Surface Modification Of Metals Research Articles

Seedless and electroless plating of silver on silica particles by using microreactor

Synthesis of silver nanoshells is still a challenge especially in the absence of surface modification of core particles and/or metal seed decoration on core surfaces. In this study, we applied a microrector to seedless and electroless plating of silver on bare silica particles, and investigated the effects of reaction temperatures and silver ion concentrations on the morphology and surface coverage of silver on the core particle surface. Our experiments demonstrated that the use of the microreactor enabled the one-step direct deposition of silver with a morphology close to complete shells and that silver ion concentrations from 0.2 to 0.5 mM at a moderate temperature of 50 °C produced high coverage and yield. Besides, the mixing sequence of NH3 and HCHO in the synthesis procedure was found to be a key factor to achieve the high silver coverage. In addition, we demonstrated that the addition of polyvinylpyrrolidone (PVP) after the silver shell growth reaction increases the stability without decreasing the reaction rate.

Cysteamine Chemisorption at Mercury-Solution Interfaces in the Context of Redox and Microdissociation Equilibria.

The redox behavior and chemisorption of cysteamine (CA) at a charged mercury surface are described, with an emphasis on its acid-base properties supported by molecular dynamics and quantum mechanical calculations. It was found that CA forms chemisorbed layers on the surface of the mercury electrode. The formation of Hg-CA complexes is connected to mercury disproportionation, as reflected in peaks SII and SI at potentials higher than the electrode potential of zero charge (p.z.c.). Both the process of chemisorption of CA and its consequent redox transformation are proton-dependent. Also, depending on the protonation of CA, the formation of typical populations of chemisorbed conformers can be observed. In addition, cystamine (CA disulfide dimer) can be reduced on the mercury surface. Between the potentials of this reduction and peak SI, the p.z.c. of the electrode used can be found. Furthermore, CA can serve as an LMW catalyst for hydrogen evolution. The mechanistic insights presented here can be used for follow-up research on CA chemisorption and targeted modification of other metallic surfaces.

PKa as a Predictive Descriptor for Electrochemical Anion Adsorption

AbstractThe adsorption of anions onto metal surfaces is important in many applications including effective (electro)catalyst design, metal surface modification, and contaminant removal in wastewater treatment. In electrocatalysis, anions can be both reactive intermediates or site‐blocking spectators, where their adsorption strength therefore dictates the rate of reaction. In this work, we have measured the adsorption energy of a series of carboxylic acids on a Pt (111) single‐crystal electrode surface from aqueous solution. We find that the adsorption strength of the carboxylate anion is linearly correlated with its acid‐dissociation constant (pKa) and therefore the heterolytic O−H bond dissociation strength in solution. Using density functional theory modeling, we split the anion adsorption energy into a sum of the adsorption energy and electron affinity of a neutral (carboxyl) radical. Surprisingly, the adsorption energy of the carboxyl radicals are similar and therefore the large difference in electron affinity is what dictates anion adsorption strength; the greater the cost in energy to remove the electron from the anion upon adsorption, the weaker its binding. Therefore, at least within a class of anions with similar structure and surface binding atoms, both electron affinity and acidity are predictive descriptors of adsorption strength.

PKa as a Predictive Descriptor for Electrochemical Anion Adsorption.

The adsorption of anions onto metal surfaces is important in many applications including effective (electro)catalyst design, metal surface modification, and contaminant removal in wastewater treatment. In electrocatalysis, anions can be both reactive intermediates or site-blocking spectators, where their adsorption strength therefore dictates the rate of reaction. In this work, we have measured the adsorption energy of a series of carboxylic acids on a Pt (111) single-crystal electrode surface from aqueous solution. We find that the adsorption strength of the carboxylate anion is linearly correlated with its acid-dissociation constant (pKa) and therefore the heterolytic O-H bond dissociation strength in solution. Using density functional theory modeling, we split the anion adsorption energy into a sum of the adsorption energy and electron affinity of a neutral (carboxyl) radical. Surprisingly, the adsorption energy of the carboxyl radicals are similar and therefore the large difference in electron affinity is what dictates anion adsorption strength; the greater the cost in energy to remove the electron from the anion upon adsorption, the weaker its binding. Therefore, at least within a class of anions with similar structure and surface binding atoms, both electron affinity and acidity are predictive descriptors of adsorption strength.

Surface modification of transition metals (TM: Mn, Fe, Co) decorated Pt-doped carbon quantum dots (Pt@CQDs) nanostructure as nonenzymatic sensors for nitrotyrosine (a biomarker for Alzheimer): Perspective from density functional theory

To develop a method for the detection of nitrotyrosine (NTS), transition metals: cobalt (Co), Iron (Fe), and Manganese (Mn) decorated Platinum-doped carbon quantum dot (Pt@CQDs) nanomaterial surfaces were computationally investigated. This study employed density functional theory (DFT) at the d3bj-B3LYP/def2SVP level of theory to gain in-depth knowledge of the adsorption, selectivity, reactivity, and trapping efficacy of nitrotyrosine (NTS) as a biomarker for Alzheimer disease. Results of the adsorption energy of the systems increased as −46.661 kcal/mol, −45.308 kcal/mol, −666.673 kcal/mol, and −12.507 kcal/mol which correspond to NTS_Co_Pt@CQDs, NTS_Fe_Pt@CQDs, NTS_Mn_Pt@CQDs, and NTS_Pt@CQDs. NTS_Mn_Pt@QDs system demonstrated the chemisorption as it has the highest adsorption energy. HOMO-LUMO analysis shows that cobalt decorated surface had the least energy gap of 1.586 eV while interaction with nitrotyrosine a decrease in the energy gap was observed particularly NTS_Pt@CQDs and NTS_Fe_Pt@CQDs exhibiting values of 1.850 eV and 1.665 eV respectively, whereas, Co_Pt@CQDs and Mn_Pt@CQDs systems showed drastic increase in the energy gap to 2.404 eV and 2.719 eV. This collective finding of this study is significant enough to present these systems as potential models for the detection and trapping of nitrotyrosine biomarkers for the diagnosis of Alzheimer's disease.

Construction of superhydrophobic surfaces with different water adhesion on the low-temperature steels by picosecond laser processing

Manufacturing superhydrophobic metallic surfaces with desired water adhesion for intended applications such as anti-icing and microdroplets transportation remains a grand challenge. Herein, we demonstrated the fabrication of the superhydrophobic surfaces with different water adhesion on the low-temperature steels including DH36, EH40 and FH36 steels via combined strategies of picosecond laser processing and room-temperature vacuum processing. The laser processing could regulate the dimension of the micro/nanostructures on the low-temperature steel surfaces and the vacuum processing controlled the surface chemical compositions of the laser-processed surfaces, leading to the transition of wetting behaviors from the superhydrophilic states, then to the superhydrophobic Wenzel's states with strong water adhesion and finally to the superhydrophobic Cassie-Baxter's states with weak water adhesion. The superhydrophobic surfaces with the Wenzel's states showed great potential in non-destructive and selective transportation of water droplets, while those with the Cassie-Baxter's states exhibited promising anti-icing performance as well as desirable corrosion, impact, and erosion resistance. This work provides an effective, pollution-free, and stable route for controlling the superwettability of the low-temperature steel surfaces and could find promising applications in surface modifications of metals and alloys.

Uniform Zinc Plating Enabled By Polyimide Nanofiber Network for Long-Life Aqueous Zinc Metal Batteries

The rapid development of portable electronics and emerging electric vehicles has created a pressing need for electrical energy storage systems. Among these systems, zinc metal batteries (ZMBs) have shown great potential due to their high theoretical capacity density, low reduction potential, and low-cost anodes. However, the large-scale application of rechargeable ZMBs has been limited by the well-known issues of dendrite growth and adverse side reactions in zinc metal electrodes[1].Various strategies have been proposed to overcome the challenges associated with zinc dendrite growth, including substrate structure optimization, surface modification of zinc metal, and design of novel electrolytes. Among these approaches, constructing a protective layer on the zinc anode surface is a promising strategy due to its simplicity and cost-effectiveness. A dense polyamide coating layer, prepared by the doctor blading method, has been developed to regulate the aqueous Zn deposition behavior by elevating the nucleation barrier and restricting the 2D diffusion of Zn2+ ions [2]. Additionally, an Al2O3 coating layer has been developed using atomic layer deposition to improve the rechargeability of Zn anodes for zinc-ion batteries (ZIBs)[3]. However, these dense layers face a significant challenge to ionic conductivity due to the high energy barrier that hinders the diffusion of Zn2+ ions, leading to poor battery performance, especially under high current densities.Herein, we report utilizing an electrospun polyimide network (noted as PI-Zn hereafter) to resolve this dilemma. The polyimide (PI) chain has numerous carbonyl oxygen atoms that function as electron donors, supported by theoretical calculations (Fig.1). These atoms can establish stable bonds with Zn ions, thereby reducing the activation energy for de-solvation and enhancing the kinetics of Zn ion deposition. Unlike traditional coating methods, our electrospinning polymers form a fiber-like network structure that provides ion channels, thereby enhancing ion transportation. From the Nyquist plots of symmetrical batteries (Fig. 2), the PI-Zn electrode exhibits smaller charge transfer resistance and lower activation energy compared to the bare Zn electrode. The Transmission X-Ray Microscope results (Fig.3) reveal that the deposition on the bare Zn is heterogeneous and dendritic. In contrast, the PI-Zn electrode presented a smooth surface and dendrite-free morphology. The result demonstrates that the charge transfer ability, de-solvation, and deposition kinetics have been improved by PI-Zn, which further increases the plating uniformity.The stability of the Zn anode was evaluated by long-term galvanostatic cycling of a symmetrical Zn cell (Fig. 4). The cell with bare Zn failed after cycling for 100 h at a current density of 1 mA cm-2 resulting from the short circuit. In comparison, the cell with PI-Zn exhibits a stable polarization voltage and an ultralong cycling life of over 1200 hours, indicating the extremely reversible plating/stripping enabled by the PI network. Further interrogation of the PI-Zn was carried out by stringent deep-discharge tests in symmetrical Zn cells under extremely high current density and capacity of 20 mA cm-2 and 10 mA h cm-2. The result shows that the cell with PI-Zn can cycle for more than 200 hours, two times longer than that with bare Zn, proving the advantages of the unique fiber-like network structure, which provides fast and homogeneous Zn ion transportation. Moreover, the fiber network effectively suppresses the hydrogen evolution reaction, verified by the corrosion test, despite the existence of numerous ion channels.Full prototype cells were assembled to prove the practical applications of our strategy. Two promising cathodes for aqueous ZIBs, MnVOH and MnO2, in two different electrolyte systems (Zn(OTf)2 and ZnSO4) were coupled with bare Zn or PI-Zn. For both systems, the capacity retention and Coulombic efficiency are both significantly improved with the help of PI network. The results are consistent with the lifespan difference of symmetrical Zn cells, as expected due to the same plating and stripping processes on Zn. These findings demonstrate that the strategy presented here stands to both dramatically extend battery cycle life and boost battery performance, a promising approach to solve the anode issues in advanced Zn batteries. Cao, Z., et al., Advanced Energy Materials, 2020. 10(30): p. 2001599. Zhao, Z., et al., Energy & Environmental Science, 2019. 12(6): p. 1938-1949. He, H., et al., Journal of materials chemistry A, 2020. 8(16): p. 7836-7846. Figure 1

High Rate Performance of Li Metal Anode in Na-Containing so2-Based Inorganic Electrolyte

Lithium metal anode is one of the best candidates for the next generation energy storage systems due to the lowest electrochemical potential (- 3.04 V vs. standard hydrogen electrode) and the highest theoretical capacity (3860 mAh g-1). However, lithium metal anode have critical problems including dendritic growth of Li deposits during cycling, poor stability of solid electrolyte interface (SEI) on lithium metal anode and severe chemical reaction between Li metal and the electrolyte. Recently, stable artificial interface layers on the Li metal anode have been proposed to solve these problems. In this work, surface modification of Li metal with a Na-containing SO2-based inorganic electrolyte was investigated as an effective way to prevent lithium dendritic growth during cell operation. The surface-modified lithium metal anode effectively prevented the dendritic deposits of Li deposits even at high current density (3 mA cm-2). More detailed reaction chemistry of Li metal with Na-containing inorganic electrolyte will be discussed in the presentation.

Revisiting a Cu-rich layer on the aluminum surface after twin-jet electropolishing

Twin-jet electropolishing (TJE) is a well-known method to prepare Cu-containing Al alloys for transmission electron microscopy (TEM) observation. Previous studies have reported a Cu-rich layer usually formed between Al matrix and outermost alumina layer at the electropolished Al surface. However, characteristics and formation mechanisms of the Cu-rich layer remain largely unexplored. Herein, configurations, formation process and property of the Cu-rich layer formed during TJE of Al alloys are revealed detailly employing aberration-corrected scanning TEM (STEM), STEM image simulations and first-principles calculations. The results reveal a new orientation relationship between the Cu-rich layer (θ’-Al2Cu) and Al matrix, which produces a low interfacial Al strain field. Formations of ∼2-nm-thick θ’ layer and its beneath ∼6-nm-thick Cu diffusion zone at the electropolished Cu-containing Al surface are mainly associated with traces of Cu in the electrolyte and anodization. Selective oxidation of elements, Cu-emitting alumina layer and spontaneous solute Cu segregation at the Al surface are also responsible for formations of the θ’ layer and Cu diffusion zone. Further study reveals that the θ’ layer behaves a strong self-healing ability after damaged by high-energy electron beam. The obtained results provide a potential insight into the surface modification of metals and alloys using electrochemical method.

Rational surface modification of zirconium-based metal–organic framework nanomaterials for the adsorption and recovery of coloured drugs and proteins from aqueous solutions

Coloured drugs and proteins in pharmaceutical wastewater cause environmental pollution. Metal–organic frameworks (MOFs) can be used for the adsorption and recovery of pollutants from wastewater, however selective adsorption and desorption on MOFs are challenging. Herein, UiO-66 and various polyethylene glycol (PEG)-modified MOFs (UiO-66 @mPEG-PO3 and UiO-66 @DSPE) were synthesised to selectively adsorb and separate model drugs [curcumin (CUR) and myricetin (MYR)] and proteins [Bovine serum albumin (BSA) and ovalbumin (OVA)]. Results show that UiO-66 adsorption efficiency for CUR and MYR in aqueous solution reached 93% and 98%, respectively. Additionally, CUR and MYR adsorbed on the UiO-66 surface exhibit good antioxidant activity during the recycling process. X-ray photoelectron spectroscopy and Hirshfeld surface analysis indicate that the adsorption mechanisms of both CUR and MYR by UiO-66 are belonging to the intermolecular interactions. The UiO-66 @mPEG-PO3 significantly reduces the surface area of UiO-66 (216 m2/g) but does not alter the adsorption behaviour of drugs. In the process of desorption and separation of CUR and MYR, the UiO-66 @PEG-PO3 exhibits a higher desorption rate than UiO-66. By contrast, the UiO-66 @DSPE MOFs exhibits optimal protein adsorption and selectively enhances the desorption of OVA rather than BSA in a 40% acetonitrile solution. This method can be used to capture and detect OVA proteins in cell lysates. Rational surface modification is an effective way to improve the adsorption selectivity and recovery efficiency of zirconium-based MOFs, providing an effective way to use MOFs in treating novel water pollutants.

Characteristics of plasma electrolytic oxide coating on magnesium-hydroxyapatite composites

Plasma electrolytic oxidation (PEO) is a surface modification of metals to grow a ceramic-like oxide coating with remarkably enhanced corrosion resistance. This work studies the characteristics of the PEO coating formed on magnesium-hydroxyapatite (Mg-HA) composites with HA concentrations of 0, 10, 20, and 30 wt% prepared by spark plasma sintering (SPS). Thin PEO coatings of 1–3 μm were successfully formed on all specimens in 0.5 M Na3PO4 electrolyte for 5 min. The plasma became finer, reducing the pore size and thickness, with increasing HA concentration. Agglomeration of HA particles in Mg-20HA and Mg-30HA inhibited coating coverage. EDS and XRD analyses confirmed the similar composition of Mg3(PO4)2 in all the coatings. The coating improved surface wettability and showed high apatite-forming ability in simulated body fluid. The optimum coating performance was obtained for Mg-10HA.

An examination and prospect of stabilizing Li metal anode in lithium–sulfur batteries: A review of latest progress

AbstractThe Li metal anode emerges as a formidable competitor among anode materials for lithium–sulfur (Li‐S) batteries; nevertheless, safety issues pose a significant hurdle in its path toward commercial viability. This review enumerates three historical challenges inherent to the Li metal anode: unavoidable volume expansion, multifunctional solid electrolyte interface formation, and uncontrollable lithium dendrite growth. In particular, when paired with a sulfur cathode, the Li anode presents an additional unique hurdle: the shuttle effect. To address these issues, this article offers a thorough examination of the latest innovations aimed at stabilizing the Li metal anode within Li‐S batteries. We categorize these approaches into five classifications: liquid electrolyte optimization, enhancement of non‐liquid‐state electrolytes, Li metal surface modification, Li anode architecture design, and Li alloy improvement. For several noteworthy results within these categories, we have compiled their electrochemical performance into tables, facilitating direct comparison. This detailed analysis illuminates feasible strategies and suggests directions warranting further exploration for optimizing the capability and safety of Li metal anodes in Li‐S batteries.

Bio-inspired nanocomposite coatings on orthodontic archwires with corrosion resistant and antibacterial properties.

The corrosion resistance and antibacterial properties of fixed orthodontic devices are insufficient in the complex oral cavity, which delays tooth movement and causes enamel demineralization. To overcome the challenges, this research constructs a series of polydopamine-graphene oxide (PDA-GO) nanocoatings on representative NiTi archwires via self-assembly. The morphology, chemical structure, and multifunctional properties of coatings showed tunability dependent on the PDA/GO ratio. Optimized PDA-GO coatings with uniform and dense characteristics prolonged the diffusion path for the corrosive medium and reduced Ni dissolution in NiTi alloys. Meanwhile, the applied coatings endowed NiTi alloys with antibacterial activity against Streptococcus mutans due to the surface structures and inherent properties of PDA-GO. In vitro cytotoxicity tests further verified their good biocompatibility. This bio-inspired nanocomposite coating provides a practical reference for modification of dental metal surfaces to better behave in the intraoral environment.

A Review of Electrode Manufacturing Methods for Electrical Discharge Machining: Current Status and Future Perspectives for Surface Alloying

In electrical discharge machining (EDM), the tool electrode is one of the substantial components of the system, and it ensures the success or failure of the EDM process. The electrode’s role is to conduct electrical charges and erode the workpiece to the desired shape. Different electrode materials have different impacts on machining. Certain electrode materials remove metal quickly but wear out rapidly, while others degrade slowly but the material removal is too slow. The choice of the electrode has an influence on both the mechanical properties, such as metal removal rate (MRR), wear rate, surface finish, surface modification and machinability, and the electrical properties, such as sparking initiation, time lag, gap contamination and process stability. There are factors to consider when fabricating an electrode, which include the type of workpiece materials, the metallurgical alloying of the materials, the choice of fabrication techniques, the intended use of the electrode, and material cost. Considerable challenges in EDM electrode fabrication have been reported, which include excessive tool wear for green compact electrodes, high toughness for sintered electrodes, and poor rigidity for additively manufactured electrodes. To address these issues, researchers have explored different manufacturing methods, such as casting, conventional machining, electrodeposition, powder metallurgy and additive manufacturing. In this paper, the various techniques attempted and adopted in EDM electrode manufacturing are analyzed and discussed. This paper also sought to give insight into EDM, its various forms, the dielectric fluid’s properties, EDM electrode’s size and shape, the effects of the electrode on the EDM process, material removal, electrode wear, present technologies for electrode fabrication, and the limitations of these technologies. Finally, directions for future research are highlighted.

CNT Film Chemically Bonding to Metal Surfaces

Carbon nanotubes can be considered as a chemically stable material with exceptional electrical and thermal conductive properties. Electrically conductive applications of carbon nanotubes (CNTs) have been limited by several factors, among them a lack of robust connections to metal surfaces is significant affecting for CNT widespread applications. In this work CNT side walls bonded to different metal surfaces including Cu, Al, Stainless steel, Au and ITO with electrically conductive aminophenyl linkers which can react with metal substrates via diazonium grafting reaction leaving basic functional groups on the metal surface to react with acidic functional groups of the oxidized CNTs. The chemical nature and robustness of the linker-metal bonding was investigated using X-ray photoelectron spectroscopy and Infrared spectroscopy following ultrasonication. Thin layer of CNTs were observed on the surface of the metal surfaces with scanning electron microscopy analysis after ultrasonication. CNT modified metal surfaces showed enhanced current densities compared to the bare metal surfaces in electrochemical analysis in Ru2+/Ru3+ aqueous solution. Finally, ability of the metal-linker-CNT bonding to enhanced the metal-CNT interface conductivity was demonstrated by measuring interface resistance of the CNT-linker-Au system compared to the direct CNT-metal contacts.

Metal-organic Zn-zoledronic acid and 1-hydroxyethylidene-1,1-diphosphonic acid nanostick-mediated zinc phosphate hybrid coating on biodegradable Zn for osteoporotic fracture healing implants.

Zn and its alloys are increasingly under consideration for biodegradable bone fracture fixation implants owing to their attractive biodegradability and mechanical properties. However, their clinical application is a challenge for osteoporotic bone fracture healing, due to their uneven degradation mode, burst release of zinc ions, and insufficient osteo-promotion and osteo-resorption regulating properties. In this study, a type of Zn2+ coordinated zoledronic acid (ZA) and 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) metal-organic hybrid nanostick was synthesized, which was further mixed into zinc phosphate (ZnP) solution to mediate the deposition and growth of ZnP to form a well-integrated micro-patterned metal-organic/inorganic hybrid coating on Zn. The coating protected noticeably the Zn substrate from corrosion, in particular reducing its localized occurrence as well as suppressing its Zn2+ release. Moreover, the modified Zn was osteo-compatible and osteo-promotive and, more important, performed osteogenesis in vitro and in vivo of well-balanced pro-osteoblast and anti-osteoclast responses. Such favorable functionalities are related to the nature of its bioactive components, especially the bio-functional ZA and the Zn ions it contains, as well as its unique micro- and nano-scale structure. This strategy provides not only a new avenue for surface modification of biodegradable metals but also sheds light on advanced biomaterials for osteoporotic fracture and other applications. STATEMENT OF SIGNIFICANCE: Developing appropriate biodegradable metallic materials is of clinical relevance for osteoporosis fracture healing, whereas current strategies are short of good balance between the bone formation and resorption. Here, we designed a micropatterned metal-organic nanostickmediated zinc phosphate hybrid coating modified Zn biodegradable metal to fulfill such a balanced osteogenicity. The in vitro assays verified the coated Zn demonstrated outstanding pro-osteoblasts and anti-osteoclasts properties and the coated intramedullary nail promoted fracture healing well in an osteoporotic femur fracture rat model. Our strategy may offer not only a new avenue for surface modification of biodegradable metals but also shed light on better understanding of new advanced biomaterials for orthopedic application among others.

Surface Refinement of Aluminium Oxide by Carbon-Based Reinforcement

This paper clarifies the surface difference and tribological performance of anodic oxide coating reinforced with three different carbon-based sources. With the rising age of oxide coating as one of the strongest metal surface protectors, modification and improvement of this coating have been rapidly explored, including reinforcing carbon-based materials. The lack of literature on how the correlation between the particles' size improves the surface condition and its tribological properties opens up the gap in expanding this coating's potential. In this study, aluminium alloy AA2017 has been chosen as the substrate to be anodized with three different carbon sources: micro-sized graphite, nano-sized graphite, and graphite plate. With a constant 2A current on the DC power supply, the substrate was anodized for 60 minutes in a 20% sulphuric acid electrolyte. The finding shows that the anodic oxide with nano-sized graphite produces the highest hardness surface with almost 50% improvement compared to the unreinforced anodic oxide coating with no visible micro-cracks on the surface observed. Tribologically, the anodic oxide reinforced with micro-sized graphite produced the lowest coefficient of friction and wear rate at 0.4 and 1.25x10-5 mm3/Nm, respectively. The wear track image shows traces of debris that are different for each type of anodic coating that might be influenced by the surface roughness and hardness of the coating.

In-situ Photo-deposition of Nd-modified Hexahydroxy Strontium Stannate Nanorods with Enhanced Photocatalytic Performance

Background:: Metal surface modification of the photocatalysts is effective for enhancing the photocatalytic properties of the semiconductor photocatalysts. Nd can be used as the modified metal for the enhancement of catalytic performance of the strontium tin hydroxide (SrSn(OH)6) nanorods due to expanding the light absorption range and reducing the recombination of the photo-generated electrons and holes. Objective:: The aim of the research is to synthesize Nd-modified SrSn(OH)6 nanorods and investigate the enhanced photocatalytic performance for crystal violet degradation. Methods:: Nd modified SrSn(OH)6 nanorods were prepared via a facile one-step in-situ photodeposition route. The obtained nanorods were analyzed by X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, solid diffuse reflectance spectra, photoluminescence spectroscopy, and electrochemical impedance spectroscopy. Results:: Nd attached to the surface of nanorods. The band gap of the Nd-modified SrSn(OH)6 nanorods was reduced due to Nd modification at the surface of nanorods. The Nd-modified SrSn(OH)6 nanorods showed enhanced photocatalytic properties for crystal violet (CV) degradation under ultraviolet (UV) light irradiation than the SrSn(OH)6 nanorods. Nd modified SrSn(OH)6 nanorods have lower charge transfer resistance and more efficient charge separation ability, thus hindering the recombination of the electrons and holes (e−/h+) pairs. Scavenger experiments reported that the holes, superoxide, and hydroxyl radicals are the main reactive species during the photocatalytic reaction. The Ndmodified SrSn(OH)6 nanorods were found to be recoverable and reusable for CV degradation. Conclusion:: The Nd modified SrSn(OH)6 nanorods showed enhanced photocatalytic performance towards crystal violet than un-modified nanorods.

Surface Modification of Titanium Implants by Metal Ions and Nanoparticles for Biomedical Application.

Implant surface modification can improve osseointegration and reduce peri-implant inflammation. Implant surfaces are modified with metals because of their excellent mechanical properties and significant functions. Metal surface modification is divided into metal ions and nanoparticle surface modification. These two methods function by adding a finishing metal to the surface of the implant, and both play a role in promoting osteogenic, angiogenic, and antibacterial properties. Based on this, the nanostructural surface changes confer stronger antibacterial and cellular affinity to the implant surface. The current paper reviews the forms, mechanisms, and applications of nanoparticles and metal ion modifications to provide a foundation for the surface modification of implants.

Preparation of 2-Butanone Gas Sensor Based on Ag-Decorated In2O3 Nanocube with High Response and Low Detection Level

In this work, 2-butanone-sensitive Ag-decorated In2O3 nanocomposites were successfully prepared using a facile one-step hydrothermal method to enhance the sensing performance of In2O3 nanocubes. The methods of scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) analysis, and X-ray photoelectron spectroscopy (XPS) were used to observe the morphology, microstructure, crystalline phase, and the existing state of the elements in the produced nanomaterials, respectively. The gas sensing test results show that the prepared compounds could respond to 100 ppm of 2-butanone with a high response (242), fourfold that of the pure In2O3 material, at the optimum working temperature of 240 °C. Moreover, the Ag@In2O3-based sensor also showed excellent selectivity, good repeatability, and even long-term stability. In addition, noble metal surface modification not only decreased the optimum operating temperature (from 270 °C to 240 °C) but also decreased the lowest detection limit (from 5 ppm to 0.25 ppm). In the final section, the gas sensing mechanism of the Ag@In2O3-based sensor and the probable reason for 2-butanone’s enhanced sensing properties are both discussed.