Electrochemical Tests Research Articles

Controlled synthesis of NiCoS@Fe6(OH)12(CO3) as efficient electrocatalyst for oxidation reaction in seawater and urea

In today's world, the efficient preparation of clean energy has become a problem for every country. Hydrogen is a very clean and easy to prepare energy source. In this paper, a hybrid materials of (Fe6(OH)12(CO3)) and sulphide (Ni9S8/Co9S8) was demonstrated as a catalytic electrode for efficient oxidation reaction in seawater and urea. The catalysts were prepared by a three-step hydrothermal-sulfuration-hydrothermal reaction, and the layered composites of hydroxides and sulfides were co-grown into nano-arrays, which exposed more reaction centers and shortened the electron transfer path. The three metal cations were also able to demonstrate different corrosion resistance and excellent adsorption properties for different environments, allowing the catalyst to present better electrochemical activity in seawater as well as in urea solution. In the oxidation reaction in urea solution (1 M KOH+0.5 M urea), the required voltage was only 1.33 V at a current intensity of 50 mA/cm2, and in the water oxidation reaction in seawater, the required voltage was only 1.47 V at a current intensity of 50 mA/cm2 for Ni9S8@Co9S8@Fe6(OH)12(CO3). Unfortunately, the durability of the catalyst need to be improved, the current density dropped from 40 mA/cm2 to 35 mA/cm2 and then remained for 12 h. Meanwhile, the comparison of electrochemical performance tests was performed before and after the IT test, it can be clearly seen that the overall performance of Ni9S8@Co9S8@Fe6(OH)12(CO3) decreased after the stability test, which may be related to the shedding of active species from the surface of the catalyst. As you can see through density functional theory (DFT) that Ni9S8 can promote the adsorption energy of urea and Co9S8 lowers the barrier to electron conduction. Many conjectures were made and confirmed in this study, and finally, it is hoped that seawater as well as industrial wastewater can be better utilized for the production of clean energy.

Proton vs Electron: The Dual Role of Redox-Inactive Metal Ions in Permanganate Oxidation Kinetics.

Redox-inactive metal-ion-driven modulation of the oxidation behavior of high-valent metal-oxo complex has garnered significant interest in biological and chemical synthesis; however, their role in permanganate (Mn(VII)) oxidation for the removal of organic pollutants has been largely neglected. Here, we uncover the impact of six metal ions (i.e., Ca2+, Mg2+, Ni2+, Zn2+, Al3+, and Sc3+) presenting in water environments on Mn(VII) activity. These ions uniformly boost the electron and oxygen transfer capabilities of Mn(VII) while impeding proton transfer, as evidenced by electrochemical tests, thioanisole probe analysis, and the kinetic isotope effect. The observed effects are intricately linked to the Lewis acidity of the metal ions. Further mechanistic insights reveal that Mn(VII) can interact with metal ions without direct reduction. Such interactions modify the electronic configuration of Mn(VII) and create an acidic microenvironment, thus increasing its electrophilicity and the energy barrier for the abstraction of proton from organic substrates. More importantly, the efficacy of Mn(VII) in removing phenolic pollutants is regulated by these ions through changing the driving force for proton and electron transfer, i.e., facilitated at pH > 4.5 and inhibited at lower pH. The contribution of active Mn intermediates is also discussed to reveal the oxidative mechanism of the metal ion/Mn(VII) system. These findings not only facilitate the rational design of Mn(VII) oxidation conditions in the presence of metal ions for water decontamination but also offer an alternative paradigm for enhancing electrophilic oxidation.

Preferred crystal surface exposure and near-crystal surface desolvation construct efficient Zn plating/stripping reversibility

The Zn/electrolyte interface stability is related to HER, passivation, dendrites, corrosion and Zn2+ deposition orientation. Reducing the occupation of H2O dipoles in the inner layer of electrical double layer (EDL) is conducive to the inhibition of interfacial side reactions and directing the deposition of Zn2+ along the (002) crystalline surface, which are beneficial to the reduction of dendrites and the improvement of plating/stripping reversibility. A mechanism is elucidated by which Acetyl-L-carnitine Hydrochloride (A-L-CN) reconfigures the EDL structure and guides the selective deposition of Zn2+ in this paper. Theoretical calculations show that A-L-CN can cover the high-energy active sites on the Zn (101) crystal plane and control the specific crystal orientation of the deposits along the (002) crystal plane to produce faceted epitaxial growth. The electrochemical test results show that the Zn anode has excellent plating/stripping reversibility as well as good cumulative capacity (10 mA cm−2, 1 mA h cm−2, ACE of 99.80 %, CPC of 7,753 mA h cm−2). The assembled Zn2+ hybrid supercapacitor (ZHS) and Zn//PANI full cell show excellent performance (ZHS up to 60,000 cycles; the capacity retention ratio of Zn//PANI full cell is 76.7 % after 1,000 cycles). The work offers the possibility of achieving stabilized Zn/electrolyte interface performance.

Dibenzodioxin-Based Polymers of Intrinsic Microporosity with Enhanced Transport Properties for Lithium Ions in Aqueous Media.

Boosting the transport and selectivity properties of membranes based on polymers of intrinsic microporosity (PIMs) toward one specific working analyte of interest is challenging. In this work, a novel family of PIM membranes, prepared by casting and exhibiting optima mechanical properties and high thermal stability, was synthesized from 4,4'-(2,2,2-trifluoro-1-phenylethane-1,1-diyl) bis(benzene-1,2-diol) and two tetrafluoro-nitrile derivatives. Gas permeability measurements evidenced a CO2/CH4 selectivity up to 170% relative to the reference polymer, PIM-1, in agreement with their calculated fractional free volume and the analysis of the textural properties by N2 and CO2 gas adsorption. Besides, the chemical modification by acid hydrolysis of the PIM membranes favored the permeability for lithium ions (LiCl 2M, 6 × 10-9 cm2·s-1) compared to other alkali metal analogs such as sodium (NaCl 2M, 7.38 × 10-10 cm2·s-1) and potassium (KCl 2M, 1.05 × 10-9 cm2·s-1). Moreover, the complete mitigation of the crossover of redox species with higher molecular sizes than the ions from alkali metal salts was confirmed by using in-line benchtop NMR methods. Additionally, the modified PIM membranes were measured in a symmetric electrochemical flow cell using an aqueous electrolyte by combining lithium ferro/ferricyanide redox compounds and lithium chloride. The electrochemical tests showed low polarization, high-rate capability, and capacity retention values of 99% when cycled at 10 mA·cm-2 for over 50 cycles. Based on these results, these polymers could be used as highly selective and conducting membranes in electrodialysis for lithium separation and lithium-based redox flow batteries and as a protective layer in high-energy density lithium metal batteries.

Achieving high capacity by controlling the size of Fe/Co-N-C(t) in the cathode of lithium-oxygen batteries

Two samples are synthesized in a bimetallic system of iron and cobalt using a Metal-Organic Framework (MOF). The duration of precursor addition to the reaction vessel is controlled to synthesize Fe/Co-N-C(10 h) and Fe/Co-N-C(At once). The structural properties of the samples are analyzed using XRD, Raman, FT-IR, SEM, TEM, BET, TGA and ICP. Electrochemical tests are performed to evaluate the activity of the prepared catalysts as lithium-oxygen battery cathode materials. The Fe/Co-N-C(At once) sample, with its larger surface area, shows a greater discharge capacity of 8670 mAhg-1 compared to the Fe/Co-N-C(10 h) sample, which has a discharge capacity of 8339 mAhg-1. However, the Fe/Co-N-C(10 h) sample has a larger electrochemical active surface area due to the presence of more metals in the MOF shell. This results in higher ORR/OER activity in an alkaline environment and greater stability (180 h) as a lithium-oxygen battery cathode compared to the Fe/Co-N-C(At once) sample, which exhibits stability for 90 h.

Harnessing the Potential of Hollow Graphitic Carbon Nanocages for Enhanced Methanol Oxidation Using PtRu Nanoparticles.

Direct Methanol Fuel Cell (DMFC) is a powerful system for generating electrical energy for various applications. However, there are several limitations that hinder the commercialization of DMFCs, such as the expense of platinum (Pt) at market price, sluggish methanol oxidation reaction (MOR) due to carbon monoxide (CO) formation, and slow electrooxidation kinetics. This work introduces carbon nanocages (CNCs) that were obtained through the pyrolysis of polypyrrole (Ppy) as the carbon source. The CNCs were characterized using BET, XRD, HRTEM, TEM, SEM, and FTIR techniques. The CNCs derived from the Ppy source, pyrolyzed at 750 °C, exhibited the best morphologies with a high specific surface area of 416 m2g-1, allowing for good metal dispersion. Subsequently, PtRu catalyst was doped onto the CNC-Ppy750 support using chemical reduction and microwave-assisted methods. In electrochemical tests, the PtRu/CNC-Ppy750 electrocatalyst demonstrated improved CO tolerance and higher performance in MOR compared to PtRu-supported commercial carbon black (CB), with values of 427 mA mg-1 and 248 mA mg-1, respectively. The superior MOR performance of PtRu/CNC-Ppy750 was attributed to its high surface area of CNC support, uniform dispersion of PtRu catalyst, and small PtRu nanoparticles on the CNC. In DMFC single-cell tests, the PtRu/CNC-Ppy750 exhibited higher performance, approximately 1.7 times higher than PtRu/CB. In conclusion, the PtRu/CNC-PPy750 represents a promising electrocatalyst candidate for MOR and anodic DMFC applications.

Effect of laser-induced grain growth on the electrochemical and immersion corrosion behavior of electrochemical deposited Ni coatings

In this study, the introduction of laser irradiation during the electrochemical deposition of Ni coatings was employed to investigate the evolution of surface morphology, microstructure, and residual stress. Furthermore, the impact of laser on corrosion performance was examined through electrochemical and immersion corrosion tests. The results showed that introducing a laser resulted in a uniform electrochemically deposited particle size distribution, and the shape evolved from granular to pyramidal. However, the average grain size increased from 0.4 ± 0.1 μm to 0.6 ± 0.3 μm after adding laser, and the grain morphology also transformed from equiaxed to columnar grains. In addition, the surface roughness increased from 34 ± 3 nm to 122 ± 16 nm compared to not adding a laser. The internal stress changed from 54 ± 17 MPa to −113 ± 19 MPa, indicating that the original tensile stress evolved into compressive stress. Electrochemical and immersion corrosion indicate that after adding laser, the passive current density decreased from 3.8 × 10−6 A·cm−2 to 6.9 × 10−7 A·cm−2 (reduced by approximately 81.8 %), indicating a significant improvement in corrosion resistance. This is attributed to the stability and density of the passive film. Although the average grain size and surface roughness increase, the uniformity of surface deposited particles improves the uniformity of electrochemical distribution, accelerates the formation of uniformly dense passive film, and limits the expansion of corrosion pits under the combined action of compressive stress.

Response characteristics of platinum coated titanium bipolar plates for proton exchange membrane water electrolysis under fluctuating conditions

Voltage fluctuations in energy input not only impact the overall hydrogen production efficiency and stability of Proton Exchange Membrane Water Electrolysis (PEMWE) systems but also pose significant challenges to the long-term service life of individual components. This study focuses on the key component − bipolar plates and investigates the response behavior of platinum-coated titanium bipolar plates under simulated fluctuating voltage conditions. By integrating surface phase analysis and electrochemical testing results, this research elucidates the response characteristics of the bipolar plates to different voltage waveforms and frequencies. And the findings hold substantial significance for the upstream energy control in hydrogen production through water electrolysis.

Activation of peroxymonosulfate by boron nitride loaded with Co mixed oxides and boron vacancy for ultrafast removal of drugs in surface water

The mediation of vacancy in catalysts is crucial for the enhancement of oxidant activation. Here the boron nitride loaded with Co mixed oxides (Co2O3-CoO) and boron vacancy (Bv) catalyst (Co/BN-X) was prepared to degrade sulfamethoxazole (SMX) by activating peroxymonosulfate (PMS). Under dark condition, Co/BN-3+PMS system can completely remove SMX in surface water within 15 min, and its removal efficiency constant (0.5154 min−1) was 4.0 and 6.7 times greater than those of Co/BN-2+PMS (0.1284 min−1) and Co/BN-1+PMS (0.0771 min−1), respectively. The system showed excellent performance in different influencing factors and cyclic experiments, and exhibited good practical application potential in secondary effluent. Electron paramagnetic resonance, radical quenching and electrochemical tests certified that singlet oxygen (1O2) was the major active species, followed by •O2–, and SO4•–, further elaborating the activation pathway of PMS in Co/BN-3+PMS system. The density functional theory (DFT) calculations confirmed that CoO and PMS-O2 sites were the main reaction sites, and the existence of Bv reduced the adsorption energy of Co/BN-3 for PMS. This work reveals the synergistic effect between Co oxide sites and Bv on the catalyst surface and offers a potential modification method to accelerate Fenton-like reaction.

Hydrophobic cement: Concept, preparation and application

Integral hydrophobic cement-based materials (CBMs) have traditionally been built by adding hydrophobic liquid solvents, hydrophobic solid powders, or admixtures modified by hydrophobic agents. In this work, we propose a new strategy to construct an integral hydrophobic CBMs based on direct hydrophobic cement. By ball milling, the 1.0 wt% stearic acid (SA) is adopted as modifier to prepare hydrophobic cement (SA1.0). SA1.0 process provides better dispersity in making CBMs. Hence, by using SA1.0 process, the CMB mechanical properties and durability can be improved. The mechanical and working performance of SA1.0 meet P·O 42.5 grade. Freeze-thaw resistance, sulfate resistance and electrochemical tests have demonstrated that CBMs prepared via SA1.0 process own excellent durability. Our findings provide new strategies for the formation of integral hydrophobic CBMs and a novel hydrophobic cementitious material for long-life CBMs.

Insight into the corrosion inhibition performance of dimethyldiallylammonium chloride acrylamide copolymer for mild steel in acidic solution

Dimethyldiallylammonium chloride acrylamide (DADMAC-AAM) copolymer was firstly applied as a novel corrosion inhibitor for carbon steel in acidic solution. Electrochemical, theoretical and computational methods were performed to illustrate the corrosion inhibition mechanism of DADMAC-AAM. Results of electrochemical tests indicated that DADMAC-AAM effectively slowed down corrosion rate of mild steel in HCl solution as a mixed-type corrosion inhibitor. Its corrosion inhibition efficiency increased with dosage, and the maximum value reached about 92.44 % with adding 100 mg/L. In-situ scanning vibration electrode technique illustrated that the corrosion inhibition performance of DADMAC-AAM increased with immersion time. Metal surface was covered with a dense hydrophobic film due to the physical-chemical adsorption of DADMAC-AAM molecules, and the adsorption behavior obeyed to the Langmuir adsorption isothermal model. Theoretical calculations were carried out to explain the corrosion inhibition mechanism, and the increase of active energy indicated that the strong inhibitive action of DADMAC-AAM molecule could be due to the increase of activation energy barrier of corrosion reaction. Results obtained from computational simulations proved that DMDMAC-AAM molecules adsorbed on metal surface through interactions between N or O and Fe atoms. This adsorption film could retard the invasion of corrosive species, thus protecting metal from corrosion.

Construction of a superhydrophobic surface with long-term durability on 5052 Aluminium for corrosion protection

Superhydrophobic surfaces have been demonstrated to offer exceptional corrosion protection for metal surfaces. However, long-term stability issues have plagued superhydrophobic surfaces. In this study, a durable superhydrophobic surface on aluminum (SHC-Al) was created using etching combined with anodizing followed by polydimethylsiloxane (PDMS) modification. To optimize the multi-scale rough structures, the optimal anodizing conditions were explored in detail. The superhydrophobic surfaces were analyzed using Field emission scanning electron microscopy (FESEM), Confocal laser microscopy (CLSM), X-ray energy spectrometry (EDS), Fourier transform infrared spectrometry (FTIR), X-ray photoelectron spectroscopy (XPS), contact angle (CA) measurements, stability tests, and electrochemical analysis. The results reveal the successful preparation of a nest-like micro-nano composite structure on metal surface, and the contact and sliding angles of SHC-Al were measured at 157.6° and 6°, demonstrating the formation of excellent superhydrophobic surface. Electrochemical tests showed a corrosion current density of only 1.38 × 10–9 A∙cm-2 for SHC-Al, with a corrosion inhibition efficiency of 99.97 %, highlighting its outstanding anti-corrosion performance. Furthermore, stability tests demonstrated the SHC-Al surface had long-term durability. This study not only provides new evidence for the preparation of long-lasting superhydrophobic surfaces, but also provides a new solution for the practical application of superhydrophobic surfaces.

Intercalation of multilayered Ti3C2Txelectrode doped with vanadium for highly sensitive electrochemical detection of dopamine in biological samples.

Theelectrochemical detection characteristics of the layered Ti3C2Tx materialwere enhanced by modifying its surface. Ti3C2Tx is used as the Ti - F chemical bond weakens with increasing pH levels. Ti3C2Tx is alkalinized by KOH, and F is substituted for - OH. The surface hydroxyl groups can be eliminated by intercalating K+. This study elaborates on the hydrothermal production of vanadium-doped layered Ti3C2Tx nanosheets intercalated with K+. Thedevelopment of a sensitive dopamine electrochemical sensor is outlinedby intercalating a vanadium-doped multilayered K+ Ti3C2Tx electrode. The chemical, surface, and structural composition of the synthesized electrode for dopamine detection was investigated and confirmed. The sensor exhibits a linear range (1-10 µM), a low detection limit (8.4 nM), and a high sensitivity of 2.746 µAµM-1cm-2 under optimal electrochemical testing conditions. The sensor also demonstrates exceptional anti-interference capabilities and stability. The sensor was applied todetection of dopamine in (spiked) rat brains, human serum, and urine samples. This study introduces a novel approach by utilizing K+ intercalation of vanadium-doped Ti3C2Tx-based electrochemical sensors and an innovative method for dopamine detection. The dopamine detection revealed the potential of (V0.05) K+ Ti3C2Tx-GCE for practical application in pharmaceutical sample analysis.

Dual redox centers in MnCo2O4 nanorod cathode for highly efficient capacitive deionization

Capacitive deionization (CDI) technology via faradic electrodes with active redox pairs has achieved tremendous success in desalination. However, the inner collaborative mechanisms of multi-redox centers in electrodes are rarely deep-analyzed. Thus, this work intensively investigated the inner enhanced mechanisms of multi-redox centers, starting from the dual-redox-based MnCo2O4 nanorod (MCO-NR) cathode in capacitive desalination. The electrochemical tests indicated a surface capacitive ratio of MCO-NR as high as 86 % when the scan rate was 100 mV s−1. Multi-dimensional CDI tests demonstrated that the highest capacity of MCO-NR could reach 61.78 mg g−1, with four theory models elaborating the electrosorption kinetics and maximum desalination capability. The refined ex-situ XPS measurements, carefully designed comparative experiments, and DFT calculations were used to analyze the Na+ (de)intercalation characteristics, the inner enhanced electrosorption mechanisms of dual redox centers, and the effects that the Mn redox center exerts on the MnCo2O4 structure. These results showed the superiority of dual- or multi-redox-center-based faradic capacitive desalination, providing a new perspective for designing high-property faradic electrode materials.

Constructing a multilayered film β[sbnd]PbO2[sbnd]ZrO2 electrode for energy-efficient zinc electrowinning

The zinc electrowinning process demands considerable energy, prompting the quest for energy-efficient solutions to curtail costs. Hence, the development of energy-saving anode materials for zinc hydrometallurgy is an important issue. Herein, multilayered PbO2 film materials were prepared through thermal decomposition and composite electrodeposition, yielding a new PbO2–ZrO2 electrode featuring ZrO2 particles as the second phase for energy-saving zinc electrowinning. The introduction of ZrO2 leads to reduced PbO2 crystal size, heightened the specific surface area of the electrode, and preferential growth of crystal planes. Electrochemical tests underscore that the PbO2–ZrO2 electrode manifests a reduced charge-transfer resistance (Rct) and overpotential alongside a 46.15 % extension in service life compared to the pure PbO2 electrode. Simulated zinc electrowinning experiment affirms PbO2–ZrO2 electrode has a 3.63 % surge in the current efficiency and a substantial 244.61 kWh/t reduction in energy consumption relative to the traditional Pb–0.6wt%Ag anode. This study provides a strategic framework for designing and developing cost-efficient, cost-effective anode materials, promoting advancements in energy conservation and consumption reduction within zinc electrowinning processes.

Degradation mechanism and assessment for different cathode based commercial pouch cells under different pressure boundary conditions

Lithium-ion pouch cell exhibits expansion behavior during cycling, which determines the overall performance and external pressure evolution. It is significant to reveal the impact of pressure boundary conditions on battery degradation. This study investigated the degradation mechanism of different cathode-based pouch cells (LiFePO4 (LFP) and Li(Ni0.6Co0.2Mn0.2)O2 (NCM622)) under four distinct pressure boundary conditions (I-II. clamping with two foam pads having varying compression force deflection (CFD) respectively, III. without foam pad, IV. unpressurized). One hundred of pre-experiment cycles determined the optimal external pressure (12.5 kPa) to slow down the degradation process. Subsequently, multi-cell paralleled cycling experiments were conducted for 1000 cycles. The capacity degradation of LFP and NCM cells with the optimal condition was 6.0 % and 12.6 % less than that of unpressurized cells. The electrochemical tests indicated that unpressurized cells had the fastest rate of lithium-ion loss, which is related to solid electrolyte interface (SEI) film growth and lithium plating. Post-mortem characterization analysis further revealed that the pressure boundary condition is crucial for the electrode morphology, pressure distribution, and gas generation, which affect battery degradation. The pressurized cells’ surface exhibited fewer instances of lithium plating. With the stiff foam clamped, pouch cell swelling can be absorbed while maintaining contact between cell components, resulting in fewer electrode folds and cracks. This study provides valuable insights for designing long-lifespan battery modules or packs.

Preparation of CeO2QDs-g-C3N4/C composites and electrochemical determination of aflatoxin B1

The presence of Aflatoxin B1 (AFB1) in food represents a significant threat to human health, leading to the development of cancer. The key factor for effective trace detection technology lies in the utilization of sensor materials that exhibit excellent selectivity and high sensitivity properties. In this study, a successfully synthesis of g-C3N4/C with a high specific surface area uses melamine and houttuynia cordata stem as starting materials. A CeO2QDs-g-C3N4/C composite was prepared by hydrothermally anchoring cerium oxide quantum dots (CeO2QDs) onto the surface of g-C3N4/C, the high redox efficiency of CeO2QDs and the small size limitation effect significantly improve the sensing performance. The composite was characterized by XRD, XPS, SEM, TEM, and N2 adsorption-desorption. The results revealed that, the CeO2QDs-g-C3N4/C composite sensor material exhibited significant advantages with a large specific surface area, a well-defined micropore structure, and abundant reactive sites. In addition, electrochemical activity tests are conducted using EIS, CV, and DPV for the purpose of electrochemical investigations. The CeO2QDs-g-C3N4/C/GCE exhibits exceptional electrocatalytic activity against AFB1, with a wide linear response range of 100–1300 pg ml-1, an impressively low detection limit (LOD) of 6.61 fg ml-1 (S/N = 3), and a sensitivity of 0.985 pg μM ml-1μA-1. Furthermore, the stability, repeatability, and interference experimental response errors all remain below 5 %. It is also noteworthy that, the sensor material demonstrates excellent practicality in AFB1 assays conducted on real samples, which serves to illustrate its immense potential for applications in food safety evaluation.

Microstructure refinement, mechanical performances and degradability of biomedical Zn-2Cu alloy by ultrasonic melting and homogenization treatment

Zn alloys are deemed to be desired body implant materials because of their moderate degradation rate. In this paper, the microstructural evolution, mechanical performances, and degradability of Zn-2Cu alloy prepared by ultrasonic melt treatment (UMT) with different ultrasonic powers (0 W, 300 W, 600 W, and 900 W) were systematically studied. Under the condition of UMT, the coarse α-Zn grains of Zn-2Cu alloy were refined into fine equiaxed grains and the mean size was significantly decreased from 133.4 μm to 65.3 μm when the ultrasound power was enhanced. The precipitating CuZn5 phase was significantly refined from the coarse block into the spherical shape. Moreover, the fraction of the CuZn5 precipitates of the Zn-2Cu alloy was greatly reduced with the increase of ultrasonic power. Tensile tests showed that the ultimate tensile strength (UTS), yield strength (YS), and elongation (El) of Zn-2Cu alloy were remarkably enhanced to 203 MPa, 167 MPa, and 8.14 %, respectively, when the Zn-2Cu alloy melting was treated by 600 W power. It was found by electrochemical polarization test that the degradation rate of Zn-2Cu alloy treated by UMT with 0 W, 300 W, 600 W, and 900 W power in Hank’s solution was gradually decreased to 1.6312 mm/a, 1.3206 mm/a, 1.0992 mm/a, and 1.2832 mm/a, respectively. In addition, after the Zn-2Cu alloys were immersed in Hank’s solution for 30 days, the degradation rate of samples was summarized as 0 W alloy (0.472 mm/a) > 300 W alloy (0.436 mm/a) > 900 W alloy (0.412 mm/a) > 600 W alloy (0.398 mm/a). The studies verified that the UMT was a very valuable technology for preparing Zn-2Cu alloy, which can meet the requirement of mechanical properties and degradable rate as a promising implant material.

Constructing three-dimensional GO/CNT@NMP aerogels towards primary lithium metal batteries

Abstract Graphene oxide (GO) can serve as cathode material for a viable primary lithium metal battery due to its richness in oxygen-containing functional groups. However, its application is hindered by non-conductivity of GO. Herein, a proposed electrode structure design strategy is carried to regulate the electron and ion conductivity of the graphene oxide aerogel (GO/CNT@NMP) electrode while retaining the original energy density. GO/CNT@NMP exhibits a discharge specific capacity of 703 mAh g−1 and an ultra-high energy density of 1655.76 Wh kg−1 at a low rate of 0.02 A g−1. Additionally, it achieves a maximum discharge rate of 1.4 A g−1, five times higher than the initial maximum discharge rate of GO. Characterization and electrochemical tests reveal that the excellent performance of GO/CNT@NMP can be attributed to its porous structure, high electrical conductivity, and large layer spacing. This study presents a potent strategy for the advancement of ultra-fast primary batteries, aiming to integrate ultra-high energy density and high-rate discharge capabilities.

Influence of TiO2-MWCNTs nanohybrid material on the corrosion resistance of epoxy low-zinc coatings

Aiming to improve the corrosion resistance of epoxy low-zinc coatings in marine environments, TiO2-MWCNTs nano-hybridized materials were prepared by sol-gel method in this study, and different contents of reinforcing phases were implanted as to improve the anticorrosive properties of epoxy low-zinc coatings. Characterization of the microscopic morphology, physical phase composition and chemical structure of the TiO2-MWCNTs materials demonstrated that the TiO2 hybridization was successful and the loading of TiO2 improved the dispersion of MWCNTs. To investigate the effect of the additive reinforcing phase on the mechanical and corrosion resistance of the coatings by characterizing the coating microscopic morphology, surface wettability, substrate adhesion, and impedance changes at different immersion times. The above results demonstrated that the epoxy composite coating had lower surface energy and 16 % larger surface contact angle compared with the pure epoxy low-zinc coating; the 0.4 wt% TiO2-MWCNTs/epoxy composite coating had the highest adhesion of 6.52 MPa. The electrochemical test results indicated that the TiO2-MWCNTs/epoxy low-zinc composite coating had the largest self-corrosion potential, the smallest self-corrosion current density of 4.538 μA/cm2, and the largest impedance of 242.3 KΩ/cm2. The addition of TiO2-MWCNTs reinforcing phase significantly extended the barrier protection time of the epoxy low zinc coating and maintained good corrosion resistance throughout the immersion cycle.