Low Corrosion Research Articles

Operando carbon corrosion measurements in fuel cells using boron-doped carbon supports

Carbonaceous materials are the most common catalyst supports in proton exchange membrane fuel cell (PEMFCs), yet their corrosion is one of the limiting factors in achieving high durability. Herein, we doped carbon supports with boron (B) to increase the corrosion-resistance of the support. Two types of B-doped carbons were synthesized and studied as platinum support materials. They varied in their morphologies, surface areas, and the types of boron species. The durability of Pt/B-doped carbon catalysts was investigated using the US-DOE catalysts’ supports accelerated stress test (AST) and a mass-spectrometer connected to the fuel cell effluent stream to quantify the mass of corroded carbon support in operando. The addition of boron to the carbon increased the stability of Pt catalysts in long-term usage of PEMFC. After 4000 AST cycles, more than 50 % of initial current density was preserved for the boron-containing systems, while less than 30 % of it remained with Vulcan carbon (Pt/V). Also, the Pt/B-doped carbon samples demonstrated better electrochemical active surface area (ECSA) stability when compared to Pt/V. Carbon loss measurements showed that B-doped carbons have higher resistance to electrochemical corrosion than unmodified carbon. Specifically, the substitutional boron-doped carbon demonstrated an extremely high stability and low corrosion rate.

Comparative study on the corrosion behavior of two arc spraying coatings in simulated marine environments

The corrosion behaviors of arc spraying 5083Al and Zn15Al coatings in a simulated marine environment were comparatively analyzed. The 5083Al coating exhibited lower corrosion rates and higher polarization resistance than the Zn15Al coating. Due to the lower solubility and higher supersaturation of Al(OH)3, the corrosion products of 5083Al coating presents a faster deposition rate and causes a denser and blocky corrosion products layer, which inhibits the penetration of Cl−, thereby enhancing corrosion resistances. Furthermore, in the case of coating cracking, the 5083Al coating, with lower potentials than EH36 steel matrix and lower self-discharge rate than the Zn15Al coating, acting as the sacrificial anode, is more suitable to provide durable protection for steels in marine environments.

Optimizing hematite filter cake treatment using reducing agents

In drilling operations, the formation of a filter cake is crucial for well stability, but its removal post-drilling is essential to restore rock formation productivity. This study focuses on hematite-based filter cakes and investigates factors influencing their solubility and removal, addressing a significant knowledge gap in the field. The research methodology involves examining the effects of various factors, including types and concentrations of reducing agents, temperature, particle size, and treatment duration, on the dissolution process. Notably, Nuclear Magnetic Resonance (NMR) tests are employed to assess the treatment's impact on core porosity. Among the diverse reducing agents examined, ferrous chloride emerges as the optimal choice for effectively enhancing hematite solubility. Particularly, a composite solution of ferrous chloride (10 wt.%) and hydrochloric acid (6 wt.%), was highly efficient demonstrated by exhibiting rapid solubilization of hematite filter cakes. A removal efficiency of approximately 99%, with a parallel enhancement in core permeability was achieved. NMR tests reveal the treatment's success in reinstating the porosity system, which had undergone reduction due to drilling fluid particles. Crucially, the solution exhibits a considerably lower corrosion rate than concentrated hydrochloric acid, highlighting its potential to mitigate environmental concerns while ensuring efficient filter cake removal. The findings of this research provide valuable insights into optimizing post-drilling operations, balancing environmental sustainability and operational efficiency. The identified composite solution offers a promising approach to efficient filter cake removal while mitigating environmental concerns associated with corrosion. Overall, this study contributes to advancing the understanding and practice of well productivity enhancement in the oil and gas industry.

Beneficial effect of 4% Ta addition on the corrosion mitigation of Ti–12% Zr alloy after different immersion times in 3.5% NaCl solutions

Abstract The recent study reports the fabrication and corrosion behavior of two Ti alloys, 88% Ti–12% Zr and 84% Ti–12% Zr–4% Ta, in 3.5% NaCl electrolyte. These alloys were manufactured using powder metallurgy, where the powders were mixed, ball milled, and sintered. The corrosion behavior of these alloys was examined using various electrochemical and spectroscopic tests. Cyclic polarization experiments indicated that adding 4% Ta reduces corrosion of the TiZr alloy by suppressing anodic dissolution, resulting in a lower corrosion rate. The Nyquist and Bode impedance spectra for the tested alloys revealed that the presence of 4% Ta within TiZr alloy highly decreases the corrosion by increasing the impedance of the interface, the maximum degree of phase angle, and polarization resistance. The chronoamperometric current measured at −0.10 V (Ag/AgCl) proved that the presence of 4% Ta powerfully alleviates both uniform and pitting corrosion for TiZr alloy by lowering the obtained absolute currents. The surface investigation using scanning electron microscopy confirmed the homogeneity of the surfaces. The elemental analysis performed on the surface using energy dispersive spectroscopy revealed that the surface of TiZr alloy forms a top film including different oxides such as TiO2 and ZrO2, and for TiZrTa alloy, the surface has TiO2 + ZrO2 plus TaO2. Experiments demonstrated that Ta has the ability to increase the corrosion passivation of TiZr alloy.

Corrosion and Protection of Electrocatalysts toward Advanced Energy Technologies

AbstractHigh‐efficiency electrocatalysts play an important role in clean energy conversion technologies. Generally, electrocatalysts in different environments, including voltage, acid, and alkali electrolytes, are more susceptible to corrosion, which will induce structural and performance changes. Based on the latest achievements in the corrosion and protection of electrocatalysts in advanced energy technologies, this review mainly studies the application of various corrosion strategies to construct superior electrocatalysts, including chemical etching, metal corrosion transformation, and corrosion reconstruction, and their affecting factors are also appraised and summarized. To improve the stability of electrocatalysts, various corrosion inhibition strategies, such as carrier improvement and composition regulation accompanied by structure optimization, are reviewed. In addition, the application of catalyst corrosion in electrochemical energy technologies is examined from the perspective of the structure‐activity‐performance relationship. In the end, this article concludes the perspective and challenges of electrocatalyst corrosion in energy conversion and storage technologies. This article provides insights and directions for designing electrocatalysts with high efficiency and low corrosion, which is beneficial for developing corrosion chemistry for sustainable energy technologies.

Structurally Tunable Graphitized Mesoporous Carbon for Enhancing the Accessibility and Durability of Cathode Pt‐Based Catalysts for Proton Exchange Membrane Fuel Cells

Low Pt utilization and intense carbon corrosion of cathode catalysts is a crucial issue for high‐efficiency proton exchange membrane fuel cells due to the highly demanded long‐term durability and less acquisition/application cost. Herein, structurally tunable graphitized mesoporous carbon (GMC) is obtained by direct high‐temperature pyrolysis and in situ‐controlled mesopore formation; the structure‐optimized GMC1300‐1800 exhibits a mesopore size of 7.54 nm and enhanced corrosion resistance. Functionalized GMC1300‐1800 is loaded with small‐sized Pt nanoparticles (NPs) (1.5 nm) uniformly by impregnation method to obtain Pt/GMC1300‐1800 and form an “internal platinum structure” to avoid sulfonic acid groups poisoning as well as ensure O2/proton accessibility. Hence, the electrochemically active surface area (ECSA) of Pt/GMC1300‐1800 reaches 106.1 m2 g−1Pt, while mass activity and specific activity at 0.9 V are 2.1 and 1.4 times those of commercial Pt/C, respectively. Notably, the ECSA decay is less than 17% for both 30 000 cycles’ accelerated durability tests (ADTs) of Pt attenuation and carbon attenuation. Accordingly, the optimized mesoporous structure of GMC1300‐1800 significantly decreases the coverage of sulfonic acid groups on Pt NPs, leading to the highest peak power density in the single‐cell test. Density functional theory calculations demonstrate the synergistic effect between graphitization and mesoporosity on enhancing the accessibility and durability of the catalysts.

Evaluation of innovative fluroapatite /silicon dioxide modified zirconia nanocomposites coated on Ti–13Nb–13Zr alloy for dental implant application

Dental implants are intended to function as a durable method for replacing missing teeth. A biocompatible dental alloy is used to achieve integration with the jawbone through Osseointegration. This creates a strong base for the implant, allowing it to withstand the mechanical forces generated during biting and chewing. Dental alloys are commonly subjected to various mouth conditions known for their intricate corrosion potential. Corrosion can weaken the structural integrity of the implant, causing issues such as implant loosening, micro-motion at the implant-bone contact, implant fracture, allergic reactions, toxicity, and possible disruption of the Osseo integration process. To improve the alloy's corrosion resistance and biocompatibility, its surface can be altered using nanocomposite materials. The materials provide a protective coating to the alloy, creating a physical barrier that effectively prevents corrosive substances from reaching the underlying bulk material. This study involves modifying the surface of the dental alloy Ti–13Nb–13Zr with Fluroapatite (FAP)/Silicon dioxide (SiO2) modified zirconia (ZrO2) nano composites. The altered surfaces are then studied in simulated body fluid and artificial saliva solutions using in vitro methods. The FAP/SiO2 modified ZrO2 nanocomposites is applied onto a Ti–13Nb–13Zr alloy utilizing Electrophoretic deposition and Dip coating techniques. The coated samples were analysis utilizing FTIR, XRD, and SEM with EDS. Corrosion analysis was carried out on coated and uncoated samples using Electrochemical methods in simulated body fluid and artificial saliva solution. The biocompatibility is assessed using MTT assay, contact angle, and immersion testing in both SBF and Artificial saliva. EIS and corrosion study results show that FAP/SiO2 modified ZrO2 nanocomposites coated Ti13Nb13Zr alloy has high polarization resistance, low corrosion rate, and good charge transfer resistance, indicating excellent corrosion resistance. The contact angle study showed that the surface-modified Ti13Nb13Zr alloy is superhydrophilic, increasing implant surface osseointegration. Cell viability measurements reveal good cell growth, while immersion investigations show calcification, leading to enhanced osseointegration between the implant and its surrounding tissues. hence, it is an excellent material for dental implants application.

A novel method for synthesis of nonylated diphenylamine by alkylation of diphenylamine with nonene over Fe-promoted SO42-/ZrO2 catalysts

As a green and efficient antioxidant, nonylated diphenylamine (NDPA) is of great significance to fields such as lubricants, synthetic rubber, and plastic. However, traditional catalysts for synthesizing NDPA still exhibit drawbacks of low efficiency, equipment corrosion, non-renewability, and environmental pollution. To overcome these challenges, a series of Fe-promoted SO42-/ZrO2 catalysts were successfully developed and employed for the first time in the alkylation of DPA and NON to synthesize NDPA in our present work. Both synthesis variables of catalysts and reaction conditions were well optimized. The as-synthesized NFe2.50S1.0Z catalyst possessed excellent catalytic performance with a high yield of mono- and di-nonyl-diphenylamine, as well as better reusability and stability than activated clay. After 5 reaction cycles, over 90 % of the catalytic activity could be recovered by the thermal treatment. These observations make the Fe-promoted SO42-/ZrO2 catalyst a promising candidate for industrials. Additionally, to systematically investigate and elucidate the promoting effects of Fe on sulfated zirconia catalysts, a thorough characterization of the physicochemical properties of these catalysts was conducted through various techniques, including XRD, SEM, TEM equipped with EDX, N2 adsorption-desorption isotherms, EA, ICP-OES, FT-IR, XPS, and NH3-TPD. The results indicated that the introduction of a small amount of Fe into the catalyst promoted the stabilization of T-ZrO2, smaller grain sizes, increased specific surface area, and strong acidity, which in turn positively affected the catalytic performance. In addition, a possible reaction mechanism of Fe-promoted SO42-/ZrO2 catalyst for catalyzing the alkylation of DPA with NON was proposed.

Mechanical and electrochemical properties of (MoNbTaTiZr)1-xNx high-entropy nitride coatings

High-entropy materials possess high hardness and strong wear resistance, yet the key bottleneck for their practical applications is the poor corrosion resistance in harsh environments. In this work, the high-entropy nitride (HEN) coatings of (MoNbTaTiZr)1-xNx (x = 0–0.47) were fabricated using a hybrid direct current magnetron sputtering technique. The research focus was dedicated to the effect of nitrogen content on the microstructure, mechanical and electrochemical properties. The results showed that the as-deposited coatings exhibited a typical body-centered cubic (BCC) structure without nitrogen, while the amorphous matrix with face-centered cubic (FCC) nanocrystalline grain was observed at x = 0.17. Further increasing x in the range of 0.35–0.47 caused the appearance of polycrystalline FCC phase in structure. Compared with the MoNbTaTiZr metallic coating, the coating containing nitrogen favored the high hardness around 13.7–32.4 GPa, accompanied by excellent tolerance both against elastic and plastic deformation. Furthermore, such N-containing coatings yielded a low corrosion current density of about 10−8–10−7 A/cm2 and high electrochemical impedance of 106 Ω cm2 in 3.5 wt.% NaCl solution, indicating the superior corrosion resistance. The reason for the enhanced electrochemical behavior could be ascribed to the spontaneous formation of protective passive layers over the coating surface, which consisted of the dominated multi-elemental oxides in chemical stability. Particularly, noted that the (MoNbTaTiZr)0.83N0.17 coating displayed the highest hardness of 32.4 ± 2.6 GPa and H/E ratio at 0.09, together with remarkable corrosion resistance, proposing the strongest capability for harsh-environmental applications required both good anti-wear and anti-corrosion performance.

Investigation on electrochemical corrosion behavior and mechanical properties of Fe-nano particles produced by high-energy ball milling technique

Abstract This study focuses on converting iron particles from grinding sludge, after removing impurities, into Fe-nanoparticles using high-energy ball billing. The goal is to examine the corrosion behaviors and mechanical properties of these Fe-nanoparticles. Nanostructured Fe-powder was synthesized through a process involving 10 h of high-energy ball milling, followed by conventional hot pressing and sintering. Structural and microstructural properties were thoroughly examined using techniques such as X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and elemental diffraction spectroscopy. Upon sintering, SEM and TEM analyses unveiled the formation of a nanostructured alloy within the samples. Notably, the milled sample exhibited high hardness value, measuring at 155 HV. However, it is noteworthy that the un-milled sample demonstrated superior compression strength compared to its milled counterpart. Furthermore, the corrosion behavior of the samples was evaluated through electrochemical corrosion studies. Interestingly, the sample subjected to 10 h of milling (coin number 5) displayed a significantly lower corrosion rate, measuring at 1.3921 mm/year, suggesting enhanced corrosion resistance attributed to the nano structuring process.

Modelling and optimization of electrodeposited amorphous Fe-P alloys using central composite design and response surface method

Central composite circumscribed (CCC) design and response surface methodology (RSM) were used to model and optimize the electrodeposition of amorphous Fe-P alloys. Based on our previous single-factor experimental results, the significance of influencing factors was ranked using analysis of variance (ANOVA) method. Three factors, significantly impacting the P content in deposits, hardness and corrosion current density, were identified, including bath temperature, pH values and H2PO2− concentration. The statistic relationships between process parameters and individual responses were established based on the CCC experimental data and RSM. The optimal parameters for each response were derived and the influences of interaction terms were investigated. The predicted maximum P content of 26.35 wt% was achieved at a bath temperature of 60℃, a pH of 1.2 and H2PO2− concentration of 60 g/L. The predicted highest microhardness was 534 HV0.1 under the optimal conditions of temperature of 60 ℃, pH value of 1.6 and H2PO2− concentration of 49 g/L. The lowest corrosion current density was predicted to be 1.34 μA·cm−2 under the conditions of a bath temperature of 60℃，a pH value of 1.2, and a H2PO2− concentration of 53 g/L. A desirability function was applied to explore the optimal comprehensive performance of both high hardness and low corrosion current density. The optimal parameter combination for comprehensive performance was bath temperature of 60℃, pH of 1.4, and H2PO2− concentration of 49 g/L, and the resulting hardness and corrosion current density were 527 HV0.1 and 2.40 μA·cm−2, respectively. Due to the complex electrodeposition mechanism of amorphous Fe-P alloys, the predicted P content in deposits largely deviated from the experimental result, but the hardness, corrosion current density and comprehensive performances show high prediction accuracy.

Quinoline derivatives as corrosion inhibitors for mild steel in acid medium: Deeper insights from experimental, ab initio density functional theory modeling, and in silico ecotoxicity investigations

Two (E)-2-(((2-((7-chloroquinolin-4-yl)amino)ethyl)imino)methyl)-4-R-phenol Schiff bases derivatives CMN (R = NO2) and CMP (R = H) were successfully prepared. Then, CMN and CMP were evaluated as corrosion inhibitors for 1020 mild steel in 1.0 mol L–1 HCl using different methods. Gravimetric experiments have shown that CMN and CMP reach efficiencies of 80 and 91% at 1.45 mmol L–1. Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) measurements have indicated the formation of a protective adsorbed film on the mild steel surface. Electrochemical Impedance Spectroscopy (EIS), Linear Polarization Resistance (LPR), Potentiodynamic Polarization (PP), and Electrochemical Frequency Modulation (EFM) have also shed some light on electrochemical behavior of compounds. These data have depicted better polarization resistance and lower corrosion current density in the presence of both organic molecules, also proving that the process is controlled by charge transfer and that CMN and CMP are mixed-type corrosion inhibitors. ab initio Density Functional Theory (DFT) investigated how two quinoline-based molecules (CMN and CMP) prevent corrosion on iron surfaces. Simulations revealed CMP bonds more strongly to iron than CMN, leading to better protection. Simulations also showed that these inhibitor molecules form a protective layer on the iron, slowing down the movement of corrosive substances. Environment risk assessment through QSAR-based models have indicated that the corrosion inhibitors do not have the potential to bioaccumulate in fish. Still, the acute and chronic toxicity values at the different trophic levels investigated call for attention for environmentally friendly structural optimization.

AZ31-calcium-deficient hydroxyapatite (CDHA) composites produced by friction stir processing: controlling the degradation by enhancing the biomineralisation

ABSTRACT In the present work, calcium deficient hydroxyapatite (CDHA) was dispersed into the surface of AZ31 Mg alloy within the solid state by friction stir processing and the role of the refined microstructure and the presence of nano-CDHA on biomineralization and corrosion performance was investigated. Fine grains (1.6 ± 2.1 µm) have been produced in AZ31-CDHA composite compared with base alloy (41 ± 6.1 µm) and nano-CDHA was observed as reinforced into AZ31 matrix. X-ray diffraction analysis confirms the texture change due to FSP in the composite. Wettability studies carried out by measuring contact angles on the surface of the composites indicated increased surface energy (37.27 ± 5.1 mJ/m2) compared with the base alloy (20.55 ± 3.4 mJ/m2) . From the potentiodynamic polarization studies, lower corrosion current density (1.69 ± 1.13 × 10-5 A/cm2) was observed for the composite. From the immersion studies in simulated body fluids, higher level of biomineralization on the composite helped to decrease the degradation rate as reflected from the lower weight loss (7.5 ± 1.1 %) compared with the base alloy (12.1 ± 1.3 %). The results demonstrate the promising role of enhanced biomineralization on controlling the degradation of AZ31-CDHA composite..

Development of non-oxidized graphene flakes (NOGF)/polyvinylidene fluoride (PVDF) composites for high-performance EMI shielding efficiency

As numerous communication devices use multiband electromagnetic waves in modern society, electromagnetic interference (EMI) shielding materials become increasingly important due to the harmful effects of electromagnetic waves. While metal-based materials have shown high shielding performance, they have many drawbacks such as high density, high processing cost, and low corrosion resistance. Conductive polymer composites (CPCs), which can overcome these shortcomings of metal-based materials, have become increasingly popular in recent years. In this study, non-oxidized graphene flakes (NOGFs) are synthesized by exfoliating the ternary graphite intercalant compound (t-GIC) and used as fillers for CPCs. The electrical conductivity and EMI shielding effiency (SE) of NOGF/polyvinylidene fluoride (PVDF), graphite/PVDF and reduced graphene oxide (rGO)/PVDF composites are investigated. NOGF/PVDF composites showed notably enhanced electrical conductivity and EMI SE than the others. This is mostly due to the non-oxidative fabrication method that does not destroy the sp2 structure of graphene sheet, thus preserving the unique electrical properties of graphene.

The effect of Dy-Cu co-deposition and grain boundary diffusion on the microstructure and magnetic properties of sintered NdFeB magnets

In this paper, Dy-Cu coating was electrodeposited on the surface of commercial sintered NdFeB magnet as a diffusion source and the grain boundary diffusion was carried out on the sintered NdFeB magnet. The experimental results show that the coercivity of the diffusion magnet is increased from 993 kA/m to 1241 kA/m, an increase of 24.95 %, and the remanence is only reduced to 1.366 T, a decrease of 0.44 % compared with the original magnet. The electrochemical behavior analysis shows that with the addition of Cu2+, the reduction potential of Dy3+ appears a large positive shift, and the Dy-Cu co-deposition process is a three-dimensional instantaneous nucleation process. The SEM images show that the Dy-Cu deposition layer has a dense and flat surface with small grain size. The energy spectrum analysis shows that the Dy-Cu elements obtained by electrodeposition are uniformly distributed, and there is no massive agglomeration phenomenon. SEM-EDS line scan observation shows that the Dy elements diffused along the grain boundary phase mainly accumulate in the grain boundary phase and the epitaxial layer of the main grain. EPMA shows that Cu and Dy elements are evenly distributed in the grain boundary phase after grain boundary diffusion. SEM-BSE shows that the near-surface grain boundary phase structure is significantly optimized after grain boundary diffusion. XRD shows that Dy partially replaces the NdFeB main phase, leading to the migration of the main peak to the large angle direction. At the same time, due to the existence of low melting point metal, Dy preferentially enters the magnet internal, resulting in the decrease of the content of (Dy, Nd)2Fe14B phase. The optimization of the microstructure and grain boundary phase composition and the formation of (Dy, Nd)2Fe14B structure are the main reasons for the significant enhancement of the coercivity According to Kronmüller plots, the coercivity mechanism of diffusion magnet is still the magnetic domain nucleation inversion mechanism. After the Tafel test, it is found that the diffusion Dy magnet has a relatively positive corrosion voltage Ecorr and a relatively low corrosion current density Icorr, and its corrosion resistance is greatly improved.

Polyoxometalate solution passivation enabling dendrite-free and high-performance zinc anodes in aqueous zinc-ion batteries

Zinc metal anodes in aqueous electrolytes commonly face challenges such as dendrite growth and undesirable side reactions, limiting their application in the field of aqueous zinc-ion batteries (AZIBs) for energy storage. Drawing inspiration from industrial practices involving molybdenum salt solutions for metal modification, a polyoxometalate solution was formulated as a passivation solution for zinc anodes (referred to as MO solution). The formed passivation layer, referred to as the MO layer, exhibited a uniform and protective nature with a thickness of approximately 10 μm. The experimental results demonstrated that this passivation layer effectively suppressed side reactions at the zinc anode interface, as evidenced by lower corrosion current density for MO-Zn anodes. Additionally, the newly plated Zn was uniformly deposited atop the MO layer, ensuring coating integrity and inhibiting dendrite growth. As a result, under more demanding conditions such as a larger current of 8 mA cm−2, the MO-Zn anode displayed an extended cycle life exceeding 420 h in a symmetric battery, with an overpotential as low as 98 mV. This performance significantly outperformed that of commercially available pure Zn foils (with a cycle life of 60 h and an overpotential of 192 mV). Notably, a self-made Na-doped V2O5 served as the cathode (referred to as NaVO), forming the MO-Zn//NaVO full battery. Even under high current test conditions of 2 A/g, the specific capacity of the MO-Zn//NaVO full battery remained substantial at 152.83 mAh/g after 1000 cycles. Furthermore, pouch batteries assembled with NaVO//MO-Zn successfully illuminated small bulbs. This study offers a viable optimization strategy for AZIB anodes and demonstrates the potential of using polyoxometalate solution for etching zinc anodes to inhibit dendrite growth and interfacial corrosion of zinc metal anodes.

Natural low corrosive phytic acid electrolytes enable green, ultrafast, stable and high-voltage aqueous proton battery

Proton is a promising charge carrier for aqueous rechargeable batteries due to its small ionic radius, fast diffusion kinetics and great abundance in nature. However, commonly-used proton battery electrolytes are strong acids, such as sulfuric acid, phosphoric acid, etc., which always leads to the notorious rapid corrosion of electrode and metal components, and thus the poor cyclability, the limited materials option and high maintenance cost. Here, we reported a new-type high-concentration phytic acid (PA) electrolytes, which exhibits marvellous superiorities including environmental friendliness, low corrosiveness, high ionic conductivity (133.3 mS cm−1) and wide working potential window (∼2.9 V) in contrast to conventional acid electrolytes. The experimental and calculation results indicated that the scarcity of free water in high-concentration PA electrolytes and the desolvation effect of the preferentially absorbed PA interfacial layer on the electrode surface work in synergy to inhibit the water activity and thus prevent electrode dissolution and side reactions. Benefiting from this, the assembled K0.2VO0.6[Fe(CN)6]0.8•6H2O (VHCF)//MoO3 button-type proton battery shows an average discharge voltage of 0.7 V with a pair of well-defined redox peak at about 1.4 V, great rate performance, excellent cycling stability (87.9% capacity retention after 1000 cycles at 5 A g−1) and superb coulombic efficiency at various current densities (1 A g−1–50 A g−1). Attributed to good anti-freezing properties of the electrolytes, the proton battery can also run normally at -60 °C and exhibit competent performance (a capacity retention of 45 mAh g−1 at 0.1 A g−1 after 540 cycles). Such green low corrosive electrolyte will be fully compatible with conventional battery fabrication process, and open brand new avenue for the development of aqueous proton battery.

A new study on the effects of clay nanoparticles on the corrosion performance of Al-Si-Cu matrix composites in both acidic and alkaline solutions

In this paper, the influence of clay nanoparticles on the corrosion properties of the Al-Si-Cu matrix was investigated. The nanocomposite fabricating method was stir-casting when stirring times and temperatures were variables to change nanocomposite characteristics. Several corrosion tests were performed to examine the relationship between the microstructure and the degradation mechanism of various fabricated nanocomposites. Tafel polarization measurements indicated a lower corrosion rate for all nanocomposites compared to the Al-Si-Cu matrix in 0.1 M NaOH solution. The reduction range was 23.6–79.0% based on the smaller size of Si precipitates. In this situation, the interconnection of surface pores was lowest. However, electrochemical impedance spectroscopy (EIS) results showed that nanocomposite impedance would be increased up to 99.7% in comparison to the matrix without clay nanoparticles in 1 M HCl solution when the stirring temperature was 750 °C. EIS calculation also displayed that an increase (about 17.1–50.8%) in the nanocomposite resistance would be achieved when the stirring time was 2 min in 0.04 H2SO4 solution. The reason could be attributed to the larger size of Si particles since coarse precipitates were more effective agents to act as barriers for anodic dissolution of the lower layer of the Al-Si-Cu matrix when Tafel polarization tests demonstrated that the anodic reaction controlled the corrosion rate of the aluminum matrix.

SiC-armoured triple-layered superhydrophobic coating with super-robustness and anti-corrosion durability

Continuously enhancing the mechanical stability and durability of superhydrophobic corrosion-resistant materials is a great challenge for researchers. In this paper, we developed a SiC armoured triple-layered superhydrophobic coating with super-robustness on Q235 carbon steel substrates. The triple-layered coating was achieved by sequentially applying an epoxy (EP) resin adhesive layer, a SiC-armored skeleton structure, and a superhydrophobic F-Al2O3@EP layer. The resulting coating demonstrated outstanding non-wetting superhydrophobicity, featuring a static water contact angle (WCA) of 157.7 ± 0.5° and a sliding angle (SA) of 3.7 ± 0.6°. Moreover, the designed triple-layered superhydrophobic coating exhibits ultra-low interfacial adhesion force and demonstrates self-cleaning ability. Its mechanical stability was significantly heightened, enduring more than 2700 sandpaper abrasion cycles, 2200 tape-peeling cycles, and 3000 g sand impact resistance. Additionally, the coating displayed superior corrosion resistance with eight orders of magnitude enhanced charge transfer resistance (Rct), 590 mV positive shift corrosion potential (Ecorr), and six orders of magnitude lower corrosion current density (Icorr) in a 3.5 wt% NaCl solution. Impressively, the SiC armoured triple-layered superhydrophobic coating demonstrated prolonged marine anti-corrosion performance, enduring immersion in a 3.5 wt% NaCl solution for over 1200 h and exposure to the outdoor marine atmospheric environment for more than 3360 h. We believe the development of superhydrophobic materials with high stability and durability contributes to their widespread adoption and multifunctional applications.

Experimental investigation of a mixed desiccant solution of potassium formate and ionic liquid

Liquid desiccant technology is a promising energy-efficient alternative to conventional temperature and humidity control systems. In the quest to identify the optimal fluid for liquid desiccant systems, alternative desiccant solutions have been explored in terms of their feasibility and compatibility in dehumidification systems. This study proposes and characterises a new type of less expensive mixture of potassium formate (HCO2K) and 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]). This novel desiccant solution was investigated in terms of corrosiveness to metals, moisture absorption and desorption ability, cost-effectiveness compared to conventional desiccant solutions. The corrosiveness of desiccant solutions to copper-nickel, copper and steel was tested at room temperature and at 60 °C. Experiments were conducted in a climatic chamber with temperatures of 25–31 °C and relative humidities of 80–90% for the absorption process and temperatures of 50–70 °C and relative humidities of 20–30% for the desorption process to assess the moisture absorption and desorption capacities and mass fraction variations of the desiccant solutions. The mixed desiccant of HCO2K/[EMIM][OAc] in the ratio 60/10% wt. showed a moisture absorption capacity of 0.146 gH2O/gsol (compared to 0.18 gH2O/gsol for aqueous lithium chloride at 33.3% wt.) for a temperature and relative humidity of the climatic chamber of 25 °C and 90%, respectively. Its low corrosiveness, good moisture absorption and desorption capacity and higher cost-effectiveness make it a promising alternative to conventional desiccants, such as aqueous solutions of lithium chloride.