Excellent Electrical Conductivity Research Articles

Structural and chemical study of complex silver patterns additively manufactured by multi-photon reduction

Multi-photon reduction (MPR) based on femtosecond laser makes rapid prototyping and molding in micro-nano scale feasible, but is limited in material selectivity due to lack of the understanding of the reaction mechanism in MPR process. In this paper, additively manufacturing of complex silver-based patterns through MPR is demonstrated. The effects of laser parameters, including laser pulse energies and scanning speeds, on the structural and chemical characteristics of the printed structures are systematically investigated. The results show that the geometric size of printed cubes deviates from the designed size further by increasing laser pulse energy or decreasing scanning speed. The reaction mechanism of MPR is revealed by studying the elemental composition and chemical structures of printed cubes. The evolution of Raman spectra upon the laser processing parameters suggests that the MPR process mainly includes two processes: reduction and decomposition. In the MPR process, silver ions are reduced and grow into particles by accepting the electrons from ethonal molecules; meanwhile carboxyl groups in polyvinylpyrrolidone are decomposed and form amorphous carbon that is attached on the surface of silver particles. The conductivity of silver wires fabricated by MPR reaches 2 × 105 S m−1 and stays relatively constant as varying their cross section area, suggesting excellent electrical conduction. The understanding of the MPR process would accelerate the development of MPR technology and the implementation of MPR in micro-electromechanical systems could therefore be envisioned.

Exploring Recent Developments in Graphene-Based Cathode Materials for Fuel Cell Applications: A Comprehensive Overview.

Fuel cells are at the forefront of modern energy research, with graphene-based materials emerging as key enhancers of performance. This overview explores recent advancements in graphene-based cathode materials for fuel cell applications. Graphene's large surface area and excellent electrical conductivity and mechanical strength make it ideal for use in different solid oxide fuel cells (SOFCs) as well as proton exchange membrane fuel cells (PEMFCs). This review covers various forms of graphene, including graphene oxide (GO), reduced graphene oxide (rGO), and doped graphene, highlighting their unique attributes and catalytic contributions. It also examines the effects of structural modifications, doping, and functional group integrations on the electrochemical properties and durability of graphene-based cathodes. Additionally, we address the thermal stability challenges of graphene derivatives at high SOFC operating temperatures, suggesting potential solutions and future research directions. This analysis underscores the transformative potential of graphene-based materials in advancing fuel cell technology, aiming for more efficient, cost-effective, and durable energy systems.

Strong and Tough MXene Bridging-induced Conductive Nacre.

Nacre is a classic model, providing an inspiration for fabricating high-performance bulk nanocomposites with the two-dimensional platelets. However, the "brick" of nacre, aragonite platelet, is an ideal building block for making high-performance bulk nanocomposites. Herein, we demonstrated a strong and tough conductive nacre through reassembling aragonite platelets with bridged by MXene nanosheets and hydrogen bonding, not only providing high mechanical properties but also excellent electrical conductivity. The flexural strength and fracture toughness of the obtained conductive nacre reach ~282 MPa and ~6.3 MPa m1/2, which is 1.6 and 1.6 times higher than that of natural nacre, respectively. These properties are attributed to densification and high orientation degree of the conductive nacre, which is effectively induced by the combined interactions of hydrogen bonding and MXene nanosheets bridging. The crack propagations in conductive nacre are effectively inhibited through crack deflection with hydrogen bonding, and MXene nanosheets bridging between aragonite platelets. In addition, our conductive nacre also provides a self-monitoring function for structural damage and offers exceptional electromagnetic interference shielding performance. Our strategy of reassembling the aragonite platelets exfoliated from waste nacre into high-performance artificial nacre, provides an avenue for fabricating high-performance bulk nanocomposites through the sustainable reutilization of shell resources.

Strong and Tough MXene Bridging‐induced Conductive Nacre

AbstractNacre is a classic model, providing an inspiration for fabricating high‐performance bulk nanocomposites with the two‐dimensional platelets. However, the “brick” of nacre, aragonite platelet, is an ideal building block for making high‐performance bulk nanocomposites. Herein, we demonstrated a strong and tough conductive nacre through reassembling aragonite platelets with bridged by MXene nanosheets and hydrogen bonding, not only providing high mechanical properties but also excellent electrical conductivity. The flexural strength and fracture toughness of the obtained conductive nacre reach ~282 MPa and ~6.3 MPa m1/2, which is 1.6 and 1.6 times higher than that of natural nacre, respectively. These properties are attributed to densification and high orientation degree of the conductive nacre, which is effectively induced by the combined interactions of hydrogen bonding and MXene nanosheets bridging. The crack propagations in conductive nacre are effectively inhibited through crack deflection with hydrogen bonding, and MXene nanosheets bridging between aragonite platelets. In addition, our conductive nacre also provides a self‐monitoring function for structural damage and offers exceptional electromagnetic interference shielding performance. Our strategy of reassembling the aragonite platelets exfoliated from waste nacre into high‐performance artificial nacre, provides an avenue for fabricating high‐performance bulk nanocomposites through the sustainable reutilization of shell resources.

Investigating the potential of powder metallurgy for fabricating graphene nanoplatelets reinforced copper nanocomposites

Copper (Cu) is highly sought for its excellent electrical and thermal conductivity. However, its limited mechanical strength hinders its wider application in demanding fields. This work explores the potential of graphene nanoplatelets (GNPs) as a strengthening agent for Cu. Cu-GNP composites with varying GNP content (0.1–1.5 wt%) were fabricated using a combined ball milling and powder metallurgy approach. The microstructure and mechanical properties of the composites were comprehensively analyzed using field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and Raman spectroscopy. Compared to pure Cu, the Cu-GNP composites showcased significantly improved mechanical performance. Notably, the Cu-1.0 wt% GNP composite exhibited a remarkable ∼27% and ∼53% enhancement in compressive strength and micro-hardness, respectively. This improvement is attributed to the effective load transfer between Cu and well-dispersed GNPs, which act as reinforcement elements and inhibit dislocation movement. These findings demonstrate the promising potential of Cu-GNP composites for applications requiring high strength.

3D printed stretchable coaxial fiber grid for dual-mode multifunctional tactile sensor array

Tactile sensors play a critical role in the Internet of Things (IoT) and wearable devices. However, although current tactile sensors can precisely measure pressure, the simple fabrication of stretchable high-performance tactile sensors with a broad measuring range and multifunctions is still challenging. Herein, an ink-direct writing 3D printing method is developed to fabricate novel stretchable dual-mode tactile sensors with coaxial fiber structure. The 3D printed coaxial fibers have an outer skin composed of silicone rubber and polytetrafluoroethylene micropowders thixotropic agent and an inner core of an ionic conductive solution composed of polyvinyl alcohol and sodium chloride. The coaxial fibers exhibit excellent electrical conductivity (0.54 S cm−1) and outstanding stretchability, as high as 390 %. The intersection of the two fibers constitutes a dual-mode tactile sensor which can operate in triboelectric or capacitive modes with complementary measurement ranges from 0.0003 to 0.4517 N. Besides, by combining the signals from the two modes, the sensor can identify the material that comes into contact with the sensor. A 3D printed network of tactile sensor arrays made of warp-weft interwoven coaxial fibers is able to accurately detect the locations of multi-point contact with the array. This dual-mode multifunctional tactile sensor can be widely used in various applications such as the IoT and wearable devices.

Ice template-induced assembly coupled with carbonization strategy for preparation of sulfur-doped porous carbon nanosheets from lignite as high-capacity anode for lithium-ion batteries

Two-dimensional (2D) porous carbon nanosheets with heteroatom doping are promising anode materials for lithium-ion batteries (LIBs) due to their distinctive sheet-like structure and excellent electrical conductivity. Limited by high preparation costs and cumbersome preparation processes, the large-scale production of carbon nanosheets remains a major challenge. Herein, a series of sulfur-doped porous carbon nanosheets (SCNSs) are successfully synthesized through ice template-induced assembly coupled with a carbonization approach using aromatic ring fragments exfoliating from lignite as the precursor and K2SO4 as the sulfur source. The prepared SCNSs exhibit well-defined sheet-like structures, abundant hierarchical nanopores, large specific surface areas (∼1761 m2·g−1), and high sulfur doping contents (∼7.72 at%). Such unique microstructure characteristics of SCNSs not only provide favorable and efficient channels for the lithium-ions/electrons transportation but also offer sufficient available space or active sites for lithium-ions storage. When used as anode materials for LIBs, the SCNS-3 shows high reversible capacity (1620 mAh·g−1 at 0.05 A·g−1), excellent rate performance (315 mAh·g−1 at 2 A·g−1), and superior cycling stability (901 mAh·g−1 at 1 A·g−1 after 500 cycles). Lithium storage behavior analysis indicated that the capacitance enhancement in SCNSs anodes is primarily due to improved capacitive behavior. This study provides a novel and effective route for the large-scale production of sulfur-doped carbon nanosheets using aromatic ring fragments exfoliated from lignite, which demonstrates promising industrial application potential in LIBs anode materials.

Self-powered photochemical cathode aptamer sensor based on ZnIn2S4 photoanode and Cu2O@Ag@Ag3PO4 photocathode for the sensitive detection of Hg2.

A self-powered photoelectrochemical (PEC) aptamer sensor based on ZnIn2S4 as the photoanode and Cu2O@Ag@Ag3PO4 as the sensing cathode is designed for the detection of Hg2+. Anindium tin oxide (ITO) electrode modified with ZnIn2S4 was used instead of a platinum (Pt) counter electrode to provide an obviously stable photocurrent signal. The suitable band gap width of ZnIn2S4 can generate photogenerated electrons well. Theunique hydrangea structure of ZnIn2S4 can enhance light absorption and accelerate the separation and transfer of photocarriers. At the same time, Cu2O@Ag@Ag3PO4 with excellent electrical conductivity further enhances the photocurrent provided by the ZnIn2S4 photoanode. Because the reducing substances in the biological medium can change the photoanode characteristics of the photoanode interface, the separation of the photoanode and the sensing bicathode is beneficial to improve the anti-interference ability of the sensor. Under optimized conditions, the PEC aptamer sensor realizes the detection of Hg2+ (1mM-1 fM), and the detection limit is 0.4 fM. In addition, the constructed self-powered PEC sensor has good selectivity, repeatability, and stability, which provides a new idea for the design of the PEC aptamer sensor platform.

Emerging MXene-based electrode materials for efficient capacitive deionization: A comprehensive review

Capacitive deionization (CDI) has been considered a potential desalination technology because of its simple operation, high repeatability and low energy consumption. It is well known that electrode materials play a crucial role in the performance of CDI. As an emerging two-dimensional material, MXene have shown great application potential in CDI due to the unique two-dimensional structure, abundant surface functional groups and excellent physicochemical properties. In order to further improve the desalination performance of CDI, MXene-based electrode materials have received extensive attention and research. In this review, the structure, properties and synthesis strategies of MXene are analyzed to clarify the relationship between properties and desalination performance. The excellent electrical conductivity, mechanical property and hydrophilicity of MXene lay the foundation for the efficient desalination of MXene-based electrode materials. Then, the latest advance of MXene-based electrode materials in CDI is summarized. The optimization strategies of MXene-based materials include surface functional group regulation, in situ derivation and heterostructure construction. Finally, the current challenges and future prospects are presented from the perspectives of novel MXene-based CDI system, desalination mechanism, CDI battery and real water environment, which provides new inspiration and insight for the further development of CDI.

Efficient U(VI) removal by Ti3C2Tx nanosheets modified with sulfidated nano zero-valent iron: Batch experiments, mechanism, and biotoxicity assessment

The MXenes, a new class of two-dimensional layered materials, have found extensive applications in water treatment for its excellent thermal stability, electrical conductivity, and excellent adsorption ability. Sulfidized nano zero-valent iron (S-nZVI) is a good reducing agent, however, the practical application of S-nZVI is currently restricted due to the tendency of nano materials to agglomerate. Herein, MXenes use as a support and in situ loading S-nZVI on it to prepare a new material (S-nZVI/Ti3C2Tx), and applied it to U(VI) removal in water treatment. The microscopic characterization proves that S-nZVI on Ti3C2Tx has good dispersion and effectively alleviates agglomeration. Batch experiments shown that S-nZVI/Ti3C2Tx has a very good effect on U(VI) removal, and the maximum adsorption capacity reaches 674.4 mg/g under the aerobic condition at pH=6.0. The pseudo-second-order kinetic model and the Langmuir isotherm model were found to be more appropriate for describing the adsorption behavior. This indicates that the removal process is a single molecular layer chemisorption. Moreover, the S-nZVI/Ti3C2Tx maintained a removal efficiency of over 85 % for U(VI) even after being reused five times, demonstrating its excellent reusability. It is worth noting that the material can remove 79.8% of 50 mg/L of U(VI) in simulated seawater, indicating that S-nZVI/Ti3C2Tx possessed an excellent uranium extraction performance from seawater. Experimental results and XPS analysis showed that U(VI) was removed by adsorption, reduction and co-precipitation. Moreover, S-nZVI/Ti3C2Tx was a low toxicity material to hyriopsis cumingii. Therefore, S-nZVI/Ti3C2Tx was expected to be a candidate as adsorbent with great potential in removal of uranium from wastewater and seawater.

Controllable fiberization engineering of cobalt anchored mesoporous hollow carbon spheres for positive feedback to electromagnetic wave absorption

In order to overcome the limitations of single attenuation mechanism materials in effectively absorbing electromagnetic waves (EMW), meticulous microstructural design of composites and an elevated degree of integration of wave absorbing mechanisms are crucial. Utilizing mesoporous hollow carbon spheres as precursors, PCHM@ComXn (X = Se, S, O) nano-microspheres were synthesized by anchoring cobalt nanoparticles on the surface, controllable encapsulating in continuous fiber structure by electrostatic spinning technique subsequently. The carbon shell-cavity core configuration interspersed with nanoparticles has the advantage of light weight, low density and extensive defects. Abundant heterogeneous interface in carbon fiber offers excellent electrical conductivity and high specific surface area, while a three-dimension conductive network optimizes the transmission loss to incident EMW. The efficient synergy of multiple mechanisms enables PCHM@CoSe2/CNFs to achieve a strong reflection loss of −50.55 dB at a matched thickness of 2.0 mm, while the EABmax value can be extended to a remarkable 6.80 GHz at 2.3 mm, which is considerably superior to fiber samples encapsulating other cobalt-based nanoparticles of the same family. This work provides an innovative direction for the development of high-performance EMW absorbers.

Preparation of Au–Ni bimetallic-coated monodisperse PS@Ni/Au microspheres with excellent conductivity and their application in acrylate-based anisotropic conductive adhesives

Anisotropic conductive adhesives (ACAs) provide an efficient and easy method of interconnecting small electronic devices compared to traditional solder joint connections. In this paper, PS@Ni/Au metal composite microspheres with excellent electrical conductivity in the size of 2.76 μm were prepared by chemical plating technique and in situ redox method. The effects of PS@Ni metal composite microspheres with different shell thicknesses and compactness on the preparation of Ni–Au bimetallic shell layers were investigated, and the effects of different Au:PS@Ni mass ratios on the volumetric conductivity of PS@Ni/Au metal composite microspheres were discussed. The composite microspheres were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), energy spectrometry (EDS), and X-ray diffraction (XRD). Thick and compact Ni metal shells are the key to preparing PS@Ni/Au metal composite microspheres with the complete degree of encapsulation. When the mass ratio of Au:PS@Ni was 0.15:1, the conductivity was as high as 1.3 × 105 S cm−1. The acrylate pressure-sensitive containing 3.1–8.3 vol% conductive particles presented an obvious anisotropy. When the mass ratio of the conductive particles was higher than 8.3 vol%, the conductive particles appear to be significantly aggregated. The research ideas and methods have great application potential for replacing the traditional solder joint connections.

Porous polyaniline/flower-like hybrid phase MoS2/phosphorus-doped graphene ternary nanocomposite for efficient room temperature ammonia sensors

Ammonia, a ubiquitous gas with diverse industrial applications, demands reliable and cost-effective sensing technologies for monitoring and control. In this context, this study presents the development of a novel ternary nanocomposite comprised of porous polyaniline (PANI), hybrid phase molybdenum disulfide (MoS2), and phosphorus-doped graphene (PGO) for the realization of highly efficient room temperature ammonia sensors. The synergistic combination of these three materials leverages their individual properties, such as high surface area, excellent electrical conductivity, and enhanced catalytic activity, to create a robust sensing platform. The PANI/1 T-2 H MoS2/PGO nanocomposites were synthesized by a combination of solvothermal processing and in-situ polymerization techniques. The morphological and structural characteristics of the PANI/1 T-2 H MoS2/PGO nanocomposites were conducted using advanced analytical techniques, that include, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Raman spectroscopy, Transmission Electron Microscopy (TEM), and X-ray Photoelectron Spectroscopy (XPS), and Brunauer-Emmett-Teller method (BET). The enhanced surface area of PANI/1 T-2 H MoS2/PGO (54.72 m2/g) compared to PANI (31.8 m2/g) has a positive impact on the sensing characteristics of PANI/1 T-2 H MoS2/PGO. The PANI/1 T-2 H MoS2/PGO nanocomposite sensor has shown sensing response values of ∼1070 %, response time of 12 s, recovery time of 30 s towards 100 ppm of NH3, and detection limit is 0.01 ppm (10 ppb). A highly linear gas response of the PANI/1 T-2 H MoS2/PGO sensor is observed in a range of 10–100 ppm ammonia concentration. The development of the PANI/1 T-2 H MoS2/PGO nanocomposite sensor aims to meet the increasing need for temperature-efficient, cost-effective, and energy-efficient gas sensing technologies that can be used in various fields including environmental monitoring and industrial safety.

Fabrication of pressure visual fiber based on liquid metal control thermochromic pigments

AbstractIn this study, pressure visual fibers (PVF) with a core‐shell structure were prepared using a coaxial wet spinning process. The fiber composite shell consists of a luminescent material (as a light source) and a thermochromic pigment (as a filter light source) mixed with a polyacrylonitrile (PAN) matrix. The fiber core layer, on the other hand, was made of gallium‐indium alloy liquid metal. In operation, the filter light source is activated by joule heat drive (resulting in the fading of the thermochromic pigment), and the PVF releases phosphorescence upon exposure to ultraviolet light. When a certain pressure is applied to the fiber shell, the liquid metal in the core layer is squeezed, resulting in a local cross‐sectional area reduction, an increase in local joule thermal power, and thus local discoloration. This localized compression, in combination with a small rated current and the presence of an ultraviolet light source, converts the mechanical force (strain and compression) into an optical response. The excellent electrical conductivity of the liquid metal, combined with its compatibility with the soft matrix, makes it a promising candidate for applications in smart textiles and flexible sensing.Highlights The technology of visual fiber controlled by current is presented. The bendability and controllability of visual composites are improved. The composite fiber can be visualized when stressed.

Research on optimizing ultrasonic frequencies for efficient single-walled carbon nanotube dispersion in water using a focused ultrasonic system

Single-walled carbon nanotubes (SWCNTs) can be applied in a wide range of fields owing to their excellent mechanical rigidity, electrical conductivity, and thermal conductivity. However, their application is limited because of their strong van der Waals forces and poor dispersion owing to their hydrophobic properties. To address this problem, ultrasonic dispersion technology has been used in the industry. However, very few studies have investigated the surface damage or effectiveness of the surfactants of SWCNTs with a focus on the frequencies of specific ultrasonic equipment. In this study, the dispersibility of SWCNTs at frequencies of 270, 400, and 700 kHz was investigated using a new focused ultrasonic instrument. The dispersion stability of the samples was analyzed according to each frequency, and the SWCNT surface was studied in detail using field-emission transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The adsorption of the polymeric surfactant to the SWCNT was most observed at 270 kHz, and the dispersion stability after processing at this frequency was better than that of the other samples. Therefore, the frequency of the ultrasonic intensity has a direct effect on the surface modification of SWCNTs.

Polyaniline layered N-doped carbon-coated iron oxide nanocapsules for extremely active Li-ion battery anode and oxygen evolution reaction

We report the effective synthesis of polyaniline (PANi)-layered nitrogen-doped carbon-coated Fe3O4 (FNC@PANi) nanocapsules (NCs) for electrocatalysis of oxygen evolution reaction (OER) as well as anode material for lithium (Li)-ion batteries (LIBs) via a simple hydrothermal method and oxidative polymerization technique. The prepared FNC@PANi NCs revealed a dual core-shell structure, in which an intermediate carbon layer allowed excellent electrical conduction between the Fe3O4 NCs and PANi. The dual core-shell structure also allowed the Fe3O4 NCs to expand freely during the Li-ion insertion/extraction and OER processes without breaking the outer layer, thus providing a high surface area (147.85 m2 g−1) and enhanced electrical conductivity. These properties facilitate the application of the dual core-shell FNC@PANi NCs as an advanced electrode material for LIBs, delivering a high reversible specific capacity of 1556.48 mAh g−1 at 0.1 A g−1, excellent rate performance (896.96 mAh g−1 at 1 A g−1), and durable cycling life (680.12 mAh g−1 at 5 A g−1 for 3000 cycles). The dual core-shell FNC@PANi NCs exhibited high electrocatalytic activity in the OER, with a small Tafel slope of 108.7 mV dec−1 owing to synergistic effects between the copious active sites of the Fe3O4 NCs and the carbon core-shell structure and a modest overpotential of 219 mV at 10 mA cm−2. The electrodes showed excellent stability over 10 h, as determined by chronopotentiometry at 10 mA cm−1. The resultant dual-core-shell FNC@PANi NCs are efficient iron-oxide-based electrode materials for LIBs and OER electrocatalysts.

Reduced Graphene Oxide-Supported SrV4O9 Microflowers with Enhanced Electrochemical Performance for Sodium-Ion Batteries.

Sodium-ion batteries (SIBs) have received considerable attention in recent years. Anode material is one of the key factors that determine SIBs' electrochemical performance. Current commercial hard carbon anode shows poor rate performance, which greatly limits applications of SIBs. In this study, a novel vanadium-based material, SrV4O9, was proposed as an anode for SIBs, and its Na+ storage properties were studied for the first time. To enhance the electrical conductivity of SrV4O9 material, a microflower structure was designed and reduced graphene oxide (rGO) was introduced as a host to support SrV4O9 microflowers. The microflower structure effectively reduced electron diffusion distance, thus enhancing the electrical conductivity of the SrV4O9 material. The rGO showed excellent flexibility and electrical conductivity, which effectively improved the cycling life and rate performance of the SrV4O9 composite material. As a result, the SrV4O9@rGO composite showed excellent electrochemical performance (a stable capacity of 273.4 mAh g-1 after 200 cycles at 0.2 A g-1 and a high capacity of 120.4 mAh g-1 at 10.0 A g-1), indicating that SrV4O9@rGO composite can be an ideal anode material for SIBs.

Electrochemical Sensors for Heavy Metal Ion Detection in Aqueous Medium: A Systematic Review.

Heavy metal ions (HMIs) are very harmful to the ecosystem when they are present in excess of the recommended limits. They are carcinogenic in nature and can cause serious health issues. So, it is important to detect the metal ions quickly and accurately. The metal ions arsenic (As3+), cadmium (Cd2+), chromium (Cr3+), lead (Pb2+), and mercury (Hg2+) are considered to be very toxic among other metal ions. Standard analytical methods like atomic absorption spectroscopy, atomic fluorescence spectroscopy, and X-ray fluorescence spectroscopy are used to detect HMIs. But these methods necessitate highly technical equipment and lengthy procedures with skilled personnel. So, electrochemical sensing methods are considered to be more advantageous because of their quick analysis with precision and simplicity to operate. They can detect a wide range of heavy metals providing real-time monitoring and are cost-effective and enable multiparametric detection. Various sensing applications necessitate severe regulation regarding the modification of electrode surfaces. Numerous nanomaterials such as graphene, carbon nanotubes, and metal nanoparticles have been extensively explored as interface materials in electrode modifiers. These nanoparticles offer excellent electrical conductivity, distinctive catalytic properties, and high surface area resulting in enhanced electrochemical performance. This review examines different HMI detection methods in an aqueous medium by an electrochemical sensing approach and studies the recent developments in interface materials for altering the electrodes.

Emerging MXene-based electrocatalysts for efficient nitrate reduction to ammonia: recent advance, challenges, and prospects

Ammonia (NH3) plays an irreplaceable role in traditional agriculture and emerging renewable energy. Its preparation in industry mainly relies on the energy-intensive Haber-Bosch process, which is associated with high energy consumption and large CO2 emissions. Recently, the nitrate reduction reaction (NO3-RR) driven by renewable energy has received extensive attention. This reaction can efficiently synthesize NH3 with water as a hydrogen source and NO3- as a nitrogen source under mild conditions, which is conducive to reducing energy consumption and promoting the carbon cycle. It is well known that the properties of electrocatalysts determine the performance of NO3-RR. As an emerging two-dimensional material, MXenes (transition metal carbides/nitrides/carbon nitrides) possess excellent electrical conductivity, large specific surface area and controllable surface functional groups, which shows great application potential in the field of NO3-RR. Herein, this review summarized the structure, properties and synthesis strategies of MXenes to elucidate the possibilities from foundation to application. Then, the latest research progress in applying MXene-based electrocatalysts to NO3-RR was summarized and the applicability of different NH3 detection methods was analyzed. Finally, the present challenges and future prospects of NO3-RR were presented. This review aimed to provide thoughtful insights into the rational design of MXene-based electrocatalysts for sustainable NH3 synthesis.

Simultaneously improving mechanical properties and electrical conductivity of Al-1.9Mn alloys with different Mg and Si addition

A simultaneous achievement of high strength and toughness, as well as high conductivity in traditional Al-1.9Mn cast aluminum alloy used in the manufacture of water-cooled radiator shells has proven to be challenging. The addition of Mg and Si elements was implemented in the cast aluminum alloy for a modified treatment to solve the problem. The results showed that the inclusion of Si facilitated the transformation of the plate-like Mn-rich phase (Al6Mn) in the initial Al-1.9Mn alloy into a Chinese-script phase (Al15Mn3Si2) in the new Al-1.9Mn alloy. A higher Si content resulted in an increased volume fraction of Al15Mn3Si2 and a decreased solid solution of Mn in the matrix. Furthermore, a high content of Mg (0.9 wt%) in the Si modified Al-1.9Mn alloy resulted in a notable property reduction, not only in its elongation, but also in its electrical conductivity. It can be attributed to the formation of Mg2Si and the increased solid solution of Mg in the matrix. Through the optimization of the Mg and Si contents, new Al-1.9Mn alloys with superior mechanical properties and excellent electrical conductivity were successfully developed. With the addition of 0.45 wt% magnesium and 0.75 wt% silicon, the new Al-1.9Mn alloy increased its tensile strength to 170 MPa and yield strength to 88 MPa while maintaining 10 % elongation. At the same time, its electrical conductivity increased by 10.7 % compared to the original Al-1.9Mn alloy. The addition of magnesium and silicon elements can achieve a simultaneous enhancement of both the strength and electrical conductivity of the Al-1.9Mn alloy. This holds the potential to meet the usage requirements for cast aluminum alloys used in water-cooled radiator shells.