Wet Chemistry Research Articles

Modification of nonwoven polymer materials for increasing of their filtration and antibacterial properties

AbstractPolytetrafluoroethylene (PTFE), octenidine dihydrochloride (OCT), and zinc oxide (ZnO) were used to modify the polypropylene nonwoven material by the methods of “wet chemistry” and low‐energy electron beam deposition (EBD). The influence of nonwoven material modification on the morphology, chemical composition, filtration, and antibacterial properties was established. The modified material has antibacterial activity against the gram‐positive strain Staphylococcus aureus and against gram‐negative strains of Escherichia coli and Klebsiella pneumoniae (suppression of bacterial growth for materials with OCT was 100%, with ZnO—70%). PTFE application to Aquaspun leads to a significant increase in the contact angle (from 141.3° to 152.7°) and air filtration efficiency (from 78.3% to 83.4%), which provides the barrier properties of the material. It was established that the material obtained using low‐energy EBD demonstrated a more pronounced antimicrobial potential against the tested strains of St. aureus.Highlights The influence of polypropylene nonwoven materials surface modification methods is systematically investigated. Low‐energy electron beam deposition increases antibacterial and filtration properties of nonwoven materials. Surface modification methods increase barrier properties of polypropylene nonwoven materials.

Effect of the ZnFe2O4 shell in Fe3O4 on the properties of its nanocomposites with P3HT

The coating of the nanoparticles (Nps), in addition to avoiding their agglomeration and degradation in the different media used, provides them with new properties and, therefore, also to the nanocomposite obtained. In this work, new hybrid nanocomposites based on poly(3-hexylthiophene) with Nps of Fe3O4 or Fe3O4@ZnFe2O4 core@shell are synthesized and characterized. Fe3O4 Nps are obtained by the chemical bath deposition method, while Fe3O4@ZnFe2O4 core@shell Nps are synthesized by wet chemistry by deposition of ZnO on the surface of Fe3O4 Nps. P3HT/Fe3O4 and P3HT/Fe3O4@ZnFe2O4 nanocomposites are obtained by in-situ synthesis of P3HT by the Grignard metathesis method (GRIM) in the presence of different concentrations of the Nps (3HT/Fe3O4 or 3HT/Fe3O4@ZnFe2O4 weight ratio: 1/0.01 and 1/0.02). The incorporation of Fe3O4 and Fe3O4@ZnFe2O4 in the P3HT polymeric matrix is corroborated by FTIR. With the incorporation of both nanoparticles (Fe3O4 and Fe3O4@ZnFe2O4) to P3HT, the roughness increased, and the absorbance was increased depending on the concentration of the particles. The presence of Fe3O4@ZnFe2O4 core@shell Nps in P3HT increases the decomposition temperature, and the photoconductivity. On the other hand, the electrochemical characterization shows an increase in the cycle area when incorporating Fe3O4@ZnFe2O4 in P3HT. The P3HT/Fe3O4@ZnFe2O4 nanocomposites obtained in this work present interesting optoelectronic properties to be applied in different optoelectronic devices.

Controlling the reactivity of hydrophilic bark extractives as biopolyols in urethane-formation reactions using various catalysts

The composition, functionality, and reactivity of black alder (Alnus glutinosa) bark extractives as a biopolyol with polymeric diphenyl methane diisocyanate (PMDI) have been studied using a variety of methods, including HPLC, GPC, GC, wet chemistry, and isothermal calorimetry. The Black alder (BA) bark extractives were identified as a prospective polyol consisting mainly of the oregonin-xyloside form of diarylheptanoid, which contains OH groups that are almost equally represented by phenolic and aliphatic origins. To identify catalysts that effectively increase the reactivity of low-active phenolic OH groups in urethane formation reactions, the kinetics of extractives and model compounds' interaction with PMDI catalyzed with tin organic, dibutyl tin dilaurate (DBTDL) and tertiary amine, 1,4-diazabicyclo[2.2.2]octane (DABCO) catalyst in dimethylsulfoxide (DMSO) solution were studied. The results showed that DABCO resulted in a fourfold higher reactivity of phenolic groups with PMDI compared to DBTDL catalyzed reactions. Furthermore, the reactivity of phenolic groups with PMDI catalyzed by DABCO was almost twofold greater than that of aliphatic OH catalyzed by DBTDL. The second-order constants of 31.9 × 10−4 mol·L−1·s−1 and 53.7 × 10−4 mol·L−1·s−1 were determined for the interaction of extractives with PMDI in the presence of DBTDL and DABCO, respectively. The disappearance of the radical scavenging effect of phenolic compounds in extractives derived PU elastomers obtained with DABCO catalyst indicates complete reactions of phenolic groups with isocyanate, while these groups remain partly free in the case of DBTDL catalysis. It is assumed that a combination of DBTDL and DABCO catalysts will be necessary to achieve high crosslinking while leaving a small portion of free phenolic groups in the bio-based PU network, thus obtaining material with high mechanical properties and thermal oxidative stability.

Experimental study on nanoparticles-assisted low-salinity water for enhanced oil recovery in asphaltenic oil reservoirs

The purpose of this research is to look into the augmentation of silica nanoparticles (NPs) with low salinity (LowSal) brine for EOR. A series of analyses, including oil/water interfacial tension (IFT) and rock wettability tests were undertaken to determine an optimal dispersion to flood into a porous carbonate core with a defined pore size distribution. At 60 °C and 14.5 psi, the maximum drop (i.e., roughly 12.5 mN/m) in oil/water IFT by 0.3 wt.% brine occurred, but when 0.08 wt.% silica was added to the brine, the IFT reduced to 14.51 mN/m at 60 °C and 14.5 psi. The wettability analysis revealed a significant reduction in contact angle, from 142° to 72° and 59°, using 0.04 and 0.08 wt.% silica in LowSal brine, but the extent reduced by brine alone was insufficient. The results of rock pore size characterization were discussed in terms of the accomplishment of operating EOR in the porous medium in the presence of NPs. The addition of 0.08 wt. % silica to the injected brine resulted in an additional oil recovery of 16.3% OOIP as well as a significant shift in the endpoints/cross-points of the oil/water relative permeability curves. The findings of this research might help improve oil recovery from asphaltenic oil reservoirs or, more environmentally friendly, remediate petroleum crude-oil polluted soil.

Identification of Design Principles for the Preparation of Colloidal Plexcitonic Materials.

Colloidal plexcitonic materials (CPMs) are a class of nanosystems where molecular dyes are strongly coupled with colloidal plasmonic nanoparticles, acting as nanocavities that enhance the light field. As a result of this strong coupling, new hybrid states are formed, called plexcitons, belonging to the broader family of polaritons. With respect to other families of polaritonic materials, CPMs are cheap and easy to prepare through wet chemistry methodologies. Still, clear structure-to-properties relationships are not available, and precise rules to drive the materials' design to obtain the desired optical properties are still missing. To fill this gap, in this article, we prepared a dataset with all CPMs reported in the literature, rationalizing their design by focusing on their three main relevant components (the plasmonic nanoparticles, the molecular dyes, and the capping layers) and identifying the most used and efficient combinations. With the help of statistical analysis, we also found valuable correlations between structure, coupling regime, and optical properties. The results of this analysis are expected to be relevant for the rational design of new CPMs with controllable and predictable photophysical properties to be exploited in a vast range of technological fields.

Autonomous Materials Synthesis Strategies Towards Accelerated Discovery of Novel Functional Nanomaterials for Green Energy Production

Electrocatalysts designed by alloying two or more elements (e.g., transition metals) showed promising enhancement in catalytic activity and durability due to synergistic effects from alloying, such as strain engineering or electron exchange. The potential of the alloying approach is constrained by standard synthesis methods (e.g., wet chemistry and thermal decomposition techniques) due to the governing thermodynamics rules (e.g., miscibility of the different alloying elements). That renders the synthesis of high entropy alloys (HEA), with more than 3 elements, to be complicated and tedious to achieve by those conventional methods.In the presented talk we are presenting different strategies to synthesize metastable high entropy alloys (HEA) and their outstanding catalytic performance towards OER, in correlation to their unique chemistries and structures. Rapid cycling of temperature from room 25 °C to highly elevated levels (1700 °C), in conjunction with ultra-rapid cooling, within milli-second range have been demonstrated by different methods including rapid Joule heating, Intense light flashing, and microwave plasma shock. Our results show successful synthesis of non-noble metals HEA NPs, possessing higher catalytic activity than IrO2 catalyst for OER. The nature of the alloying elements dictates OER activity by promoting different oxidation states of the catalytically active transition metals (e.g., Fe, Ni and Co). In addition, a phenomenal in-situ chemical welding of HEA NP to carbon support, yielded HEA catalysts with two orders of magnitude longer durability than IrO2. Our developed techniques resulted in formation of super-strong metal-carbide bonds “chemically welding” HEA NP to the catalyst support.Synthesis of various HEA catalyst and their electrocatalytic performance screening has been carried out by using liquid handler robots and multi-axes robotic arm systems. Moreover, to optimize the design of materials (structure and chemistry), we are using active learning techniques to evaluate the achieved performance results by applying Gaussian process, followed by applying Bayesian Optimization techniques to propose novel chemistries and structures with a higher probability to achieve further improved performances. The presented the study does not open the door only towards developing novel catalysts for energy production. However, it presents a strategy with multiple successfully demonstrated platforms towards accelerated discovery of novel materials. The high-throughput nature of the synthesis protocols presented in this talk can produce tens of thousands of different novel chemistries, at the same time taken by conventional methods to synthesize just a few, at a minimal energy consumption, cost, and manpower.

High Entropy Oxides Synthesis by Rapid Plasma Generation with Applications Towards Electrocatalytic Hydrogen Generation

It has been challenging over the past three decades to find viable energy alternatives with higher efficiency and lower cost to beat the non-friendly and commercially dominant hydrocarbon energy sources. Hydrogen is deemed to be one of the most prominent candidates, as a green fuel. Hydrogen can be generated in abundance from water splitting. Utilization of hydrogen in fuel cells, with no doubt, produces no harmful gases. Nevertheless, the two parts of the technology: hydrogen production and reduction are cumbersome. Both processes rely on kinetically sluggish electrocatalytic reactions. Enormous research efforts have been spent, with thousands of studies presented in literature, despite the technology left with a dim light shed on from commercial and practical point of views. Many materials-related challenges are hindering the flourishing of green hydrogen technology, where poor catalyst durability is a major challenge, despite being made from very expensive elements (e.g., Ir, ru or Pt). Therefore, gigantic effort of research has been devoted to find inexpensive alternatives. Transition metals showed interesting performance towards water splitting (e.g., oxygen evolution (OER)).Recent research showed that electrocatalysts designed by alloying two or more elements (e.g., transition metals) showed promising enhancement in catalytic activity and durability due to synergistic effects from alloying, such as strain engineering or electron exchange. The potential of the alloying approach is constrained by standard synthesis methods (e.g., wet chemistry and thermal decomposition techniques) due to the governing thermodynamics rules (e.g., miscibility of the different alloying elements). That renders the synthesis of high entropy alloys (HEA), with more than 3 elements, to be complicated and tedious to achieve by those conventional methods.In the presented talk we are presenting the utilization of microwaves to generate plasma to synthesize metastable high entropy oxides (HEA) and their outstanding catalytic performance towards OER, in correlation to their unique chemistries and structures. Plasma generated enable temperature increase of the precursor substrate to elevated levels (~1000s °C), in conjunction with rapid cooling, within seconds range. Our results show successful synthesis of non-noble metals HEA NPs, possessing higher catalytic activity than IrO2 catalyst for OER. The nature of the alloying elements dictates OER activity by promoting different oxidation states of the catalytically active transition metals (e.g., Fe, Ni and Co). Our developed techniques resulted in formation of super-strong metal-carbide bonds “chemically welding” HEA NP to the catalyst support.

Development of Lithium/Sodium-Ion Battery Electrodes Based on Solvent Engineered Tin(II) Oxide Nanomaterials

With the global economy pushing towards a greener and cleaner energy future for the world, renewable energy storage technologies must continue to develop and improve to allow for a seamless transition from the ways of the past to a carbon neutral future. To this end, renewable battery technology and in particular the capacity of the anode must be improved. Furthermore this improvement must be made across various battery technologies (Lithium/Sodium-ion) and be cost-effective to allow for its widespread implementation and use worldwide.In this work, Tin(II) Oxide (SnO)/single wall carbon nanotube (SWCNT) composite electrodes are analysed as a possible alternative dual anode material for both lithium (LIB) and sodium-ion batteries (NIB). The LIB is limited by the current commercial anode material of graphite with a relatively low theoretical capacity of 372 mAh g-1 whilst NIBs use hard carbon with a capacity of roughly 300 mAh g-1. Alloy/de-alloy materials are envisioned to be a suitable candidate for next generation LIBs/NIBs due to their large specific capacities (875mAh g-1/ 847 mAh g-1 for SnO respectively) although major drawbacks concern the poor cycling life associated with the volume change and the associated irreversible capacity. To overcome such issues the downsizing of materials and the fabrication of composites which incorporate both lithium active and inactive material are viewed as promising solutions. Nanostructured metal oxides, forming an inactive oxide matrix are appealing candidates.Through the implementation of a solvent engineered wet chemistry synthesis, various layered SnO microparticles are produced with several morphologies well-suited to energy storage applications. This synthesis method is facile, scalable and is favourable in comparison to hydrothermal synthesese normally used to synthesise nanomaterials. While SWCNTs are themselves not suited towards energy storage applications, their incorporation in the electrodes allows them to act as a conductive additive at a lower weight loading than other conventional carbon sources (carbon black/graphite), presenting a more effective strategy to form an effective electrical percolation network while also removing the need for polymer binders/copper current collector.The optimised morphology of SnO produces a high capacity, high rate and stable anode for LIB technology. An initial coloumbic efficiency (ICE) in excess of 80% is recorded and a stable cycling capacity of 815 mAh g-1 at 0.5C after 300 cycles is also achieved, demonstrating its long term stability. A maximum capacity of 980 mAh g-1 is recorded at 0.1C, whilst high rate capacities of 775, 671 and 364 mAh g-1 are recorded at 1,2 and 5C respectively. Furthermore a full-cell is composed with a NMC cathode to demonstrate a potential full-cell real world device. As an NIB anode, a maximum capacity of 568 mAh g-1 was recorded at 0.05C, whilst a low ICE of 50% proves an issue under further investigation. Furthermore a cycling capacity of 595 mAh g-1 is recorded after 50 cycles at 0.1C, dropping to 360 mAh g-1 at 100 cycles which is still in excess of that recorded for hard carbon in NIBs.A high capacity, scalable and cost effective anode has been developed that is interchangeable between LIBs/NIBs and exceeds the performance of the current commercial anodes. Reference s : [1] S. Jaśkaniec, S. R. Kavanagh, S. Ryan, J. Coelho, C. Hobbs, A. Walsh, D. O. Scanlon and V. Nicolosi, npj 2D Mater. Appl., 2021, 5, 27. [2] J. H. Shin and J. Y. Song, Nano Converg., 2016, 3(1), 9. [3] F. Zhang, J. Zhu, D. Zhang, U. Schwingenschlögl and H. N. Alshareef, Nano Lett., 2017, 17, 1302–1311.

Development of reduced graphene oxide (rGO) reinforced poly(lactic) acid/ cellulose nanocrystal composite through melt mixing: Effect of nanofiller on thermal, structural, biodegradation and antibacterial properties

The intent of this research work was to synthesised a synthetic polymer that is biodegradable, bioresorbable, and biocompatible, while also exhibiting favorable thermal characteristics. The present study reports the successful fabrication of bionanocomposites by incorporating Cellulose nanocrystals (CNCs) and Reduced graphene oxide (rGO) into host matrix (PLA) using the melt-mixing technique. Various weight percentages (wt%) of rGO were employed in the process and various characterization techniques, including BET analysis, XRD, FTIR and field emission scanning electron microscopy (FE-SEM) were used to verify the efficient fabrication of a number of nanoformulations and nanofiller’s effect. Introduction of CNC and rGO in PLA matrix increases the surface area as well as porosity of the composites, established by BET analysis. DSC results indicate that the assimilation of rGO into the polymer matrix improved thermal stability of the composite material and leads to boost in the degree of crystallinity which was supported by XRD analysis. TGA results found no noticeable change in glass transition temperature (Tg) due to the addition of Nanofiller (rGO). The wettability analysis was done by contact angle measurement to determine the hydrophilicity of the composite and it is shown that with the increasing amount of rGO, hydrophilicity increases and contact angle reaches to 69° for 0.75 wt% of rGO in composite in comparision to 100° Neat PLA. The rGO/CNC/PLA nanocomposites exhibit a unique antibacterial effectiveness against both the S. aureus (Gram-positive) and E. coli (Gram-negative) bacterial strains. The highest antimicrobial activity was obtained in the nanocomposite tested against S. aureus. Biodegradation through Lysozyme in PBS solution shows promising result after incorporation of nanofillers. Hence, the nanocomposite manufactured through melt mixing process has promising uses in the biomedical and food packaging industries.

Directional formation of microtubes by soft-template electropolymerization from fully conjugated triphenylamine-based monomers

Microtubular structures have been prepared by soft-template electropolymerization of conjugated organic monomers with the aim to mimic the strong water-adhesive forces of gecko foot or rose petals. Water-saturated solvent of low water solubility (dichloromethane) was used to form a micellar solution stabilized by tetrabutylammonium perchlorate as the electrolyte and the surfactant, in which case the formation of nanotubes was particularly efficient. The studied monomers were built from a triphenylamine core conjugated with three arms differing by their structure and positions: (i) 2- or 3-positions in the thiophene arms or (ii) carbazole arms attached to para, meta or ortho-positions of the benzene ring of the core. The formation of microtubes is due to preferential growth of polymer films and an aggregation of formed polymers/oligolymers in one direction (1D) facilitated by π–stacking interactions. The key factors influencing on the surface morphologies (monomer structures and reactivity, electrodeposition conditions, etc) are discussed. Impressive results have been obtained in studies of carbazole-containing monomers and the effect of regioisomerism in the monomers (the position of the carbazole attachment to the core). Extremely long microtubes (tens to >100 μm length, diameter ≈ 1.0–1.5 μm) were formed on the electrode surface from the monomer N-Ph-p-Cb with the carbazole attachment in the para-position. Wettability analysis showed highly hydrophobic surfaces with apparent contact angles up to 154.0° and extremely strong water adhesion comparable to rose petals or gecko feet. Such coatings can find applications in water-harvesting systems, sensing platforms or electrochemical analyses.

Octacalcium Phosphate-Laden Hydrogels on 3D-Printed Titanium Biomaterials Improve Corrosion Resistance in Simulated Biological Media.

The inflammatory-associated corrosion of metallic dental and orthopedic implants causes significant complications, which may result in the implant's failure. The corrosion resistance can be improved with coatings and surface treatments, but at the same time, it might affect the ability of metallic implants to undergo proper osteointegration. In this work, alginate hydrogels with and without octacalcium phosphate (OCP) were made on 3D-printed (patterned) titanium alloys (Ti Group 2 and Ti-Al-V Group 23) to enhance their anticorrosion properties in simulated normal, inflammatory, and severe inflammatory conditions in vitro. Alginate (Alg) and OCP-laden alginate (Alg/OCP) hydrogels were manufactured on the surface of 3D-printed Ti substrates and were characterized with wettability analysis, XRD, and FTIR. The electrochemical characterization of the samples was carried out with open circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). It was observed that the hydrophilicity of Alg/OCP coatings was higher than that of pure Alg and that OCP phase crystallinity was increased when samples were subjected to simulated biological media. The corrosion resistance of uncoated and coated samples was lower in inflammatory and severe inflammatory environments vs. normal media, but the hydrogel coatings on 3D-printed Ti layers moved the corrosion potential towards more nobler values, reducing the corrosion current density in all simulated solutions. These measurements revealed that OCP particles in the Alg hydrogel matrix noticeably increased the electrical charge transfer resistance at the substrate and coating interface more than with Alg hydrogel alone.

Improved Electrochemical Performance of Li-Rich Cathode Materials via Spinel Li2MoO4 Coating.

Li-rich manganese-based cathode materials (LRMs) are considered one of the most promising cathode materials for the next generation of lithium-ion batteries (LIBs) because of their high energy density. However, there are problems such as a capacity decay, poor rate performance, and continuous voltage drop, which seriously limit their large-scale commercial applications. In this work, Li1.2Mn0.54Co0.13Ni0.13O2 coated with Li2MoO4 with a unique spinel structure was prepared with the wet chemistry method and the subsequent calcination process. The Li2MoO4 coating layer with a spinel structure could provide a 3D Li+ transport channel, which is beneficial for improving rate performance, while protecting LRMs from electrolyte corrosion, suppressing interface side reactions, and improving cycling stability. The capacity retention rate of LRMs coated with 3 wt% Li2MoO4 increased from 69.25% to 81.85% after 100 cycles at 1 C, and the voltage attenuation decreased from 7.06 to 4.98 mV per cycle. The lower Rct also exhibited an improved rate performance. The results indicate that the Li2MoO4 coating effectively improves the cyclic stability and electrochemical performance of LRMs.

Direct measurement of hydrogen relative permeability hysteresis for underground hydrogen storage

Underground Hydrogen Storage (UHS) is a long-term storage solution which utilises hydrogen as an energy carrier to store large-scale excess renewable energy in the subsurface. Key petrophysical properties, such as wettability and interfacial tension of hydrogen and water have been discovered which provide a practical basis for simulation models. Our work directly measures relative permeability hysteresis during co-injection core floods of hydrogen and water with a capillary number of Nc=2.92×10−7. Segmented micro-CT images are used to determine saturation in the Bentheimer sandstone. Our results demonstrate that hydrogen relative permeability in sandstones is very low, with an end-point relative permeability of krg0=0.049 at Swi= 0.24. Capillary trapping results in residual gas saturation of Sgr= 0.4. Wettability analysis confirms the system is water-wet, with contact angles of 57° at Sgr and 44° at Swi. These results improve the reliability of numerical simulations and demonstrate the possible challenges involved with the commercial application of UHS.

Clever Nanomaterials Fabrication Techniques Encounter Sustainable C1 Catalysis.

ConspectusC1 catalysis, which refers to the conversion of molecules with a single carbon atom, such as CO, CO2, and CH4, into clean fuels and basic building blocks for chemical industries, has built a bridge between carbon resource utilization and valuable chemical supply. With respect to the goal of carbon neutrality, C1 catalysis also plays an essential role owing to its integrated functions in the green catalytic process with fewer CO2 emissions and even direct high-value-added utilization of greenhouse gases (CO2 and CH4). However, the inert nature of the C-O or C-H bond in C1 molecules as well as uncontrollable C-C coupling render C1 catalysis challenging. The rational design of highly active catalytic materials (denoted as C1 catalysts) with strong capacities for C-O or C-H bond activation and C-C coupling by convenient nanomaterials fabrication methods to boost the catalytic performance of C1 molecule conversion, including targeted product selectivity and long-term stability, is the cornerstone of C1 catalysis.Notably, the familiar concepts in heterogeneous catalysis, such as tandem catalysis and confinement catalysis, are applicable for C1 catalysis and have been successfully used to design a C1 catalyst. Regarding the tandem catalysis concept that integrates multiple reactions in a single-pass via a bi- or multifunctional catalyst, it is promising to shed new light on the oriented conversion of C1 molecules, especially for C2+ hydrocarbon or oxygenate synthesis. The confinement effect is powerful for controlling the product distribution and enhancing activation efficiency of inert chemical bonds in C1 catalysis due to the unique reactants/intermediate adsorption and evolution behaviors on the confined catalytic interface with a special electronic environment. Moreover, metal-support interactions (MSIs), electronic properties of the active site, and catalytic engineering issues are also susceptible to the C1 molecule conversion performance. Therefore, under the guidance of basic and novel rules in heterogeneous catalysis, the innovation of catalytic materials with the aid of advanced catalytic materials fabrication techniques has always been a hot research topic in C1 catalysis.In this Account, we briefly describe the challenges in thermal-catalytic C1 molecule (mainly CO, CO2, and CH4) conversion. At the same time, the synergistic functioning of the physicochemical properties of the catalytic materials on the performance in C1 molecule conversion is highlighted. More importantly, we summarize our progress in rationally designing tailor-made C1 catalysts to enhance C1 molecule activation efficiency and targeted product selectivity via powerful nanomaterials fabrication techniques, such as traditional wet-chemistry strategies, the magnetron sputtering method, and 3D printing technology. Specifically, the ingenious capsule catalyst and ammonia pools in zeolites fabricated by a wet chemistry process possess an extraordinary effect on the transformation of CO, CO2, and CH4 molecules. Also, the sputtering method is reliable in modulating the electronic properties of metallic active sites for C1 molecule conversion, thereby tailoring the final product selectivity. Furthermore, we showcase the strong capability of metal 3D printing technology in fabricating a self-catalytic reactor, by which the functions of the reaction field and nanoscale active sites are well integrated. Finally, we predict the future research opportunities in highly efficient C1 catalyst design with the assistance of clever nanomaterials fabrication techniques.

Effects of Ultrahigh Vacuum Treatments on Wet Chemically Cleaned Si Surfaces

Ultrahigh vacuum (UHV) environment has been widely used in surface science, but UHV technology has been often considered too complex and expensive methodology for large-scale industrial use. Because the preparation of atomically smooth and clean Si surfaces has become relevant to some industrial processes, we have re-addressed the question if UHV could be utilized in these surface tasks using industrially feasible parameters. In particular, we have studied how UHV treatments might be combined with the widely used semiconductor cleaning methodology of wet chemistry.

Atomic Level Chemical and Structural Properties of Silicon Surface and Initial Stages of Oxidation

This work aims to summarize previous results reported in literature on atomic level properties of the wet chemically treated hydrogen-terminated silicon surfaces and of the Si oxidation, in comparison to a model system of ultraclean Si surfaces prepared in ultrahigh vacuum (UHV) conditions. A literature review shows that a proper wet chemical treatment of Si(111) provides an atomically smooth, high-quality surface, similar to the model template obtained in UHV conditions after high temperature heating. However, it seems that Si(111) is an exception among semiconductor surfaces concerning the effects of wet chemistry. Although the insulator films grown by the atomic layer deposition (ALD) have replaced the thermal oxide of SiO2 in many applications, still an intermediate SiO2 layer is formed and often grown intentionally beneath the ALD film to improve the device performance. However, a detailed atomic structure of the SiO2/Si interface is still debatable, which might be due to differences in atomic level smoothness of the used Si(100) starting surfaces.

Surface Characterization - Gallium Nitride Depth Profiling with LEIS

With the increasing use of III-nitride semiconductors, more knowledge is needed about the manufacturing processes and reactions with different chemicals. Gallium nitride semiconductors show a different behavior in wet chemistry compared to the known silicon technologies [4,5]. The different behavior can be explained, among other things, by the polar axis in the c-direction [0001] [6]. Surface characterization is necessary to gain a better understanding of the native surface and after different processes. We have used Low Energy Ion Scattering (LEIS) with its very high sensitivity for surface characterization to characterize the surface of different gallium nitride semiconductors and to establish a depth profile by sputtering [1,8].

Mechanisms and kinetics of C-S-H nucleation approaching the spinodal line: Insights into the role of organics additives

Wet chemistry C-S-H precipitation experiments were performed under controlled conditions of solution supersaturation in the presence and absence of gluconate and three hexitol molecules. Characterization of the precipitates with SAXS and cryo-TEM experiments confirmed the presence of a multi-step nucleation pathway. Induction times for the formation of the amorphous C-S-H spheroids were determined from light transmittance. Analysis of those data with the classical nucleation theory revealed a significant increase of the kinetic prefactor in the same order as the complexation constants of calcium and silicate with each of the organics. Finally, two distinct precipitation regimes of the C-S-H amorphous precursor were identified: i) a nucleation regime at low saturation indexes (SI) and ii) a spinodal nucleation regime at high SI where the free energy barrier to the phase transition is found to be of the order of the kinetic energy or less.

Ultrathin hetero-nanosheets of cobalt oxide and nanoclusters for catalytic desulfurization

It is still a big challenge to synthesize well-defined nano-heterostructures by wet chemistry method, as realizing accurate control on each nanocrystal is difficult in solution. In this contribution, the cobalt oxide-phosphomolybdic acid (CoO-PMA) hetero-nanosheets are synthesized by introducing PMA clusters, which have comparable size to the crystal nuclei of CoO. Time-dependent experiments reveal how the nanosheets form: nanoclusters and nuclei first assemble into nanowires and then grow into nanosheets with the assistance of oleylamine. And the results of electrospray ionization ion-trap time-of-flight mass spectrometry (ESI-IT-TOF-MS) also demonstrate the existence of PMA clusters in the final product. Moreover, in this strategy, both metal oxides and nanoclusters can be extended, leading to a series of ultrathin heterostructures. Finally, the CoO-PMA hetero-nanosheets exhibit excellent property in the oxidation of thioether at room temperature, making it a potential catalyst in desulfurization.

Predicting Nutritional Quality of Dual-Purpose Cowpea Using NIRS and the Impacts of Crop Management

Cowpea fodder has been one of the favored livestock forages for centuries in sub-Saharan Africa, particularly in Senegal. However, little research has been conducted on quantifying the nutritional quality of cowpea fodder because of the costly wet chemistry analysis. The main objective of this study was to develop predictive equations for a sustainable quantification of the nutritional quality of dual-purpose cowpea fodder using near infrared spectroscopy (NIRS) and to investigate the influence of cropping system, fertilizer, genotype, and their interaction on biomass yield and cowpea forage nutritional value. In this study, 120 samples from a dual-purpose cowpea variety trial were used to develop NIRS equations to estimate forage quality parameters including concentrations of crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), calcium (Ca), phosphorus (P), potassium (K), and iron (Fe). Partial least squares (PLS) regression generated prediction equations using NIRS wavelength measurements, and reference wet chemistry analysis from calibration samples were developed. The PLS prediction equations for the different forage quality parameters had an R2 of calibration 0.94, 0.93, 0.88, 0.63, 0.69, 0.87, and 0.94 for CP, ADF, NDF, Ca, P, K, and Fe, respectively. Using these prediction equations, correlation of the predicted values of the calibration subset and the prediction test subset resulted in significant positive relationships, with R2 of 0.83, 0.74, 0.70, 0.63, 0.59, 0.75, and 0.83 for CP, ADF, NDF, Ca, P, K, and Fe, respectively. The corresponding RMSE of these relationships was 0.91, 2.68, 3.45, 0.23, 0.06, 0.11, and 100 for CP, ADF, NDF, Ca, P, K, and Fe, respectively. The range and mean concentrations of the calibration subset overlapped with that of the prediction subset for all parameters evaluated. Cross-validation procedures indicated good correlations between wet chemistry analysis and NIRS forage quality estimates. Results of the second experiment showed that the cropping system had no significant effect on cowpea forage yield and nutritive value. However, cowpea variety and fertilizer, both individually and their interaction, had a significant effect on fodder yield and cowpea forage quality. We conclude that the NIRS calibration equations developed can be used to accurately predict the cowpea forage quality parameters evaluated in this study.