Compact Film Research Articles

Preparation, physicochemical characteristics and bioactivity evaluation of pitaya peel extract/soy protein nanocomposite film containing zinc oxide nanoparticles by photocatalysis

Interactions between components in film-forming solution affected the physicochemical properties of active packaging. A series of soy protein isolate (SPI)-based nanocomposite films reinforced with zinc oxide nanoparticles and different pitaya peel extract (PPE) levels were fabricated by photocatalysis. Results showed that the tensile strength, oxygen and water vapor barrier properties, thermal stability and DPPH scavenging activity were substantially improved, but the elongation at break and transmittance decreased with the proportion of PPE increased due to the formation of a more compact film structure caused by the crosslinking of PPE and SPI, particularly at the SPI/PPE ratio of 1:2. However, excessive PPE was not conducive to the integrity and continuity of film structures. The SPI/PPE films had more favorable anti-bacterial activities against Staphylococcus aureus than Vibrio parahaemolyticus. Therefore, our finding suggested that photocatalytic SPI/PPE nanocomposite film is an interesting alternative to obtain materials with antimicrobial and antioxidant properties. Novelty impact statement Pitaya peel extract (PPE) was added into soy protein isolate (SPI)/ZnO film matrix through photocatalysis. Addition of PPE resulted in compact inner microstructures of the films. SPI-PPE conjugate greatly improved the antibacterial and antioxidant properties of the films.

Effects of switching layer morphology on resistive switching behavior: A case study of electrochemically synthesized mixed-phase copper oxide memristive devices

Resistive switching (RS) behavior can serve as a building block in the development of non-volatile memory and neuromorphic computing applications. Thus far, various device parameters have been modulated appropriately to achieve the desired characteristics from RS devices. However, no clear guideline for device parameter modulation has been reported. Herein, we systematically investigate the effect of the switching layer morphology and thickness, as well as the choice of the bottom electrode, on RS properties by using electrochemically synthesized mixed-phase copper oxide (CuxO) as a model material for memristive devices. By controlling various electrochemical parameters, we have fabricated CuxO switching layers with various morphologies (microcrystal, microcubic, compact thin film, short dendritic nanowire, granular, and nanoparticle). Interestingly, the CuxO-based RS devices fabricated by means of electrodeposition (CuxO/FTO) exhibit the forming-free digital RS property, which is suitable for non-volatile memory, whereas those fabricated by utilizing anodization (CuxO/Cu) exhibit the analog RS property, which makes them suitable for use in synaptic learning applications. A convolutional neural network (CNN) was implemented using experimental synaptic weights of the anodized CuxO RS device for image edge detection application. In addition, conduction mechanisms and possible RS mechanisms are suggested for both types of devices. These results indicate that the electrochemically synthesized switching layers are promising for use in both non-volatile memory and neuromorphic computing applications.

Tribological performance of hydrogenated diamond-like carbon coating deposited on superelastic 60NiTi alloy for aviation self-lubricating spherical plain bearings

It is imperative to develop a novel matching of metallic substrate and self-lubricating coating for aircraft spherical plain bearing in a wide range of service conditions. As a new type of superelastic material, 60NiTi alloy meets the performance requirements of aerospace bearing materials, but exhibits poor tribological performance, especially under the conditions of dry sliding friction. A Hydrogenated Diamond-Like Carbon (H-DLC) coating was deposited on the 60NiTi alloy to improve its tribological performance. The microstructure and mechanical behavior of the 60NiTi alloy and its H-DLC coating were explored. Results show that improvement of friction and wear performance of the H-DLC coating deposited on the 60NiTi substrate is mainly achieved by graphitization at the friction interface and the transfer film produced on the counterpart ball. The increased friction load leads to intensification of graphitization at the friction interface and formation of continuous and compact transfer film on the surface of the counterpart ball.

Conductive Silicone Rubber Coated by Reduced Graphene Oxide Pseudo-Photonic Crystal Film

Graphene aqueous dispersion is difficult to be prepared as conductive film by simple solvent evaporation deposition, not only because of the agglomeration in its aqueous solution, but also caused by the “coffee ring” phenomenon during solvent evaporation process. Herein, as a derivative of graphene, graphene oxide (GO) would be used as film forming material due to its good dispersion in aqueous solution and its liquid crystallinity. If GO can self-assemble as a compact pseudo-photonic crystal film by solvent evaporation deposition, it will be converted into a conducive graphene film after thermal reduction. In order to prepare a flexible and conductive elastomer material covered with graphene film, compact GO pseudo-photonic crystal film can be transferred onto the surface of a 10% stretched silicone rubber plate. After releasing the stretched force, GO pseudo-photonic crystal film can form a lot of folds, which provide allowance of shrinkage for this GO pseudo-photonic crystal film to avoid cracking during the high temperature reduction. Benefiting from transferring the GO film onto a stretched silicone rubber, a flexible, colored and conductive graphene/SR can be obtained.

Laser-Assisted Ultrafast Fabrication of Crystalline Ta-Doped TiO2 for High-Humidity-Processed Perovskite Solar Cells.

A titanium dioxide (TiO2) compact film is a widely used electron transport layer (ETL) for n–i–p planar perovskite solar cells (PSCs). However, TiO2 sufferers from poor electrical conductivity, leading to high energy loss at the perovskite/ETL/transparent conductive oxide interface. Doping the TiO2 film with alkali- and transition-metal elements is an effective way to improve its electrical conductivity. The conventional method to prepare these metal-doped TiO2 films commonly requires time-consuming furnace treatments at 450–600 °C for 30 min to 3 h. Herein, a rapid one-step laser treatment is developed to enable doping of tantalum (Ta) in TiO2 (Ta-TiO2) and to simultaneously induce the crystallization of TiO2 films from its amorphous precursor to an anatase phase. The PSCs based on the Ta-TiO2 films treated with the optimized fiber laser (1070 nm) processing parameters (21 s with a peak processing temperature of 800–850 °C) show enhanced photovoltaic performance in comparison to that of the device fabricated using furnace-treated films at 500 °C for 30 min. The ambient-processed planar PSCs fabricated under high relative humidity (RH) of 50–70% display power conversion efficiencies (PCEs) of 18.34% and 16.04% for devices based on Cs0.1FA0.9PbI3 and CH3NH3PbI3 absorbers, respectively. These results are due to the improved physical and chemical properties of the Ta-TiO2 films treated by the optimal laser process in comparison to those for the furnace process. The laser process is rapid, simple, and potentially scalable to produce metal-doped TiO2 films for efficient PSCs.

Dictating the interfacial stability of nickel-rich LiNi0.90Co0.05Mn0.05O2 via a diazacyclo electrolyte additive – 2-Fluoropyrazine

Nickel-rich (Ni-rich) cathode materials, LiNixCoyMnzO2 (NCM, x ≥ 0.9, x + y + z = 1) hold great promise for developing high energy density lithium ion batteries especially for vehicle electrification. However, the practical application of Ni-rich cathode materials is still suffered from fast structural and interfacial degradation, and the resulted capacity decay. In this study, a diazacyclo type electrolyte additive, 2-fluoropyrazine (2-FP), was explored for the first time to boost the interfacial stabilization of single crystal LiNi0.90Co0.05Mn0.05O2 (NCM90) cathode. The capacity retention of the NCM90 is evidently promoted from 72.3% to 82.1% after 200 cycles at 1C (180 mA g−1) when adding 0.2% 2-FP into the electrolyte. The improvement of the electrochemical performance is ascribed to the generation of a compact and homogeneous cathode electrolyte interphase (CEI) film through ring-opening electrochemical polymerization of 2-FP upon the NCM90 electrode particles. This enhanced CEI layer benefits the suppression of the decomposition of LiPF6 electrolyte and the dissolution of the transition metals (Co and Mn), thus preventing the detrimental side reactions between the NCM90 electrode and the electrolyte.

Sulphonamide derivatives as the inhibitors for mild steel: The correlation of molecular structure effect and the corrosion efficiency

The corrosion mitigation of different functional groups of the sulphonamide derivatives, sulfadiazine (SD), p-toluenesulfonylhydrazide (p-TSH) and sulfathiazole (STI), were compared in this paper. The strong correlation result between the inhibition efficiency and molecular structure could provide a novel insight in inhibition mechanism. Electrochemical experimental results together with the Langmuir adsorption isotherm observation suggested sulphonamides could spontaneously adsorb on the surface of Q235 to form compact protection films for blocking corrosive media. By density function theory (DFT) calculations for the protonated molecules with the metal (Fe atom), we found that protonated SD molecule had stronger interaction with the metallic surface in comparison with the protonated p-TSH and STI, which fully validated the inhibition efficiency (η) on the mild steel surfaces is in order of SD (η = 92.7%) > p-TSH (η = 79.8%) > STI (η = 66.8%) by using elecetrochemical experiments. Experimental studies together with theoretical calculations have presented a good direction for exploring the mechanism of structural effect of sulphonamides on the corrosion mitigation efficiency, which is beneficial to sheding insight on the design of new organic inhibitors in the future.

Correlation of microstructural with corrosion behaviour of Ti-6Al-4V specimens developed through selective laser melting technique

Ti-6Al-4 V (Ti64) alloy is majorly preferred for fabricating the parts in biomedical, aerospace and automobile industries. Traditional manufacturing techniques are mostly involved in making these parts. This work is focused on evaluating the as-cast and Selective Laser Melting (SLM) printed Ti64 specimens in terms of microstructure, hardness and corrosion resistance. The microstructure and the hardness of as-cast and SLM printed samples were examined using FESEM with EDS followed by Vickers microhardness test The corrosion resistance offered by both samples at different durations was investigated in an electrochemical workstation followed by the examination of the corroded surface roughness. The results showed that the existence of martensite microstructure in the SLM printed Ti64 sample has paved the way for enhancing the hardness property compared with the as-cast specimen. Furthermore, the corrosion analysis revealed that the formation of strong and compact passive film has been observed on the SLM samples which resist corrosion. This is due to the even distribution of stabilizing elements followed by martensite phase formation with subsequent solidification during the SLM process. The electrochemical impedance spectroscopy (EIS) analysis and surface roughness evaluation also confirm that the SLM samples have a better passive film with higher Rp and lower Ra values, thereby providing greater resistance against corrosion.

Adsorption and corrosion inhibition performance of two planar rigid pyridinecarboxaldehyde-based double Schiff bases for mild steel in HCl solution: Experimental and computational investigations

Two planar rigid double Schiff bases, (1E,1′E)-N,N’-(1,4-phenylene)bis(1-(pyridin-2- yl)methanimine) (PBPM2) and (1E,1′E)-N,N’-(1,4-phenylene)bis(1-(pyridin-3-yl)methan- imine) (PBPM3), were investigated as corrosion inhibitors for mild steel in HCl solution. The experimental resultspresented that the inhibition efficiencies in 1.0 mol L−1 HCl slightly negatively correlate with temperature, while positively correlate with inhibitor concentration and soaking time, respectively. The maximum inhibition rates of PBPM2 and PBPM3 obtained by weight loss measurement at 30 °C reach up to 91.88 % and 92.18 %, respectively. The fitting analysis indicated that PBPM2 and PBPM3 conform to Langmuir adsorption isotherm, and physicochemical adsorption mechanism occurred onthe surface of mild steel. Potentiodynamic polarization measurement showed that PBPM2 and PBPM3 are mixed-type inhibitors with anodic characteristics. The contact angle and energy dispersive spectroscopy data indicated that the hydrophobicity for mild steel surface is modified by PBPM2 and PBPM3 applied in HCl solution, which causes the formation of the compact protective film on the metallic surface. The structure–activity relationship and protonation behavior were investigated by density functional theory and Fukui indexes. The computational results conformed PBPM3 has higher inhibition performance the PBPM2. Furthermore, molecular dynamics simulation revealed real adsorption configuration of PBPM2 and PBPM3 molecules on mild steel surface and certified that PBPM3 has stronger adsorption capacity and better inhibition performance than PBPM2, which agree with the experimental results.

Rapid thermal sintering of screen-printed LiCoO2 films

A rapid photonic sintering process (rapid thermal processing) was used to obtain compact films of cathode active material of lithium batteries. LiCoO2 (LCO) thick films were screen-printed on a steel substrate followed by a contactless thermal processing at 1000 °C in only 90 s. A homogenous densification of such layers could be verified by scanning electron microscopy, while the structural consistency of the LCO phase in these layers could be detected by X-ray diffraction and Raman spectroscopy. Furthermore, electrochemical activity of the layer was confirmed by electrochemical cell tests with a liquid electrolyte.

Effect of Oil-Displacing Agent Composition on Oil/Water Interface Stability of the Asphaltene-Rich ASP Flooding-Produced Water.

In this work, the effect of oil-displacing agent composition on oil/water interface stability of the asphaltene-rich alkali-surfactant-polymer (ASP) flooding-produced water was systematically investigated, especially from the perspective of the interaction between oil displacement agents and asphaltene at the oil/water interface. Primarily, adsorption behavior of the artificial and natural interfacial substances (oil displacement surfactant and asphaltenes) on the oil/water interface was investigated by molecular dynamics simulation. The oil displacement surfactant and asphaltenes formed a cross-linked and compact interfacial film structure, which significantly enhanced the interface stability; the more the oil displacement surfactants adsorbed on the interface, the more stable is the cross-linked structure formed between them and asphaltenes. Then, the interfacial property variations that are originating from the interactions differences between oil displacement agents and asphaltenes were monitored via interfacial tension, zeta potential, and interfacial film rheology tests. Moreover, the effect of oil displacement agent concentrations on the interfacial film thinning and rupture kinetic behavior was further investigated. Finally, cream experiments were conducted to verify the effect of oil displacement agent composition on the oil/water separation efficiencies of asphaltene-rich ASP flooding-produced water. When 5% asphaltenes was added, the creaming oil removal rate reduced from 90.0 to 85.3% at 19 h. The interactions between asphaltenes and oil displacement agents immensely enhance the oil/water interfacial film strength and impede the oil/water separation process.

Uncovering synergistic effect of chloride additives for efficient quasi-2D perovskite solar cells

• MACl and PbCl 2 binary additives form MAPbCl 3 intermediate phase. • Perovskite crystallization is retarded and volatilization of MACl is prevented. • Such a synergistic effect leads to high-quality Q-2D perovskite films. • Charge recombination is suppressed and charge extraction efficiency is enhanced. • The champion PCE of 18.67% is one of the highest PCE for Q-2D RP PSCs with n ≤ 4. Methylammonium chloride (MACl) and lead chloride (PbCl 2 ) are commonly used for improving perovskite film quality. However, the rapid release of volatile MACl would lead to low-quality perovskite films with pinholes and defects. Here, we report a strategy of employing MACl&PbCl 2 binary additives together to prepare high-quality quasi-two-dimensional (Q-2D) Ruddlesden–Popper (RP) perovskite films. We found that MAPbCl 3 intermediate phase is formed via a reaction between MACl and PbCl 2 , which suppresses the fast volatilization of MACl, resulting in a compact and pinhole-free perovskite film with large grains. Moreover, the trap states are passivated via the incorporation of Cl – into the Q-2D perovskite crystals along with the addition of PbCl 2 , leading to a reduced charge recombination loss and an improved charge extraction. A remarkable power conversion efficiency (PCE) of 18.67% is achieved in such Q-2D RP PSCs, one of the highest PCE values among the low-dimensional RP PSCs with n ≤ 4. The environmental stability of the devices is also significantly enhanced. Our results provide an effective strategy by using chloride based additives for fabricating high-quality low-dimensional RP perovskite films for efficient solar cells.

Hydrogen inhibition of sodium alginate and sodium phosphate on waste magnesium alloy dust particles: A new suppression method for magnesium alloy waste dust

Magnesium alloy waste dust particles will be generated during alloy grinding, which undergoes a hydrogen production reaction in wet dust removal systems and introduces the risk of hydrogen explosion. To inhibit the generation of hydrogen, environmental friendly sodium alginate (SA) and sodium phosphate (SP) are combined to inhibit the hydrogen evolution reaction of waste magnesium alloy dust and water. The results of the hydrogen evolution experiment and chemical kinetics show that the combined action of 3 g/L sodium alginate and 2 g/L sodium phosphate can completely inhibit the hydrogen evolution reaction of magnesium alloy waste dust. The SEM, EDS, FTIR spectroscopy, XRD and adsorption theory results show that a compact and smooth protective film with sodium alginate as the main body and sodium phosphate as the supplement is formed on the surface of the ZK61 magnesium alloy, blocking the reaction pathway between the external water molecules and Mg2+. This research fills the gap of hydrogen evolution inhibitors for wet dust collectors used in magnesium alloy grinding enterprises and provides a novel, safe and effective method for clean and sustainable production of dust removal system.

Enhanced switchable ferroelectric photovoltaic in BiFeO3 based films through chemical-strain-tuned polarization

Ferroelectric photovoltaic (FE-PV) materials have generated widespread attention due to their unique switchable photovoltaic behavior, but suffering from low photocurrent and remanent polarization. Herein, enhanced ferroelectric polarization and switchable photovoltaic in BiFeO3 based thin films were achieved by the optimization of Bi content. The compact and uniform films with few defects were obtained by the control of chemical composition. The remanent polarization increased from 3.4 to 73.9 μC cm−2 showing a qualitative leap. Intriguingly, the control range of photovoltaic signal between two polarization directions of the short-circuit current density (JSC) and open circuit (VOC) in present films exhibited an increase of 99.2% and 278.9%, respectively. It is suggested that the ferroelectric polarization was the main driving force for enhancing switchable ferroelectric photovoltaic. Therefore, the present work outstands a simple idea to enhance switchable ferroelectric photovoltaic based on the chemical engineering, providing a promising pathway for the development of photovoltaic devices.

High-Efficiency and scalable Solution-Sheared perovskite solar cells using green solvents

In this work, high-quality and large-area (10 × 10 cm2) perovskite film was prepared by solution-shearing method using acetonitrile as solvent at a substrate temperature of 45 °C. In contrast to the similar process with conventional DMF/DMSO solvent at substrate temperature of 140 °C, more compact film with much reduced crystalline domains and narrower domain boundaries was obtained. High-performance solar cell with a power conversion efficiency of 20.30% and significantly improved device stability can be fabricated from such film. Furthermore, uniform layers over a large area up to 100 cm2 were prepared by sequential shearing of c-TiO2, mp-TiO2, MAPbI3, and Spiro-OMeTAD on FTO substrate all using green solvents. The solar cell based on the all-solution-sheared films gave a high efficiency of 17.77% for device with the standard active area of 0.04 cm2 and 13.41% for large active area of 1.5 cm2. This strategy demonstrates the huge potential for module fabrication and future PSC commercialization.

Preparation of tin-based perovskite solar cell thin films assisted by stannous fluoride

While the conversion efficiency is constantly refreshing, perovskite solar cells are also actively moving towards the goal of commercial application. However, its structure contains Pb, a toxic substance, which violates the original intention of energy saving and environmental protection of solar cells and hinders the development of its commercialization. The purpose of this paper is to improve the device performance of environment-friendly lead-free tin-based perovskite solar cells. In this paper, SnF2 is firstly precipitated in perovskite solution and used as heterogeneous nucleation point, which helps tin-based perovskite precipitate faster and more uniformly, and then grows into a flat and compact film after annealing. With the increase of x, the lattice shrinkage of perovskite becomes more obvious, and the unit cell size of the film surface becomes larger. When x increases from 0 to 0.5, the energy conversion efficiency of the same batch of devices reaches 1.803% and VOC is 0.3283 V when x=0.5 is used. Low dimensional tin-based perovskite is formed by doping phenylethylamine into FASnI3 structure, and perovskite thin films are prepared by one-step method with different anti-solvent spin coating, which improves the device performance and greatly improves the stability of solar cells.

High saturation structural color based on lithography-free planar thin film with doped indium-gallium-zinc-oxide semiconductor

We propose a compact multilayer thin film color pixel and a method for efficient transmissive color in the visible regime. When the angle of incidence (AOI) varies between 0° and 60°, there is almost no change of the transmitted color. Meanwhile, additional dielectric layers at the top and bottom of the hybrid structure work as anti-reflection (AR) layers, which greatly improve the transmission efficiency. The performance can be switched by adjusting the thickness of the film, as well as controlling the charge carrier concentration in a doped indium-gallium-zinc-oxide (IGZO). Besides their simple, large scale compatible, and electron beam lithography (EBL) free fabrication route, the designed structure provides relatively high efficiency, high color purity, and low crosstalk, which may provide some new insights for structural color applications.

Study of Pb-based and Pb-free perovskite solar cells using Cu-doped Ni1-xO thin films as hole transport material

SCAPS solar cell simulation program was applied to model an inverted structure of perovskite solar cells using Cu-doped Ni1-xO thin films as hole transport layer. The Cu-doped Ni1-xO film were made by co-sputtering deposition under different deposition conditions. By increasing the amount of the Cu-dopant, the film crystallinity enhanced whereas the bandgap energy decreased. The transmittance of the thin films decreased significantly by increasing the sputtering power of copper. High quality, uniform, compact, and pin-hole free films with low surface roughness were achieved. The structural, chemical, surface morphology, optical, electrical, and electronic properties of the Cu doped Ni1-xO films were used as input parameters in the simulation of Pb-based (MAPbI3-xClx) and Pb-free (MAGeI3) perovskite solar cells. Simulation results showed that the performance of both Pb-based and Pb-free perovskite solar cell devices significantly enhanced with Cu-doped Ni1-xO film. The highest power conversion efficiency (PCE) for the Pb-free perovskite solar cell is 8.9% which is lower than the highest PCE of 17.5% for the Pb-based perovskite solar cell.

Toward Reduced Interface Contact Resistance: Controllable Surface Energy of Sb2Te3 Films via Tuning the Crystallization and Orientation.

The electrical contact resistance between a metal and semiconductor is one of the keys to improving the output performance of thin-film thermoelectric devices. Herein, we reduced the interface contact resistance by controlling the surface energy of a Sb2Te3 semiconductor via tuning of the crystallization and orientation, preparing an intrinsically compact and flat Sb2Te3 film with high surface energy and low roughness, which can give rise to a low average specific contact resistivity (8.2 × 10-6 Ω cm2) with a Ni/Cu metal. The improvement in interface electrical properties is due to the increase in the surface energy and decrease in the surface roughness of the semiconductor surface, which lead to a transformation from three-dimensional island-shaped nucleation to two-dimensional layered nucleation for surface-attached metal films, forming a longitudinally tight connection contact with a low resistance. This approach allows the resistivity to become close to the fundamental theoretically calculated limit. Our work provides a new idea for reducing the contact resistivity of thin-film thermoelectric devices, which is conducive to supporting the development of thermoelectric semiconductor planarization.

Controlled aggregation of phytic acid metal complex on polysulfone ultrafiltration membrane toward simultaneous rejection of highly emulsified oils and dyes

Despite enormous application prospect in wastewater treatment, the moderately hydrophilic ultrafiltration (UF) membrane with the intrinsic pore size has been proved ineffective for removal of highly emulsified oil droplets and organic dyes merely by the size screening effect. Although modification of polymer fibrous membranes by the phytic acid (PA)-metal complex coatings has been widely investigated for updating the membrane performances, the feasibility of this simple dip-coating approach in modifying polymer UF membrane with an asymmetric structure is still unrevealed and required testifying. Herein, we report the modification of asymmetric polysulfone (PSF) UF membranes through the formation of hydrophilic PA-FeIII complex coatings via controlled aggregation. We reveal that 1-cycle crosslinked PA-FeIII sequential assembly with adequate reaction time represents the optimal conditions for achieving PA-FeIII/PSF membranes with desired wettability, separation performances and reusability. The PA-FeIII complex aggregations afford the hierarchical roughness and the high density of phosphonic acid group, which favors the trapping of water and formation of a stable hydration layer to separate highly emulsified oil droplets and prevent them from fouling the membrane. Besides, the molecular layer deposition mode of the PA-FeIII compact film enables a fine adjustment of the pore aperture, guaranteeing the simultaneous rejections to small-sized emulsified droplets and non-specific organic dye molecules. The rapid, easy to scale up, and cost-effective modification process for polymer UF membranes is expected to be of technological significance for various practical applications, especially for sophisticated oily wastewater decontamination.