstrates remarkable responsivity of 1.66mA/W (UV), 24.58mA/W (Visible), and 0.024mA/W (IR) under respective light intensities of 0.6mW/cm², 0.4mW/cm², and 4.41mW/cm. The detectivity metrics are equally impressive, measuring at 9.9×1010 Jones (UV), 5.01×1011 Jones (Visible), and 4.48×1010 Jones (IR). The successful combination of Zinc tungstate and Cobalt tungstate on a paper substrate represents an advancement in photodetector technology, offering enhanced sensitivity, extended spectral range, and the potential for seamless integration into wearable electronics and portable devices.

Solution-processed Sb2O3: A promising electrode material for high-performance supercapacitors and electrocatalysts

Easy accessibility, wide range of redox states, affordable cost, and simple synthesis methods of metal oxides have gained a significant interest in the domains of electrochemical supercapacitors and electrocatalysts. The successive ionic layer adsorption and reaction (SILAR) chemical synthesis approach has been introduced to preparing nanocrystalline antimony oxide (Sb2O3) for both energy storage and water splitting applications. The Sb2O3 electrode demonstrates a remarkable specific capacitance of 3011 F/g at a current density of 2 A/g in a 1 M solution of potassium hydroxide (KOH). The current design of the Sb2O3//Bi2O3 (bismuth oxide) asymmetric electrochemical supercapacitor device has endowed a specific capacitance of 391 F/g, a maximum energy density of 78.2 Wh/Kg at a power density of 1000 W/Kg, and an outstanding capacitance retention of 77 % even after 5000 redox cycles. The Sb2O3 electrode demonstrates outstanding performance in the oxygen evolution process at a current density of 10 mA cm2, with an overpotential of 206 mV. The Sb2O3 as an electrocatalyst also exhibits exceptional results in the hydrogen evolution reaction with an overpotential of 124 mV/dec. Both of these electrochemical processes are distinguished by the evolution of oxygen which is capable of facilitating the process of water splitting to obtain clean energy for day by day growing population.

A comparative analysis of solid-state quantum dot-sensitized solar cells employing various hole transport layers, metal contacts, and a sensitizer comprising PbS/CdS/ZnS quantum dots

Quantum dots, as a sensitizer in quantum dot-sensitized solar cells (QDSSCs), hold the promise of revolutionizing solar energy conversion. This research mainly focuses on employing PbS/CdS/ZnS quantum dots (QDs) as both light harvesters and passivation layers in QDSSCs, which are directly synthesized onto the pre-deposited TiO2 substrate through the Successive Ionic Layer Adsorption and Reaction (SILAR) technique. Particularly, the sample with a composition of 2 cycles of PbS, 6 cycles of CdS, and 2 cycles of ZnS (2/6/2) exhibited a wide-ranging and intense absorption spectrum, attributed to the reduction in band gap with escalation in number of SILAR cycles. The prepared samples underwent analysis through characterization methods, including SEM and XRD, and the elemental composition was examined using EDX spectroscopy. Subsequently, the 2/6/2 sample was employed as a sensitizer, with P3HT and PEDOT:PSS serving as the hole transport layers (HTL). For the metal contacts, thermally evaporated gold (Au), silver (Ag), and Ag paste were used in the fabrication of six distinct devices. FTO/TiO2/PbS/CdS/ZnS/P3HT/Au shows the best performance demonstrating PCE of 2.17 %, Jsc of 7.9 mA/cm2 Voc of 0.54 V and FF of 0.51. However, overall efficiency dropped significantly for other configurations. Additionally, impedance spectroscopic analysis revealed a notably low series resistance for the P3HT/Au configuration.

Investigation of gamma induced effects on the properties of gamma irradiated Ce2S3 thin films

Nanostructure cerium sulphide (Ce2S3) thin films were prepared using successive ionic layer adsorption and reaction (SILAR). The properties of the prepared samples were investigated as a function of gamma rays’ doses of 0, 250, 500, and 1000Gy, respectively. The X-ray diffraction (XRD) results suggest an orthorhombic phase structure for Ce2S3 thin films and the crystallinity is enhanced with increasing gamma-ray doses. The irradiated thin films exhibit a variation in the energy band gap associated with the quantum confinement effect with larger grain size. This simple strategy of modifying properties of Ce2S3 thin films by the incident gamma rays can be an attractive way to investigate this material for dosimetry and radiation detection.

Growth kinetics of novel nickel oxide (NiO) nano fibers on glass substrates by SILAR process: A solution to remove AZO dye

This article presents the growth of uniformly distributed nickel oxide (NiO) nanofibers on a glass substrate by the Successive Ionic Layer Adsorption and Reaction (SILAR) process and explores its photocatalytic features towards an AZO dye. The nanofiber grown by the SILAR process is subjected to annealing at 400°C to decompose the hydroxide group into oxide. X-ray diffraction pattern divulges the Face-Centered Cubic (FCC) structure of NiO, and its average crystallite size (46–61 nm). The fibrous morphology with the width varying from 37.83 to 42.05 nm is confirmed through FESEM micrographs. The existence of nickel and oxide, with atomic percentages in the ratio 40:60 is confirmed by EDX analysis. From the UV–visible spectrum, the band gap energy Eg is determined using a Tauc plot and the values are varied between 3.38 eV and and 3.41 eV. Photocatalytic degradation efficiency for the Congo red dye is found to be 93% for reusable NiO nanofibers under the illumination of UV light. The photodegradation pathway of Congo red dye is presented based on gas chromatography-mass spectrometry (GC-MS) analysis. The prospective applications of the current work in wastewater treatment make it significant.

SILAR Growth of ZnO NSs/CdS QDs on the Optical Fiber-Based Opto-Electrode with Guided In Situ Light and Its Application for the "Signal-On" Detection of Inflammatory Cytokine.

In this study, a novel integrated photoelectrochemical (PEC) sensor platform was proposed, utilizing an optical fiber (OF) as the working electrode for guided in situ light. A CdS quantum dots (QDs)/ZnO nanosheets (NSs) n-n heterojunction was quickly and easily constructed on the OF surface by successive ionic layer adsorption and reaction (SILAR). Au nanoparticles (NPs)@dsDNA as a capturing probe were modified on the CdS QDs/ZnO NSs@OF (CZ@OF). Due to the energy transfer between Au NPs@dsDNA and CdS QDs, the resultant opto-electrode has a lower background near zero, enabling the "signal-on" detection of biomarkers (interleukin-6 (IL-6) as a model). The OF-PEC biosensor demonstrated a wide linear range from 1 to 100 pg mL-1 with a regression coefficient (R2) of 0.9958 and an impressive detection limit (LOD) of 0.19 pg mL-1. More significantly, the proposed OF-PEC can be successfully used for the detection of IL-6 in serum samples from patients with pulmonary arterial hypertension, and it showed consistency and is more sensitive to trace concentrations compared to BD FACSCanto II flow cytometry used at the hospital. This holds significance for an early disease diagnosis. Therefore, the proposed OF-PEC not only achieves integration of the light source and sensing interface but also enables sensitive and accurate "signal-on" detection of IL-6. Furthermore, due to the flexibility and remote detection capabilities of OF, the application of OF-PEC is expected to be expanded more widely. This approach opens up possibilities for advances in PEC sensing.

Synthesis, Characterization and Power Factor Estimation of SnSe Thin Film for Energy Harvesting Applications

In this work, a simple, cost-effective successive ionic layer adsorption and reaction (SILAR) deposition technique has been used to deposit a high-quality tin selenide (SnSe) thin film onto a glass substrate. Structural, morphologic, and thermoelectric properties have been characterized for the prepared thin film. X-ray diffraction (XRD) results of the SnSe thin film reveal an orthorhombic structure phase. The morphological properties of the prepared thin films have been studied using field emission scanning electron microscopy (FESEM). The stoichiometric composition of the deposited thin film and the elemental binding energies of the Sn and Se elements have been investigated with energy-dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The Fourier transformation infrared (FTIR) spectrum of the SnSe thin film displays vibrational modes of chalcogenides bonds. These results suggest that the developed thin film is crystalline, uniform, and without impurities and is appropriate for energy harvesting applications. The prepared thin film’s Seebeck coefficient and electrical resistivity were estimated through ZEM-3 from room temperature to 600 K. The power factor was evaluated. A substantially high electrical conductivity is observed, which decreases somewhat with temperature, suggesting a semimetal conducting transport—the absolute values of the Seebeck coefficient increase with temperature. The resulting power factor showed the highest values near room temperature and a somewhat decreasing trend as the temperature increased. Despite lower values of the Seebeck coefficient, the substantially enhanced power factor is due to the higher electrical conductivity of the thin film, superior to that reported previously. This precursor study demonstrates promising results for developing high-performance flexible thermoelectric devices via a simple and facile SILAR strategy.

Copper-Enriched Nanostructured Conductive Thermoelectric Copper(I) Iodide Films Obtained by Chemical Solution Deposition on Flexible Substrates

The objects of our research are flexible thin-film thermoelectric materials with nanostructured CuI layers 0.5–1.0 μm thick, fabricated by the chemical solution method Successive Ionic Layer Adsorption and Reaction (SILAR) on flexible polyethylene terephthalate and polyimide substrates. These cubic γ-CuI films differ from films obtained by other chemical solution methods, such as spin-coating, sputtering, and inject printing, in their low resistivity due to acceptor impurities of sulfur and oxygen introduced into CuI from aqueous precursor solutions during SILAR deposition. Energy barriers at the boundaries of 18–22 nm CuI nanograins and a large number of charge carriers inside the nanograins determine the transport properties in the temperature interval 295–340 K characterized by transitions from semiconductor to metallic behavior with increasing temperature, which are typical of nanostructured degenerate semiconductors. Due to the resistivity of about 0.8 mΩ· m at 310 K and the Seebeck coefficient 101 μV/K, the thermoelectric power factor of the CuI film 1.0 μm thick on the polyimide substrate is 12.3 μW/(m · K2), which corresponds to modern thin-film p-type thermoelectric materials. It confirms the suitability of CuI films obtained by the SILAR method for the fabrication of promising inexpensive non-toxic flexible thermoelectric materials.

Impact of Co:Fe cations composition in amorphous and mesoporous cobalt iron phosphate electrocatalysts synthesized by SILAR method on durable electrochemical water splitting

Efficient and durable electrocatalysts are crucial for energy conversion devices that perform the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The structural and morphological characteristics of the electrocatalyst can significantly impact the HER/OER performance. Therefore, it is essential to develop a high-performing electrocatalyst with desired properties using a simple and cost-effective chemical process. So, herein, successive ionic layer adsorption and reaction (SILAR) deposited amorphous, hydrous cobalt iron phosphate (CFP) thin film electrocatalysts are implemented toward electrochemical water splitting. Moreover, in the present work, the molar proportions of cobalt and iron were streamlined to study their synergistic effect on electrochemical HER and OER performance. The electrode of best-performing (CFP–S2) requires the lowest overpotentials of 242 mV for OER and 67.9 mV for HER at a current density of 10 mA/cm2, which maintains its activity after 24 h. The alkaline water splitting into a similar electrolytic bath using two electrode systems was demonstrated for 100 h with the lowest overpotential of 1.72 V. The remarkable electrochemical performance and postmortem analysis unambiguously demonstrate that CFP electrodes are a highly promising and robust option for long-duration water-splitting devices, and the facile SILAR method for scalable CFP electrode synthesis indicates enormous potential for commercial applications.

Highly Efficient CdSe Quantum Dot-Sensitized Solar Cells via a Facile SILAR Method: Dependence of the SILAR Cycles on Optical Properties and Photovoltaic Performance

This work emphasizes using CdSe as a sensitizer in quantum dot-sensitized solar cells (QDSSCs) due to its beneficial band alignment with TiO2, enhancing effective charge injection. This study presents highly efficient CdSe QDSSCs developed using the successive ionic layer adsorption and reaction (SILAR) method. The XRD analysis revealed a hexagonal crystal structure for the synthesized CdSe quantum dots (QDs) with an average particle size of 9.2 nm. Increasing the SILAR cycles from 3 to 5 showed a decrease in the energy bandgap, reducing it from 1.79 eV to 1.68 eV, as observed in the investigation of optical properties. The optimal photovoltaic performance of CdSe QDSSCs was achieved at 4 SILAR cycles, yielding a notable power conversion efficiency (PCE) of 6.77% (Jsc = 14.63 mA/cm2, Voc = 0.71 V, FF = 65.2%), which is higher than that of a previous report of SILAR-prepared CdSe QDSSCs.

Crystallinity transformation engineering of hydrous cobalt nickel phosphate cathodes for hybrid supercapacitor devices: Extrinsic/battery to intercalation type pseudocapacitors

The necessitating strategies of rationalizing nanostructures and crystallinity of electrode material are crucial to developing high-efficiency hybrid energy storage devices. To enhance the energy storage performance of bimetal phosphates, it is important to have a strategic blend of metal cations that can work together synergistically. So, this work describes the scalable preparation of binder-free cobalt nickel phosphates thin film cathodes with cations variation (Co/Ni) via the facile Successive Ionic Layer Adsorption and Reaction (SILAR) process. The distinct roles of cations in cobalt nickel phosphate electrodes resulted in a noteworthy structural transformation from crystalline to amorphous with an increment of Ni content. The change in cations composition influences the pseudocapacitive performance from extrinsic/battery to intercalation type, and cobalt nickel phosphate electrode with an ideal cations composition (Co:Ni) ratio of approximately 1:1 attain the highest specific capacitance (SCs) of 2142 F g−1 (1071 C g−1). To fulfil the demand for high-performance hybrid supercapacitor devices, aqueous (HASC) and solid-state (HSSC) supercapacitors are assembled using optimized cobalt nickel phosphate (S-CNP5) as a cathode. The HASC device represents maximum SCs of 120 F g−1 with specific energy (SE) and specific power (SP) of 42.59 Wh kg−1 and 1600 W kg−1, respectively. The flexible HSSC device shows impressive SCs of 89 F g−1 and SE of 31.54 Wh kg−1 at SP of 2057.14 W kg−1. The practical demonstration of an HSSC device to power a 12-white LED lamp suggests that the SILAR strategy offers commercializing insights for fabricating high-specific capacity hydrous cobalt nickel phosphate thin film cathodes.

Evolution of structural features in GO/CdS multilayer films for advanced optoelectronic devices

In this work graphene oxide/cadmium sulphide [GO/CdS]n multilayer films were obtained onto FTO/SLG substrates by cyclic electrophoretic deposition (EPD) and successive ion layer adsorption and reaction (SILAR) methods, with 3, 5, 7 and 10 cycles. The optical characterization for 3 cycles sample exhibits an optical band gap of ∼2.9 eV due the nanocrystalline nature of CdS, from 5 to 10 cycles a blue shift is observed in the band gap around ∼2.15 eV by the electronic disorder induced by graphene oxide intercalation and the mixture of hexagonal/cubic phases of CdS. Raman spectra shows the longitudinal optical modes LO, 2LO and 3LO, the LO peak position shows a blue shift in comparison to the bulk CdS. The multilayer films of 3 and 5 cycles shows a wide range of photoluminescence emission from 350 to 700 eV, for samples of 7 and 10 cycles a quenching and red shift is observed attributed to the CdS crystals growth with a peak emission at 615 eV from bulk CdS, which make the materials suitable for photovoltaic solar cells and UV-Vis diodes for optoelectronic devices.

Carbon fabric coated with nanostructured zinc oxide layers for use in triboelectric self-powered touch sensors

An environmentally friendly, low-cost, and lightweight biocompatible textile triboelectric material was made by in situ coating carbon fabric (CF) with nanostructured zinc oxide (ZnO) layers using the automatic Successive Ionic Layer Adsorption and Reaction (SILAR) method. Depending on the deposition mode, we created triboelectric CF/ZnO textiles with multidirectionally intergrown short ZnO nanorods or with arrays of ZnO nanosheets. The Raman spectra confirmed the hexagonal wurtzite structure of both types of ZnO layers and the unique a-axis texture of the nanosheets. In the developed triboelectric CF/ZnO/PET/ITO sensors, the upper tribonegative part was made of a polyethylene terephthalate film coated with a thin layer of indium-tin oxide, and the lower tribopositive part was made of CF/ZnO textile. In tests with repeated hand tapping at low frequency 1.3–13 Hz and a force of ∼ 5 N (pressure of ∼ 33 kPa), the open-circuit voltage pulses were ∼ 15 V for short ZnO nanorods and ∼ 30 V for ZnO nanosheets, their duration did not exceed a few milliseconds. Due to the nanosheet morphology of the ZnO layer, the maximum touch-induced surface charge density for the corresponding triboelectric textile (0.7 µC/m2) was almost twice than for the CF/ZnO textile with intergrown ZnO short nanorods (0.4 µC/m2). The touch sensor with ZnO nanosheets showed an output voltage of 3.6 V, a current density of 1.47 µA/cm2, and a power density of 1.8 µW/cm2. It can be used as a dual-mode sensor due to ability to recognize the hardness of objects by analyzing the output current peaks.