Metal Substrate Research Articles

A novel UV-curable composite coating with superior anti-corrosion and mechanical properties

The UV curing method is free from volatile organic compounds (VOC) and exhibits high curing efficiency. However, pore flaws and inadequate mechanical qualities after cure greatly hinder their utilization in metal anti-corrosion. Herein, layered double hydroxides (LDH) supported by molybdic acid and cerium ions were synthesized in situ on the sericite (SC) surface, enhancing the shielding, corrosion inhibition, resin compatibility, and cross-linking density of the coating. Compared with carbon steel immersed in a 3.5 wt% NaCl solution, the incorporation of SC/KH560@LDH reduced the corrosion current density (Icorr) from 2.001 × 10−5 A/cm2 to 7.883 × 10−6 A/cm2. Moreover, the low-frequency impedance of the UV-SC/KH560@LDH coating remained high at 1.939 × 1010 Ω·cm2 after 70 days of immersion in a 3.5 wt% NaCl solution. The excellent corrosion resistance of UV-SC/KH560@LDH can be attributed to the barrier properties of the filler, the chloride ion trapping, and the passivation effect. Furthermore, the UV-curable alkyd resin used in this work formed a chemical bond with the metal substrate, enhancing the mechanical properties of the coating. The adhesion strength of the UV-SC/KH560@LDH was measured at 11.50 MPa. The thickness loss (21.3 μm) of the UV-SC/KH560@LDH were minimal after 5000 cycles of wear. A new research concept for preparing the UV-SC/KH560@LDH with superior anti-corrosion and mechanical properties for carbon steel plate surfaces has been proposed to meet the demands of practical applications.

Electronic Oxide-Metal Strong Interactions (EOMSI) Localized at CeOx-Ag Interface.

Electronic oxide-metal strong interactions (EOMSI) refer to the electronic oxide-metal interactions (EOMI) between oxide adlayers and underlying metal substrate that is strong enough to stabilize supported oxide adlayers in a low-oxidation state, which individually is not stable under an ambient condition, from high temperature oxidation in air to a certain extent. Herein we report the deposition and electronic structure of CeOx adlayers on capping ligand-free cubic Ag nanocrystals, i.e., CeOx/Ag inverse catalysts. The EOMI occur via the charge transfer from Ag substrate to CeOx adlayers in the CeOx/Ag inverse catalyst, and the EOMSI are observed in the CeOx/Ag inverse catalyst with the average thickness of CeOx adlayers about 0.9 nm to exclusively form Ce2O3 adlayers stable against oxidation at 400 °C. As the thickness of CeOx adlayers increases, ceria adlayers with oxygen vacancies (CeO2-x) emerge and grow in the CeOx/Ag inverse catalysts, and the Ce3+/Ce4+ ratio decreases. Catalytic performance of CeOx/Ag inverse catalysts in the CO oxidation reaction is closely linked with the thickness and electronic structure of CeOx adlayers. These results demonstrate that the EOMSI and EOMI in the oxide/metal inverse catalysts are localized at the oxide-metal interface and sensitively vary with the thickness of oxide adlayers, offering a strategy of thickness engineering to tune electronic structures of oxide adlayers in oxide/metal inverse catalysts.

Remote vapor-phase dual alkali halide salts assisted quasi-van der Waals epitaxy of m-phase ZrO2 thin films with high dielectric constant and stable flexible properties

High-κ dielectric constant and wideband gap of ZrO2 material render it as an excellent candidate for transistor gate dielectric layers. However, current reported synthesis techniques suffer the problems of high precursor volatilization rate, ultrasmall grains with low dielectric constant, and high leakage current, which largely impede its application in electronic devices. Here, the quasi-van der Waals epitaxy growth of compact m-phase ZrO2 thin films has been developed, in which the stable supply of Zr source is realized by the tuned sublimation of ZrC powder with remote vapor-phase dual halide salts assistant. The formation of m-phase ZrO2 is due to the lower Gibbs free energy, in which the crystal nucleates at the etched hole edges of mica substrate, thus forming hexagonal shape polycrystal grains and merging as the continuous thin films. The microstructures and Raman spectrum characterization reveal the two dominated growth orientations and good crystal qualities, which indicate the uniform dielectric constant. The excellent growth reproducibility could be easily adapted to thin metal substrates, such as tungsten, molybdenum, and stainless steel, where the adhesion strength is strong because of the higher density of interfacial chemical bonding. Meanwhile, the metal–insulator–metal flexible capacitors show the high dielectric constant of 23–26 and low leakage current density of 10−4 A/cm2 at large voltage and only exhibit the decreased capacitance density of 7% after several hundred bending cycles. Our work paves a way to achieve the high-quality dielectric thin films on various substrates by the unique chemical vapor deposition design strategy.

Theoretical study on the electrochemical CO2 reduction performance of MoS2-supported Ni single atoms with transition metal substrate doping

In the context of increasing energy issues and climate change, the development of electrochemical CO2 reduction strategies using single atom catalysts (SACs) presents a viable solution by converting CO2 into high-value-added products. Transition metal dichalcogenides (TMDs) have emerged as the main candidates for SACs in electrocatalytic CO2 reduction reaction (CO2RR) catalysts. The regulation of the second coordination sphere of SACs is known to modulate their electronic structure and catalytic behavior. This study delves into the effect of transition metal-doped substrates on SACs. We employed spin-polarization density functional theory (DFT) to design a series of Ni/TM-MoS2 monolayer MoS2 materials, with transition metals (including Cr, Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, W, Re, Os, Ir, Pt and Au) substituting the Mo atoms and anchoring single atom Ni. Among them, six Ni/TM-MoS2 catalysts doped with Mn, Fe, Co, Ru, Rh, and Ir demonstrate enhanced CO2RR activity and selectivity when compared to unmodified Ni/MoS2. The Ni/Ru-MoS2 SAC exhibits the best catalytic activity and selectivity for formic acid production, with a limiting potential (UL) of -0.06 V. The incorporation of the metal-doped substrate lowers the work function of the catalyst, facilitating electron transfer and reaction progression. Furthermore, a volcanic relationship was observed between the work function and UL. This study provides strategic insights into the design and development of SACs, highlighting the potential for future modifications and applications.

Study on rapid growth and improved performance of superconducting YBa2Cu3O7-δ coated conductors assisted by transient liquid phase

This study employs a fluorine-free metal organic deposition method (FF-MOD), with transient liquid phase assistance, to expedite the growth (TLAG) of superconducting YBa2Cu3O7-δ (YBCO) thin films on LaMnO3 metal substrates. The research evaluates the phase formation and performance of YBCO films with varying proportions of preformed BaZrO3 (BZO) nanocrystals. The experimental results indicate that the optimal proportion for incorporating BZO nanocrystals is 5 %, leading to the YBCO film displaying critical current density at 77 K under zero-field conditions. This achievement marks a significant advancement in the rapid growth of YBCO films on metal substrates with enhanced current-carrying capacity. Additionally, the research assesses the changes in overall uniformity and microstrain of YBCO films after the addition of BZO nanocrystals, shedding light on the key factors contributing to performance enhancement and offering insights for future improvements. This investigation offers valuable insights for attaining high-speed, high-performance growth of superconducting YBCO coating conductors.

Electron-Beam-Induced Modification of N-Heterocyclic Carbenes: Carbon Nanomembrane Formation.

Electron irradiation of self-assembled monolayers (SAMs) is a versatile tool for lithographic methods and the formation of new 2D materials such as carbon nanomembranes (CNMs). While the interaction between the electron beam and standard thiolate SAMs has been well studied, the effect of electron irradiation for chemically and thermally ultrastable N-heterocyclic carbenes (NHCs) remains unknown. Here we analyze electron irradiation of NHC SAMs featuring different numbers of benzene moieties and different sizes of the nitrogen side groups to modify their structure. Our results provide design rules to optimize NHC SAMs for effective electron-beam modification that includes the formation of sulfur-free CNMs, which are more suitable for ultrafiltration applications. Considering that NHC monolayers exhibit up to 100 times higher stability of their bonding with the metal substrate toward electron-irradiation compared to standard SAMs, they offer a new alternative for chemical lithography where structural modification of SAMs should be limited to the functional group.

Multifunctional Ti3C2Tx-based epoxy composite coating towards intelligent response and corrosion/wear resistance

Questions remain about the unreasonable collocation of Ti3C2Tx and nanocontainers resulting in the performance degradation of multi-function Ti3C2Tx-based epoxy composite coating. Here, mesoporous SiO2 nanocontainers (SNT) containing both potassium thiocyanate and hexadecyl trimethyl ammonium bromide (CTAB) were loaded on MXene-based platform (SNT-on-MP) to achieve a novel epoxy coating (SNT-on-MP@EP) with the integrated functions of self-warning, self-healing, anti-corrosion and anti-wear. In the damaged area, the thiocyanate groups combined with Fe3+ ions to form a blood-red color display, and the formed coordination compound and CTAB as corrosion inhibitors were deposited on the metal substrate, thus showing intelligent response function. Besides, because of passive and active synergistic protection functions, the lowest-frequency impedance value of SNT-on-MP@EP maintained 5.74 × 107 Ω·cm2 after 4 weeks of exposure in salt water environment, which was increased by two orders of magnitude compared with pure epoxy coating. Under the reciprocating sliding friction, the wear rate of SNT-on-MP@EP reached 5.32 × 10−5 mm3/N·m, and was reduced by 58.29 %, owing to the formation of lubricant film at the friction interface and the enhancement of the deformation resistance of the coating. The reasonable collocation of SNT and Ti3C2Tx-based platform eliminated the problem of weak interaction between traditional inorganic nanocontainer and water-based epoxy coating, thus giving full play to the advantages of both.

Tribological properties of YG8/steel friction pair in an aqueous lubrication system with an ionic liquid: Experimental results and molecular dynamics simulations

In this work, an ionic liquid (G-RIC) with excellent lubricating performance was successfully prepared, and the tribological properties as an additive in glycerol-water solutions were explored. The results indicated that 2.0 % additive content can reduced the friction coefficient to below 0.1, leading to a decline in the wear volume of 76 %. Gray cast iron corrosion tests revealed that the additive exhibited excellent corrosion resistance. Quantum chemical calculations revealed that the anion RIC has a low energy gap (ΔE = 0.034 Ha), which implies that it is more prone to undergoing tribochemical reactions with the metal substrate under frictional heat. The synergistic action of the liquid lubrication layer, adsorption film, and friction protective film created an interface that easily shears.

Chirality-Induced Magnetic Polarization by Charge Localization in a Chiral Supramolecular Crystal.

The chirality-induced spin selectivity (CISS) effect is a fascinating phenomenon that correlates the molecular structure with electron spin-polarization (SP). Experimental procedures to quantify the spin-filtering magnitude have extensively used magnetic-field-dependent conductive AFM. In this work chiral crystals of imide-substituted coronene bisimide ((S)-CBI-GCH) are studied to explain the dynamics of the current-voltage I - V spectra and the origin of superimposed peaks are investigated. A dynamic voltage-sweep rate-dependent phenomenon can give rise to complex I - V curves. The redox group, capable of localization of charge, acts as a localized state that interferes with the continuum of the π - π stacking, giving rise to Fano resonances. A novel mechanism for dynamic transport is introduced, which provides insight into the origin of spin-polarized charge in crystallized CBI-GCH molecules after absorption on a metallic substrate, guided by transient charge polarization. Crucially, interference between charge localization and delocalization during transport may be important properties in understanding the magnetochiral phenomena observed by electrostatic force microscopy. Finally, it is observed that charge trapping sensitively modifies the injection barrier from direct tunneling to Fowler-Nordheim tunneling transport supporting nonlinearity in CISS for this class of molecules.

A study on the impact of liquid metal droplets onto metal and elastomer substrates

A study on the impact of liquid metal droplets onto metal and elastomer substrates

Effect of phytic acid/rust conversion layer on corrosion protection of rusty mild steel

In this study, a rust/phytic acid (rust/PA) conversion layer was prepared on rusty mild steel by dipping rusty steel panels into a phytic acid solution. After treating with phytic acid, the free phosphate group in the conversion layer chelated with Fe3+ and generated insoluble salt, which could form a new dense conversion layer. The dense rust/PA conversion layer effectively strengthened the interfacial bonding between the coatings and rusty metal substrate and exhibited good corrosion protection and defect healing abilities.

Predicting the Adhesive Layer Thickness in Hybrid Joints Involving Pre-Tensioned Bolts.

While most academic studies focus on the properties of cured joints, this research addresses the manufacturing process of hybrid joints in their uncured state. Hybrid joints that combine adhesive bonding with pre-tensioned bolts exhibit superior mechanical performance compared to exclusively bonded or bolted joints. However, the adhesive flow during manufacturing in hybrid joints often results in a nonuniform adhesive thickness, where obtaining an exact thickness is crucial for accurate load capacity predictions. This paper presents experiments involving three different adhesives, providing precise measurements of the adhesive layer thickness distribution, which served as a reference when evaluating and validating the subsequent numerical predictions. The numerical predictions were performed using computational fluid dynamics (CFD) to model the flow behavior of the adhesives during the bonding process and their interactions with the metal substrates. The CFD predictions of the adhesive layer thickness showed good agreement with the experimental data, with the relative differences between the average experimental and numerical thickness values ranging from 4.07% to 27.1%. The results were most accurate for the adhesive with sand particles, whose particles remained intact, ensuring that the adhesive's rheology remained unchanged. The results highlight the importance of the rheological behavior of the adhesive in the final distribution of the adhesive layer thickness, thereby expanding the understanding of these joints.

A novel antibacterial and wear-resistant strategy based on metal surface micro-texture nitriding coupled functional mesoporous silicon coating

Modified metal layers coupling durable antifouling and antibacterial properties have garnered considerable interest in various fields, including but not limited to medical equipment, kitchen utensils, public facilities, and specific industrial applications, such as transportation, energy utilization, and aerospace. Nevertheless, wear and corrosion resulting from harsh operating environments can significantly compromise the modified metal layers, leading to diminished antifouling and antibacterial capabilities. Currently, maintaining excellent antibacterial properties on the surface of metal-modified layers under complex working conditions remains a key challenge for metal protection technology. Herein, we innovatively propose a ternary collaborative strategy to optimize and extend the antifouling and antibacterial activity of metal substrate surfaces. Firstly, laser surface texturing (LST) is used to create micro-textured topography on the metal surface to serve as a reservoir for collecting debris and storing functionalized nanoparticles. Then, the surface micro-textures are treated with plasma nitriding to form a wear-resistant passivation layer that protects the aforementioned microstructures. Finally, a lubricant containing functional mesoporous silicon nanoparticles (Ag2O-MSNs@OTES) is coated on the metal surface, which not only reduces the friction coefficient but also achieves antibacterial and antifouling effects by continuously releasing silver ions from the mesoporous silicon spheres. Employing the aforementioned ternary coordination strategy, the fabricated coupling layer exhibits not only exceptional antifriction and wear properties but also remarkable antibacterial efficacy against both E. coli and S. aureus, attributed to the Ag2O-MSNs@OTES. Therefore, the wear-resisting and antibacterial coupling layer for the protection of metal surfaces has promising and versatile applications in wide areas.

High-temperature aqueous corrosion of MO–Na2O–B2O3–SiO2 glass and glass-ceramic coatings on metallic substrates: Effect of alkaline earth metals M2+= {Ca2+, Sr2+, Ba2+}

This investigation aims to assess the impact of 2 A alkaline-earth oxides on the alteration of glass/glass-ceramic coatings on steel under conditions of exposure to hot water. Experiments involved integrating CaO, SrO, and BaO into sodium-borosilicate glass systems after that a melting-quenching process to obtain frits. Coated and sinter-crystallized samples denoted as GC-Ca, GC-Sr, and GCC-Ba were exposed to hot aqueous corrosion according to DIN 4753–3 at 95 °C, which determined weight loss after 42 days. ICP-MS analyzed aqueous solutions for element leaching. Results indicated that glass-ceramic coatings (GCC-Ba) outperformed glass coating(GC-Ca, GC-Sr). GCC-Ba demonstrated enhanced stability, attributed to limited ion exchange and diffusion at high temperatures, enhancing corrosion resistance, supported by sanbornite crystal phase presence. Total element release by ICP-MS and 42 days of hot water corrosion coatings' weight loss after 42-day corrosion test lined up: GC-Sr > GC-Ca > GCC-Ba.

(Invited) Comparing and Contrasting the Advantages and Challenges of Catalysts for Low Temperature AEM, AEL, and PEM Electrolysis

Electrolysis has been promoted as a critical route to enabling green hydrogen and a broader US Department of Energy supported H2@Scale vision enabling a clean, economic and sustainable energy system.1 Low temperature electrolysis offers advantages over high temperature electrolysis in high temperature materials challenges, limited intermittency capabilities, thermal integration, lower manufacturing and technology readiness, steam conversion and separation challenges.2 Within low temperature electrolysis anion exchange membrane (AEM), (liquid) alkaline (AEL) and proton exchange membrane (PEM) electrolysis are the three primary electrolysis technologies being investigated.These electrolysis environments are different and the catalyst materials they employ, and the cost, natural abundance, performance, and durability limitations are all different. These factors have a significant impact on the research focus and needs for each of these competing technologies. This presentation will explore catalysis in each one of these systems and compare critical limitations of each.The PEM system depends on Ir for anode (OER) catalysis. Ir is expensive and one of the least abundant elements in the earth’s crust. While earth abundance of Ir may is a potential concern for projections of electrolysis needs,3,4 the ability to thrift Ir more efficiently and achieve improved durability are critical for achieving hydrogen cost targets. Specific features impacting the cost, performance and durability trade-offs of Ir in PEM electrolysis will be discussed in terms of hydrogen levelized costs and the research advances necessary to have a positive impact on PEM electrolyzers.AEM and AEL electrolysis are distinct in terms of the concentration of supporting (KOH) electrolytes being investigated and the types of electrodes typically employed. AEM electrolyzers typically work at 1M KOH concentrations or below and employ thin film electrodes with alkaline ionomer as a parallel to most PEM designs. AEL electrolyzers typically operate at high (30 wt% KOH) concentrations and consist of electrodes deposited onto metal substrates rather than deposited as a thin film onto the membrane/separator. The materials sets and some of the performance and durability challenges of each of these systems are similar. They also have challenges at both the anode and cathode, where as PEM cathodes operate highly efficiently and durably with low loadings of Pt. The primary advantage of alkaline systems is the ability to enable highly earth abundant electrocatalysis, but challenges remain for performance and durability tradeoffs. These aspects as well as their implications for hydrogen levelized cost will be presented along with target research needs. https://www.energy.gov/eere/fuelcells/h2scale.Alex Badgett, Mark Ruth, Bryan Pivovar, “Economic considerations for hydrogen production with a focus on polymer electrolyte membrane electrolysis,” Electrochemical Power Sources: Fundamentals, Systems, and Applications, 2022, 327-364.Cortney Mittelsteadt, Esben Sorensen, and Qingying Jia, Ir Strangelove, or How to Learn to Stop Worrying and Love the PEM Water Electrolysis Energy Fuels 2023, 37, 17, 12558–12569.Mark Clapp, Christopher M. Zalitis, Margery Ryan, Perspectives on current and future iridium demand and iridium oxide catalysts for PEM water electrolysis, Catalysis Today 420 (2023) 114140.

(Digital Presentation) Synthesis of Carbon Materials on Aluminum Foil from a Vapor-Gas Environment

Due to its excellent electrical conductive properties and large specific surface area, one of the allotropic modifications of carbon, carbon nanotubes (CNTs), grown on a metal substrate, have great potential for use in supercapacitor electrodes. After all, growing layers of nanotubes directly on the surface of electrodes. can make it possible to achieve the best adhesion and electrical contact of CNTs with the current collector [1]. The large surface area and exceptional electronic conductivity of CNTs make them prime candidates for high-performance and high-speed electrochemical applications [2].The aim of the work was to investigate the effect of synthesis conditions on the structure and properties of a carbon layer grown on the surface of aluminum foil.We used technical aluminum foil with a thickness of 16 microns. Aluminum foil was previously degreased with acetone, kept in an aqueous 1 M NaOH solution for 3 minutes and 30 minutes in a 20% aqueous solution of nickel nitrate at 90 °C. The synthesis of carbon materials on the surface of aluminum foil was carried out by pyrolysis of ethanol vapor in argon at 550 and 600 °C.Analysis of SEM picture (fig. a) and Raman spectrum (dig. b) allows to conclude that the synthesized carbon materials are nanotubes or nanofibers.It has been established that pre-treatment of aluminum foil with acetone does not affect the properties and uniformity of distribution of the carbon layer. On aluminum foil, without pretreatment and kept in acetone, after the synthesis of carbon materials from the vapor-gas phase, initial sections of aluminum foil without a carbon layer are observed. Preliminary exposure of aluminum foil in an alkali solution contributed to the uniform distribution of the synthesized carbon; the entire foil was evenly covered with carbon.When pyrolysis of ethanol vapor is carried out in argon at 550 °C, the carbon layer is heterogeneous (fig. c) and volumetric growths are observed on the foil. When synthesizing carbon materials at 600°C, the carbon layer is dense without bulky formations (fig. d).This work was performed as part of the Ministry of Science and Higher Education of the Russian Federation[Government Order Theme No. 121111900148-3]. References Redkin, A. N., Mitina, A. A., & Yakimov, E. E. (2021). Simple technique of multiwalled carbon nanotubes growth on aluminum foil for supercapacitors. Materials Science and Engineering: B, 272, 115342. DOI:10.1016/j.mseb.2021.115342;Moyer-Vanderburgh, K., Ma M. C., Park, S.J., Jue, N.L., Buchsbaum, S.F., Wu K.J., Wood, M., Ye, J. Fornasiero, F., Growth and Performance of High-Quality SWCNT Forests on Inconel Foils as Lithium-Ion Battery Anodes: ACS Appl. Mater. Interfaces 2022, 14, 49, 54981–54991. DOI: 10.1021/acsami.2c18396 Figure 1

Porous Dielectric Structure and Response Speed of Moisture Sensors

Humidity sensors are typically made of alpha-alumina films as porous dielectric materials deposited through the anodic spark deposition (ASD) technique, a unique anodic oxidation method to deposit ceramic coatings on the exterior of metals. Close attention to the precise composition of electrolyte solution is crucial when mixing chemical compounds. Moreover, the ASD process, which happens during dielectric breakdown at the anode surface in an electrochemical cell, is clearly followed by visible sparking at the anode/electrolyte interface, leading to the formation of various ceramic coatings on metal substrates. Electrical breakdown happens over an anodized barrier layer, typically amorphous aluminum oxide, which has been produced on the metal anode. The local high temperature (>2000°C) produced by electrical sparks melts the amorphous aluminum oxide and converts it to alpha-aluminum oxide, forming the stable foundation for a reliable humidity sensor.In this study, we produced a variety number of small pores to investigate the response speed of moisture sensors. The ASD current can be adjusted to control the number of small pores. The smaller current gives a greater number of small pores. We focused on low-humidity sensors, often referred to as dew-point sensors. In fabrication of dew-point sensors, Scanning Electron Microscopy (SEM) was used to examine and determine the size of pores. Three different currents, 30 mA, 25 mA, and 10 mA, have been tried for comparative analysis of small pores existing within large pores. Two pores have been measured for current 10 mA, resulting in sizes of 47 nanometer (nm) and 71 nm, respectively. Similarly, three small pores for current 30 mA were measured with sizes of 32 nm, 42 nm, and 31 nm respectively. After the testing of low-humidity (dew-point) sensors, we found that the number of small pores does not significantly affect the response speed of the sensors.

On-Surface Chemistry: Probing the Presence of Adatoms on Differently Terminated Surfaces by Porphyrin Metalation

Reactive adsorbates in on-surface reactions and in heterogeneous catalysis on different substrates are of emerging importance. This is for the crucial roles they take in reaction pathways and for their decisive influence on reaction kinetics. [1] The thermally activated 2D mobility [2] of reaction precursors and reactive adatoms as well as their spatial and temporal coincidence at reaction sites is of mechanistic importance for many interface-specific reactions. In our work, we use the well-studied metalation reaction of H2-porphyrins to investigate the action of adatoms on metallic and passivated surface substrates. Porphyrin metalation has been established on atomically clean metallic substrates [3] as well as on metal-oxides [4] and metallic surfaces modified by oxygen [5].We perform spectro-microscopy correlation experiments combining X-ray Photoelectron Spectroscopy, Ultraviolet Photoelectron Spectroscopy, Low Energy Electron Diffraction and Scanning Tunnelling Microscopy on Cl- and N terminated Cu(001). Thereby we find extended layers of adsorbate-induced superstructures that have decisive and contrasting impact on the reactivity of the surface, as well as on molecular self-assembly. The O and N termination of Cu facilitates the metalation reaction and self-assembled domains of CuTPP are formed at room temperature. Cl termination on the contrary, fully inhibits the metalation reaction and causes 2HTPP to assemble into small ‘magic’ clusters.

Anhydride Photolysis on a Semiconductor Surface

The on-surface synthesis (OSS) method has facilitated the growth of diverse carbon-based nanomaterials, with the goal of integrating them into electronic devices. However, the reliance on metallic substrates in OSS restricts these materials' applications, necessitating strategies for transferring these materials into technological relevant substrates or direct synthesis on non-metallic surfaces, where the low absorption energies and lack of catalytic activity from the substrate complicate this approach. Addressing these limitations, we explore on-surface photochemistry as an alternative to thermally induced reactions, enabling controlled chemical processes at lower temperatures. While prior works have demonstrated light-induced reactions on metallic surfaces, where the hot electrons photogenerated from the metallic surface play a crucial role, synthesizing nanostructures directly on semiconducting or insulating surfaces through a purely intramolecular energy absorption remains challenging.The photolysis and pyrolysis of anhydrides has proven to be a suitable approach for the formation of arynes, as schematically shown in the Figure. Our study focuses on the selective photodissociation of maleic anhydride-containing precursors on a semiconductor surface (SnSe), unveiling their distinct photochemical behaviors. Specifically, tetraphenylphthalic anhydride (TPPA) undergoes successful photolysis on SnSe, forming tetraphenyl benzyne (TPBY) intermediates, and eventually, tetraphenyl benzene (TPBE) products. Furthermore, TPPA photolysis occurs efficiently also at room temperature, leading to the direct formation of TPBE. Contrastingly, benzo[ghi]perylene-1,2-dicarboxylic anhydride (BPA) possesses an extended pi-conjugated backbone and exhibits no photoactivity upon irradiation on the same semiconductor surface. Our calculations of TPPA and BPA excited states predict different behaviors, demonstrating the relationship between molecular structure, pi-conjugation, and photochemical reactivity, offering insights into the design principles for light-induced reactions on inert surfaces. Figure 1

Graphene-skinned alumina fiber fabricated through metalloid-catalytic graphene CVD growth on nonmetallic substrate and its mass production

Graphene growth on widely used dielectrics/insulators via chemical vapor deposition (CVD) is a strategy toward transfer-free applications of CVD graphene for the realization of advanced composite materials. Here, we develop graphene-skinned alumina fibers/fabrics (GAFs/GAFFs) through graphene CVD growth on commercial alumina fibers/fabrics (AFs/AFFs). We reveal a vapor-surface-solid growth model on a non-metallic substrate, which is distinct from the well-established vapor-solid model on conventional non-catalytic non-metallic substrates, but bears a closer resemblance to that observed on catalytic metallic substrates. The metalloid-catalytic growth of graphene on AFs/AFFs resulted in reduced growth temperature (~200 °C lower) and accelerated growth rate (~3.4 times faster) compared to that obtained on a representative non-metallic counterpart, quartz fiber. The fabricated GAFF features a wide-range tunable electrical conductivity (1-15000 Ω sq−1), high tensile strength (>1.5 GPa), lightweight, flexibility, and a hierarchical macrostructure. These attributes are inherited from both graphene and AFF, making GAFF promising for various applications including electrical heating and electromagnetic interference shielding. Beyond laboratory level preparation, the stable mass production of large-scale GAFF has been achieved through a home-made roll-to-roll system with capacity of 468-93600 m2/year depending on product specifications, providing foundations for the subsequent industrialization of this material, enabling its widespread adoption in various industries.