Superior Material Research Articles

Use of Innovative Methods to Produce Highly Insulating Walls Using 3D-Printing Technology.

The article explores innovative methods for creating high-insulation walls, essential for the future of energy-efficient and sustainable construction. It focuses on advanced 3D-printing technologies that allow for the construction of walls with superior insulation materials, optimizing thermal properties and significantly reducing energy for heating and cooling. The integration of thermal insulation within wall structures and innovations in building materials like lightweight composites, aerogels, and nanotechnology-based insulations are highlighted. It discusses the environmental, economic, and technical benefits of these innovations and the challenges to fully leverage 3D printing in construction. Future development directions emphasize materials that enhance thermal efficiency, sustainability, and functionality, promising a new era of sustainable and innovative construction practices.

(Invited) Development of Ir-Based Electrocatalyst for Proton Exchange Membrane Water Electrolysis

PEMWE (proton exchange membrane water electrolysis) is one of the most prospective way to produce hydrogen without environmental damage. So far, various materials have been studied for more efficient water electrolysis. These studies have mainly focused on anode-side material since the over potential for the anode side reaction (H2O → 1/2O2 + 2H+ + 2e-) is much higher than that of the cathode side reaction (2H++2e- → H2).Among various materials, iridium oxide (IrOx, IrO2) is one of the most superior anode side material. As a company, which address PGM (platinum group metal) and their technologies, we have been developing the iridium-based catalyst for PEMWE.We have TEC77100, TEC77110 etc. as catalyst line-up for water electrolysis. TEC77100 is an amorphous-type iridium oxide catalyst with large surface area which reaches about 100 m2 g-1, whereas, TEC77110 is a crystalline (rutile) -type catalyst with high durability. The amorphous-type TEC77100 shows higher activity (–1.86 V@2A cm-2, 50°C, measured in MEA with NafionTM 115 membrane) than the rutile-type TEC77110 (–1.92 V@2A cm-2, 50°C). In terms of durability, however, TEC77110 is superior to TEC77100. The degradation was suggested to be due to the crystallization of TEC77100 under water electrolysis condition. Except for these two types of catalyst, I’ll also introduce a catalyst to countermeasure cross leaking hydrogen in the anode side from the cathode side briefly. Figure 1

Confined graphitization induced pore generation for designing novel potassium-ion battery carbon anode with large capacity and ultra-long cycle life

Carbon is one of the most superior anode materials for K-ion batteries but faces the challenges of low capacity and poor cycle stability. In general, the K+ storage capacity depends on the graphitized carbon layers and defective structure, while the cycle stability can be enhanced by constructing sufficient nanospace to alleviate the volume expansion during the potassiation/depotassiation process. However, the above structures are difficult to integrate into a single carbon material because graphitization often eliminates defects and pore structures. In this work, we find that ultrathin carbon sheets have a confined graphitization effect, which allows the carbon layer to orientationally arrange at a low heating-treatment temperature. More importantly, this orientational arrangement causes size shrinkage, inducing structural splitting on the faces of the carbon sheets and producing abundant defects and a large number of pores. Based on this, we obtain a novel carbon with highly graphitized, large-surface-area and defect-rich frameworks, which gives a K+ storage capacity of 358 mAh g−1, and after 4000 cycles, this carbon shows no obvious capacity degradation, with a capacity retention rate of nearly 100 %. Carbon anodes of K-ion batteries with such large capacity and long cycling life have rarely been achieved before.

Me–C8B5: A novel two-dimensional carbon boride as reversible hydrogen storage material with high capacity

In this work, we predict a new two-dimensional metallic carbon-boron material, named Me–C8B5, which is composed of octagons, pentagons and hexagons. By DFT calculation, we examine the efficacy of hydrogen storage in alkali and alkaline-earth metals modified Me–C8B5 structures. Our findings reveal that these metals exhibit a robust affinity for the Me–C8B5 substrate, characterized by substantial binding energies, thereby mitigating the tendency to form clusters. In particular, the hydrogen storage capacity for Li, Na, Mg and Ca modified Me–C8B5 reach 6.87 wt%, 7.60 wt% and 5.74 wt% and 9.51 wt%, respectively, higher than the DOE requirement of 4.5 wt%. The results of relative energy reveal that the Li-modified system exhibits more appropriate pressure (8.4 bar) and temperature (370 K) for maintaining stable hydrogen storage. Notably, the suitable average desorption temperatures coupled with the stability exhibited in AIMD simulations indicate that Me–C8B5 scaffolds modified with metals Li, Na, Mg, and Ca may possess viable practical applications in the realm of reversible hydrogen storage. These outcomes are anticipated to stimulate the pursuit and continued refinement of novel, superior two-dimensional materials for hydrogen storage.

Graphene-enhanced manganese dioxide functional ink infused with polyaniline for high-performance screen-printed micro supercapacitor

In the world of miniature advancements in technology, a current champion has emerged: the micro supercapacitors. In order to fabricate these micro-supercapacitors, we have developed a promising and user-friendly approach for printing a conductive functional ink containing a ternary composite of manganese dioxide (MnO2) nanoparticles, Graphene, and polyaniline (PANI) as a dopant. Screen-printing technique was employed to fabricate micro-supercapacitors using the nanocomposite conductive ink. The performance of the energy storage device was examined using flexible symmetric and asymmetric, with an aqueous 1 M KOH electrolyte. According to this strategy, the characterisation and electrochemical study results revealed that doping PANI into both symmetric and asymmetric devices significantly increased the material’s capacitive performance of areal capacitance 167 mFcm−2 for MnO2/Graphene/PANI-5 composite (MGP-5) and 292.5 mFcm−2 for asymmetric supercapacitor (ASSC) at 5 mVs−1. Furthermore, the asymmetric supercapacitor displayed outstanding cyclic stability, retaining 93.6% of its capacitance after 10000 cycles. This underscores the possibility of incorporating polyaniline (PANI) into MnO2 and graphene matrices as efficient blueprints for the development of superior electrode materials. The improvement represents a significant step forward, opening avenues for the future development of novel devices and their integration into top-of-the-line flexible energy storage systems.

The impact of Ru and Gd dopants on the dielectric and conductive properties of NiO nanoparticles: A comparative study

This comparative study investigates the difference between the transition metal (Ru) and rare earth element (Gd) as dopants in NiO nanoparticles, to unveil their suitability in various applications. Pure, Ru- and Gd-doped NiO nanoparticles have been synthesized by the chemical co-precipitation method, in the presence of polyvinylpyrrolidone, as a capping agent. The EDX pattern revealed the purity, the un-stoichiometric nature of the synthesized nanoparticles, and the influence of the Ru- and Gd-dopants in generating advantageous structural imperfections, including oxygen and nickel vacancies. The dielectric and conductivity measurements have provided valuable insights into the electrical behavior of Ru- and Gd-doped NiO nanoparticles. The influence of the Ru- and Gd-dopants on the Debye model, universal dielectric model, and relaxation mechanism was implemented. The dielectric constant was affected by the dopants, where the Ru-dopants reduced it by a factor of 0.24, however, the Gd-dopants boosted it by a factor of 4. Moreover, the opposing influence of the Ru- and Gd-dopants on the nickel vacancies has tuned the ac conductivity of the NiO lattice, where it was reduced by 75 % with Ru-dopants due to the suppressed nickel vacancies and enhanced by 70 % with the Gd-dopants due to the augmented nickel vacancies. The dc conductivity was examined at ranging temperatures to explore the conduction mechanism and the effect of the dopants. The multi-functional ability of the pure, Ru- and Gd-doped NiO nanoparticles was tested by studying the complex power and temperature coefficient of resistance (TCR), from which the dominating capacitive and resistive nature is identified for the samples. Besides, NiO nanoparticles have attained a maximum TCR value of −10.41 %, rendering it a superior material for bolometric devices, even better than the used conventional materials. The studied dielectric and conductive properties unveiled the potential applicability of the samples in microelectronics, storage capacitor applications, and bolometric devices.

Simultaneous cloning and selection of Psidium genotypes resistant to Meloidogyne enterolobii

One of the obstacles to arboreal plant breeding is the time required between the selection of superior genotypes and their multiplication. This study investigates Psidium (guava) hybrids developed to obtain rootstock or new scions resistant to the nematode Meloidogyne enterolobii. The use of half-siblings or hybrid seeds of these genetic materials does not preserve the genetic profile of resistant individuals, making destructive selection methods unfeasible. Propagating juvenile Psidium material by minicutting produces a high rooting percentage, facilitating the cloning of segregating families and reducing the time required to produce replicas. In this study, segregating families for resistance to M. enterolobii were cloned by minicutting, with replicas maintained in clonal minigardens while the mother plants were inoculated and evaluated for nematode reproduction in the root system. The results indicate resistance segregation both among and within families. Early cloning by minicutting demonstrated 100% efficiency, allowing the identification of 30 resistant individuals to occur simultaneously with the first multiplication cycle of these individuals, reducing the time and uncertainty involved in recovering superior materials. The methodology adopted is an effective strategy, allowing advances in guava breeding programs. Additionally, individuals resistant to M. enterolobii were observed in the hybrids P. guajava x P. cattleianum; P. cattleianum x P. guineense and P. guineense x P. cattleianum.

Novel approach to produce 3D boron-doped diamond for pollutant removal from water

Diamond growth from Chemical Vapor Deposition (CVD) on foreign substrates can require different pretreatment not only to improve the film nucleation but also to assure its adhesion by decreasing the expected film/substrate interface stress. To improve boron-doped film nucleation, growth, and adherence, different substrate pretreatments have been used mainly from the seeding process with diamond powder at various particle sizes. Despite this, the development of diamond growth on a Ti mesh remains difficult because of the requirement of a cohesive film to cover a 3D macroporous sample with varying growth rates based on its distinct network geometry. Then, this work describes a novel approach to growing boron-doped diamond (BDD) and boron-doped ultrananocrystalline diamond (B-UNCD) on titanium dioxide nanotubes (TDNT) produced simultaneously on both sides of Ti mesh by an anodization process. The films were obtained from two-step growth processes by assuring the entire diamond overlay on both TDNT/Ti mesh sides, including their outer/inner surfaces, as a 3D sample. TiO2 - TiC conversion has dominated the renucleation process, facilitating the nanometric scale control. The film morphologies were systematically analyzed by FEG-SEM images at different sample planes and depths for both sample sides at different stages of film growth. The unique morphology of titania nanotubes associated with columnar and/or renucleation development of BDD, considering the film defects and valley, can systematically increase the electrode specific area. Raman spectra showed the film quality and its micro and/or ultrananodiamond structure and the boron doping features. Also, this growth process allowed a dopant-controlled adjustable conductivity. Then, the boron doping levels for both films were evaluated from Mott-Schottky plots at around 1019 Bcm−3, characterizing them with good conductivity. In addition, electrochemical measurements from Cyclic Voltammetry (CV) confirmed the expected diamond response on redox pair following the quasi-reversible criteria as high-performance diamond electrodes and in situ Raman spectroelectrochemical measurements assessed the stability of samples during electrochemical measurements, ensuring structural integrity. Finally, the samples were applied to the degradation of methylene blue, proving to be superior materials for electrochemical applications due to their advantages compared to those of similar 2D electrodes.

Research on production of microgroove arrays on TiAl intermetallic alloy by micro milling

TiAl intermetallic alloy is a superior lightweight material with excellent performance, and its micro features or components have promising applications in manufacturing fields. In this work, an investigation of micro milling of microgroove arrays on TiAl alloy was studied. The effects of cutting parameters including the feed per tooth (fz) and depth of cut ( ap) on the milling force, surface morphology, surface roughness and burr size of the micro-slots were investigated. The wear types and mechanisms of the micro end mills were also studied. The results showed that the optimal cutting parameters were fz = 3.5 μm/z and ap = 4 μm, which provided the best surface roughness Sa of 152 nm, top-burr heights on up- and down-milling sides of 19 and 19.5 μm respectively. Using the optimized cutting parameters, microgrooves with a width of 500 μm, aspect ratio of 5 and array period of 10 were fabricated successfully. Surface topography, dimensional accuracy and perpendicularity of the microgroove arrays were characterized. Results demonstrated that an increase in the microgroove number, microgroove edge chipping as well as burrs of the entrance and exit increased gradually. The dimensional error between the obtained width and the designed width of the microgroove was less than 2%, and the slope of the sidewalls reached more than 89°. The wear mechanisms of the micro end mills were abrasive wear and adhesive wear, and wear types were coating delamination, cutting edge chipping, and tool nose breakage.

Dual carbon protected ultrafine SnO2 nanoparticles with Sn–C interface for robust lithium storage

Stannic oxide (SnO2)-based lithium-ion batteries (LIBs) have garnered tremendous attention due to their high theoretical capacity and suitable lithium ion insertion potential. However, their widespread applications have been hindered by severe electrode degradation caused by substantial volume expansion of SnO2. In this study, we embedded amorphous carbon encapsulated ultrafine SnO2 nanoparticles on hollow macroporous carbon (AC@SnO2/HMC) as a superior anode material for LIBs. The unique Sn–C interface and dual carbon protection layers effectively mitigated SnO2 nanoparticle agglomeration and volume expansion, reinforcing the cycling stability. Additionally, the capacitive contribution from amorphous carbon significantly improved the reversible capacity and rate capability. As such, the resulting AC@SnO2/HMC electrode exhibited high capacity (1828 mAh g−1 after 200 cycles at 0.1 A g−1), excellent rate capability (1017.6 mAh g−1 at 1 A g−1), and outstanding cycling performance (792.1 mAh g−1 after 880 cycles at 2 A g−1), surpassing previously reported SnO2-based anodes. Furthermore, the AC@SnO2/HMC-based Li-ion full cell demonstrated a remarkable capacity of 566.3 mAh g−1 at 0.2 A g−1 after 200 cycles. This study offers valuable insights into the development of advanced SnO2-based anodes for LIBs and beyond, highlighting their potential for future advancements in battery technology.

Experimental and theoretical investigation of silicon-based carbon composite electrode for high performance Li-ion capacitors

Lithium-ion capacitors (LICs) have garnered significant attention in recent years due to their ability to overcome the shortcomings of lithium-ion batteries (LIBs) and supercapacitors (SCs). Silicon (Si) stands out as a superior anode material for LICs due to its compelling attributes, including a high theoretical specific capacity (4200 mAh/g) and a low de-lithiation potential. Nevertheless, the inherent challenges of Si, such as low electrical conductivity and significant volume expansion (300 %), contribute to low electrochemical performance. To address this issue, a conductive carbon layer is introduced on Si using a simple and scalable approach. The resulting architecture, known as carbon-encapsulated Si (Si/C), not only improves electrical properties by enhancing Li+ diffusion but also mitigates volume expansion, leading to enhanced capacity and cyclic stability. Theoretical findings based on density functional theory (DFT) support these enhancements, confirming improved interactive properties at an atomic scale, including low binding energy and accelerated charge transfer kinetics (higher valence charge transfer) between the Si/C electrode and Li ions. As a result, the ‘binder-free’ and flexible Si/C electrode exhibits a notable initial discharge capacity (3450 mAh/g at 0.05 C) with improved rate capability (3010 mAh/g at 0.1 C). When employed as an anode in LICs, the Si/C electrode exhibits outstanding performance, boasting a large energy density (222.29 Wh/kg), high power density (25 kW/kg), and superior cyclic stability (81.3 % over 10,000 cycles). These findings highlight the potential of the Si/C electrode as a formidable candidate for advanced energy storage applications.

Hall effect analysis of boron and nitrogen background concentration in undoped CVD diamond

Pure single crystal diamond is a superior material for electronic, quantum, and detection applications. The state-of-the-art level of background concentrations of boron and nitrogen in such diamonds is about 1 ppb, which is quite close to the detection limit of the best chemical analysis techniques. In this work, we show that the boron concentration of ∼0.1 ppb causes conductivity of ∼5 kΩ cm of the single crystal diamond if the nitrogen concentration is lower. In such a case, the temperature dependent Hall effect measurement provides ∼100 times better detection limit for the concentration of the impurities in diamond compared to the conventional optical techniques. As a result, we have found the background concentrations of boron and nitrogen at the level of 0.07 and 0.02 ppb, respectively. This fact leads to a conclusion that growth of the insulating diamond is possible only when the nitrogen concentration is higher than the boron concentration.

Wire arc additive manufacturing of a high-strength low-alloy steel part: environmental impacts, costs, and mechanical properties

Additive manufacturing (AM) technologies have demonstrated a promising material efficiency potential in comparison to traditional material removal processes. A new directed energy deposition (DED) category AM process called wire arc additive manufacturing (WAAM) is evolving due to its benefits which include faster build rates, capacity to build large volumes, and inexpensive feedstock materials and machine tools compared to more technologically mature powder-based AM technologies. However, WAAM products present challenges like poor surface finish and lower dimensional accuracy compared to powder-based processes or machined parts, prevalence of thermal distortions, residual stresses, and defects like porosity, cracks, and humping, often requiring post-processing operations like finish machining and heat treatment. These post-processing operations add to the production cost and environmental footprint of WAAM-built parts. Therefore, considering the opportunities and challenges presented by WAAM, this paper analyses the environmental impact, production costs, and mechanical properties of WAAM parts and compares them with those achieved by laser powder bed fusion (LPBF) and traditional computer numerical control (CNC) milling. A high-strength low-alloy steel (ER70S) mechanical part with medium complexity was fabricated using WAAM. Based on the data collected during this experiment, environmental impact and cost models were built using life cycle assessment and life cycle costing methodologies. WAAM was observed to be the most environmentally friendly option due to its superior material efficacy than CNC milling and has a better energy efficiency than LPBF. Also, WAAM was the most cost-friendly option when adopted in batch production for batch sizes above 3. The environmental and cost potential of WAAM is amplified when used for manufacturing large products, resulting in significant material, emission, and cost savings. The fabricated WAAM part demonstrated good mechanical properties comparable to that of cast/forged material. The methodology and experimental data presented in this study can be used to calculate environmental impacts and costs for other products and can be helpful to manufacturers in selecting the most ecofriendly and cost-efficient manufacturing process.

A review on the current status of dye‐sensitized solar cells: Toward sustainable energy

AbstractDye‐sensitized solar cells (DSSCs) are among the most attractive third‐generation photovoltaic technologies due to their low toxicity, versatility, roll‐to‐roll compatibility, ultralightness, and attractive power conversion efficiencies (PCEs). However, their transition from the laboratory scale to the industrial scale has been slow due to their inability to compete with silicon‐based cells in terms of efficiencies and stabilities. Research activities on DSSCs have been ongoing for several decades to improve the efficiency and cost‐effectiveness of photovoltaics but these attempts are still inadequate. Their chemical and physical properties must be refined to increase efficiency and commercialization. This review provides a concise overview of the recent advances taking place in the DSSCs research field, including molecular engineering technologies, the quest for superior carrier transport materials (CTMs), efficient sensitizers, and better electrodes. Also, this review compiles knowledge of the historical development of DSSCs, the current advancements such as control of surface morphologies, doping strategies, modeling and simulation, characterization, and recent cutting‐edge research happenings in photovoltaic research. Finally, nanostructured materials that have been used as photoelectrodes and the practical applications of DSSCs in internet of things (IoT) and portable electronics are examined to identify challenges and future advancements. The main aim of this work is to be a pathfinder for scientific researchers in this field exploring various energy harvesting materials and optimization strategies of different components of DSSCs.

Superfine Nanodomain Engineering Unleashing Ferroelectricity in Incipient Ferroelectrics.

Incipient ferroelectrics have emerged as an attractive class of functional materials owing to their potential to be engineered for exotic ferroelectric behavior, holding great promise for expanding the ferroelectric family. However, thus far, their artificially engineered ferroelectricity has fallen far short of rivaling classic ferroelectrics. In this study, we address this challenge by developing a superfine nanodomain engineering strategy. By applying this approach to representative incipient ferroelectric of SrTiO3-based films, we achieve unprecedentedly strong ferroelectricity, not only surpassing previous records for incipient ferroelectrics but also being comparable to classic ferroelectrics. The remanent polarization of the thin film reaches up to 17.0 μC cm-2 with an ultrahigh Curie temperature of 973 K. Atomic-scale investigations elucidate the origin of this robust ferroelectricity in the emergent high-density superfine nanodomains spanning merely 3-10 unit cells. Combining experimental results with theoretical assessments, we unveil the underlying mechanism, where the intentionally introduced diluted foreign Fe element creates a deeper Landau energy well and promotes a short-range ordering of polarization. Our developed strategy significantly streamlines the design of unconventional ferroelectrics, providing a versatile pathway for exploring new and superior ferroelectric materials.

Advancing electrochemical activity: Insights from Li doped Ni-MOF synthesis and performance

This study presents the first-time synthesis of a novel Li doped Ni-MOF electrode material, achieved via a one-step hydrothermal strategy. Microstructural analysis using FESEM and HRTEM revealed hierarchical hollow spherical-like nanostructures within the Li doped Ni-MOF, providing abundant active sites for ion transport and storage. This structural feature resulted in enhanced specific capacity, exhibiting battery-like behaviors. Specifically, the Li doped Ni-MOF electrode displayed a notable specific capacity of 214.2 C/g in CV curves at 0.5 mV/s and 814 C/g in GCD curves at 1 A/g. These findings underscore the potential of the Li doped Ni-MOF as a superior electrode material for supercapacitors, indicating its promising prospects for advancing next-generation high-performance energy storage devices.

Naphthenic Acid Corrosion Mitigation: The Role of Niobium in Low-Carbon Steel.

Naphthenic acid corrosion is a well-recognized factor contributing to corrosion in the construction of offshore industry pipelines. To mitigate the corrosive effects, minor quantities of alloying elements are introduced into the steel. This research specifically explores the corrosion effects arising from immersing low-carbon steel, specifically A333 Grade 6, in a naphthenic acid solution. Various weight percentages of niobium were incorporated, and the resulting properties were observed. It was noted that the addition of 2% niobium in low-carbon steel exhibited the least mass loss and a lower corrosion rate after a 12 h immersion in naphthenic acid. Microstructural analysis using scanning electron microscopy (SEM) revealed small white particles, indicating the presence of oil sediment residue, along with corrosion pits. Following the addition of 2% niobium, the occurrence of corrosion pits markedly decreased, and only minor voids were observed. Additionally, the chemical composition analysis using energy-dispersive X-Ray analysis (EDX) showed that the black spot exhibited the highest percentage of carbon, resembling high corrosion attack. Meanwhile, the whitish regions with low carbon content indicated the lowest corrosion attack. The results demonstrated that the addition of 2% niobium yielded optimal properties for justifying corrosion effects. Therefore, low-carbon steel with a 2% niobium addition can be regarded as a superior corrosion-resistant material for offshore platform pipeline applications.

Highly Crystalline Multivariate Prussian Blue Analogs via Equilibrium Chelation Strategy for Stable and Fast Charging Sodium-Ion Batteries.

Prussian blue analogs (PBAs) have been widely recognized as superior cathode materials for sodium-ion batteries (SIBs) owing to numerous merits. However, originating from the rapid crystal growth, PBAs still suffer from considerable vacancy defects and interstitial water, making the preparation of long-cycle-life PBAs the greatest challenge for its practical application. Herein, a novel equilibrium chelation strategy is first proposed to synthesize a high crystallinity (94.7%) PBAs, which is realized by modulating the chelating potency of strong chelating agents via "acid effect" to achieve a moderate chelating effect, forcefully breaking through the bottleneck of poor cyclic stability for PBAs cathodes. Impressively, the as-prepared highly crystalline PBAs represent an unprecedented level of electrochemical performance including ultra-long lifespan (10000 cycles with 86.32% capacity maintenance at 6Ag-1), excellent rate capability (82.0mAhg-1 at 6Ag-1). Meanwhile, by pairing with commercial hard carbon, the as-prepared PBAs-based SIBs exhibit high energy density (350Whkg-1) and excellent capacity retention (82.4% after 1500 cycles), highlighting its promising potential for large-scale energy storage applications.

Polypyrrole/waste molasses composites as a superior adsorbent for highly efficient and selective removal of Cr(VI) from aqueous environments

Reduction of Cr(VI) to Cr(III) or elimination of Cr(VI) from aqueous environments is the most commonly used method to address Cr(VI) contamination. Waste molasses (WM) is a by-product from the sugar industry, if discharged arbitrarily without treatment can lead to waste of resources and cause serious environmental pollution. In this study, the modification of polypyrrole (PPy) with WM (PPy/WM) not only provided PPy with good dispersibility and higher specific surface area, but it can also enrich the functional groups on the surface of PPy. The findings indicated that PPy/WM composites can serve as superior adsorbent materials for highly efficient and selective removal of Cr(VI) when different interfering ions are present. e.g., 150 mg/L of Cr(VI) can be eliminated completely within 6 h under the condition of PPy/WM amount of 0.8 g/L, temperature of 303 K, and pH of 2.0. PPy/WM showed excellent performance for removal of Cr(VI) in a wide pH range (2.0 - 10.0). PPy/WM exhibited excellent reusability for five cycles without obvious loss of its adsorption capacity. The maximum Cr(VI) adsorption capacity of PPy/WM was 662.25 mg/g at 323 K, evidently higher than that of unmodified PPy (194.17 mg/g). Cr(VI) removal by PPy/WM was chiefly accomplished by electrostatic adsorption, ion exchange and in-site reduction. This study not only provides a new technology for efficient adsorption and in-situ reduction of Cr(VI), but also realizes the resource utilization of WM and solves the WM pollution problems.

Dye-sensitized sepiolite clay as natural scaffolds for visible light driven photocatalytic hydrogen evolution

Natural clay minerals are increasingly used as superior support materials for various photocatalysts due to their excellent adsorption capacity, negative surface charge, suitable thermal/chemical stability, large specific surface area, and strong surface reactivity, resulting in low agglomeration and suppression of charge recombination. However, they are still insufficient for photocatalysis due to their low efficiency. Therefore, sensitization of clay minerals with dyes to improve the efficiency and specificity of catalysts is considered a promising route for photocatalytic applications. In this work, the effect of dye sensitization on visible light-driven photocatalytic water splitting of microfibrous sepiolite scaffolds as natural photocatalyst supports was investigated for the first time by using various xanthene dyes (eosin Y, rhodamine B and eryhtrosine B (ErB)) and triethanolamine as photosensitizers and sacrificial agents, respectively, in the absence and presence of platinum as a co-catalyst. The clay/dye system was characterized using various techniques such as X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy and energy dispersive X-rays. Sep/ErB photocatalysts produced the highest amount of hydrogen among the other Sep/dye scaffold systems because they act as an effective matrix by preventing nanoparticle aggregation and promoting electron transfer due to their excellent crystal structures and physicochemical properties.