Reduction Process Research Articles

An Overview of Carbon Dioxide Photo/Electrocatalyzed by Titanium Dioxide Catalyst

AbstractThis study provides a comprehensive review of recent advancements in photocatalytic and electrocatalytic carbon dioxide reduction using titanium dioxide catalysts. The basic concepts of light absorption, electron transport, and reduction processes are introduced in this paper, which also delves into the specifics of photocatalytic and electrocatalytic reduction of carbon dioxide. The paper highlights the key applications and benefits of titanium dioxide, including its strong stability, outstanding light absorption capacity, and good electron transport performance, in the photocatalytic and electrocatalytic reduction of carbon dioxide. Furthermore, it examines the impact of various surface modification techniques on catalytic performance, as well as the effects of various titanium dioxide catalyst forms on catalytic activity and selectivity in carbon dioxide reduction. The in‐depth analysis exhibit promising catalytic properties and hold significant potential for future advancements. However, some obstacles still need to be overcome, such as increasing catalytic activity and selectivity while minimizing energy dissipation. In order to improve catalytic performance and efficiency, future research should prioritize the optimization of structural design and surface modification techniques for catalysts. Additionally, the paper provides a scientific foundation for accomplishing sustainable carbon conversion, it also calls for additional experimental and theoretical research into the mechanism of action for titanium dioxide catalyst.

H2O2 oxidation – CaO precipitation pretreatment combining forward osmosis for electroless nickel spent tank liquid (ENSTL) reduction

ABSTRACT The electroless nickel spent tank liquid (ENSTL), as a typical hazardous waste, contains a variety of refractory organic substances as well as heavy metals and inorganic salts. Generally, ENSTL is delegated for disposing by qualified hazardous waste disposal departments in China. However, the temporary storage, transportation, and higher entrusted disposal expenses increase the burden on enterprises producing the hazardous ENSTL. This paper explored an oxidation/precipitation pretreatment and forward osmosis (FO) combined process for ENSTL reduction. 400 mmol/L Hydrogen peroxide and 5.0 wt% calcium oxide were selected as the optimal pretreatment in order to minimize the osmotic pressure of ENSTL, by which the conductivity was significantly reduced from 50.8 mS/cm to 26.8 mS/cm. As a result, the concentrating factor (N) could be dramatically increased from 2.45 by the direct FO to 8.71 by the combined system. Accordingly, the average water flux during the 24 h concentrating cycle increased from 2.47 L/(m2·h) to 4.56 L/(m2·h). TOC rejection rate decreased from 90.23% to 84.39% due to the transformation of organic matter forms by the chemical oxidation during the pretreatment. Meanwhile, TP, Ni and NH4 + rejection rates decreased to a certain extent, which may related to the mitigation of membrane fouling by the pretreatment.

Alocasia Indica Assisted Green Synthesis of Metallic Cu Nanoparticles for Enhanced Antimicrobial Activities

In the past several years, the widespread utility of copper nanoparticles (CuNPs) has spurred global interest in streamlining synthesis methodologies. Notably, this study introduces an environmentally conscious strategy for synthesizing CuNPs using the extract of Alocasia indica. Employing a chemical reduction process, A. indica, abundant in phenolics and flavonoids, acts as a potent reducing agent. The nanoparticles (NPs) synthesized by A. indica have been carefully characterized by Ultraviolet–Visible (UV–Viz) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD) analysis and antimicrobial analysis. UV testing, spanning wave length, elucidates light absorption attributed to the newly formed CuNPs by showcasing a surface plasmonic resonance peak at 204 nm. The evolution of the FTIR spectrum of the produced CuNPs confirms the presence of diverse biomolecules. TEM delineates the synthesis of irregularly shaped particles. Elemental composition analysis via EDX identifies the presence of various elements, including C, O, Al, Cl, K and Cu, with detailed insights into their mass percentages, standard deviations, atom percentages and characteristic X-ray energy levels. The successful synthesis of CuNPs is validated by XRD, which reveals characteristic copper peaks at 2[Formula: see text] = [Formula: see text], [Formula: see text] and [Formula: see text]. The synthesized NP showed 98.99% inhibition against Staphylococcus aureus and 99.99% inhibition against Escherichia coli. This research presents an easy, economical and ecologically friendly process for producing CuNPs utilizing A. indica extracts.

Origin of copper dissolution under electrocatalytic reduction conditions involving amines.

Cu dissolution has been identified as the dominant process that causes cathode degradation and losses even under cathodic conditions involving methylamine. Despite extensive experimental research, our fundamental and theoretical understanding of the atomic-scale mechanism for Cu dissolution under electrochemical conditions, eventually coupled with surface restructuring processes, is limited. Here, driven by the observation that the working Cu electrode is corroded using mixtures of acetone and methylamine even under reductive potential conditions (-0.75 V vs. RHE), we employed Grand Canonical density functional theory to understand this dynamic process under potential from a microscopic perspective. We show that amine ligands in solution directly chemisorb on the electrode, coordinate with the metal center, and drive the rearrangement of the copper surface by extracting Cu as adatoms in low coordination positions, where other amine ligands can coordinate and stabilize a surface copper-ligand complex, finally forming a detached Cu-amine cationic complex in solution, even under negative potential conditions. Calculations predict that dissolution would occur for a potential of -1.1 V vs. RHE or above. Our work provides a fundamental understanding of Cu dissolution facilitated by surface restructuring in amine solutions under electroreduction conditions, which is required for the rational design of durable Cu-based cathodes for electrochemical amination or other amine involving reduction processes.

Magnetic doping engineering in perovskite microcrystals for boosted photocatalytic CO2 reduction

Conversion of carbon dioxide into value-added chemicals through sunlight is a promising approach to reducing our reliance on fossil fuels. Spin provides another freedom to manipulate the photocatalytic CO2 reduction (CO2RR) process and enhance the corresponding properties of optoelectronic applications. In this work, improved photocatalytic CO2RR efficiency was obtained by manipulating spin-polarized species in inorganic halide perovskite microcrystals (MCs) with the introduction of manganese cations (Mn2+) and an employment of a magnetic field. Mn2+-doped CsPbBr3 MCs were prepared through self-assembly process, where Mn2+ is incorporated into CsPbBr3 matrices successfully. Introducing Mn2+ into CsPbBr3 matrices not only induces structural change but also generates new emission band as well as magnetic properties. Thereby, Mn2+-doped CsPbBr3 MCs show significantly enhanced photocatalytic CO2RR properties in contrast with pristine samples (the CO yield is significantly elevated from 22.1 to 41.9 μmol/g in Mn2+-doped CsPbBr3 MCs), as they generate spin-polarized electrons with the introduction of Mn2+. Remarkably, the photocatalytic CO2RR of Mn2+-doped CsPbBr3 MCs is greatly improved under the employment of a magnetic field, achieving 5.0 times higher performance compared to pristine CsPbBr3 MCs when the magnetic field strength is 300 mT. This enhancement is experimentally demonstrated by using magnetic circular dichroism spectroscopy. The increased photocatalytic CO2RR efficiency of Mn2+-doped CsPbBr3 MCs stems from the cooperative doping of Mn2+ and the application of magnetic fields, which generates more spin-polarized photoexcited carriers, thereby leading to extended carrier lifetime and reduced recombination process. These findings demonstrate that introducing spin into optoelectronic semiconductors is a powerful approach to enhancing photocatalytic CO2RR efficiency.

Tailoring three-dimensional conjugated microporous polymers for photo-enhanced gold extraction

Extracting gold from discarded electronic devices can alleviate the growing environmental problems associated with e-waste and provide a sustainable avenue for the secondary utilization of precious metal resources. Unfortunately, viable green recycling methods have not yet been implemented beyond the large-scale incineration of electronic circuit boards, mainly due to the lack of emerging strategies for efficient gold extraction. It is foreseeable that using green photocatalytic technology to extract gold can provide alternative to existing strategies. Herein, we explore the application of D-π-A-type thiazole-functionalized three-dimensional (3D) conjugated microporous polymer (CMP) (BTD-TEP) for photo-enhanced gold extraction from e-waste. With a large specific surface area, abundant high-affinity sites, good chemical stability, and excellent photocatalytic activity, BTD-TEP can be used as an advanced platform for selective extraction and photocatalytic reduction of gold, thus exhibiting a breakthrough gold recovery capacity (3217.8 mg/g). In the dark, BTD-TEP can selectively extract gold through thiazole motifs integrated on the highly accessible 3D skeleton. Meanwhile, the construction of a highly conjugated 3D D-π-A framework significantly increases the exposure of the catalytic center, enhances the photocatalytic activity of BTD-TEP, and allows for an additional gold photocatalytic reduction process under visible light, which greatly improves the recovery capacity and kinetics.

Synergy of atomic hydrogen reduction and reactive oxygen species oxidation over confined Mn bifunctional site for electrocatalytic deep mineralization

Traditional reduction or oxidation processes generating one−component free radicals face challenges in deep dechlorination and mineralization of chlorophenols from wastewater. Herein, an efficient electrocatalytic process has been developed, which couples atomic H* reduction with reactive oxidation species (•OH and 1O2) oxidation on a bifunctional cathode for 4 −chlorophenol (4 −CP) removal. The N − doped carbon nanotubes encapsulated manganese nanoparticles was fabricated as cathode, which could generate atomic H* , initiating nucleophilic hydrodechlorination in presence of confined MnO sites. Subsequently, electrophilic oxidation by generating mainly 1O2 on confined Mn7C3 sites and •OH on confined MnO sites, facilitating the oxidative processes. Experimental results and theory calculations demonstrated that reductive dechlorination and oxidative mineralization processes could mutually promote each other, resulting in an enhancement factor of 2.90. At pH 7, this process achieved 100 % removal for 4 −CP, 84 % dechlorination, 76 % total organic carbon (TOC) removal and low energy consumption (0.76 kWh g−1TOC) within 120 min. Notably, TOC for chlorophenols containing Cl substituents at different positions and real lake water containing 4 −CP could be almost completely removed. This research establishes confined non−noble bifunctional active sites that synergistically enhance reductive dechlorination and oxidative degradation processes, holding significant treatment potential for application in deep mineralization of organochlorine from water/wastewater.

Atomic-level insight into the carburization process of iron-based catalysts: A ReaxFF molecular dynamics study

Transition metal carbide catalysts have garnered widespread attention due to their outstanding catalytic performance. The carbide catalysts, such as FexC and MoxC are typically obtained from their oxide carburization. The reduction and carburization processes are key steps during the activation of oxide precursors, which determine the activity and stability. An understanding of the carburization process mechanism is very important for the optimization of carbide catalysts. Iron-based catalysts are widely used in the large-scale coal-to-liquid industry because of their low price and high activity. In this paper, the carburization process of iron oxide nanoparticles was simulated by the Reactive force field (ReaxFF) molecular dynamics method. The results illustrate that the competition between CO dissociation and reduction of oxides occurs at the 100 ps time scale, which can be tuned by particle size and oxygen vacancy. We have explained the counter-intuitive finding that small oxide particles are more difficult to achieve fully carburization than larger ones; this is because rapid carbon accumulation on the surface blocks the oxygen diffusion channels from bulk to surface. The atomic distribution heat map was carried out to demonstrate the carbon and oxygen penetration processes. Meanwhile, the volumetric strain analysis reveals the driving force comes from the strong tendency to form Fe-C bonds. The dependence on surface orientation was further systematically investigated. This work provides microscopic insights into the carburization process of iron-based materials and the fundamental knowledge for the optimization of catalyst synthesis procedures.

Water model study on the mixing behaviour of gas-liquid two-phase flow for the SKS lead reduction process in a bottom-blown furnace

A 1:10.3 water model was constructed by geometrically scaling down an industrial bottom-blown furnace (BBF) used in the Shuikoushan (SKS) lead reduction process. An innovative method was devised, which combines a chemical decolorization technique with an image analysis method rooted in the RGB colour model, to visualize the mixing characteristics of gas–liquid two-phase flow and quantitatively assess fluid mixing time. The effects of various process parameters (the level height H, gas flow rate Q, feeding port P, vertical angle of the lance θ, and deflection angle of the lance relative to the wall normal α) on the mixing time t were studied via dimensional analysis. Furthermore, a mathematical correlation was developed for t as a function of Fr’, H/D (aspect ratio), P/D, θ, and α. Research findings can serve as a reference for the efficient smelting and optimal design of the SKS lead reduction process in a BBF.

Study on Denoising Method of Weld Defect Signal Based on SSA-VMD-WPD

Defects in welds can affect the structural safety and reliability of workpieces. Currently, the method of using phased array ultrasonic inspection technology for non-destructive testing of weld structures with high detection efficiency, good sensitivity, and good visualization of the results is widely used. However, the defective A-scan data collected by the ultrasonic phased array detector inevitably contain noise data, including the test piece material structure noise, equipment noise, and environmental noise, which undoubtedly affects the analysis of the A-scan signal. In addition, when defects are interpreted, the presence of noise also interferes with the process, which affects the accuracy of the interpretation. Therefore, to enhance the accuracy of defect identification based on phased array ultrasonic inspection technology, we must prevent the series of consequences caused by misjudgments. In this study, ultrasonic phased array inspection experiments were carried out, and the specific process flow of ultrasonic phased array inspection of flat plate butt welds was summarized. Utilizing pre-fabricated flat plate butt specimen blocks containing five types of typical defects, defect A-sweep signals based on ultrasonic phased array inspection were obtained. Combining the sparrow optimization algorithm (SSA), variational mode decomposition (VMD), and wavelet packet decomposition (WPD), a defect signal noise reduction method based on parameter optimization was studied. A noise reduction study was carried out using the noise-added simulated signal, and the results indicated that the noise reduction method proposed in this paper had a better noise reduction effect and the proposed method could effectively retain the detailed features of the ultrasonic phased array defective A-scan signal and realize the noise reduction processing of the defective A-scan signal.

Facile synthesis of poly(tannic acid-1,4-butanediamine) microsphere based on the “self-assembly to polymerization” mechanism and its fast removal feature toward Cr(VI) ions

To remediate toxic Cr(VI) ions in wastewater is a daunting environmental challenge nowadays, thus advanced adsorbents are developed and used to overcome the low removal rate of existing technologies. Herein, poly(tannic acid-1,4-butanediamine) (PTBA) microspheres were synthesized for the purpose of fast removal of Cr(VI) from the aqueous phase. The synthesis was based on the “self-assembly to polymerization” mechanism. The microstructures and chemical characteristics of the fresh and used adsorbents PTBA were characterized systematically by means of TEM, SEM, FT-IR, XPS, TGA and XRD. Effects of pH, contact time, Cr(VI) initial concentration, PTBA dosage, temperature, and the presence of foreign ions on the removal of Cr(VI) had been investigated sequentially. The results indicated that almost 100% of removal efficiency could be achieved in short time intervals, based on the initial concentration of Cr(VI). The spontaneous and endothermic adsorption behavior could be well described by the pseudo-2nd-order (P2O) and Langmuir isotherm models. Finally, the process of partial reduction of Cr(VI) to non-toxic Cr(III) during the adsorption process was explained. Overall, the refined PTBA adsorbent presents a satisfactory behavior to ameliorate the Cr(VI)-pollution elimination means.

Nitrogen fertilization and soil nitrogen cycling: Unraveling the links among multiple environmental factors, functional genes, and transformation rates

Anthropogenic nitrogen (N) inputs substantially influence the N cycle in agricultural ecosystems. However, the potential links among various environmental factors, nitrogen functional genes, and transformation rates under N fertilization remain poorly understood. Here, we conducted a five-year field experiment and collected 54 soil samples from three 0–4 m boreholes across different treatments: control, N-addition (nitrogen fertilizer) and NPK-addition (combined application of nitrogen, phosphorus and potassium fertilizers) treatments. Our results revealed pronounced variations in soil physiochemical parameters, metal concentrations and antibiotic levels under both N and NPK treatments. These alternations induced significant shifts in bacterial and fungal communities, altered NFG abundance and composition, and greatly enhanced rates of nitrate reduction processes. Notably, nutrients, antibiotics and bacteria exerted a more pronounced influence on NFGs and nitrate reduction under N treatment, whereas nutrients, metals, bacteria and fungi had a significant impact under NPK treatment. Furthermore, we established multidimensional correlations between nitrate reduction gene profiles and the activity rates under N and NPK treatments, contrasting with the absence of significant relationships in the control treatment. These findings shed light on the intricate relationships between microbial genetics and ecosystem functions in agricultural ecosystem, which is of significance for predicting and managing metabolic processes effectively.

Nitrogen-Site Engineering in Covalent Organic Frameworks for H2O2 Photogeneration via Dual Channels of Indirect Two-Electron O2 Reduction.

Photocatalytic H2O2 production is a green and sustainable route, but far from meeting the increasing demands of industrialization due to the rapid recombination of the photogenerated charge carriers and the sluggish reaction kinetics. Effective strategies for precisely regulating the photogenerated carrier behavior and catalytic activity to construct high-performance photocatalysts are urgently needed. Herein, a nitrogen-site engineering strategy, implying elaborately tuning the species and densities of nitrogen atoms, is applied for H2O2 photogeneration performance regulation. Different nitrogen heterocycles, such as pyridine, pyrimidine, and triazine units, are polymerized with trithiophene units, and five covalent organic frameworks (COFs) with distinct nitrogen species and densities on the skeletons are obtained. Fascinatingly, they photocatalyzed H2O2 production via dominated two-electron O2 reduction processes, including O2-O2 •‒-H2O2 and O2-O2 •‒-O2 1-H2O2 dual pathways. Just in the air and pure water, the multicomponent TTA-TF-COF with the maximum nitrogen densities triazine nitrogen densities exhibited the highest H2O2 production rate of 3343µmol g-1 h-1, higher than most of other reported COFs. The theoretical calculation revealed the higher activity is due to the easy formation of O2 •‒ and O2 1 in different catalytic process. This study gives a new insight into designing photocatalysis at atomic level.

Study on strength and reduction characteristics of iron ore powder-green carbon composite briquettes

The metallurgical industry is a key sector for carbon emissions, and in recent years, there has been widespread attention on the use of biomass resources as a green, renewable, and carbon–neutral energy source material for low carbon ironmaking processes. The waste wood after hydrothermal-pyrolysis carbonization has the characteristics of low content of harmful elements and high content of fixed carbon. In this study, the waste wood after hydrothermal-pyrolysis two-step carbonization treatment was used as a reducing agent for the reduction of iron ore to prepare iron ore powder- green carbon composite briquettes (ICCB) with two carbon–oxygen ratios. The study investigated the effects of reduction behavior and reaction temperature on the reduction performance of the ICCB. The results indicate that with the increase in reaction temperature, the volume of the ICCB gradually contracts, leading to a reduction in mass. The shrinkage rate of the ICCB during self-reduction at 1200℃ is significantly higher than during co-reduction, and the shrinkage effect of the C/O 0.5 ICCB is more pronounced than that of the C/O 0.8 ICCB. Due to the excessive carbon content in the C/O 0.8 ICCB, the carbon cannot be fully consumed during the reaction process, resulting in consistently low compressive strength of the ICCB, with a compressive strength of 12 N after reduction at 1200℃. In contrast, the iron phase in the C/O 0.5 ICCB gradually recrystallizes during the reduction process, ultimately yielding plastic iron briquettes with compressive strengths exceeding 3000 N after different reaction behaviors at 1200℃. In summary, reducing the carbon-to-oxygen ratio and increasing the reaction temperature contribute to the volume contraction and enhanced compressive strength of the ICCB during the reduction process.

Room-Temperature CrI3 Magnets through Lithiation.

The pursuit of two-dimensional (2D) magnetism is promising for energy-efficient electronic devices, including magnetoelectric random access memory and radio frequency/microwave magnonics, and it is gaining fundamental insights into quantum sensing technology. The key challenge resides in overseeing magnetic exchange interactions through a precise chemical reduction process, wherein manipulation of the arrangement of atoms and electrons is essential for achieving room-temperature 2D magnetism tailoring in a manner compatible with device architectures. Here, we report an electrochemically crafted CrI3 layered magnet─a van der Waals material─with precisely tailored lithiation and delithiation degrees. The crystalline and packing structure within the intralayer are preserved during the lithium intercalation within the interlayer, owing to weak interlayer coupling. Intrinsic ferromagnetism featuring a Curie temperature reaching 420 K has been unequivocally demonstrated, showcasing a coercivity of 1120 Oe at room temperature. The degree of lithiation through the reduction from Cr3+ to Cr2+ plays a crucial role in determining a 28.5% change in magnetization and a 0.29 eV shift in the bandgap. Room temperature ferromagnetism and magnetoelectricity are critical for noncontact, specifically photon-driven, dynamic magnetism control of 2D magnet-based magnonics devices.

Improving interfacial microstructure and mechanical properties of ODS-W/Cu joints via anodization treatment and spark plasma sintering

The bonding properties at the interface between the first wall oxide dispersion strengthened tungsten (ODS-W) and the heat sink copper (Cu) are vital for their application in future nuclear fusion reactors. However, the immiscibility and significant differences in the coefficient of thermal expansion between ODS-W and Cu pose considerable challenges for bonding these two materials. This study utilizes anodization and hydrogen reduction processes to form a nanoporous structure on the surface of ODS-W, thereby achieving effective bonding between ODS-W and Cu by spark plasma sintering (SPS). The effects of the anodization parameters on the surface characteristics of ODS-W, and the influence of the bonding temperature on the interfacial microstructure and mechanical properties of the ODS-W/Cu joints were investigated. The results demonstrate that under an anodization condition of 50 V for 40 min, a nanoporous structure with an average pore size of about 90 nm can forms on the surfaces of ODS-W. This significantly increases the surface roughness, thereby enhancing the interfacial bonding of ODS-W with Cu during SPS. As the bonding temperature increases, the interfacial microstructure changes from linear to serrated shape, effectively suppressing crack propagation and forming a stronger mechanical interlock between ODS-W and Cu. This significantly enhances the mechanical properties of the joints. Typically, at a bonding temperature of 1000 °C, the tensile strength of the anodized ODS-W/Cu joints reaches 245.2 MPa, which is 157.9 % higher than that of directly bonded joints. Additionally, the tensile fracture primarily occurs within the Cu substrate, transitioning from brittle to ductile fracture modes.

The cooperative p-n heterojunction and Schottky junction in Au-decorated hierarchical CuS@SnS2 hollow cubes for boosted charge transport and CO2 photoreduction

During the photocatalytic CO2 reduction process, fast charge transport, abundant active sites, and high visible light utilization in photocatalysts are key to achieving excellent CO2 conversion efficiency. In this work, we have designed and prepared hierarchical CuS@SnS2p-n heterostructure hollow cubes for photocatalytic CO2 reduction. First, a monolayer of CuS was in situ generated on the pre-prepared Cu2O cubes to construct core–shell Cu2O@CuS cubes by sulfidation of Cu2O cubes. The following etching process led to the formation of CuS hollow cubes. Finally, the hierarchical CuS@SnS2p-n heterostructure hollow cubes were obtained by growing SnS2 nanosheets on the CuS hollow cubes. The prepared CuS@SnS2p-n heterostructure hollow cubes showed an improved photocatalytic CO2 reduction activity compared with the bare CuS and SnS2 control samples. The p-n heterojunction formed between SnS2 and CuS as well as its hollow structure enhanced the charge carrier separation efficiency and the light absorption capacity of the hybrid catalyst. Furthermore, after the decoration of Au nanoparticles, the formed Schottky junction further discouraged the charge carrier recombination. Thus, the cooperative p-n heterojunction and Schottky junction greatly facilitated photocatalytic CO2 reduction, and exhibiting the maximum CO and CH4 yields of 140.1 and 77.5 μmol g−1 h−1, respectively. This work presents an efficient design of high-performance catalysts for photocatalytic CO2 reduction.

Variable valence I3−/I− ionic bridge assisting CuI nanoparticle/BiOI nanosheet S-scheme photocatalyst with hydrophobic surface for boosting CO2 conversion with 100 % CO selectivity

The photocatalyst film, composed of tetragonal BiOI nanosheets and cubic phase CuI nanoparticles, was synthesized on the FTO substrate by a simple electro-deposition method. The orderly crisscrossed nanosheet structure caused exterior hydrophobic property, resisting the excess H2O molecules and further inhibiting the competitive H2O reduction process. The novel BiOI/CuI catalyst exhibited excellent photocatalytic ability of CO2 reduction into CO with 100 % selectivity in H2O vapor. Typically, the optimal 150BiOI/CuI photocatalyst exhibited CO yield of 7237.65 μmol/cm2 after 11 h of simulated sunlight illumination, achieving quantum efficiency of 2.5 % at 380 nm. The excellent performance of the BiOI/CuI composite film in photocatalytic CO2 reduction can be attributed to the construction of hydrophobic surface and S-scheme heterojunction with I3−/I− redox mediator, as confirmed by the in-situ XPS, hole injection test and cyclic voltammetry results. This study lays the groundwork for employing highly efficient iodide-based photocatalysts in gas-liquid-solid triphase catalytic systems.

In-Situ investigation of the catalytic hydrogenation reaction of 4-nitrothiophenol by using single Pt@Au nanowires as a new platform

Investigating the kinetics and mechanisms of catalytic hydrogenation reaction is important for fundamental research and chemical engineering, especially at single nanowire/nanoparticle level. In this work, we constructed a dual-functional single Pt@Au nanowire (Pt@Au NW) reaction platform, which was used for in-situ monitoring the p-nitrothiophenol (4-NTP) catalytic reduction process by using surface-enhanced Raman scattering (SERS) and UV–vis spectroscopy. The conversion of reactants and intermediates as well as the product generation during the reaction process were analyzed carefully, and the influencing factors of temperature and light were also discussed. Moreover, the density functional theory (DFT) was used to further investigate the effect of the single Pt@Au NW on catalytic hydrogenation reaction of 4-NTP. The results show that the single Pt@Au NW can be a good platform for in-situ monitoring catalytic hydrogenation reaction of 4-NTP with excellent catalytic activity, high stability, and good reproducibility, and clarified that trans-dimercaptoazobenzene (trans-DMAB) intermediates were produced that are further converted to the p-aminothiophenol (4-ATP). The work will not only give researchers new insights into the combination of the single nanowire/nanoparticle with spectroscopic techniques, but may also inspire further in-depth studies of multifunctional catalysts for catalytic hydrogenation reaction at single entity level.

Helicopter cockpit speech recognition method based on transfer learning and context biasing

Currently, Chinese speech recognition technology is generally designed for common domains, primarily focusing on accurate recognition of standard Mandarin Chinese in low-noise environments. However, helicopter cockpit speech presents unique challenges, characterized by high-noise environments, specific industry jargon, low contextual relevance, and a lack of publicly available datasets. To address these issues, this paper proposes a helicopter cockpit speech recognition method based on transfer learning and context biasing. By fine-tuning a general speech recognition model, we aim to better adapt it to the characteristics of speech in helicopter cockpits. This study explores noise reduction processing, context biasing, and speed perturbation in helicopter cockpit speech data. Combining pre-trained models with language models, we conduct transfer training to develop a specialized model for helicopter cockpit speech recognition. Finally, the effectiveness of this method is validated using a real dataset. Experimental results show that, on the helicopter speech dataset, this method reduces the word error rate from 72.69% to 12.58%. Furthermore, this approach provides an effective solution for small-sample speech recognition, enhancing model performance on limited datasets.