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Several Ni-W-P-TiO2 nanocomposite coatings were developed by the sol-enhanced electroplating method. The phase and elemental compositions of coatings were determined, and the surface and cross-section morphology were characterized. The mechanical and corrosion performance were systematically tested. The results revealed the addition of 5 ml·L−1 TiO2 sol caused a compact coating surface, while higher concentrations of TiO2 reduced the coating thickness and led to the inferior surface microstructure. The comparison in physiochemical properties of prepared coatings confirmed the superior performance of the Ni-W-P-TiO2 nanocomposite coating at 5 ml·L−1 TiO2 sol addition. Under this condition, the best mechanical properties were achieved when abrasive wear was the dominating wear-resistance mechanism, and the best corrosion resistance was obtained due to its smooth and compact surface microstructure.

This work aims to investigate the effect of hBN on the friction and wear resistance of Sialon composite. Sialon and its composite with 10 wt% hBN were fabricated by SPS sintering. The effect of hBN additive on the phase composition, microstructure, densification behavior, mechanical and dry sliding tribological properties of Sialon material was studied. Being sintered at 1600 °C for 10 min, compared to monolithic Sialon, Sialon-hBN composite has more refined β-Sialon grains with smaller aspect ratios and slightly declined relative density. The hardness of the Sialon-hBN composite was reduced due to the weak bonding between Sialon and hBN grains. Nevertheless, its fracture toughness increased ascribing to the toughening mechanisms, including crack deflection and crack bridging. hBN had an essential impact on the tribological performances of the composite due to its lower friction coefficient and good lubrication action. Under the same densification level (i.e., with a relative density of around 97.5%), the friction and wear resistance of Sialon-hBN composite were much better than monolithic Sialon. The main wear mechanisms were tribolayer formation, oxidized wear, and abrasive wear.

The power conversion efficiency (PCE) of perovskite solar cells (PSCs) is already higher than those of other thin-film photovoltaic technologies, but the stability issue limits their applications. The introduction of sulfur-based compounds in PSCs could contribute to their stability. Herein, sulfur-based compounds have been embedded into each functional layer to stabilize carbon-based PSCs (C-PSCs). Results showed that the simultaneous introduction of sulfur-based compounds could decrease the trap states of perovskite film, enlarge the grain size of perovskite, and accelerate the charge transfer and extraction, leading to an improved performance. Comparing with the device without sulfide (10.77%), all sulfide C-PSCs obtained a PCE of 15.38%. The stability test showed much better resistance to humidity and thermal stress for all sulfide C-PSCs. They could retain 80% of initial PCE after aging about 700 h at relative humidity (RH) 45% ± 10% and 80 °C.

Ni–Fe–Sn electrocatalyst supported on nickel foam (Ni–Fe–Sn/NF) with high efficiency of hydrogen evolution reaction (HER) has been successfully fabricated through one-step potentiostatic electrodeposition route. The optimized Ni–Fe–Sn/NF displayed an extremely low overpotential of, respectively, 144 and 180 mV at 50 and 100 mA cm−2 for HER in alkaline condition. Moreover, it could retain its superior stability for at least 12 h. The remarkable electrocatalytic activity of our electrocatalyst is ascribed to the high conductivity originated from synergistic effects between Ni, Fe, and Sn during HER process.

Ultrasmall nitrogen-doped carbon-coated CoSe2/ZnSe nanospheres (CoSe2/ZnSe@C nanospheres) are fabricated by direct selenization of a delicately designed Co1.6Zn0.4-(benzimidazole)4 metal–organic framework (MOF) nanosheet precursor and used as the anode materials in sodium-ion batteries (SIBs). The fabricated CoSe2/ZnSe@C nanospheres deliver a remarkable rate performance (395 mAh g−1 at 0.1 A g−1 and 341 mAh g−1 at 5.0 A g−1) and excellent long-term durability (346 mAh g−1 after 2500 cycle at 2.0 A g−1). The superior Na storage performance of the fabricated CoSe2/ZnSe@C nanospheres could be mainly attributed to their ultrasmall particle sizes and the phase boundaries between CoSe2 and ZnSe, which improve the kinetics of the electrode, relieve the volume change during the charge/discharge process, and provide extra Na+ storage sites. This work opens up possibilities to fabricate metal selenide–based hybrid materials with desired nanostructures and compositions from rationally designed multimetal MOF precursors for high-performance anode materials in SIBs.

Application of nitrogen-doped carbon for electroreduction of CO2 to CO receives increasing attentions, and improving the CO selectivity of carbon-based materials is prominent. Here we introduce a halogen-assisted calcination strategy for constructing two-dimensional (2D) nitrogen-doped carbon from ZIF-8 precursor. Benefitting from the abundant graphitic-N (G-N) and the enlargement of electrochemical surface area (ECSA), 2D nitrogen-doped carbon presents excellent catalytic activity with the high faradaic efficiency (FE) of CO reaching 99.5% and current density of −2.6 mA cm−2 at a low potential of −0.5 V (vs. RHE) in H-type cell, with the long-term stability up to more than 20 h. A positive correlation between FECO and the ratio of G-N (the ratio of graphitic-N content to total N content.) is revealed. The halogen-assisted calcination can effectively increase the G-N ratio and enlarge ECSA, thereby increasing FECO, which is a promising strategy for improving CO selectivity of carbonaceous materials.

PurposeThe purpose of this paper is to investigate and explain thermal oxide effect on electrochemical corrosion resistance anodized stainless steel (SS).Design/methodology/approachElectrochemical corrosion resistance of thermal oxides produced on anodized 304 SS in air at 350°C, 550°C, 750°C and 950°C in 3.5 wt.% NaCl solution have been investigated by dynamic potential polarization, EIS and double-loop dynamic polarization. Anodized 304 SS were obtained by anodization at the constant density of 1.4 mA.cm-2in the solution containing 28.0 g.L-1H3PO4, 20.0 g.L-1C6H8O7, 200.0 g.L-1H2O2at 70°C for 50 min. SEM and EDS had been also used to characterize the thermal oxides and passive oxide.FindingsInterestingly, anodized 304SS with thermal oxide produced at 350°C displayed more electrochemical corrosion and pitting resistance than anodized 304 SS only with passive oxide, as related to the formation of oxide film with higher chromium to iron ratio. Whereas, anodized 304SS with thermal oxide formed at 950°C shows the worse electrochemical corrosion and pitting resistance among those formed at the high temperatures due to thermal oxide with least compact.Originality/valueWhen thermally oxidized in the range of 350°C–950°C, electrochemical corrosion and pitting corrosion resistance of anodized 304 SS decrease with the increase of temperature due to less compactness, more defects of thermal oxide.

Superhydrophobic surfaces – driven from natural biology – are being increasingly studied in many engineering fields. This study fabricated hydrophobic AAO/Ni coatings and superhydrophobic AAO/Ni/Ni...

Summary Electrocatalytic CO2 reduction reaction (CO2RR) has attained great attention as it can transform the greenhouse gas CO2 to value-added chemicals, such as carbon monoxide, formic acid, ethylene, ethanol, and n-propanol. However, the electrocatalytic performance of materials, especially the metal materials, toward the CO2RR is still limited due to the complex reaction processes and broad product distribution. Very recently, surface modification of metal materials has emerged as an effective way to boost their electrocatalytic CO2RR performance. Herein, recent advances in the surface modification of metal materials, which includes surface molecular functionalization, surface elemental doping, and surface plasma treatment, for CO2RR are presented. The surface modification-induced variations of surface states and electrocatalytic performances of metal materials, together with the underlying mechanisms, are highlighted. It is believed that the development of surface modification could promote the rational design and preparation of advanced CO2RR electrocatalysts toward practical applications.

Annealed Rh nanoclusters on an ordered thin film of Al2O3/NiAl(100) were shown to exhibit a promoted reactivity toward the decomposition of methanol-d4, under both ultrahigh vacuum and near-ambient-pressure conditions. The Rh clusters were grown with vapor deposition onto the Al2O3/NiAl(100) surface at 300 K and annealed to 700 K. The decomposition of methanol-d4 proceeded only through dehydrogenation, with CO and deuterium as products, on Rh clusters both as prepared and annealed. Nevertheless, the catalytic reactivity of the annealed clusters, measured with the production of either CO or deuterium per surface Rh site from the reaction, became at least 2–3 times that of the as-prepared ones. The promoted reactivity results from an altered support effect associated with an annealing-induced mass transport at the surface. Our results demonstrate a possibility to practically prepare reactive Rh clusters, regardless of the cluster size, that can tolerate an elevated reaction temperature, with no decreased reactivity.

The corrosion behavior of an ultralow iron nickel-based alloy Inconel 625 under high-temperature water has been evaluated. The results show that surface oxidation and pitting were the principal corrosion mechanisms of Inconel 625 during the initial immersion period. The surface layer of the oxide film is first Ni-enriched and then Fe-enriched as immersion time increases. The iron ions dissolved from the autoclave could lead to the formation of NiFe2O4 and have a great influence on the oxidation behavior of Inconel 625. The oxides nucleated by solid-state reactions with selective dissolution of Fe and Ni and then grew up through precipitation of cations from solution.

ConspectusGold (Au), a transition metal with an atomic number of 79 in the periodic table of elements, was discovered in approximately 3000 B.C. Due to the ultrahigh chemical stability and brilliant golden color, Au had long been thought to be a most inert material and was widely utilized in art, jewelry, and finance. However, it has been found that Au becomes exceptionally active as a catalyst when its size shrinks to the nanometer scale. With continuous efforts toward the exploration of catalytic applications over the past decades, Au nanomaterials show critical importance in many catalytic processes. Besides catalysis, Au nanomaterials also possess other promising applications in plasmonics, sensing, biology and medicine, due to their unique localized surface plasmon resonance, intriguing biocompatibility, and superior stability. Unfortunately, the practical applications of Au nanomaterials could be limited because of the scarce reserves and high price of Au. Therefore, it is quite essential to further explore novel physicochemical properties and functions of Au nanomaterials so as to enhance their performance in different types of applications.Recently, phase engineering of nanomaterials (PEN), which involves the rearrangement of atoms in the unit cell, has emerged as a fantastic and effective strategy to adjust the intrinsic physicochemical properties of nanomaterials. In this Account, we give an overview of the recent progress on crystal phase control of Au nanomaterials using wet-chemical synthesis. Starting from a brief introduction of the research background, we first describe the development history of wet-chemical synthesis of Au nanomaterials and especially emphasize the key research findings. Subsequently, we introduce the typical Au nanomaterials with untraditional crystal phases and heterophases that have been observed, such as 2H, 4H, body-centered phases, and crystal-phase heterostructures. Importantly, crystal phase control of Au nanomaterials by wet-chemical synthesis is systematically described. After that, we highlight the importance of crystal phase control in Au nanomaterials by demonstrating the remarkable effect of crystal phases on their physicochemical properties (e.g., electronic and optical properties) and potential applications (e.g., catalysis). Finally, after a concise summary of recent advances in this emerging research field, some personal perspectives are provided on the challenges, opportunities, and research directions in the future.

In the present study, we used low-field nuclear magnetic resonance (LF-NMR) measurements and mercury intrusion porosimetry (MIP) to evaluate the influence of the water–binder (w/b) ratio, fly ash (FA) replacement and curing regimes on the pore structure of concrete. The main advantage of LF-NMR is that it is nondestructive and suitable for large concrete samples compared with other traditional methods, such as MIP, adsorption methods and scanning electron microscopy methods. Hence, the LF-NMR relaxometry method measures the pore structures that are closer to reality. The LF-NMR relaxation time, T2, represents the change in the pore structure during the hydration and hardening processes of concrete. The results showed that the T2 spectrum of the concrete sample was mainly composed of 3–5 signal peaks. Additionally, the w/b ratio, FA replacement and the curing regimes have significant effects on the T2 spectrum, porosity, and pore size distribution of concrete. In addition, the compressive strength of concrete has a close relationship with its pore structure. Based on the LF-NMR test results, the relationship between the compressive strength and the porosity, pore size distribution of concrete was established.

Increased generation of spent lithium-ion batteries (LIBs) has driven the exploration of new methods for reusing and/or recycling LiCoO₂ cathode materials. Herein, an electrochemical relithiation method was proposed to directly regenerate LiCoO₂ cathode materials using the waste LiₓCoO₂ electrode as a base. It was shown that Li⁺ was successfully inserted into the waste LiₓCoO₂ electrode, and this relithiation process became faster with either a higher Li₂SO₄ concentration or a higher cathodic current density. The XRD analysis confirmed that the peak positions of the relithiation products were consistently close to those of a standard LiCoO₂ material. The crystal structure of the relithiation products was restored with a post-annealing process. The activation energy for electrochemical relithiation (Eₐ) was estimated at 22 kJ mol–¹, and the constant of equilibrium constant k₀ was determined as 1.35 × 10–⁶ cm s–¹. The relithiation process was controlled by the charge transfer process when the Li₂SO₄ concentration was high (e.g., 1, 0.8, and 0.5M), and a lower concentration at 0.01–0.3 M led to a diffusion control pattern. The electrode made of the regenerated LiCoO₂ materials had a charge capacity of 136 mAh g–¹, close to that of the commercial LiCoO₂ electrode (140 mAh g–¹). A potential mechanism of electrochemical relithiation was proposed involving lithium defects, relithiation, and crystal regeneration.

A series of LiNi0.5-xCuxMn0.5O2 (0 ≤ x ≤ 0.05) samples were synthesized through a combination of co-precipitation (CP) and solid-state reaction. The synthesized cathode materials were systematically investigated by X-ray diffraction (XRD), Rietveld refinement, inductively coupled plasma (ICP) spectroscopy, X-ray photoelectron spectroscopy (XPS), and charge-discharge tests. The structural measurements indicated that Cu2+ was successfully doped into the structure of the LiNi0.5Mn0.5O2 material. The results of the electrochemical measurements suggest that the electrochemical performances of LiNi0.5Mn0.5O2 can be obviously improved by Cu -doping, and the best doping amount is 1 mol%. Specifically, the capacity retention of a 1 mol% Cu-doped sample is 18% higher than that of pure LiNi0.5Mn0.5O2 in the range of 2.5~4.6 V at 0.2 C. Most importantly, the cycle stability of LiNi0.5Mn0.5O2 at high currents can also be improved by Cu-doping. We found that Cu-doping can lower the Li/Ni cation mixing, enlarge the migration channels of lithium ions, reduce migration resistance, and retard polarization, and in turn, it can improve the electrochemical properties of LiNi0.5Mn0.5O2.

The nano SiC coatings were prepared on the surface of graphite by laser irradiation under different laser energy densities (7.07–14.15 kJ/cm2). The influence of laser energy density on the structure and quality of coatings was systematically investigated. The results show that laser irradiation can transform the preset micron-SiC particle coating into nano-SiC particle coating. The nano-SiC coating prepared by laser irradiation can effectively enhance the high temperature oxidation resistance of the graphite substrate. When the laser energy density is 7.07 kJ/cm2, the prepared coating displays a single crystal structure and a good morphology without cracks and spheroidization. The coating prepared under the laser density of 10.61 kJ/cm2 shows a mixed crystal structure with obvious spheroidization. Further increase the laser energy density to 14.15 kJ/cm2, the main structure of prepared coating turns to polycrystalline and obvious cracks can be observed. The cross-section analysis of coating prepared under laser energy density of 7.07 kJ/cm2 indicates that there existed elemental diffusion between the coating and the substrate which increased the adhesion of coating. The calculations based on the Arrhenius formula present that this prepared coating has higher activation energy and therefore it has better high temperature oxidation resistance than the other prepared coatings.

Using alternative power sources to drive hydrogen production in microbial electrolysis cells (MECs) is important to implementation of MEC technology. Herein, thermoelectric generators (TEG) were to power MECs using simulated waste heat. With the MEC anolyte as a cold source for TEG, current generation of the MEC increased to 2.46 ± 0.06 mA and hydrogen production reached 0.14 m3 m−3 d-1, higher than those of the TEG-MEC system without hydraulic connection (1.16 ± 0.07 mA and 0.07 ± 0.01 m3 m−3 d-1). A high recirculation rate of 30 mL min-1 doubled both current generation and hydrogen production with 10 mL min-1, benefited from a stronger cooling effect that increased the TEG voltage output. However, the optimal recirculation rate was determined as 20 mL min-1 because of comparable performance but potentially less energy requirement. Reducing anolyte hydraulic retention time to 4 h has increased hydrogen production to 0.25 ± 0.05 m3 m−3 d-1 but decreased organic removal efficiency to 69 ± 2%. Adding three more TEG units that captured more heat energy further enhanced hydrogen production to 0.36 m3 m−3 d-1. Those results have demonstrated a successful integration of TEG with MEC through both electrical and hydraulic connections for simultaneous wastewater treatment and energy recovery.

Cu–Sn–Zn (CSZ) coatings are widely applied in communication devices due to their excellent performance in electrical/thermal conductivity, solderability, and corrosion resistance. Particularly, a novel TiO2–sol-enhanced electrodeposition method has been proposed to prepare CSZ–TiO2 nanocomposite coatings with different volume fractions of TiO2–sol. A series of CSZ–TiO2 nanocomposite coatings were prepared in the current study. The crystal phase, surface morphology, and micro- to nanostructures of sol-enhanced nanocomposite coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Based on the prior research, we studied the microhardness, surface friction behavior, and corrosion behavior of the coatings. Our results indicate that adding 12.5 mL L−1 TiO2–sol increased the average microhardness of CSZ coating from 325 to 421 HV and reduced the corrosion rate by 42.8%. Those results reveal that the TiO2–sol affected the performance of CSZ coatings depends on the volume added. Additionally, we investigated the effects of TiO2–sol volume fraction on the morphology, microhardness, dry sliding wear-resistant capability, and corrosion-resistant capability.

Rechargeable magnesium ion batteries are potential candidates to replace the lithium ion batteries due to their high volumetric energy density, dendrite free cycling, and low costs. In present work, we have critically reviewed the recent advances made in the field of cathode materials development to achieve the high reversible capacities and working potentials. In first part, carbon-based cathodes such as fluorine-doped graphene nanosheets and graphite fluoride (CF0.8) are discussed in terms of compatibilities of positive electrode materials and electrolyte solutions for rechargeable magnesium-ion batteries. Whereas, the second part of this review focuses on crystal structure of vanadium oxide and its capability to accommodate the Mg2+ ions. Likewise, electrochemical performance of selected vanadium oxide based cathodes including VO2 (B), FeVO4.0.9H2O, Mo2.5+yVO9+δ, RFC/V2O5 and V2O5/Graphene composite, are discussed at different temperatures. To support the future research on magnesium ion batteries, particularly positive electrode material developments, several innovative research directions are proposed.

In this article, the influence of combined pretreatment such as ultrasonic or torrefaction assisted deep eutectic solvents (DESs) on the bio-oil upgrading from corn stalk was evaluated. Moreover, t...

Interatomic potential plays an important role in molecular dynamics simulation, which determines both the efficiency and accuracy of the simulations. Lattice inversion is a method which can be used to develop interatomic potential from first principle results directly. In present work, a robust potential model based on lattice inversion is proposed. Then the potential model is applied to develop interatomic potentials for eight common FCC metals. The cohesive energy curves calculated using first principle calculations can be well reproduced, which verifies the reliability of the developed potential. Additional physical properties, including equilibrium lattice constant and cohesive energy, elastic constants, are predicted and found reasonable agreement with corresponding first principle results.

Flue gas carbonation of three commonly used cement-based building products, concrete masonry blocks, cement-bond fiberboards and cement-bond bead boards, was studied to investigate the feasibility of using as-captured cement kiln flue gas to accelerate hydration and store carbon dioxide for emission reduction. Compared to pure gas carbonation, the use of flue gas does not require chemical separation which is energy-intensive. However, the reaction efficiency was low because of low CO2 concentration in flue gas. It could take up to two weeks to achieve required strength. This paper presents an innovative process in which flue gas carbonation was carried out in 5 h with 7 cycles of injection and release. Cement-based building products could achieve 5-6% CO2 uptake independent from types of products. Compared to pure gas carbonation, degree of carbonation was low in flue gas but strength gain was in the same order of magnitude. Reaction product was typical calcium silicate carbo-hydrates, a carbonate modified hydrate. The size of carbonate crystal was much smaller by flue gas carbonation. However, their contribution to strength gain was comparable to larger crystals in pure gas carbonation. The successful capture and utilization of cement kiln flue gas made it feasible to establish a network to link cement plants (CO2 sources) to concrete plants (CO2 sinks) for emission reduction through utilization.

The current work mainly investigates the corrosion resistance and conductivity of TiN layer on Ti–6Al–4V with liquid phase plasma electrolytic nitridation for PEMFC bipolar plate (BP). The X-ray diffraction (XRD) results show that TiN phase presents in the nitriding samples. The surface morphology analysis indicates that higher CH4NO2 concentration tends to form more compact structure. The potentiodynamic polarization test indicates that sample N-600 prepared by 600 g/L CH4NO2 concentration possesses the lowest corrosion current density of 0.57 μA cm−2 in the simulated PEMFC cathode potential (+0.6 VSCE), which completely satisfies the DOE 2020 technical targets. Meanwhile, sample N-600 also exhibits the highest corrosion resistance and stability in the potentiostatic polarization, electrochemical impedance spectroscopy (EIS) and high potential (+1.6 VSCE) polarization test. Interfacial contact resistance (ICR) results show that sample N-600 possesses the lowest ICR value of 6 ± 0.4 mΩ cm2, which fully meets the DOE 2020 requirements.

The rechargeable magnesium ion batteries (MIBs) are ideal candidates to replace currently commercialized high energy density lithium ion batteries (LIBs) owing to their cost effective and environmentally friendly nature. However, bad performance of MIBs is a big challenge for researchers. In this review, we have critically discussed the state-of-the-art research activities made for the development of Mg-ion battery electrolytes and cathode materials with fast magnesiation kinetics. Emphasizing the chemical structures of both organic and inorganic electrolytes and their compatibilities with different cathode materials, the kinetic properties of electrochemical reactions for achieving optimized energy and power densities, are critically reviewed. To tackle the large polarizations of MIBs, the latest and emerging hybrid ion electrochemistries such as Mg–Li, Mg–Na, aqueous rechargeable Mg–Na, and Mg–Zn hybrid ion batteries, are highlighted to elaborate the merits and challenges of each electrolyte and nanostructured cathodes. The cathode materials covered in this review include various kinds of inorganic materials (i.e. metal oxides, metal sulfides), organic polymers, Prussian blue analogous and NASICON-type Li/Na cathodes with high working potentials. At the end, this review discuss comprehensive future research strategies for exploring new cathodes with high working voltages for MIBs.

In this work, a method has been presented to analyze the influence of control saturation and structural flexibility on the stable radius of highly flexible aircraft. A dynamic model of aircraft is constructed followed by the analysis of kinetic characteristics. In this paper, the closed-loop stability boundary of highly flexible aircraft with open-loop instability is studied. The amplitude limit and bandwidth limit of the control signal are considered in the closed-loop stability boundary calculation. Our analysis shows that the boundary is related to the left eigenvector corresponding to the unstable poles and the amplitude constraint of the control signals. Stability of the boundary of feedback control system further reduces the limitation of the bandwidth of actuators. Focused on the phugoid instability of highly flexible aircraft, computational formulation of the closed-loop stable boundary is achieved. The Monte Carlo analysis has been employed to validate the stable region, under the LQR controller. Both the theory and simulations have nice correlations with each other which verify the stability of the closed-loop system, restricted by the open-loop system, and the influence of control signal bandwidth constraints.

The effects of heat treatment on the properties of electrodeposited Co–P–TiO2 nanocomposite coatings were systematically investigated. The TiO2 nanoparticles-reinforced Co–P–TiO2 nanocomposites wer...

Two-dimensional (2D) metal–organic frameworks (MOFs) and their derivatives with excellent dimension-related properties, e.g. high surface areas, abundantly accessible metal nodes, and tailorable structures, have attracted intensive attention as energy storage materials and electrocatalysts. A major challenge on the road toward the commercialization of 2D MOFs and their derivatives is to achieve the facile and controllable synthesis of 2D MOFs with high quality and at low cost. Significant developments have been made in the synthesis and applications of 2D MOFs and their derivatives in recent years. In this review, we first discuss the state-of-the-art synthetic strategies (including both top-down and bottom-up approaches) for 2D MOFs. Subsequently, we review the most recent application progress of 2D MOFs and their derivatives in the fields of electrochemical energy storage (e.g., batteries and supercapacitors) and electrocatalysis (of classical reactions such as the HER, OER, ORR, and CO2RR). Finally, the challenges and promising strategies for the synthesis and applications of 2D MOFs and their derivatives are addressed for future development.

Non-precious transition metal oxide-based materials have shown a promising prospect as electrocatalysts for the oxygen evolution reaction (OER). Herein, we report a template-free and annealing-free one-step electrodeposition approach for the in situ fabrication of composition- and morphology-controllable NixFe3−xO4/Ni hybrid and NixFe3−xO4 nanosheet arrays (NSAs) on different conducting substrates as highly active and robust oxygen-evolving electrocatalysts. The optimal NixFe3−xO4/Ni hybrid NSA electrodeposited on nickel foam requires low overpotentials of only 218 and 262 mV to deliver OER current densities of 10 and 100 mA cm−2, respectively, with a small Tafel slope of 45 mV dec−1, which are the best among the reported Ni–Fe oxide-based OER electrocatalysts. The NixFe3−xO4/Ni hybrid NSA also exhibits robust stability under the OER conditions, showing no decline in the catalytic activity after a continuous oxygen-evolving test conducted at current densities ranging from 10 to 500 mA cm−2 for a total of 220 h. The excellent electrocatalytic OER performance of the electrodeposited NixFe3−xO4/Ni hybrid NSA could be attributed to its vertically aligned nanosheet morphology providing a large electrochemically active surface area, better matched Fermi energy of NixFe3−xO4 with the O2 production potential and faster electron transfer due to proper Ni incorporation, and low interfacial resistance and robust contact between the NixFe3−xO4/Ni hybrid and the substrate due to in situ electrodeposition. This work provides a facile (around 3 min of electrodeposition) and low-cost synthesis strategy that could be applicable for the fabrication of nanostructures of various metal oxides or metal oxide/metal hybrids for different applications.

The development of nonprecious metal-nitrogen-carbon (M-N-C) materials with efficient metal utilization and abundant active sites for the oxygen reduction reaction (ORR) is of great significance for fuel cells and metal-air batteries. Ultrasmall 2 D Cox Zn2-x (benzimidazole)4 [Cox Zn2-x (bim)4 ] bimetallic metal-organic framework (MOF) nanosheets (≈2 nm thick) are synthesized by a novel bottom-up strategy and then thermally converted into a core-shell structure of sub-5 nm Co nanodots (NDs) wrapped with 2 to 5 layers of Co,N-codoped graphene (Co@FLG). The size of the Co NDs in Co@FLG could be precisely controlled by the Co/Zn ratio in the Cox Zn2-x (bim)4 nanosheet. As an ORR electrocatalyst, the optimized Co@FLG exhibits an excellent half-wave potential of 0.841 V (vs. RHE), a high limiting current density of 6.42 mA cm-2 , and great stability in alkaline electrolyte. Co@FLG also has great ORR performance in neutral electrolyte, as well as in Mg-air batteries. The experimental studies and DFT calculations reveal that the high performance of Co@FLG is mainly attributed to its great O2 absorptivity, which is endowed by the abundant Co-Nx and pyridinic-N in the FLG shell and the strong electron-donating ability from the Co ND core to the FLG shell. This elevates the eg orbital energy of CoII and lowers the activation energy for breaking the O=O/O-O bonds. This work sheds light on the design and fabrication of 2 D MOFs and MOF-derived M-N-C materials for energy storage and conversion applications.

Assembling various nanowires together, enabling the assemblies with tailored optical, electrical, and multifunctional properties, represents a promising technology for next generation multifunctional electronics. Here we demonstrate a novel multicolor electrochromic device by coassembling W18O49 and V2O5 nanowires using solution-based Langmuir-Blodgett technique. The transparent W18O49 nanowire film became orange with the increasing addition of V2O5 nanowires and the film underwent a dynamic color change (orange, green, and gray) on application of different electrochemical biases of 2, 0, and -0.5 V (vs Ag/AgCl). Both the transmittance and color of the device can be easily controlled by manipulating the layers of coassembled nanowires and the ratios between the two nanowires. On the basis of this approach, different patterns can be easily fabricated with the addition of corresponding masks, and the solid electrochromic device is assembled, suggesting its significant potentials in smart windows and multicolor electrochromic displays.

High-quality electron transport layers (ETLs) are essential for stable and efficient perovskite solar cells (PSCs). Metal sulfides (MSs) are considered potential candidates for ETLs due to their high carrier mobility, low cost, and favorable chemical and physical stability. The quality of the MS films plays important role in the photovoltaic performance of PSCs. However, few reports focus on the relative preparation, characteristics, and corresponding mechanisms of MS-based ETLs. In this review, MS-based ETLs are summarized according to their preparation strategies and the mechanism. We hope that this review can help others understand the intrinsic phenomena of MS-based ETLs and motivate further investigations.

An Fe induction strategy is introduced to achieve template-free synthesis of Co,Fe dual-metal N-codoped hollow porous carbon from zeolitic imidazole frameworks, which is beneficial for the exposure of highly dispersed metal (M)–Nx active sites and enhancement of mass transport, thereby exhibiting a superior electrocatalytic activity (E1/2, 0.86 VRHE).

Ultrathin necklace-like Ag2Te nanowires with a diameter of 10 nm and a length of several micrometers are fabricated by a simple solution-based process at low temperature, and the Ag2Te nanowire films are fabricated by a Langmuir–Blodgett technique. A reversible structural phase transition of the nanowire films obtained can be observed, and in addition is also reflected by the electrical properties.

A series of Co–P–TiO2 nanocomposite coatings were prepared via pulsed electrodeposition technique. TiO2 nanoparticles were embedded into the coating matrix using TiO2 sol. The phase constituents of...

Chromium coatings are largely restricted in electrical and electronic industries due to the environmental concerns. To address these concerns, a cobalt–phosphorus–titanium oxide (Co–P–TiO2) nanocomposite coating is developed in this study using a nanoparticle-reinforced electrodeposition process. The effects of TiO2 nanoparticles on the properties of co-deposited Co–P–TiO2 nanocomposite coatings are investigated. The surface characterisation is carried out by scanning electron microscopy and atomic force microscopy, while the crystal structure is studied using X-ray diffraction. The mechanical properties of nanocomposite coatings including microhardness and wear resistance are also determined. To study the electrochemical behaviour of the coatings, the potentiodynamic polarisation analysis combined with electrochemical impedance spectroscopy is performed. The Co–P–TiO2 coating at 1 g/L TiO2 addition displays the best physicochemical performance. Compared to Co–P coating, the mechanical properties of the nanocomposite coating are significantly improved by the strengthening effects of the well-dispersed TiO2 particles. Excellent corrosion resistance is also achieved for the Co–P–TiO2 at proper TiO2 addition due to its smooth and defect-free microstructure. However, it is found that the excessive addition of TiO2 decreases the coating quality, resulting in an unfavourable microstructure and properties.

Direct electrochemical reduction of CO2 to multicarbon products is highly desirable, yet challenging. Here, we present a potentiostatic pulse-electrodeposition of high-aspect-ratio CuxAuy nanowire arrays (NWAs) as high-performance electrocatalysts for the CO2 reduction reaction (CO2RR). The surface electronic structure related to the Cu:Au ratio in the CuxAuy NWAs could be facilely modulated by controlling the electrodeposition potential and the as-fabricated CuxAuy NWAs could be directly used as the catalytic electrode for the CO2RR. The morphology of the high-aspect-ratio nanowire array significantly lowers the onset potential of the alcohol formation due to the diffusion-induced enhancement of the local pH and CO concentration near the nanowire surface. Besides, the properly adjusted surface electronic structure of the CuxAuy NWA enables the adsorption of CO and facilitates the subsequent CO reduction to ethanol via the C-C coupling pathway. Owing to the synergistic effect of morphology and electronic structure, the optimized CuxAuy NWA selectively reduces CO2 to ethanol at low potentials of −0.5–−0.7 V vs. RHE with a highest Faradaic efficiency of 48%. This work demonstrates the feasibility to optimize the activity and selectivity of the Cu-based electrocatalysts toward multicarbon alcohols for the CO2RR via simultaneous adjustment of the electronic structure and morphology of the catalysts.

In this study, Ni–P, Ni–W–P and Ni–B coatings were electrolessly plated on aluminium alloy substrates. All coatings were uniform and adherent with shiny metallic appearances. A systematic study was...

Three kinds of IT-like non-fullerene electron acceptors, acting as electron transport layer, were introduced into the inverted perovskite solar cell. Based on systemically adjusting the thickness of the electron transport layer, the devices with three indacenodithieno[3,2-b]thiophene (IT) like (IT-like) non-fullerene acceptors wholly performed better superiority than that based on phenyl-C61-butyric acid methyl ester (PCBM), and a high efficiency of 14.29% was achieved by the device with ITIC electron transport layer. Comparing the detail parameters, the open-circuit voltage is all enhanced because the recombination loss is further suppressed with PCBM replacing by IT-like non-fullerenes. More importantly, the IT-like non-fullerenes show an unparalleled ability in extraction and transportation of photo-generated carrier and the radiation loss is largely inhabited. Benefits from the high quality perovskite film, lower recombination loss and trap passivation, the abnormal hysteresis effect is dramatically suppressed by IT-like non-fullerenes. By comparing with PCBM based devices, the hysteresis index (HI) of the inverted PSCs based on ITIC, ITIC-Th and IT-M are 1.78, 1.35, 1.83 and reduced by 47%, 46% and 60%, respectively. This work preliminary reveal the obvious advantage for the application of IT-like non-fullerenes in inverted perovskite solar cells, which shows great potential in preparing non-hysteresis, high efficient inverted perovskite solar cells.

Inverted planar perovskite solar cells (PSCs) with a poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) layer as the hole transport layer (HTL) are shown to exhibit high power conversion efficiency (PCE). To date, efficient PTAA HTLs have required dopants to increase conductivity. These dopants, which include 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane and bis(trifluoromethane)sulfonimide lithium salt/4-tert-butylpyridine, are harmful to the stability of the devices and may increase the cost of the PSCs. We realized efficient inverted planar PSCs with nondoped PTAA as the HTL. We used contact angle, absorption spectra, X-ray diffraction, fluorescence spectra, and atomic force microscope to measure the impact of nondoped PTAA on the upper perovskite films. The results showed that the nondoped PTAAs work as effectively as the doped ones. The inverted planar PSCs based on nondoped PTAA exhibited relatively excellent performance. We achieved a higher PCE of 18.11% and a very small hysteresis index of 0.32% were using a very thin nondoped PTAA film. This efficient nondoped HTL provided an easy way for inverted planar PSCs to solve problems introduced by dopants. This study provides a reference for the future preparation of highly efficient and stable PSCs with nondoped HTL.

Here, we prepared nano-SiO2-coated graphite films using a novel laser-assisted sol–gel method. The SiO2 sol–gel prepositioned on the graphite substrate was irradiated by the fiber laser at different energy densities. The growth mechanism of the coatings under laser irradiation was studied and the effects of processing parameters on the coating structure were systematically investigated. In addition, the high-temperature oxidation resistance of these samples was examined. Surface morphology and elemental composition were examined using scanning electron microscopy and energy-dispersive spectrometer. Phase constituents and microstructure were identified by x-ray diffraction and transmission electron microscopy. The oxidation resistance was analyzed by thermal gravimetric analysis. The results found that laser irradiation significantly modifies the sol–gel-deposited nano-SiO2 layer. A uniform and compact nano-SiO2 coating was obtained when irradiated by laser energy density of 14.4 kJ/cm2. Optimum high-temperature oxidation resistance was achieved for the two-layer SiO2-coated films.

CO2 sequestration in cement-bonded cellulose fiberboards through carbonation curing was studied. The maximum possible carbon dioxide uptake by ordinary Portland cement within a curing process was determined by a cement solution carbonation. It was 28.5% based on cement mass after 18 h initial hydration and 24 h carbonation. The best combination of material and process parameters in fiberboard carbonation had facilitated a curing process to allow 24.4% carbon uptake in 8 h carbonation and 20% carbon uptake in 0.5 h carbonation, a 70–85% reaction efficiency within 24 h. It was found that the CO2 sequestration was dependent on the water content in fiberboards after preconditioning. An optimal water content was ranged from 40 to 60%. Carbonated fiberboards had shown a flexural strength at least 70% of ultimate strength within 24 h and a much improved freeze-thaw and wet-dry durability performance. If all cement-bonded cellulose fiberboards in United States adopt carbonation production, the annual CO2 consumption by fiberboards can reach 0.36 Mt.

Despite its high energy density, high-voltage LiNi0.5Mn0.5O2 cathode which suffers from a poor cycle performance that originated from the cathode structural collapse is still far from commercialization. Doping heteroatom into the lattice of LiNi0.5Mn0.5O2 is believed to be a valid strategy in overcoming this bottleneck. Herein, Si was employed as a dopant to comprehensively improve the electrochemical performance of LiNi0.5Mn0.5O2. X-ray diffraction and Rietveld refinement revealed that doping Si into LiNi0.5Mn0.5O2 can optimize its structure, which reduced the degree of Li/Ni cation mixing. As a result, an enhanced interfacial reaction kinetics of Li-ion intercalation/de-intercalation could be achieved, rendering the doped LiNi0.5Mn0.5O2 a remarkably improved reversible capacity in comparison with its pristine. Moreover, it was found that Li0.99Si0.01Ni0.5Mn0.5O2 showed a significantly higher capacity than LiNi0.5Mn0.5O2 does at 25 °C. It is believed that this work affords an effective strategy for high-performance LiNi0.5Mn0.5O2 cathode.

Titanium matrix composites (TMCs) offer high specific strength and stiffness compared with steel and nickel-base materials. High-temperature TMCs can offer up to 50% weight reduction relative to monolithic superalloys while maintaining equivalent strength and stiffness in jet engine propulsion systems. Regardless of the reinforcements are continuous fibres or discontinuous particulates, the unique properties of TMCs have thrust them to the forefront of extensive research and development programmes around the world. Even though TMCs are one of the most studied and sought-after material systems, useful information about their properties, fabrication methods and design is scattered in the literature. This review covers important research work that has led to the advances in TMCs material systems. It also provides comprehensive details about common reinforcements, manufacturing processes, and reviews static and dynamic properties of some common TMCs. The review also presents common industrial applications of TMCs and highlights the promising outlook of TMCs.

We report a series of semi-aromatic thermosetting polyimide (PI) resins that can be used as matrix for copper-clad laminates for high-frequency applications. The poly(amic ester) (PAE) resins derived from the diester of 1,2,4,5-cyclohexanetetracarboxylic dianhydride, aromatic diamines (the mixture of 2,2′-dimethylbenzidine and 2,2′-bis[4-(4-aminophenoxy) phenyl] propane), and the monoester of nadic anhydride were synthesized by Polymerization of Monomer Reactants (PMR) method. The structure conversion of PAE resins at different temperatures was investigated and the B-stage PI powders prepared by thermally baking the PAE resins at 220°C are nearly fully imidized. The viscosities of the B-stage PI powders and the mechanical and thermal properties of the cured PI resins were optimized by varying the molar ratio of the two diamines. The cured PI resins possess low and steady dielectric constants ( Dk) below 3.0 and dielectric dissipation factors ( Df) of less than 0.01 at high frequency of 1–12 GHz. Furthermore, the quartz fiber cloth-reinforced semi-aromatic thermosetting PI composites (QF/PI) exhibit excellent dielectric performance, good heat resistance, and mechanical properties. At a high frequency of 1–12 GHz, the Dk of QF/PI-4 is stable in the range of 3.16–3.2, and the Df is stable in the range of 0.0026–0.0046. These results suggest the potential of the semi-aromatic QF/PI for use in high-frequency IC boards.

The inherent disadvantages of untreated carbon felt (pristine-CF) still restrict the vanadium redox flow battery (VRFB) from further improving in electrochemical performances. To solve this problem, the carbon felt (CF) decorated with bismuth hydrogen edetate (Bi(HEDTA)) complex was synthesized and studied as anode for VRFB. The cyclic voltammetry curve reflects the great improvement in electrochemical reversibility by reducing the peak potential difference from 0.73 to 0.50 V. Electrochemical impedance spectrum shows the better charge transfer process by reducing the charge transfer resistance from 7.14 to 1.13 Ω. The VRFB assembled by the CF modified with Bi(HEDTA) exhibits an energy efficiency of 66.25% at a current density of 160 mA cm−2, which is 11.76% higher than that of the pristine system. Moreover, the mechanism of Bi(HEDTA) involved in the anodic half-reaction of VRFB has been put forward. The results demonstrate that not only the metal but also the ligand of the complex are significant for improving the electrochemical activity of the reaction towards V3+/V2+ redox couple. In more detail, the oxygen-containing functional groups in the ligand could increase the wettability of the CF as well as act as the active sites, and the metal could decrease the evolution of hydrogen at the same time. Therefore, the effective combination of the respective functions of ligand and metal, makes Bi(HEDTA) a feasible ornament of the CF for VRFB.

Ionic zinc is considered as an environmental pollutant. This work systematically investigated leaching mechanisms of calcium sulfoaluminate cement (CSA) pastes incorporated with/without ZnCl2 under the attacks of chloride and/or sulfate. The leaching behaviors of CSA pastes in the leaching solution are in-situ and continuously monitored by innovative non-contact electrical impedance measurement (NCEIM) and pH meter. The dissolution and diffusion during the leaching process are experimentally identified. Other techniques are also performed to verify the finding of NCEIM: the ion chromatograph and inductively coupled plasma optical emission spectrometer reveal the leaching or decomposition sequence of CSA pastes during the leaching process. Besides, results from XRD and SEM techniques demonstrate that main solid products in CSA pastes are ettringite and calcium monosulfoaluminate hydrates. The incorporation of Zn in the pastes has great impact on the decomposition of CSA pastes in the temperature elevation. External chloride and/or sulfate attacks significantly alter the pore structure of CSA pastes during the leaching process.