Types Of Metal Oxides Research Articles

Photocatalytic water splitting over K3Li2Ta5O15 with a C-site-filled tungsten bronze structure and influence of metal cations at C-site on photocatalytic properties

Abstract K3Li2Ta5O15 is found as a novel photocatalyst for overall water splitting under UV light irradiation. K3Li2Ta5O15 possesses a characteristic crystal structure with Li+ ions-filled C-sites in (A1)4(A2)2C4M10O30 as the general formula of a tungsten bronze type metal oxide. Most of the reported photocatalysts with a tungsten bronze structure possess empty C-sites. K6Ta10.8O30 also possesses a C-site-filled tungsten bronze structure where C-sites are partially filled by Ta5+ ions. In diffuse reflectance spectra, K6Ta10.8O30 has an absorption edge at longer wavelength than K3Li2Ta5O15. This narrower band gap of K6Ta10.8O30 than K3Li2Ta5O15 is considered to be due to the presence of Ta5+ ions at C-sites in K6Ta10.8O30. Ta5+ ions located at 9-fold coordination C-sites with totally different surrounding environment from the 6-fold coordination M-sites will form the conduction band minimum at lower potential than those located at 6-fold coordination M-sites. The optimized K3Li2Ta5O15 shows almost the same water splitting activity with the optimized K6Ta10.8O30. Thus, it is found that the conduction band formed by Ta5+ ions at C-sites is also effective for photocatalytic reaction, being similar to that formed by Ta5+ ions at M-sites.

Transparent p-type copper iodide for next-generation electronics: fundamental physics and recent research trends

Development of transparent and flexible p -type semiconductors has been a significant challenge for scientific curiosity and industrial interest. Unlike n -type metal oxide semiconductors, such as zinc oxide (ZnO), In2O3, and SnO2, transparent p -type oxide semiconductors have suffered from low optical transparency and poor electrical performance. To overcome the intrinsic limitation of p -type oxide semiconductors, copper iodide (CuI) is gaining attention as a multifunctional p -type semiconductor with excellent optical transparency, decent mechanical flexibility, high hole mobility, high electrical conductivity, and even promising thermoelectric performance. Here, we present the recent progress of CuI-based transparent p -type electronics from materials to applications. In this review, we summarize the physical and chemical properties of CuI by reviewing computational studies, focusing on the band structure, intrinsic defects, and promising dopants. Additionally, various applications of CuI, including its use as active layers, hole transport layers (HTLs), transparent electrodes, and energy harvesters, are examined, highlighting important studies and their findings. Strategies to enhance device performance, such as controlling carrier concentrations and refining fabrication methods, are discussed, offering insights for developing next-generation electronic devices. Finally, we discuss current challenges and perspective opportunities of CuI-based transparent p -type electronics.

Efficiency, characterization, and kinetics during removal of COS and H2S in gasified syngas by red soil

Application of red soil in dry desulfurization process for removal of H2S and COS from coal gasified gas is preferable due to its metal oxides content, sustainability, and low cost. This study examined the performance of several red soil types around Taiwan, including Loupi/LP, Houdi/HD, and Dadusan/DDS for removal of COS and H2S. LP red soil presented the best removal efficiency with 91.8 % utilization value and chosen in further assessment on the performance under various operating conditions and cycle test. Moreover, this study was also aimed to explore the type of active metal oxides for removal of COS and H2S, along with the reaction kinetics and exhausted gas analysis after the process. The presence of iron oxides in LP red soil beneficially supported the removal of COS and H2S. Moreover, increasing of CO content in the syngas prolonged the breakthrough time and utilization value. On the other side, higher H2 content triggered the occurrence of water–gas-shift reaction. The cycle test indicated sintering process due to intense reaction under high temperature which led to deterioration of performance. Analysis of reaction kinetics using both Type I and Type II deactivation models indicated their well fitting data with the data of this study.

Synthesis of a Novel and Highly HOR/HER Selective Ru@Pt/TiOx/C Catalyst Exhibiting Strong Metal-Support Interactions (SMSI) for PEMFC Applications

One main goal in Proton Exchange Membrane Fuel Cell (PEMFC) research is to make Fuel Cell Electric Vehicles (FCEV) viable for long-haul travel and increase their durability. Besides many degradation modes which target different parts of a PEMFC such as the catalyst layer, the membrane, bipolar plates, and other components, one major concern is the start-up/shut-down (SUSD) of the cell, inducing degradation of the catalyst support on the cathode. Addressing this, two mitigation strategies are possible: a) the system approach, e.g., reducing number of damaging SUSD events; b) the catalyst approach, e.g., suppressing the Oxygen Reduction Reaction (ORR) activity of the anode.The latter is feasible by utilizing a highly selective HOR/HER (Hydrogen Oxidation/Evolution Reaction) catalyst on the anode side that catalyzes the HOR but has a poor ORR activity, a property that was reported for a Pt/TiOx/C catalyst by Stühmeier et al.[1,2] The high selectivity towards the HOR/HER is explained by the Strong-Metal-Support-Interaction (SMSI) formed between the Pt nanoparticles and the TiOx-support, where the support creeps over the particle during a reductive heat treatment, as observed in HR-TEM.[1] In general, the SMSI effect between a metal and a suitable metal support is found in various heterogeneous catalytic applications, altering the catalyst’s activity for various reactions.[3] In the particular case of Pt/TiOx/C, the SMSI layer forming on the Pt nanoparticle is said to be permeable for protons but impermeable for any other oxygen-containing species, explaining a still rather high HOR/HER activity compared to a Pt/C catalyst (≈ 30% vs Pt/C) and an ORR activity that is decreased by two magnitudes (≈ 2% vs Pt/C).[1] Such interaction was also observed by Stühmeier et al. between Ru and a TiOx-support, where similar trends were determined. However, since the intrinsic HOR/HER activity of a Ru catalyst is quite low compared to Pt, a Ru/TiOx/C catalyst is not feasible for PEMFC applications.[4] Ru@Pt core-shell particles, as shown by Schwämmlein et al., exhibit a 3-5x higher HOR/HER activity compared to a Pt/C catalyst, making a Ru@Pt/C catalyst viable even for alkaline fuel cell applications.[5] Due to the already successfully explored interaction of Pt and Ru with a TiOx-support, we will examine the HOR and ORR activity of Ru@Pt/TiOx/C catalysts..In this work we successfully synthesized a novel catalyst system by forming an SMSI between Ru@Pt core-shell particles and a TiOx-support. Via RDE (Rotating Disk Electrode) characterization, we elucidate if the Ru@Pt/TiOx/C catalyst gains all the benefits from the single parts of the catalyst, namely: i) a high HOR/HER activity from the Ru@Pt core-shell particles; ii) a low ORR activity due to the SMSI effect. Figure 1 shows the HOR/HER performance catalysts based on Ru@Pt particles supported on Vulcan carbon (black line) or on TiO2 nanoparticles, whereby for the latter support the catalysts were either tested as-synthesized (red line) or after a reductive heat-treatment under 5% H2/Ar to induce SMSI effects (green line). Apparently, the SMSI layer on the Ru@Pt core-shell particles enable a sustained HOR/HER activity at > 1.0 VRHE, in contrast to the other two catalysts which show the typical decrease of the HOR/HER activity at high potentials. Similar observations had been made by Stühmeier et al. for a Pt/TiOx/C and Ru/TiOx/C catalyst.[1,2,4] The findings in this particular study with the TiOx-support, as an example, should serve as proof of principle to possibly translate the gained knowledge on different types of metal oxide supports, since the stability of TiOx is known to be limited under PEMFC operation.[2,6] References [1] B. M. Stühmeier, S. Selve, M. U. M. Patel, T. N. Geppert, A. Hubert, H. A. Gasteiger, H. A. El-Sayed, ACS Appl. Energy Mater. 2019, 1–8.[2] B. M. Stühmeier, A. M. Damjanović, K. Rodewald, H. A. Gasteiger, J. Power Sources 2023, 558, DOI 10.1016/j.jpowsour.2022.232572.[3] C. J. Pan, M. C. Tsai, W. N. Su, J. Rick, N. G. Akalework, A. K. Agegnehu, S. Y. Cheng, B. J. Hwang, J. Taiwan Inst. Chem. Eng. 2017, 74, 154–186.[4] B. M. Stühmeier, R. J. Schuster, L. Hartmann, S. Selve, H. A. El-Sayed, H. A. Gasteiger, J. Electrochem. Soc. 2022, 169, 034519.[5] J. N. Schwämmlein, H. A. El-Sayed, B. M. Stühmeier, K. F. Wagenbauer, H. Dietz, H. A. Gasteiger, ECS Trans. 2016, 75, 971–982.[6] J. Zhang, F. Coms, S. Kumaraguru, J. Electrochem. Soc. 2021, 168, 024520. Figure 1

Plasma‐assisted Surface Engineering to Stabilize Mn3+ in Electrodeposited Manganese Oxide Films for Water Oxidation

Manganese oxide is a unique type of transition metal oxide that effectively functions as a catalyst for the oxygen evolution reaction (OER). Here, manganese oxide (MnOx) polymorphs are synthesized through electrochemical deposition and treated with an atmospheric pressure plasma jet (APPJ). The APPJ surface treatment can generate numerous oxygen vacancies and modify the crystallinity of the MnOx films, which can enhance the long‐term stability of the MnOx films by stabilizing the Mn3+ content in the highly oxidizing environment. The increase in Mn3+ content and concentration of oxygen vacancies in the material synergistically increase the adsorption capacity of OH* and the electron‐transferring capacity of MnOx films in the OER process, making them more stable and effective for OER. MnOx films treated with APPJ exhibit significantly higher activity, better stability, and lower Tafel slopes for OER than untreated MnOx films. The MnOx films treated with APPJ can remain stable for up to 92 hours during OER with a current density of 10 mA cm‐2, with an onset overpotential of 310 mV. This strategy, which combines APPJ surface treatment techniques with electrodeposition methods, is innovative in the surface modification of manganese oxides with mixed valences to create OER catalysts with stable Mn3+ content.

Two-dimensional iron oxide/graphene-based nanocomposites as high-performance solid lubricants

Beyond conventional 2D layered materials such as graphene and transition metal dichalcogenides, 2D metal oxides have also received much interest in recent years. They have unique electronic (such as 2D TiO2 and MoO2), catalytic (such as 2D CeO2 and MnO2), and magnetic properties (such as 2D Fe2O3) compared with bulk metal oxides due to their atomically thin structures. Certain types of 2D metal oxides also have the potential to be a new type of high-performance solid lubricants due to the tunable interlayer interaction and possibility for 2D heterostructure formation, but this remains largely unexplored. In this work, we developed a scalable microwave-assisted solid-state synthesis of 2D Fe2O3 and their nanocomposites with reduced graphene oxide (rGO). The 2D Fe2O3/rGO nanocomposites were systematically characterized by electron microscopies and spectroscopies, and their utilization as solid lubricants was studied by pin-on-disk tribometer on both silicon and steel substrates. The results show that due to the easy sliding between 2D Fe2O3 and rGO nanosheets and their unique magnetic-induced assembled morphology, low coefficient of friction (COF) can be achieved for both steel-silicon and steel-steel interfaces. Superlubricity (COF ∼ 0.007) can be achieved for the 2D Fe2O3/rGO nanocomposite with a GO primer layer on a steel substrate. This work provides new insights into the development of functional 2D nanocomposites and expands their applications to solid lubrication and beyond.

Growth of micro-flowers behind hydrophobic polymer surface and impact of silver and tungsten oxide on the wetting characteristics

In this work, a simple and one-step process was demonstrated to develop hydrophobic polymer surfaces. Commercially available polycarbonate (PC) was treated to turn the front surface hydrophobic with an average wetting contact angle (WCA) as high as 110.5°. The formation of micro-flowers with a coverage density of 9.29 × 106/cm2 on the top of fine base nanostructures was confirmed by a high-resolution field emission scanning electron microscope (FESEM). Impact of typical metal and metal oxide such as silver (Ag) and tungsten oxide (WO3) deposited on such hydrophobic surfaces was demonstrated. Petals of micro-flowers and fine base nanostructures were well decorated with functional metals such as Ag and thus the front surface remained hydrophobic with an average WCA as high as 106.6°. Abundant sharp spikes on the top of narrow hills and dips as revealed in the high-resolution FESEM investigation, were speculated to be the reason behind this hydrophobic characteristic. On the other hand, the hydrophobic surface (WCA of ∼ 110.5°) turned hydrophilic (WCA of ∼11.7°) when the surface was decorated with functional metal oxides, such as WO3. Sessile drop tests were carried out to record average WCA and to understand the wetting characteristics of the specimens. A plausible mechanism for such hydrophobic characteristics as well as the transition from a hydrophobic state to a hydrophilic state has been elucidated.

Flexible Electrochemical Supercapacitors: A Review

Flexible supercapacitors (FSCs), especially wearable ones, have become a hotspot of research because of their advantages such as energy density, high specific capacitance, good mechanical properties, decent stability, and eco-friendliness. The storage mechanism in FSCs is either a faradaic mechanism in pseudocapacitors (PCs) or a non-faradaic mechanism as in double-layer supercapacitors (ELSCs). This review summarized the research progress for manufacturing electrodes from various types of materials, whereas carbon, metal oxides, or conductive polymers are utilized as electrodes. An overview of what researchers have performed in changing the original shape of materials and combining them to obtain flexible electrodes with good electrochemical performances. The review includes the presence of different types of electrolytes in the FSCs structure. Perspectives on the direction of future development of research in the field of FSCs are also discussed.

Characterization of lead dioxide composite electrode and its electrochemical properties

TiO2 nanoparticles, as a typical inert metal oxide, were added into [Formula: see text] plating solutions to prepare Ti/PbO2+nano-TiO2 composite coatings. The effect of TiO2 nanoparticles on the electrodeposition process of PbO2 was investigated by voltammetric studies. The composition, structure and morphology of the obtained composite coatings were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy (SEM), respectively. Cyclic voltammetry was employed to study the effect of nano-TiO2 particles on the PbO2 electrodeposition process. It is found that high doping (2–8 g/L) of TiO2 nanoparticles significantly decreased the crystallite size which can be attributed to a crystallite-refining effect of nano-TiO2 during the electrodeposition of PbO2.

Oxygen Vacancy-Induced Low-Valence reactive species enabling High-Efficient nonenzymatic glucose detection

NiCo2O4 (NCO), a typical spinel-type transition metal oxide, emerges as a promising candidate for non-electroenzymatic glucose sensors because of its stable structure and low overpotential. However, the practical applications of NCO are hindered by its limited intrinsic activity for glucose detection. Herein, we intentionally incorporated low-valence redox species into NCO nanowires by modulating the oxygen vacancies (VO-NCO NWs), thereby facilitating glucose oxidation reactivity. The concentration of low-valence species increases with the generated oxygen vacancies, which enriches the reactive redox species and enhances the intrinsic electrical conductivity, thereby improving the catalytic activity. Consequently, the optimized VO-NCO NWs exhibit highly efficient glucose detection with high sensitivity up to 19.65 mA·mM−1·cm−2, which is 4.6 times higher than that of the pristine NCO NWs, as well as a low limit of detection (LOD) of 0.15 μM. Furthermore, a flexible miniaturized three electrode (FMTE) assembled with optimized VO-NCO NWs provides a high sensitivity of 15.89 mA·mM−1·cm−2 and a low LOD of 0.18 μM in synthetic sweat. Under various bending conditions, the FMTE demonstrates good mechanical flexibility, with no discernible alterations in the response current. These findings provide a promising protocol for the dynamic monitoring of sweat composition to reveal human physiological health status.

Cooperative and Bifunctional Adsorbent-Catalyst Materials for In-situ VOCs Capture-Conversion.

Volatile organic compounds (VOCs) are gases that are emitted into the air from products or processes and are major components of air pollution that significantly deteriorate air quality and seriously affect human health. Different types of metals, metal oxides, mixed-metal oxides, polymers, activated carbons, zeolites, metal-organic frameworks (MOFs) and mixed-matrixed materials have been developed and used as adsorbent or catalyst for diversified VOCs detection, removal, and destruction. In this comprehensive review, we first discuss the general classification of VOCs removal materials and processes and outline the historical development of bifunctional and cooperative adsorbent-catalyst materials for the removal of VOCs from air. Subsequently, particular attention is devoted to design of strategies for cooperative adsorbent-catalyst materials, along with detailed discussions on the latest advances on these bifunctional materials, reaction mechanisms, long-term stability, and regeneration for VOCs removal processes. Finally, challenges and future opportunities for the environmental implementation of these bifunctional materials are identified and outlined with the intent of providing insightful guidance on the design and fabrication of more efficient materials and systems for VOCs removal in the future.

Synthesis and characterization of coprecipitated layered NCM oxide as cathode for sodium-ion batteries: Kinetics and hydrodynamics studies

Interest in the development of high-performance sodium-ion batteries (SIBs) as a sustainable alternative to lithium-ion batteries (LIBs) for emerging energy storage systems has motivated to delve into a novel approach for the synthesis of layered transition metal oxide (LTMO) type cathode for SIBs batteries. In this study, we introduce novel chemical synthesis method that diverges from traditional methodologies reported till date. Rather than relying on sulfur, nitrate, or acetate metal precursor salts, we employ metal carbonate salt coupled with oxalic acid as a chelating agent, and sodium carbonate as a precipitating agent. This novel chemistry enhances the microstructure of the cathode material inherited from its precursor exhibiting spherical morphology, influence on the electrochemical properties, bestowing the material with high specific capacity, extended cycle life, and an elevated charge–discharge rate. The primary focus of this work centers on a comprehensive investigation of the hydrodynamic and kinetics aspects of the co-precipitation reaction, guided by the principles of chemical engineering. The effects of key parameters such as impeller speed, impeller type, and scale-up effects on the co-precipitation process have been systematically explored. This research introduces insights into optimizing reaction conditions such as pH, reaction temperature, metal precursor salt ratio, precipitating agent, through rigorous experimentation and characterization reports. The notable effect of precipitating agent on morphology has been demonstrated by electron microscopy images. The kinetics study shows the activation energy of 8.9 kJ mol−1 depicts the reaction is controlled by mass transfer resistance and to overcome this effect, impeller type and speed plays significant role and experimentation results shows the axial mixing pattern created by pitched blade impeller is effective to improvise electrochemical properties. The synthesized cathode material exhibits remarkable electrochemical properties, including tap density of approximately 1.3 g cc−1 with reversible capacity of 215 mAh g−1, along with excellent cyclic stability (90 %) over 60 cycles. Furthermore, it shows the high energy density up to 1300 Wh/L and a rapid charge–discharge rate. These findings contribute to the advancement of SIBs technology and offer promising prospects for future researchers to efficient development of high-performance energy storage solutions.

An innovative strategy towards highly efficient flame-retardant silk

As a luxurious textile raw material, silk fiber (SF) and its products are widely favored by consumers because of their elegant appearance and excellent comfort. However, their flammability causes potential fire risks and hazards in daily fires and has gained significant attention in recent years. In this work, an ultrathin and uniform TiO2, Al2O3, and ZnO nanofilms with thicknesses of 1 ∼ 200 nm (less than one in a hundred of SF diameter) were deposited on the surface of a silk fabric (SFR) by atomic layer deposition (ALD). By tuning the types of metal oxides and nanofilm thickness, the modified SFR quickly self-extinguished, and its pristine weave was completely preserved after exposure to a flame in a torch burn test, representing superior performance compared to numerous conventional coating technologies reported with higher loadings. An expanded charcoal residue formed on the surface of the modified SFR, acting as a physical barrier that enhanced flame retardancy. Furthermore, the modified SFR showed excellent laundering durability, which helps improve the service life of the fabric. Most importantly, the nanofilms had a negligible impact on the intrinsic comfort and other comprehensive properties of the silk.

Structure, Properties, and Preparation of MXene and the Application of Its Composites in Supercapacitors

Two-dimensional transition metal carbides/nitrides (MXenes) are emerging members of the two-dimensional material family, obtained by removing the A layer of the MAX phase through methods such as liquid-phase etching. This article summarizes the structure and properties of MXenes, as well as several preparation methods, including etching with hydrofluoric acid and fluoride salts, alkali-based etching, electrochemical etching, Lewis acid molten salt etching, and direct synthesis. Due to their unique two-dimensional structure and surface chemistry, MXenes exhibit good metallic conductivity, hydrophilicity, excellent flexibility, and ion intercalation properties, showing great potential in the research and application of supercapacitors and attracting widespread attention. The combination of MXene with other types of materials, including polymers, metal hydroxides, metal oxides, and carbon materials, takes advantage of composites to improve energy storage performance and shows great potential in the research and application of supercapacitors. This article provides a detailed summary of MXene composite materials and capacitor performance and introduces the research progress of MXene materials in the field of supercapacitor energy storage applications, aiming to provide references for the preparation of high-performance MXene supercapacitor electrode materials.

Breaking Barriers in Eco-Friendly Synthesis of Plant-Mediated Metal/Metal Oxide/Bimetallic Nanoparticles: Antibacterial, Anticancer, Mechanism Elucidation, and Versatile Utilizations

Nanotechnology has emerged as a promising field in pharmaceutical research, involving producing unique nanoscale materials with sizes up to 100 nm via physiochemical and biological approaches. Nowadays more emphasis has been given to eco-friendly techniques for developing nanomaterials to enhance their biological applications and minimize health and environmental risks. With the help of green nanotechnology, a wide range of green metal, metal oxide, and bimetallic nanoparticles with distinct chemical compositions, sizes, and morphologies have been manufactured which are safe, economical, and environment friendly. Due to their biocompatibility and vast potential in biomedical (antibacterial, anticancer, antiviral, analgesic, anticoagulant, biofilm inhibitory activity) and in other fields such as (nanofertilizers, fermentative, food, and bioethanol production, construction field), green metal nanoparticles have garnered significant interest worldwide. The metal precursors combined with natural extracts such as plants, algae, fungi, and bacteria to get potent novel metal, metal oxide, and bimetallic nanoparticles such as Ag, Au, Co, Cu, Fe, Zr, Zn, Ni, Pt, Mg, Ti, Pd, Cd, Bi2O3, CeO2, Co3O4, CoFe2O4, CuO, Fe2O3, MgO, NiO, TiO2, ZnO, ZrO2, Ag-Au, Ag-Cr, Ag-Cu, Ag-Zn, Ag-CeO2, Ag-CuO, Ag-SeO2, Ag-TiO2, Ag-ZnO, Cu-Ag, Cu-Mg, Cu-Ni, Pd-Pt, Pt-Ag, ZnO-CuO, ZnO-SeO, ZnO-Se, Se-Zr, and Co-Bi2O3. These plant-mediated green nanoparticles possess excellent antibacterial and anticancer activity when tested against several microorganisms and cancer cell lines. Plants contain essential phytoconstituents (polyphenols, flavonoids, terpenoids, glycosides, alkaloids, etc.) compared to other natural sources (bacteria, fungi, and algae) in higher concentration that play a vital role in the development of green metal, metal oxide, and bimetallic nanoparticles because these plant-phytoconstituents act as a reducing, stabilizing, and capping agent and helps in the development of green nanoparticles. After concluding all these findings, this review has been designed for the first time in such a way that it imparts satisfactory knowledge about the antibacterial and anticancer activity of plant-mediated green metal, metal oxide, and bimetallic nanoparticles together, along with antibacterial and anticancer mechanisms. Additionally, it provides information about characterization techniques (UV–vis, FT-IR, DLS, XRD, SEM, TEM, BET, AFM) employed for plant-mediated nanoparticles, biomedical applications, and their role in other industries. Hence, this review provides information about the antibacterial and anticancer activity of various types of plant-mediated green metal, metal oxide, and bimetallic nanoparticles and their versatile application in diverse fields which is not covered in other pieces of literature.

Catalytic Oxidation of BTX (Benzene, Toluene, and Xylene) Using Metal Oxide Perovskites

AbstractThe high toxicity, volatility, and dispersion of the light aromatics, benzene, toluene, and xylene (BTX) pose a serious threat to the environment and human health. Compared to incineration, catalytic oxidation technologies for BTX removal offer benefits such as low energy consumption, high efficiency, and low pollution. ABO3–type perovskite catalysts (ABO3–PCs) are particularly promising materials for the catalytic oxidation of BTX due to their high activity and thermal stability, as well as their adjustable elemental composition and flexible structure allowing their properties to be improved. Nonetheless, the full potential of ABO3–PCs for the oxidation of BTX has yet to be reached. This review systematically and critically analyses progress in the catalytic oxidation of BTX by ABO3–PCs. Catalytic performance is assessed for each category of perovskite, including non–doped, doped (A–, B–, or A/B–site doped), and loading type (noble metal, metal oxide, and matrix composite), with structure–activity relationships are established. A kinetic model and proposed mechanism for the catalytic oxidation of BTX are also presented. Finally, the challenges and opportunities of ABO3–PCs applied to BTX oxidation and other reactions are highlighted.

Vanadyl Sulfate Based Hole‐Transporting Layer Enables Efficient Organic Solar Cells

Comprehensive SummaryIt remains an urgent task to develop alternative hole‐transporting layer (HTL) materials beyond commonly used PEDOT:PSS to increase the shelf‐life of organic solar cells (OSCs). Inorganic metal oxide type materials, such as NiOx, CoOx and VOx, with suitable work functions have attracted numerous research attention recently. In this work, more abundant and easily accessible oxygenated salt, vanadyl sulfate (VOSO4) has been demonstrated to be excellent choice as HTL for OSCs. The VOSO4‐based HTL can be readily processed by spin‐coating from the precursor solution with subsequent thermal annealing and UVO treatment. As a consequence, a high power conversion efficiency (PCE) of 18.72% can be achieved for PM8:L8‐BO based OSCs with the VOSO4‐based HTL. High transmittance, smooth film surface, suitable energy level and high conductivity were revealed to contribute to the high OSC performance. More importantly, compared to device with PEDOT:PSS, VOSO4‐based OSCs exhibit improved stability when stored in the N2 filled glove box. After being stored for 600 h, VOSO4‐based device can retain 89% of its initial efficiency. Notably, VOSO4 can be used as general HTL in PM6:BTP‐BO‐4Cl and PM6:IT‐4F based OSCs, yielding high PCEs of 17.87% and 13.85%, respectively.

Glucose-Assisted Synthesis of Porous, Urchin-like Co3O4 Hierarchical Structures for Low-Concentration Hydrogen Sensing Materials.

The Co3O4 is a typical p-type metal oxide semiconductor (MOS) that attracted great attention for hydrogen detection. In this work, porous, urchin-like Co3O4 was synthesized using a hydrothermal method with the assistance of glucose and a subsequent calcination process. Urchin-like Co3O4 has a large specific surface area of 81.4 m2/g. The response value of urchin-like Co3O4 to 200 ppm hydrogen at 200 °C is 36.5 (Rg/Ra), while the low-detection limit is as low as 100 ppb. The obtained Co3O4 also exhibited good reproducibility, long-term stability, and selectivity towards various gases (e.g., ammonia, hydrogen, carbon monoxide, and methane). Porous, urchin-like Co3O4 is expected to become a potential candidate for low-concentration hydrogen-sensing materials with the above advantages.

Engineered biosorbents of pomelo (Citrus maxima (Burm.f.) Merr) peels modified with zinc oxide and titanium dioxide for methylene blue dye sorption

The pomelo-doped zinc oxide beads (PZB), pomelo-doped titanium dioxide beads (PTB), and pomelo-doped zinc oxide and titanium dioxide beads (PZTB) were synthesized for sorbing methylene blue (MB) dye. Their characterizations were explored by X-Ray Diffractometer (XRD), Field Emission Scanning Electron Microscopy and Focus Ion Beam (FESEM-FIB), Energy Dispersive X-Ray Spectrometer (EDX), and Fourier Transform Infrared Spectroscopy (FT-IR). In addition, their sorbent efficiencies for sorbing MB dye were investigated through batch experiments, sorbent reusability studies, sorption isotherms, kinetics, and thermodynamic studies. They were crystalline phases presenting the specific peaks of zinc oxide (ZnO) or titanium dioxide (TiO2). Their surfaces had lamella structures with coarse surfaces, and they also found specific structures of ZnO or TiO2 on the surfaces. Zn–O or Ti–O–Ti was also detected in PZB or PTB or, PZTB depending upon metal oxide types added into pomelo beaded sorbents. For batch experiments, they could adsorb MB dye of more than 86%, and PZTB showed the highest MB dye removal efficiency. In addition, they could be reused for more than three cycles with high MB dye sorptions of more than 72%. They corresponded to Freundlich and pseudo-second-order kinetic models. Moreover, the increasing temperature affected their decreasing MB dye sorptions which were exothermic processes.

Metal Oxide-Based Sensors for Ecological Monitoring: Progress and Perspectives

This paper aims to provide a large coverage of recent developments regarding environmental monitoring using metal oxide-based sensors. Particular attention is given to the detection of gases such as H2, COx, SOx, NOx, and CH4. The developments and analyses of the design of sensors and types of metal oxide sensing materials are emphasized. The sensing mechanisms and peculiarities of metal oxides used in chemoresistive sensors are provided. The main parameters that affect the sensitivity and selectivity of metal oxide sensors are indicated and their significance to the sensor signal is analyzed. Modern data processing algorithms, employed to optimize the measurement process and processing of the sensor signal, are considered. The existing sensor arrays/e-nose systems for environmental monitoring are summarized, and future prospects and challenges encountered with metal oxide-based sensor arrays are highlighted.