Nickel Research Articles

N/S‐codoped Nickel oxide supported on activated Montmorillonite clay as an Efficient Bifunctional Electrocatalyst for Overall Water Splitting

Developing low‐cost, highly effective, and durable electrocatalysts for complete water splitting (OER/HER) is crucial for future energy provision. Herein, we report N/S‐codoped Nickel oxide supported on activated Montmorillonite clay as an efficient bifunctional electrocatalyst for water electrolysis. The different wt% of Ni‐MMT catalysts were synthesized using an effortless one‐step solvothermal method and their phase recognition, morphology, analysis of elements, and electrochemical performance were confirmed by various characterization techniques. The optimal 10 Ni‐MMT catalyst exhibits outstanding efficiency in both HER (170 mV) and OER (365 mV) at a current density of 10 mAcm‐2 in 1M KOH. Furthermore, doping of N/S heteroatoms increases the active sites for HER/OER, facilitates charge transfer and achieves electrochemical stability of 15 h. The Ni‐MMT catalyst achieved an overall water‐splitting performance in 1M KOH, reaching 10 mAcm‐2 at a cell voltage of 1.82 V.

Pollution risk assessment and spatial distribution of potentially hazardous elements in selenium-rich soils in the Menyuan Basin of the northeastern Tibetan Plateau

The scientific utilization of selenium (Se)-rich soils necessitates the evaluation of the contents of potentially hazardous elements (PHEs). The Menyuan Basin, a representative Se-rich region located on the northern periphery of the Qinghai–Tibet Plateau, was chosen as the research area. Pollution risk and spatial source analysis was conducted for eight PHEs (As, Cr, Cu, Pb, Zn, Cd, Ni and Hg) using 5297 topsoil samples and 480 deep-soil samples. The results show that more than 50% of the total area has a Se content >0.24 mg kg –1 . According to both single and comprehensive pollution indices, there are extremely few sampling sites with PHEs at risk of contamination. Low ecological risk was seen in 93.34% of the topsoil samples. The results show that although the overall level of surface soil pollution in the study area may be deemed negligible, on the surface or in deeper layers, the concentration centres of As, Cr, Ni, Zn, Pb and other elements show consistency, indicating that underlying parent rocks are the primary source of these elements. The findings presented in this study establish a scientific foundation for the secure development and utilization of Se-rich soils.

System analysis with life cycle assessment for NiMH battery recycling.

The nickel metal hydride (NiMH) battery technology has been designed for use in electric vehicles, solar-powered applications and power tools. These batteries contain the critical and strategic raw materials cobalt, nickel and several rare earth elements (REE). When designing a battery recycling process, there are several choices to be made regarding end-products and process chemicals. The aim of this study is to investigate and compare the environmental and economic sustainability of different recycling options for NiMH batteries by taking projected market developments into consideration and by applying life cycle assessment and life cycle costing methods. The comparative study is limited to recovery of the REEs. Two hydrometallurgical processes for recovery of the REEs from the anode material are compared with extraction of REEs from primary sources in China. The processes compared are a high-temperature sulfation roasting process and a process based on hydrochloric acid leaching followed by precipitation of REE oxalates. By comparing the different recycling approaches, the hydrochloric acid process performs best. However, the use of oxalic acid has a large impact on the overall sustainability footprint. For the sulfation roasting process, the energy, sodium hydroxide and sulphuric acid consumption contribute most to the total environmental footprint. This article is part of the discussion meeting issue 'Sustainable metals: science and systems'.

Comparative Analysis of Structural, Optical, and Electronic Properties of Nickel Oxide and Potassium‐Doped Nickel Oxide Nanocrystals

ABSTRACTMetal oxide semiconductors, known for their exceptional optical transparency, high carrier mobility, and stability, have found extensive use in emerging technologies such as optoelectronics and energy storage devices. Among all metal oxide semiconductors, nickel oxide (NiO) stands out as a highly favorable candidate due to its p‐type conductivity along with its substantial band gap (3.5–4 eV) for the broad range of applications, including gas sensors, high‐rate Lithium‐ion batteries, high‐performance supercapacitors, and photovoltaic devices. In light of these versatile applications, our current study presents a comprehensive comparative analysis of the structural and optoelectronic properties of NiO and potassium (K)‐doped NiO nanocrystals. The nanocrystals were synthesized using the co‐precipitation route and subsequently annealed at 500°C under ambient conditions. The effect of K doping on the structural and optoelectronic characteristics was systematically examined using various techniques, including x‐ray diffraction, UV–visible spectroscopy, Raman spectroscopy, and Hall effect measurements. To explore the structural characteristics, XRD measurements were performed, which confirm the FCC structure of nanocrystals. The optical property analysis suggested that the formation of the energy level can contribute to reduction of the band gap. A sharp peak at 397 cm−1 is associated with NiO bond in FTIR spectra which verifies the formation of nanocrystals. Moreover, the incorporation of K increases the intensity of the Raman peaks, which provides evidence for the higher degree of crystallinity in doped samples. These results of Raman scattering are in good agreement with XRD outcomes. In addition, the resistivity of NiO nanocrystals decreases monotonically with the increasing K concentration. The results of temperature‐dependent resistivity further demonstrate that electrons required more energy to jump from one polaron state to another in the case of x = 0.01 M and 0.03 M doped Ni0.5‐xKxO samples. The combination of a diminished band gap and enhanced conductivity makes these materials exceptionally promising for applications in optoelectronics and energy storage.

Utilizing cationic vacancies to enhance nickel-cobalt layered double hydroxides for efficient electrocatalytic urea oxidation reaction

Electrocatalytic urea oxidation reaction (UOR) is a promising approach for urea-rich wastewater splitting, which benefits for reducing energy consumption in hydrogen production accompanying environmental protection and sustainable energy development. To address the limitations posed by the self-oxidation of nickel-based catalysts on the activity of UOR, we here developed a NiCo LDH nanosheet catalyst with abundant Ni vacancies to initiate the UOR process prior to nickel oxidation. Electrochemical impedance spectroscopy and In-situ spectroscopic characterizations confirm that the UOR process primarily occurs on the surface of the catalyst, rather than being driven by nickel oxidation products. The favorable electronic structure modulation induced by Ni vacancies makes the catalyst more energetically favorable for the UOR compared to nickel self-oxidation. The catalyst exhibits excellent UOR activity, only requiring 1.27 V vs. RHE at 10 mA cm−2 and 1.34 V vs. RHE at 100 mA cm−2, with no significant decay observed after over 120 h of operation. Furthermore, it can function as a bifunctional catalyst, requiring only 1.66 V to achieve 100 mA cm−2 for the UOR||HER system. This study expands the pathway for the application of cationic vacancies in UOR.

Molten Salt Assisted Assembly (MASA) of novel mesoporous Ni0.5Mn0.5Co2O4 for high-performance asymmetric supercapacitors

Mesoporous transition metal oxides (TMO) are immensely investigated as electrode materials in supercapacitors. The molten salt assisted self-assembly (MASA) process enables a facile route for the synthesis of the mesoporous TMO. In this study, mesoporous nickel manganese cobaltite (Ni0.5Mn0.5Co2O4) is synthesized for the first time using a MASA process and is evaluated as a novel electrode-active material for asymmetric supercapacitors. The objective of this work is to quantitatively measure the performance improvement in the Ni0.5Mn0.5Co2O4 electrode based on its composition and reveal the improvement mechanism through electrochemical methods. The electrochemical performance of the NiCo2O4 and MnCo2O4 prepared by MASA is also investigated, in order to understand the synergistic effect of Ni and Mn elements in the same cobaltite structure. In line with the data obtained from half cells, a full asymmetric cell is prepared by assembling the appropriate amount of Ni0.5Mn0.5Co2O4 and activated carbon through the charge balance theory. The test results show that the specific capacitance (Cs) values are 2.62F/cm2 (92.1F/g) for mesoporous NiCo2O4, 0.26F/cm2 (9.8F/g) for mesoporous MnCo2O4, and 9.53F/cm2 (338.5F/g) for mesoporous Ni0.5Mn0.5Co2O4 under the test conditions of 5 mA/cm2. The asymmetric supercapacitor assembled with Ni0.5Mn0.5Co2O4 and activated carbon demonstrates a superior energy density of 79.52 Wh.kg−1 at 1 mA/cm2. The findings of the study highlight the importance of substituting the electrode with Ni0.5Mn0.5Co2O4 to enhance the Cs by achieving proper surface properties and electrochemical activity.

Microstructure and friction properties of NiTi2-based composite layer prepared by ultrasonic assisted underwater wet laser deposition

An in situ TiC-enhanced NiTi2-based composite deposition layer was prepared by ultrasonic assisted underwater wet laser deposition. The evolution of the microstructure and interface state, and the friction properties in the air and brine solution environments of the deposition layer were analyzed and researched. The results demonstrated that the thermal and steady-state cavitation from ultrasound effects increase the total energy of the melt pool and promote mixing. The dilution rate of the ultrasonic assisted underwater laser deposition layer increases to 86.72 % compared with that of the underwater laser deposition layer (78.75 %). Ultrasonic reduced underwater laser deposition defects such as lack of fusion and weld slag, and enhanced the wettability between the deposition layer and substrate. The contact angle of the UWNT layer (24.40°, in average) is smaller than the WNT layer (29.80°, in average). Ultrasonic shortened the contact time between the deposition layer surface and the solution, which reduced the reaction of the Ni element with the brine solution. It also transformed the deposition layer from hypereutectoid microstructure to hypoeutectic microstructure and from planar interface to cellular interface. With the effect of the ultrasonic field, the elements in the deposition layer become more uniformly distributed and the secondary phases undergo spheroidization. In the ultrasonic assisted deposition layer, stress-induced FCC-Ti was discovered. Ultrasonic field also reduced the dispersion of the microhardness and increased the average microhardness to 863.3 ± 45.1 HV0.3. Tribology properties show that ultrasonic field effectively improved the wear resistance and friction stability of the ultrasonic assisted deposition layer. The COF of the ultrasonic assisted deposition layer was less affected by the environment, with values of 0.25 and 0.24 observed in air and brine solution, respectively. Overall, the research results in this paper can provide a new insight to improve the surface properties of NiTi2-based alloy underwater laser deposition.

Corrosion mechanisms of plasma sprayed porous coatings of Ni80Cr20 and alloy C-276 investigated by numerical and experimental method

Abstract: In this study, the corrosion performance of Ni80Cr20 and alloy C-276 (UNS N10276) coatings on 7075 aluminum alloy substrates was evaluated using a variety of performance characterization tests. Significant amounts of nickel oxide were found in the corrosion products of the two coatings that were stripped, with molybdenum in the two coatings that were not stripped effectively slowing down the corrosion rate. Both coatings selectively corrode Cr, where it is worth noting that the preferential corrosion of W elements in alloy C-276 has a positive effect on its surface protection. It is not only the amount of molybdenum content, but also the influence of the W element that leads to better corrosion resistance of alloy C-276 coating than Ni80Cr20 alloy coating. The coating spraying process due to process parameters and its own nature, etc. has caused different sizes of pores, while these pores in the corrosion process will have a certain degree of influence on the corrosion process. The size of the pore defects for the coating transverse corrosion effect was more significant, and small pore defects accelerated the corrosion process. The number of pore defects had a more significant effect on the longitudinal corrosion of the coating, and multiple pore defects slowed the corrosion process.

Mitigating Long Range Jahn‐Teller Ordering to Stabilize Mn Redox Reaction in Biphasic Layered Sodium Oxide

AbstractTo develop the next‐generation commercial oxide cathodes for sodium‐ion batteries, it is crucial to reduce the expensive Ni element content, and further regulate redox reaction of cheap transition metal elements such as Mn to elevate specific capacity. Nevertheless, the activation of Mn redox reaction (MRR) remains a challenge, and notably, MRR induces pronounced Jahn‐Teller effect, resulting in severe structural distortion and fast performance decay. Herein, activated by Na vacancies and weakened hybridization of O (2p)‐TM (3d‐t2g) orbital, a biphasic low‐Ni Mn‐based oxide P2/O3‐Na0.8Ni0.23Fe0.34Mn0.43O2 (P2/O3) exhibits reversible MRR, which performs the transition between Mn4+ and Mn3+ during charging and discharging. Due to the interlaced arrangement of P2‐type and O3‐type crystal domains in P2/O3, the long range Jahn‐Teller ordering is restricted to mitigate the cooperative distortion of MnO6 octahedron induced by MRR and the Jahn‐Teller effect is suppressed, ensuring sustained stable involvement of MRR in charge compensation. In addition, owing to the introduction of P2‐type phase, there is a significant reduction of the migration barrier for sodium ions and no obvious capacity decline after air exposure, leading to a marked enhancement in dynamic performance and air stability of P2/O3, respectively. Consequently, P2/O3 exhibits excellent electrochemical and processing performance.

Unveiling the influence of dopants on structural, defect chemistry, morphological and optical characteristics of NiO nanostructures

Abstract In this paper, undoped and doped (Fe, Co and Fe-Co) nickel oxide (NiO) nanostructures have been synthesized using co-precipitation method. Prepared samples were characterized for the structural, compositional, morphological and optical properties using x-ray diffraction, scanning electron microscopy (SEM), Energy dispersive spectrocopy (EDS), UV-visible spectroscopy and photoluminescence spectroscopy. Structural analysis confirmed the single cubic phase formation of undoped and doped samples. Defect chemistry showed that Fe-Co co-doped NiO possesses a lower density of defects than other samples. SEM results revealed the agglomeration of particles. EDS results confirmed the presence of Ni, O, Fe and Co in the respective undoped and doped samples. Optical analysis revealed the band edge shifts with the incorporation of dopants in the NiO crystal lattice confirmed the variation of band gap energy. Emission peaks were observed in the UV and visible regions. The Incorporation of dopants in the crystal lattice causes variation of emission centers. Surface oxygen vacancies and imperfections significantly impact the emission characteristics of NiO. Variable spectral response of NiO with dopant incorporation has potential for optoelectronic applications.

Kinetic modelling of carbothermal reduction of nickel oxide (NiO): Design of Experiments (DOE) approach

ABSTRACT This study presents a mathematical model to evaluate the kinetics of the carbothermal reduction of NiO using graphite. Based on the shrinking core theory, the model was validated against experimental data obtained under both isothermal and non-isothermal conditions. The shrinking core model for isothermal and non-isothermal conditions was created using MATLAB software for the kinetic modelling of the reduction process to determine the extent of reduction and the reaction rate. The kinetics were mathematically modelled from independently measured physical and thermodynamic properties of the reaction system and experimentally measured properties. The carbothermal reduction method was effective in producing Ni metal from NiO and was considered an established basis for evaluating the modelling aspect of the solid–gas system. The experimental investigation of carbothermal reduction was conducted using a statistical design of experiments (DOE), employing a two-level factorial design (23). The experiments were performed for a range of different factors, namely reduction temperature (800-1000°C), reduction time (1-2 h), and the molar ratio of graphite to NiO (0.5-1.5) on the extent of reduction. The extent of reduction increases with increasing reduction temperature, reduction time, and molar ratio of C to NiO. The highest extent of reduction (77.9%) was achieved at a reduction temperature of 1000°C, 2 h of reduction time, and the molar ratio of C to NiO as 1.5. The X-ray diffraction (XRD) studies confirmed the formation of Ni at a lower reduction time, but the intensity of the Ni phase was higher for a longer duration of reduction. SEM-EDS analysis of the reduced products confirmed the formation of Ni in the form of elongated and larger grains, along with traces of residual or unreacted carbon. The predicted extent of reduction is then compared with the experimentally measured results. The kinetic modelling results proved that both isothermal and non-isothermal shrinking core models showed similarity and significant closeness to the experimental data. The deviation between the experimental and model results could be due to the varying geometry and porosity of the reactants and intermediate products.

Impact of Metal Deposition on the Optical and Interface Properties of NiO: Growth and Characterization of NiO/Metal Thin Bilayer Films

Abstract Since transparent conductive oxides (TCOs) provide electrical conductivity together with optical transparency, they have found wide applications in optoelectronic devices and photovoltaics. Among the TCOs, nickel oxide (NiO) is challenging due to its inherent trade-off between transparency and electrical conductivity. To address this challenge, one effective approach is to deposit a metal layer onto NiO thin films. In this work, NiO, NiO/Au, NiO/Ag, and NiO/Cu thin films are prepared by sputtering and thermal evaporation technique on glass substrates and fully characterized finding the proper film for optoelectronic applications. The electrical and optical properties of the fabricated films are examined by four-point probe measurements and optical spectrometry. According to the obtained results, the NiO/Au, NiO/Ag, and NiO/Cu bilayers show sheet resistance of 200, 338, and 925 Ω / sq respectively while their optical bandgaps vary from 3.2 to 3.76 eV. These findings provide valuable insights into the perfor-mance of these films, making them potentially viable choices for various optoelectronic applications.

Synthesis of NiO: BaO nano structure by chemical method with Antibacterial activity to Escherichia coli, Klebsiella spp., Staphylococcus aureus, Staphylococcus epedermidis andcandida spp

Nanostructured materials have garnered significant attention due to their remarkable chemical and physical characteristics. Because of their exceptional qualities and potential uses in technology. Nanostructured transition metal oxides are one of the many nanomaterials that need particular attention. The goal of this study was to synthesize nickel oxide and barium oxide nanostructures by the reaction of Nano powders: nickel sulphate NiSO4, barium chloride BaCl3, and molten sodium hydroxide, potassium hydroxide (NaOH: KOH) and examine their physical and biological properties. According to the results of UV–Vis, the gap band of the nanostructure was calculated with a range of 3.6–3.27 eV. Scanning Electron Microscopy (SEM) pictures appear to create aggregated nanoparticles with particle size of 29 nm according to Transmission electron microscopy (TEM) with a spherical shape. This results proved that NiO: Ba nanostructure an efficient and stable. It was observed that the diameter of the inhibition zone bacteria include E. coli and Klebsiella spp. (21,18) mm while inhibition zone of bacteria S. aureus,S. epidermidisgram positive bacteria and yeast candida spp.(19,19 and 21)mm. As can be shown, the antibacterial activity of the (NiO: BaO), nanostructure increases with decreasing concentration and is more effective against E. coli gram-negative than it is against S. aureus and S. epedermidis gram-positive. This finding might be explained by the fact that, due to differences in their cell wall composition, gram-negative bacteria are more vulnerable to antibacterial medications than gram-positive ones. The synthesized NiO: Ba nanostructures had the potential for higher inhibition and killing of gram-negative than gram-positive bacteria.

Nickel-doped zinc tartrate (Ni@ZnT) nanocrystals: Synthesis, optical properties, and antimicrobial activity

This work used the sol-gel method to synthesize nickel-doped zinc tartrate nanocrystals (Ni@ZnT NCs) to study their optical properties and antimicrobial activities. Using the Scanning electron microscopy study, these NCs show irregular-shaped morphology. Their crystalline nature and average crystalline size of 45 ​nm were studied by X-ray diffraction. Using an Energy-Dispersive X-ray confirmed the presence of zinc (Zn), nickel (Ni), carbon (C), hydrogen (H), and oxygen (O) elements. FTIR analysis was used to identify several functional groups like O–H stretching (3461.6 ​cm−1), CO stretching mode (2367.55 ​cm−1), and stretching vibrations of Ni–Zn–O (below 800 ​cm−1). The thermal stability was confirmed by thermogravimetric analysis. UV–Vis spectroscopy studied the optical properties; an absorption peak represents the Zn–Ni transition at about 336 ​nm and a band gap of 3.86 ​eV and was also used to calculate the refractive index and extinction coefficient at 280 ​nm. For ZnT and Ni@ZnT NCs, the maximum absorption λ was found to be 295 ​nm and 278 ​nm. The antibacterial activity of ZnT and Ni@ZnT NCs was evaluated against Bacillus subtilis and Escherichia coli; for these strains, the NCs (15.3 ​mm and 15.6 ​mm) showed a somewhat larger zone of inhibition than ZnT (13.6 ​mm and 12.3 ​mm). The study also evaluated the antifungal activity of these materials against some fungal strains, such as Penicillium chrysogenum, Aspergillus niger, Candida albicans, and Fusarium spp, the zone of inhibition varied from 12 to 13.6 ​mm, and there was a significant difference between the two materials. Therefore, this work successfully synthesized Ni@ZnT NCs and studied their optical properties and antimicrobial activity.

Bifunctional SnO2/NiO/rGO nanocomposite electrode for hydrogen evolution reaction and detection of winter wheat cold-resistant RNA.

Aconvenient, non-toxic, and low-cost tin dioxide (SnO2)/nickel oxide (NiO)/reduced graphene oxide (rGO) nanocatalytic electrode was investigated, which can effectively promote the hydrogen evolution reaction and can also be used to construct a sensitive winter wheat cold-tolerant RNA sensor. Due to the good synergy and photocurrent generation between SnO2 and NiO, which accelerates the electron transfer and catalyzes the hydrolysis reaction, the resultant data for the hydrogen evolution reaction in alkaline environment of this material are very impressive, with cathodic current densities of up to 10mAcm-2. The marvelous heterostructures and photovoltaic properties form a signal amplification system, which enables the nanocomposites to have an excellent linear sensitivity in low-concentration RNA solutions. The single-stranded complementary RNA of the target RNA was immobilized on the surface of the nanocomposites, which enabled the materials to recognize the target RNA under enzyme-free conditions. The test results showed that the modified electrode materials had good single detection performance in a wide linear range from 0.1nM to 2mM, with the limit of detection (LOD) of 0.078nM. The developed nanocomposite electrode has good performance in hydrogen evolution and winter wheat cold-resistant RNA detection, and is a bifunctional device with superior performance.

The synergistic effects on the magnetic CoNi and Fe3O4 nanoparticles co-embedded porous carbon toward enhanced microwave absorbing performance

Abstract Lightweight and environmentally friendly three-dimensional biomass-derived porous carbon (3D BPC) holds great potential as a highly effective material for microwave absorption (MA) applications. However, the high complex permittivity and lack of magnetic loss in a single 3D BPC lead to impedance mismatching and a limited absorption bandwidth. Developing 3D BPC–based absorbers with multiple loss mechanisms and excellent impedance matching remains a notable yet challenging task. In this study, inspired by a synergistic composition and microstructure design, 3D BPC co-embedded with magnetic cobalt–nickel (CoNi) and iron(III) oxide (Fe3O4) nanoparticles (3D BPC@CoNi@Fe3O4) was developed. 3D BPC@CoNi@Fe3O4 exhibited consistently low complex permittivity, primarily due to the suppression of conductive loss, whereas the introduction of magnetic phases (CoNi and Fe3O4) enhanced the magnetic loss. Optimised impedance matching, achieved through the synergistic regulation of the electromagnetic parameters, emerged as the key mechanism for improving the MA properties. The as-synthesised 3D BPC@CoNi@Fe3O4 composite, with only 20 wt.% loading demonstrated a wide effective absorption bandwidth (reflection loss [RL] < −10 dB) of 6.08 GHz and an impressive minimum RL value of −40.08 dB. These findings offer valuable insights into the development of high-performance 3D BPC–based microwave absorbers through composition and microstructure optimisation.

Investigation of the Effect of Milling Time on Elemental Powders of Oxi‐Reduction Nickel and Hydrogenation–Dehydrogenation Titanium

Mechanical alloying (MA) is widely applied in the synthesis of blended elemental or prealloyed powders. This work evaluates the effect of milling time on elemental nickel and titanium powders produced by oxi‐reduction and the hydrogenation–dehydrogenation process, respectively. The powders are characterized by scanning electron microscopy, X‐ray diffraction, particle size, powder yield, and differential scanning calorimetry. It is observed that increasing the milling time promotes the formation of a structure composed of thin lamellae of nickel and titanium, which results in the beneficial effect of lowering the temperature for the formation of the intermetallic of the Ni–Ti system and in the powder yield achieved. The reduction of milling time in the MA process of NiTi alloys enhances technological efficiency by decreasing their overall processing time.

Optimizing electrokinetic remediation for pollutant removal and electroosmosis/dewatering using lateral anode configurations

Soil electrokinetics (SEK) research has been widely used in various fields such as soil remediation, dewatering, land restoration, geophysics, sedimentation, pollution prevention, consolidation, and seed germination. According to our most recent published research on SEK process design modifications during the last 30 years (1993–2022), more than 150 designs have been introduced to assure SEK’s maximum performance. Incorporating lateral electrodes/anodes was not documented in the existing literature, which motivated us to investigate the output of this design. In this study, we aimed to enhance the performance of the perforated cathode pipe soil electrokinetic remediation (SEKR) system (PCPSS) for removing inorganic pollutants by installing lateral anodes (LA-PCPSS) using two approaches. In the first approach, the LA-PCPSS was connected to different sources of applied voltages (DSAV) from different power supplies, while in the second approach, the entire operation system was connected to the same source of applied voltage (SSAV). We used the Taguchi approach (L9OA) to determine the optimal levels of applied voltages for the DSAV system. The results indicated that the DSAV-(LA-PCPSS) could be optimized at an applied voltage of 1 V cm−1 for the surface and the first and second lateral anodes. The indigenous Sr (elements found in the tested soil without artificial pollution) in kaolinite showed the best response among other elements (Ni and other indigenous elements) when optimizing the DSAV-(LA-PCPSS) using the Taguchi approach. Installing lateral anodes (position B) supplied to low applied voltage (0.5 V cm−1) improved the electroosmosis (EO) rate/dewatering. Reverse migration of ions was observed during the remediation of real contaminated soil using the SSAV-(LA-PCPSS). The DSAV-(LA-PCPSS) is considered an appropriate design for the SEKR of inorganic pollutants, and increases the EO flow/dewatering. Additionally, the increased energy consumption employing the DSAV-(LA-PCPSS) was extremely minimal compared to the traditional PCPSS, which is an economic advantage for SEKR research. The DSAV-(LA-PCPSS) is still under optimization/intensification process, and subsequent processes will be examined to achieve high efficiency.

Modeling of the perovskite nickelate SmNiO3 nucleation from amorphous thin films: A Volmer's thermodynamical approach

We present a thermodynamical model based on Volmer's nucleation theory adapted to the case of the perovskite nickelate SmNiO3 crystallization (SNO) from an amorphous (aSNO) thin film. This amorphous phase is synthesized via reactive magnetron sputtering and then subsequently annealed in air at temperatures between 725 and 925 K to crystallize it. This model allows to predict the theoretical nucleation rate of the crystallized perovskite phase according to the annealing temperature, the type of the nucleation (homogeneous and heterogeneous mechanisms) and to estimate some physical and thermodynamical data related to this transformation. A theoretical evaluation of the nucleation rate shows that the optimum temperature for crystallization is close to 800 K for which the nucleation rate can reach 1021 m-3.s-1 if considering both homogeneous and heterogeneous nucleation mechanisms. As the annealing temperature moves away from 800 K, the theoretical nucleation rate drops drastically, as observed experimentally by X-ray Diffraction (XRD) when we annealed 200 nm thick aSNO films. The good agreement between the presented model and the experimental crystallization results allows us to numerically evaluate some physical parameters not yet reported to date in the literature for SNO perovskites such as the surface energy between the amorphous and the crystallized SNO phases, the strain energy when the crystallization occurs and the enthalpy associated with crystallization.

Recrystallizing Sputtered NiOx for Improved Hole Extraction in Perovskite/Silicon Tandem Solar Cells

AbstractSputtering nickel oxide (NiOx) is a production‐line‐compatible route for depositing hole transport layers (HTL) in perovskite/silicon tandem solar cells. However, this technique often results in films with low crystallinity and structural flaws, which can impair electronic conductivity. Additionally, the complex surface chemistry and inadequate Ni3+/Ni2+ ratio impede the effective binding of self‐assembled monolayers (SAMs), affecting hole extraction at the perovskite/HTL interface. Herein, these issues are addressed using a recrystallization strategy by treating sputtered NiOx thin films with sodium periodate (NaIO4), an industrially available oxidant. This treatment improved crystallinity and increased the Ni3+/Ni2+ ratio, resulting in a higher content of nickel oxyhydroxide. These enhancements strengthened the SAM's anchoring capability on NiOx and improved the hole extraction at the perovskite/HTL interface. Moreover, the NaIO4 treatment facilitated Na+ diffusion within the perovskite layer and minimized phase separation, thus improving device stability. As a result, single‐junction perovskite solar cells with a 1.68 eV bandgap achieve a power conversion efficiency (PCE) of 23.22% for an area of 0.12 cm2. Perovskite/silicon tandem cells with an area of 1 cm2 reached a PCE of 30.48%. Encapsulated tandem devices retained 95% of their initial PCE after 300 h of maximum power point tracking under 1‐sun illumination at 25 °C.