Two-step Preparation Research Articles

Thermoplastic Starch with Maltodextrin: Preparation, Morphology, Rheology, and Mechanical Properties

This work describes the preparation of highly homogeneous thermoplastic starches (TPS’s) with the addition of 0, 5, or 10 wt.% of maltodextrin (MD) and 0 or 3 wt.% of TiO2 nanoparticles. The TPS preparation was based on a two-step preparation protocol, which consisted in solution casting (SC) followed by melt mixing (MM). Rheology measurements at the typical starch processing temperature (120 °C) demonstrated that maltodextrin acted as a lubricating agent, which decreased the viscosity of the system. Consequently, the in situ measurement during the MM confirmed that the torque moments and real processing temperatures of all TPS/MD systems decreased in comparison with the pure TPS. The detailed characterization of morphology, thermomechanical properties, and local mechanical properties revealed that the viscosity decrease was accompanied by a slight decrease in the system homogeneity. The changes in the real processing temperatures might be quite moderate (ca 2–3 °C), but maltodextrin is a cheap and easy-to-add modifier, and the milder processing conditions are advantageous for both technical applications (energy savings) and biomedical applications (beneficial for temperature-sensitive additives, such as antibiotics).

Two-Step Preparation of Asphalt-based Porous Carbon Adsorbent with Superior C2H6/CH4 Selectivity for Ethane Recovery from Natural Gas

Efficient recovery of ethane from natural gas is of industrial importance, yet it poses considerable challenges. Herein, we report the two-step green preparation of asphalt-based carbon adsorbent AsCs with exceptional C2H6/CH4 selectivity and high capacity, where the KOH usage can be significantly reduced by 75% than conventional chemical activation processes. More importantly, the resulting AsC-0.75-900 exhibits exceptional C2H6/CH4 separation performance with the IAST selectivity of 30.74 and ethane capacity of 4.53 mmol/g at 298 K and 100 kPa. Notably, even at the low pressure of 10 kPa, its ethane uptake remains high at 2.25 mmol/g, comparable to many advanced MOFs. Molecular simulation was used to elucidate the adsorption mechanism. Fixed-bed experiments further demonstrate dynamic separation performance, achieving complete separation of a C2H6/CH4 binary mixture (10:90, v/v) at ambient condition. In addition to its superior separation performance, AsC-0.75-900 offers inherent structural stability and cost-effectiveness, positioning it a highly promising candidate for ethane recovery from natural gas.

Co-crosslinking and anchoring strategy: One-step preparation of N-doped porous carbon for supercapacitors and zinc ion hybrid capacitors

Porous carbon has been widely used in aqueous capacitors due to its wide source, high stability, and controllable preparation. However, the two-step preparation strategy of carbonization and activation with complex operation and serious energy consumption severely limits its further application. In this paper, resorcinol/urea-furfural resin was successfully prepared by using cleaner and greener furfural as raw material and co-crosslinking with resorcinol and urea under the action of catalyst. It is noteworthy that during the curing process, KOH is uniformly anchored inside the resin, so the system only needs one-step high-temperature pyrolysis to obtain a N-doped ant-nest-like three-dimensional interconnected porous carbon material. Consequently, the porous carbon exhibited an impressive specific capacitance of 283F g−1. The assembled symmetrical device shows a capacitance retention of 92 % after 50 000 cycles, showing excellent cycle stability. In addition, the assembled zinc ion hybrid capacitor exhibits a capacitance of 138 mAh g−1 and an energy density of 111 Wh kg−1. The one-step carbonization-doping-activation strategy of this bottom-up in-situ anchoring activator will provide further insights into the hierarchical pore structure design of porous carbon and facilitate the simple and efficient preparation of carbon materials.

Increasing softening point of isotropic spinnable asphalt by two-step preparation from ethylene tar residue modified with bio tar residue

Carbon fiber prepared from asphalt may be a critical type of low-weight chemical material of excellent mechanical performances. Here, an isotropic spinnable asphalt (EBA) was prepared from ethylene tar residue (ETR) by a two-step method of bio tar residue (BTR) through co-polymerization-air blowing, and isotropic asphalt carbon fibers were prepared from the product asphalt. The main types of molecules contained in the two feedstocks were determined by 1H NMR and LDI-TOF MS analyses. The co-polymerization behavior and thermal stability of the asphalt blends were analyzed using polarized light microscopy and thermogravimetric analyzer, respectively. Finally, the morphology and mechanical properties of carbon fibers made from EBA were evaluated by scanning electron microscope and universal testing machine. The results show that BTR contains much more oxygen-containing functional groups and unique long-chain sawtooth molecular structure; the former can promote the reactivity of the co-polymerization reaction, and the latter can limit the formation of large-plane cyclic aromatic hydrocarbon polymers due to the spatial resistance effect to greatly reduce the content of the mesophase. The softening point of the product asphalt shows a tendency of increasing and then decreasing with the increase of the proportion of BTR in the raw material mixture, and a reaction mechanism based on linear and bulky molecules is proposed to explain it by analogy with the structure of macromolecules. Consequently, the EBA made from a mixture of ETR and BTR at ideal moderate proportions has excellent performance in terms of softening point and mesophase content than ETRO made from ETR alone, and the carbon fiber made has a high tensile strength of 1.82 GPa with an elastic modulus of 38.9 GPa, which has reached the level of high tensile strength carbon fiber. Therefore, the use of inexpensive renewable energy bio-asphalt in the modification of heavy oil to obtain high softening point isotropic asphalt for preparing isotropic carbon fiber with excellent properties is achievable.

Development of Bifunctional Electrocatalyst for Overall Water Electrolysis: Vanadium and Phosphorus Dual-Doping Strategy on Ni3S2 Nanoneedle

Along with the rapid consumption of fossil fuels and serious environmental pollution, the development of renewable and clean energy has been receiving a lot of attention recently. Among the various renewable energy sources, hydrogen (H2) is considered as most promising substance in future energy society owing to its high gravimetric energy density and environmental friendliness. Electrochemical water electrolysis system is powerful strategy for high-purity hydrogen production without emission of any pollutants. It consists of two electrocatalytic reactions: oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). However, the practical efficiency of water electrolysis is limited due to the intrinsically sluggish reaction kinetics of OER and HER. To date, the precious metal-based electrocatalysts such as RuO2 and Pt/C for OER and HER, respectively, were employed as state-of-the-art electrocatalyst to enhance the performance of water electrolysis. However, due to the high expense, mono-functionality, and unsatisfactory stability of the precious metal-based materials, research on bifunctional electrocatalysts with low cost and high activity has become an urgent topic. To date, numerous scientific endeavors have been dedicated to the advancement of highly efficient non-noble metal-based bifunctional electrocatalysts such as transition metal oxides, hydroxides, sulfides, carbides, nitrides, and phosphides. Among these, Ni3S2 has emerged as a particularly promising electrocatalyst for water splitting, garnering substantial attention owing to its high electric conductivity, rich redox property, abundance in the Earth's crust, and environmentally friendly characteristics. Nevertheless, the electrocatalytic activity of Ni3S2 lags behind that of noble metal counterparts. Therefore, elaborate modification of Ni3S2 catalyst should be conducted to further improve its intrinsic activity toward OER and HER. Among the various strategies, heteroatom doping into Ni3S2 structure could be adopted as powerful technique for enhancement of electrocatalytic performance. The homogeneously incorporated dopants not only generate lattice disorders but elaborately modulate the surface electronic property. Specifically, high-valent cation dopants such as vanadium and molybdenum can effectively mediate the change of chemical states of Ni active sites during the step-wise electrocatalytic procedure. Meanwhile, additionally introduced anion dopants, which have lower electronegativity compared with sulfur, can reduce the electron trapping phenomenon induced by excessive electron transfer from nickel to sulfur. Inspired by above features, we synthesized V and P co-doped Ni3S2 nanoneedles directly grown on nickel foam (V-Ni3S2-P/NF) through facile two-step preparation method. First, V doped Ni3S2 nanoneedles were homogeneously grown on NF (V-Ni3S2/NF) by hydrothermal process without use of nickel precursor. The vanadium ions promote the nucleation of Ni3S2 species and lead the preferential growth toward 1D direction during the hydrothermal reaction. After that, the V-Ni3S2/NF was annealed in the tube furnace with the NaH2PO2 as a phosphorus precursor under the Ar flow. Under the mild annealing condition, the PH3 gases generated from thermal decomposition of NaH2PO2 reacted with the V-Ni3S2 species. Consequently, the V-Ni3S2 was partially phosphidated into V-Ni3S2-P throughout anion exchange process. As a result, the V-Ni3S2-P/NF electrocatalyst exhibited excellent bifunctional activity toward both OER and HER compared with mono-doped and un-doped counterparts and precious metal-based electrocatalysts. Furthermore, the outstanding electrocatalytic performance of V-Ni3S2-P/NF was well-maintained over the 100 h of continuous operation under alkaline condition. This study will contribute to the development of efficient and cost-effective electrocatalysts for future energy conversion and storage technologies.

Interfacial studies of Cu2O/TiO2 junction deposited at different electropotentials

Based on the simplistic two-step preparation method, a Cu2O/TiO2 junction was synthesized by electrodepositing a Cuprous Oxide layer on Titanium Oxide thin films at different deposition potentials. The thin films and junction were characterized for their structural, morphological, optical, and electrical properties using X-ray diffraction, Scanning Electron Microscopy, UV–visible spectroscopy, and Electrochemical Impedance Spectroscopy. The XRD analysis of the Cu2O/TiO2 junction indicated no sharp diffraction peaks of TiO2, only Cu2O peaks were observed. The Scanning Electron Microscopy also demonstrated that the Cuprous Oxide thin films possessed three-sided pyramidal structures on their surface. The band gaps of Cu2O and TiO2 thin films were calculated as 2.2 eV and 3.3 eV respectively by using Tauc’s plots. Electrochemical impedance spectroscopy revealed reduced interfacial charge transfer resistance and a boost in charge carrier generation in fabricated junctions (grown at −0.6 V). The flat band potentials and carrier concentrations of the fabricated thin films and their junction were calculated using Mott-Schottky analysis. Meanwhile, charge transfer resistance, solution resistance, constant phase element, and other circuit parameters of the electrochemical cell were studied using Nyquist plots.

Two-step preparation of methylammonium lead triiodide perovskite film via electrospray deposition of methylammonium iodide solution for solar cell applications

Solution-processable perovskite solar cells (PSCs) have the potential to revolutionize solar cell technology by enabling low power generation costs via low-cost device fabrication. However, most existing research regarding PSCs relies on the spin-coating method, which is not conducive to large-area film deposition. Therefore, the development of an alternative deposition method for perovskite films has become increasingly important for commercialization, for which electrospray deposition is a promising technique. This study investigates the two-step preparation of methylammonium lead triiodide (MAPbI3) perovskite films via the electrospray deposition of a methylammonium iodide (MAI) solution on a spin-coated PbI2 film. The gradual conversion of PbI2 to MAPbI3 with increasing MAI deposition time was revealed, accompanied by an increase in the size of the perovskite crystals. In addition, PSCs were successfully fabricated by electrospraying MAI, achieving a considerable power conversion efficiency of 7.86 % at the optimal MAI deposition time.

A multiscale mechanics model for elastic properties of densified wood

We introduce a multiscale mechanics model for analyzing the elastic properties of super-strong densified wood (DW). Our model incorporates microstructural features such as microfibril angle and densification ratio, along with chemical parameters including degree of polymerization, crystallinity, and density of hydrogen bonds. At the nanoscale and microscale, the elastic properties of cellulose nanofibril and cell wall layers are derived analytically using the mechanics of composite materials. Finite element simulations based on representative volume elements are conducted at the mesoscale to obtain homogenized effective elastic properties at the macroscale. Our quantitative investigations validate that microstructural changes and alterations in chemical components significantly enhance DW's mechanical performance. Densification and chemical changes, especially increased cellulose content and reduced lignin, emerge as vital mechanisms for strengthening DW. The model's insights offer valuable guidance for optimizing the two-step preparation process of DW to achieve superior mechanical performance. Additionally, the versatility of the model allows for exploring the influence of cell dimensions and potential applications in designing bioinspired materials.

Two-Step Preparation of 3D Fluffy, Single-Sided Composite Nanofiber Skeleton with Continuous Internal Network for Multifunctional Sensing

Two-Step Preparation of 3D Fluffy, Single-Sided Composite Nanofiber Skeleton with Continuous Internal Network for Multifunctional Sensing

Effect of pretreatment and activation conditions on pore development of coal-based activated carbon

Abundant pore volume and appropriate pore configuration are two crucial characteristics of high-performance carbonaceous adsorbents and catalysts. In this study, influences of pre-treatments (e.g., breaking, sieving and ash removal by acid) and activation conditions (e.g., activation time) on pore parameters (including BET surface area, pore diameter and pore hierarchy degree) of resultant activated carbon were systematically investigated. In addition, the difference between conventional carbonization-activation (i.e., the two-step preparation method) and one-step activation in pore development of activated carbons was revealed. The sample prepared by a 120-minute one-step activation exhibited a BET surface area high to 1038.1 m2/g and a pore hierarchy at 50.7 %. Based on the kinetics analysis using TGA reactor, reaction between the activator (i.e., CO2) and carbon matrix was found enhanced in one-step activation, contributing to the generation of mesopores. Remarkably, a new indicator, Effective Activation Rate (EAR) was proposed to accurately describe the activation rate in one-step synthesis after decoupling the release of moisture and volatile compounds. The above conclusions provide guidance for flexibly regulating the pore configurations of activated carbons derived from natural precursors.

Towards elevated perfluorooctanoic acid (PFOA) enrichment in water: Sequential liquid-liquid extraction pretreatment for ion chromatography detection

The widespread detection of perfluorooctanoic acid (PFOA) in the environment has raised significant concerns. The standard PFOA analytical method relies on expensive solid-phase extraction (SPE) and liquid chromatography tandem mass spectrometry (LC-MS/MS) instruments, making routine use prohibitive. We herein proposed a cost-effective yet novel enrichment method for determining PFOA at ng L−1 level. This method entailed a two-step sample preparation process: firstly, PFOA was extracted and enriched using a forward-extraction under acidic conditions, followed by a backward-extraction and enrichment step utilizing alkaline water. The enriched samples were subsequently subjected to a common ion chromatography (IC). Results reveal that maintaining a forward-extraction pH below its pKa value (2.8) is essential, as protonated PFOA proves effective in enhancing the enrichment factor (EF). The challenge lied in driving PFOA from forward-extractant to aqueous backward-extractant due to the decreased hydrophobicity of deprotonated PFOA (log Kow2 = 1.0). In addition, we found that evaporating forward-extractant with alkaline backward-extractant (containing 5% methanol) reduced potential analytical uncertainties associated with PFOA evaporation and sorption. Under optimal conditions, the method achieved a detection limit of 9.2 ng L−1 and an impressive EF value of 719. Comparison with SPE-LC-MS/MS confirmed the proposed method as a promising alternative for PFOA determination. Although initially targeted for PFOA, the novel methodology is likely applicable to preconcentration of other poly-fluoroalkyl substances.

Two-step preparation of steel slag–lignin hybrid materials for effective removal of methylene blue

Two-step preparation of steel slag–lignin hybrid materials for effective removal of methylene blue

Regulating the crystal orientation of vapor-transport-deposited GeSe thin films by a post-annealing treatment

Recently, GeSe has emerged as a highly promising photovoltaic absorber material due to its excellent optoelectronic properties, nontoxicity, and high stability. Although many advantages make GeSe well suited for thin-film solar cells, the power conversion efficiency of the GeSe thin-film solar cell is still much below the theoretical maximum efficiency. One of the challenges lies in controlling the crystal orientation of GeSe to enhance solar cell performance. The two-step preparation of GeSe thin films has not yet been reported to grow along the [111] orientation. In this work, we study the effect of a post-annealing treatment on the GeSe thin films and the performance of the solar cells. It was found that amorphous GeSe films can be converted into polycrystalline films with different orientations by changing the post-annealing temperature. [111]-oriented and [100]-oriented GeSe thin films were successfully prepared on the same substrate by optimizing the annealing conditions. With the structure of Au/GeSe/CdS/ITO cell devices, PCEs of 0.14% and 0.16% were ultimately achieved.

A two-step method preparation of semaglutide through solid-phase synthesis and inclusion body expression

Semaglutide is currently the most promising antidiabetic drug, especially for the treatment of type 2 diabetes mellitus, due to its excellent efficacy in glycemic control and weight loss. However, the production of semaglutide remains high cost, and high yield, low cost, and high purity still remains a challenge. Herein, we reported a convenient and high-yield strategy for the preparation of semaglutide through fragmented condensation coupling, involving solid-phase peptide synthesis of tetrapeptide and on-column refolding and on-column enzyme cleavage based inclusion body expression of Lys26Arg34GLP-1 (11–37) with fused protein tags in an X-Y-D4K-G pattern. The optimized N-terminal protein tag significantly boosts inclusion body expression level, while on-column refolding and on-column enzyme cleavage avoid precipitation, enhancing efficiency and yield together with one-step purification. The successful preparation of semaglutide is expected to achieve large-scale industrial production with low cost, high yield and high purity.

Differences in microorganisms causing infection after cranial and spinal surgeries.

The primary aim of this retrospective study was to assess differences in the pathogens causing surgical site infections (SSIs) following craniectomies/craniotomies and open spinal surgery. The secondary aim was to assess differences in rates of SSI among these operative procedures. ANOVA tests with Bonferroni correction and incidence risk ratios (RRs) were used to identify differences in pathogens by surgical site and procedure using retrospective, de-identified records of 19,993 postneurosurgical patients treated between 2007 and 2020. The overall infection rates for craniotomy/craniectomy, laminectomy, and fusion were 2.1%, 1.1%, and 1.5%, respectively, and overall infection rates for cervical, thoracic, and lumbar spine surgery were 0.3%, 1.6%, and 1.9%, respectively. Craniotomy/craniectomy was more likely to result in an SSI than spine surgery (RR 1.8, 95% CI 1.4-2.2, p < 0.0001). Cutibacterium acnes (RR 24.2, 95% CI 7.3-80.0, p < 0.0001); coagulase-negative staphylococci (CoNS) (methicillin-susceptible CoNS: RR 2.9, 95% CI 1.6-5.4, p = 0.0006; methicillin-resistant CoNS: RR 5.6, 95% CI 1.4-22.3, p = 0.02); Klebsiella aerogenes (RR 6.5, 95% CI 1.7-25.1, p = 0.0003); Serratia marcescens (RR 2.4, 95% CI 1.1-7.1, p = 0.01); Enterobacter cloacae (RR 3.1, 95% CI 1.2-8.1, p = 0.02); and Candida albicans (RR 3.9, 95% CI 1.2-12.3, p = 0.02) were more commonly associated with craniotomy/craniectomy cases than fusion or laminectomy SSIs. Pseudomonas aeruginosa was more commonly associated with fusion SSIs than craniotomy SSIs (RR 4.4, 95% CI 1.3-14.8, p = 0.02), whereas Escherichia coli was nonsignificantly associated with fusion SSIs compared to craniotomy SSIs (RR 4.1, 95% CI 0.9-18.1, p = 0.06). Infections with E. coli and P. aeruginosa occurred primarily in the lumbar spine (p = 0.0003 and p = 0.0001, respectively). SSIs due to typical gastrointestinal or genitourinary gram-negative bacteria occur most commonly following lumbar surgery, particularly fusion, and are likely to be due to contamination of the surgical bed with microbial flora in the perianal area and genitourinary tract. Cutibacterium acnes in the skin flora of the head and neck increases risk of infection due to this microbe following surgical interventions in these body sites. The types of gram-negative bacteria associated with craniotomy/craniectomy SSIs suggest potential environmental sources of these pathogens. Based on the authors' findings, neurosurgeons should consider using a two-step skin preparation with benzoyl peroxide, in addition to a standard antiseptic such as alcoholic chlorhexidine for cranial, cervical, and upper thoracic surgeries. Additionally, broader gram-negative bacterial coverage, such as use of a third-generation cephalosporin, should be considered for lumbar/lumbosacral fusion surgical antibiotic prophylaxis.

Preparation and Self-Cleaning Properties of a Superhydrophobic Composite Coating on a Stainless Steel Substrate

In order to improve the anti-fouling of stainless steel surfaces in outdoor or humid environments, a superhydrophobic modification is often used to improve its self-cleaning performance. However, the mechanical stability of superhydrophobic surfaces remains a challenge. In this paper, a two-step preparation method was adopted to prepare the micro–nanocomposite coating, which innovatively combined “top-down” and “bottom-up” approaches, and also coupled together two key factors that affect superhydrophobicity: a rough microstructure, and low surface energy. The silver mirror, adhesion, and pollution-resistance results show that the composite coating samples, which were obtained by optimizing the preparation process, have excellent water repellency and self-cleaning properties. Meanwhile, the samples demonstrate outstanding mechanical stability, and can resist damage from sandpaper and tape. The two-step preparation method was simple, fast, and efficient. This method could be popularized and applied to the preparation of superhydrophobic surfaces on metal substrates.

Regulation of Low-dose Stannous Iso-octanoate for Two-step Preparation of Sn-Pb alloyed Perovskite Solar Cells

Regulation of Low-dose Stannous Iso-octanoate for Two-step Preparation of Sn-Pb alloyed Perovskite Solar Cells

Efficient Synthesis of Nitric Acid Under Air Atmosphere with Lattice-Confined Ru Clusters

Nitrate (NO3 -) is an important industrial chemical used as fertilizers in agriculture, as well as oxidizing agents in explosives. Today, NO3 - is manufactured predominantly via an Ostwald process by oxidizing ammonia (NH3), and the ammonia used here comes primarily from the Haber–Bosch (HB) process.However, this process operates at high temperatures (300–500 °C) and pressures (200–300 bar), and requires a coupled steam reforming plant for hydrogen (H2) production. As a result, approximately 1.9 metric tons of CO2 is formed per metric ton of NH3 produced, contributing significantly to climate change. In addition, due to the complexity of the Ostwald and Haber-Bosch processes, it is only economical at large scales, leading to centralized production, which situation is poorly matched with the distributed nature of HNO3 utilization. Therefore, it is highly desirable to bypass the ammonia route and develop a direct and sustainable approach for HNO3 synthesis.Electrochemical synthesis of chemicals has been regarded as an attractive alternative to traditional thermochemical methods. In electrochemical reactions, electric potential can replace high temperature and pressure as the thermodynamic driving force.Therefore, direct electrochemical oxidation of molecular nitrogen appears to be a very potential approach for HNO3 synthesis,which could be sustainable, modular and easily integrated with intermittent renewable electricity. However, due to the lack of natural or artificial electrocatalysts as a reference, the nitrogen oxidation reaction (NOR) remains largely unexplored despite its enormous practical value as a replacement for the fossil fuel-driven two-step HNO3 preparation approach.Until 2019, Zhang et al. reported the first experimental NOR electrocatalyst composed of well-dispersed Pd nanoparticles on MXene nanosheets that can effectively convert N2 into nitrate, which definitely proved the feasibility of using electrochemistry to motivate the endothermic NOR at ambient conditions. Unfortunately, to date, there are still only a few works that reported the electrosynthesis of nitrate from nitrogen, and the proposed electrocatalysts can only achieve limited NOR activity.An in-depth exploration of the NOR process, which consists of two main steps: the first step is a rate-limiting step that converts inert N2 into the active NO* intermediate; the second step is a nonelectrochemical step where NO* reacts with H2O and the generated O* from electrocatalytic water splitting to form nitrate. Therefore, the main factors restricting the development of the electrochemical nitrate synthesis technology can be inferred as follows: (1) the strong N≡N triple bond in the dinitrogen molecule (bond energy: 940.95 kJ mol−1) is highly challenging to oxidate nitrogen to nitrate under mild conditions; (2) the potential window between the NOR and oxidation evolution reaction (OER) is quite narrow, and thus the latter as a competitive reaction can severely restrict the selectively of the nitrogen oxidation synthesis of nitrate; (3) the extremely low solubility and diffusion coefficient of N2 in aqueous electrolytes can significantly inhibit the nitrogen available for the reaction, resulting in unfavorable NOR performance. Therefore, to overcome the above obstacles, extensive studies should focus on designing efficient nitrogen oxidation catalysts and improving electrochemical reaction systems to promote NOR and suppress OER.In the present work, we firstly discovered that synthesizing Ru particles grow along the TiO2 lattice (Ru-TiO2) as the working electrode and can achieve excellent NOR performance by using air as a gas source. Textural analysis sufficiently demonstrates that the matching lattice constants of metal Ru and TiO2 allow the Ru to be confined in the TiO2 lattice, leading to the formation of Ru-Ti bonds and the transfer of electrons from TiO2 to Ru metal. Our results reveal that the electron redistribution of Ru-TiO2 can significantly alter the electronic structure of Ru, leading to the formation of highly occupied Ru 4d bands, which can effectively change the adsorption of surface species and improve the NOR activity. In addition, the Ru confined in TiO2 exhibits particularly high stability towards NOR up to potentials above 1.7 V (versus RHE). As a result, Ru-TiO2 could achieve a record-high NOR performance with a nitric acid yield rate of 18.71 ug h-1 cm-2 (150.2 μmol h-1 g-1) and Faraday efficiency of 25.17% in the air atmosphere. This discovery suggests that the surface oxophilicity and electronic structure of metal particles can be effectively modified by lattice confinement in semiconductors and offers an alternative concept for designing catalysts with unique properties for use in catalysis and beyond. Figure 1

Evolution of mechanical and corrosion properties of TiN/TiO2 nanocomposite multi-stage coating on AZ31 magnesium alloy using atomic layer deposition and in-situ oxidation

TiN/TiO2 nanocomposite film has been deposited on AZ31 magnesium alloy by two-step preparation involving atomic layer deposition and in-situ oxidation. The compact single and multi-stage coatings uniformly cover the surface. Mechanical property evaluation indicates that the resulting coating has good adhesion strength, well wear resistance and compressive residual stress. Furthermore, neutral salt spray test shows a uniform corrosion mode. Hydrogen evolution and electrochemical tests indicate excellent corrosion resistance. For example, compared to AZ31 magnesium alloy, the hydrogen evolution rate of the two-stage sample decreases by a farceur to 1/2, and corrosion current density drops by a farceur to 10-3. The single stage sample has a crystalline/amorphous interlayer structure and ∼ 20 nm thickness, which could lead to a compressive residual stress for the single stage sample and even for the multi-stage coating. The compressive residual stress delays the germination of tiny defects. Furthermore, the multi-stage structure presents more interfaces that can impede longitudinal crack propagation and limit corrosion media diffusion, which contribute to the corrosion resistance. The work not only proposes a good protective coating for magnesium alloy but also presents a strategy for corrosion resistant coating design.

Two-step pyrolytic preparation of biochar for the adsorption study of tetracycline in water

In this study, cow dung biomass was converted into biochar (BC). BC900 was obtained through one-step pyrolysis at 900 °C, while BC700–900 and BC900–700 were obtained via two-step pyrolysis at temperature ranges of 700–900 °C and 900-700 °C, respectively. The primary objective was to investigate the adsorption performance and application value of BCs for tetracycline (TC) in water. The samples underwent characterization using scanning electron microscopy and mapping analysis, Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis. Subsequently, the effects of reaction time, adsorbent dosage, temperature, pH, and ionic strength were analyzed. Based on the fitting results of adsorption kinetics, the pyrolytic BCs exhibited a better fit with the pseudo-secondary kinetic model. The adsorption isotherm indicated monolayer adsorption on the surface of the adsorbents, with maximum adsorption capacities of 158.93 mg/g for BC900–700, 150.15 mg/g for BC700–900, and 142.56 mg/g for BC900, respectively. Furthermore, results from simulated wastewater and regeneration experiments demonstrated that BC900–700 exhibited not only excellent adsorption performance in wastewater but also remarkable regeneration capabilities. The two-step pyrolysis BCs in this study displayed a higher adsorption capacity compared to the one-step pyrolysis BCs in practical applications. These findings provide insights for further exploring the adsorption mechanism and optimizing the process.