High Surface Area Research Articles

Investigation of the properties of Mg(OH)2 extracted from magnesium-rich brine via the use of an industrial by-product

Compared with magnesium oxide (MgO) produced through the dry route, the wet route production can lead to MgO with a high purity and reactivity. During this process, the use of chemical alkalis to precipitate the precursor, magnesium hydroxide (Mg(OH)2), is the highest contributor to cost and energy consumption. This study proposes a low-cost and sustainable way to recover Mg(OH)2 from simulated reject brine using concrete wash water (CWW). Mg(OH)2, with a purity of 94 % and a recovery degree of 98 % was synthesized at room temperature. Higher stirring speed and use of low pH CWW increased the impurity (CaCO3) content. The synthesized Mg(OH)2 showed a similar reactivity to MgO synthesized from reject brine with chemical bases due to its high specific surface area (102.8 m2/g). The calcination of the synthesized Mg(OH)2, led to MgO with a higher reactivity than similar ones obtained through the wet-route. Furthermore, the textural properties of Mg(OH)2 synthesized under different conditions were evaluated to establish a correlation between the reaction conditions and reactivity of Mg(OH)2. Increase in reaction temperature led to a small crystalline size, whereas the aging process resulted in the agglomeration of the synthesized Mg(OH)2, influencing its reactivity. The findings presented in this study can pave the way for the sustainable recovery of Mg(OH)2 and its direct use as a binder or as a precursor for the production of reactive MgO.

Investigation of the properties of Mg(OH)2 extracted from magnesium-rich brine via the use of an industrial by-product

Compared with magnesium oxide (MgO) produced through the dry route, the wet route production can lead to MgO with a high purity and reactivity. During this process, the use of chemical alkalis to precipitate the precursor, magnesium hydroxide (Mg(OH)2), is the highest contributor to cost and energy consumption. This study proposes a low-cost and sustainable way to recover Mg(OH)2 from simulated reject brine using concrete wash water (CWW). Mg(OH)2, with a purity of 94 % and a recovery degree of 98 % was synthesized at room temperature. Higher stirring speed and use of low pH CWW increased the impurity (CaCO3) content. The synthesized Mg(OH)2 showed a similar reactivity to MgO synthesized from reject brine with chemical bases due to its high specific surface area (102.8 m2/g). The calcination of the synthesized Mg(OH)2, led to MgO with a higher reactivity than similar ones obtained through the wet-route. Furthermore, the textural properties of Mg(OH)2 synthesized under different conditions were evaluated to establish a correlation between the reaction conditions and reactivity of Mg(OH)2. Increase in reaction temperature led to a small crystalline size, whereas the aging process resulted in the agglomeration of the synthesized Mg(OH)2, influencing its reactivity. The findings presented in this study can pave the way for the sustainable recovery of Mg(OH)2 and its direct use as a binder or as a precursor for the production of reactive MgO.

A Nanostructured Phenazine‐based Conjugated Microporous Polymer Hybrid Anode Boosts Power and Practicability of Organic‐Manganese Hydronium‐ion Batteries

Organic‐manganese hydronium‐ion batteries are gaining attention for their safety, sustainability, and high rate capabilities. However, their electrochemical performance faces challenges due to organic active‐materials' inferior properties, including low conductivity and solubility, and limited content (<60 wt%) and loading (<2 mg/cm2) in the anode. To address this, we developed a high‐performance battery using a phenazine‐based conjugated microporous polymer hybrid anode (IEP‐27‐SR), utilizing hydronium‐ion coordination/un‐coordination chemistry. The IEP‐27‐SR features enhanced structural characteristics, such as high BET specific surface area, mixed micro‐/mesoporosity, nanostructurization, and hybridization, enabling rapid hydronium‐ion mobility. The resulting IEP‐27‐SR//MnO2@GF full‐cell demonstrates high capacity (101 mAh/g at 2C), excellent rate performance (41 mAh/g at 100C), ultrafast‐charging capability (80% charged in 18 seconds), and impressive cyclability with 83% capacity retention over 20400 cycles at 30C with a regular polymer mass loading of 2 mg/cm2, despite its high content (80 wt%) in the anode. Moreover, it shows operability at low temperatures (63 mAh/g at ‐40 ºC). Most importantly, full‐cell with a high‐mass‐loading polymer anode (30 mg/cm2) achieves practically relevant areal capacity (3.4 mAh/cm2 at 4 mA/cm2) and sustains 2 mAh/cm2 under an extremely high areal current (50 mA/cm2). This breakthrough highlights the progress of organic hydronium‐ion batteries, representing progress toward practical battery solutions

Metal-organic framework-derived base catalyst for conversion of dimethyl carbonate to glycerol carbonate

Glycerol carbonate (GLC) offers a range of benefits including biodegradability, versatility, and its potential for carbon capture and utilization. Base catalysts play a crucial role for GLC synthesis by facilitating the activation of reactants, enhancing nucleophilicity, accelerating reaction kinetics, and enabling catalyst regeneration. In this study, metal–organic framework (MOF) derived hybrid structure, CaO-MgO@Al2O3, was developed as a base catalyst to promote transesterification of glycerol with dimethyl carbonate (DMC) to form GLC. The results show that hydrothermal plus wet-impregnation routes formed the hybrid nanostructure with homogenously dispersed Ca, Mg and Al elements. Further, the synthesized catalysts showed significantly high specific surface area and basicity (2.656 mmol g−1). High selectivity (>99 %) and high GLC yield (96.2 %; 208.9 mmol g-cat−1) were achievable. This study demonstrated the rational design concept of MOF-derived hybrid structures used in the enhancement of base catalysis for transesterification of DMC to GLC, offering an effective solution with mild reaction conditions and high conversion.

Elevating Oxygen Evolution using Iron Phthalocyanine Infused Vanillic acid Electrocatalyst.

Oxygen evolution reaction (OER) is the bottle neck step in water splitting reaction towards the realization of hydrogen based clean energy production and storage. Transition metal based N4 organics are explored extensively as oxygen electrocatalysts i.e.,(OER) and oxygen reduction reaction (ORR) catalysts because of their ease of synthesis, tuneable properties, low cost and high performance with long term stability. Here, vanillic acid functionalized iron phthalocyanine (FeVAPc) was synthesised and characterised. The novel FeVAPc exhibited good thermal stability and was coated on Ni foam for OER studies. The scanning electron microscopy images showed net-work like surface morphology and the X-ray photoelectron spectroscopy indicated the presence of Fe in +3 oxidation state. The Ni/FeVAPc demonstrated excellent electrocatalytic activity for OER with overpotential of 312 mV at 10 mA.cm-2 current density in 1.0 M KOH . The designed catalyst exhibited lesser Tafel slope value which is nearer to the benchmark catalyst, IrO2. The proposed catalyst exhibited good stability as phthalocyanines are highly stable and do not undergo decomposition even in strong acidic and basic corrosive media. Integration of FeVAPc onto Ni foam resulted in higher mass activity, lower charge transfer resistance, high active surface area leading to enhanced conductivity and activity.

Mesoporous graphene-supported nanostructured nickel telluride for efficient electrocatalytic oxygen evolution reaction

The electrocatalytic oxygen evolution reaction (OER) imposes significant constraints on the operational overpotential of electrochemical energy devices, such as water electrolyzers, metal-air batteries, and fuel cells. However, the sluggish kinetics of OER reactions hinder these applications, which has prompted efforts to design more effective electrocatalysts. In this study, we have synthesized NiTe via in-situ growth into mesoporous graphene (MG), with varying nominal weight percentages (5- wt%, 10- wt%, and 15- wt%) of NiTe. The resulting NiTe/MG nanohybrids displayed hexagonally structured NiTe nanoparticles with a predominant (101) surface that promotes the OER kinetics. The wrinkled 3D mesoporous graphene scaffold facilitated the attachment and dispersion of NiTe particles of nanoscale on its surface, preventing their agglomeration. The porous characteristics of the MG significantly increased the high surface area of the NiTe/MG nanohybrids (583–671 m2 g−1), promoting enhanced accessibility of active sites and mass transport beneficial for the OER. Moreover, the altered electronic structure of the NiTe in the MG nanohybrid indicates enhancing O2 desorption during the OER. The optimized composition of the 10 wt% NiTe-loaded MG nanohybrid electrocatalyst demonstrates superior OER activity compared to other nanohybrids. It exhibits a small overpotential of 250 mV at 10 mA cm−2, a low Tafel slope of 63 mV dec−1 and maintained stability in 1 M KOH (pH = 14) as the electrolyte for a prolonged period. This enhanced OER activity is ascribed to the synergistic effect of MG’s high conductivity and the improved intrinsic activity of NiTe within the nanohybrid structure.

Electrochemical treatment of textile wastewater using electrodes from pyrolyzed rice husk

Rice husk char (RHC) electrodes were used for the first time in electrochemical treatment of textile wastewater. SEM analysis revealed RHC's porous structure, while TGA showed it decomposes in four stages and is stable up to 189 °C. BET analysis indicated a high surface area of 734 m2/g and a microporous structure with 11.7 Å pore diameter and 0.213 mL/g pore volume. RHC electrodes pyrolyzed at 700 °C for 2 h and placed 15 cm apart worked best in a 2 L batch reactor with methylene blue (MB) as the model pollutant and 6 g/L NaCl as the electrolyte. The process followed first-order kinetics, with fastest reaction at 100 mg/L initial MB. Reduced TOC and changed FTIR spectra confirmed MB breakdown. The batch system removed 85.8 % of dye from real textile wastewater in 150 min. In continuous flow, lower rates achieved higher efficiencies, up to 90 % at 0.45 L/h after 210 min. Although RHC electrodes had lower conductivity and strength than metal, they represent a sustainable, cost-effective alternative for electrochemical wastewater treatment.

Multiple Heteroatom Doped Nanoporous Biocarbon for Supercapacitor and Zinc-ion Capacitor.

The use of nanoporous carbon for energy storage has seen a significant rise due to its exciting properties such as high surface area, hierarchical porosity and exceptional electrochemical properties. These unique advantages of exceptional surface and electrochemical properties of these porous carbon nanostructures can be coupled with the individual doping of heteroatoms for achieving high energy storage capacity and stability. Herein, we integrated the synthesis of carbon nitride (CN) and borocarbonitride (BCN) with solid state activation for introducing multiple heteroatoms (B, N, O and S) onto the nanoporous carbon frameworks. The produced materials exhibit abundance of micro and mesoporosity, a high surface area of 2909 m2 g-1, and a pore volume of 0.87 cm3 g-1. Also, it offers an exceptional capacitance of 233.5 F g-1 at 0.5 A g-1 with 3M KOH as electrolyte. Further, the optimised material was explored as cathode in zinc ion capacitor which delivers an energy and power density of 50.4 Wh kg-1 and 400 W kg-1 respectively in addition to high cyclability. Studies on the formation of the intermediate phases during charging/discharging of the cell through ex situ characterization result in some useful insights into the stability of ZIC.

Multiple Heteroatom Doped Nanoporous Biocarbon for Supercapacitor and Zinc-ion Capacitor.

The use of nanoporous carbon for energy storage has seen a significant rise due to its exciting properties such as high surface area, hierarchical porosity and exceptional electrochemical properties. These unique advantages of exceptional surface and electrochemical properties of these porous carbon nanostructures can be coupled with the individual doping of heteroatoms for achieving high energy storage capacity and stability. Herein, we integrated the synthesis of carbon nitride (CN) and borocarbonitride (BCN) with solid state activation for introducing multiple heteroatoms (B, N, O and S) onto the nanoporous carbon frameworks. The produced materials exhibit abundance of micro and mesoporosity, a high surface area of 2909 m2 g-1, and a pore volume of 0.87 cm3 g-1. Also, it offers an exceptional capacitance of 233.5 F g-1 at 0.5 A g-1 with 3M KOH as electrolyte. Further, the optimised material was explored as cathode in zinc ion capacitor which delivers an energy and power density of 50.4 Wh kg-1 and 400 W kg-1 respectively in addition to high cyclability. Studies on the formation of the intermediate phases during charging/discharging of the cell through ex situ characterization result in some useful insights into the stability of ZIC.

A Novel Hydrated Iron Vanadate Cathode Material for Advanced Aqueous Nickel-Ion Batteries.

Aqueous nickel-ion batteries (ANIBs) as an emerging energy storage device attracted much attention owing to their multielectron redox reaction and dendrite-free Ni anode, yet their development is hindered by the divalent properties of Ni2+ and the lack of suitable cathode materials. Herein, a hydrated iron vanadate (Fe2V3O10.5∙1.5H2O, FOH) with a preferred orientation along the (200) plane is innovatively proposed and used as cathode material for ANIBs. The FOH cathode exhibits a remarkable capacity of 129.3 mAh g-1 at 50mA g-1 and a super-high capacity retention of 95% at 500mA g-1 after 700 cycles. The desirable Ni2+ storage capacity of FOH can be attributed to the preferentially oriented and tunnel structures, which offer abundant reaction active planes and a broad Ni2+ diffusion path, the abundant vacancies and high specific surface area further increase ion storage sites and accelerate ion diffusion in the FOH lattice. Furthermore, the Ni2+ storage mechanism and structural evolution in the FOH cathode are explored through ex situ XRD, ex situ Raman, ex situ XPS and other ex situ characteristics. This work opens a new way for designing novel cathode materials to promote the development of ANIBs.

Simultaneous treatment of trace pollutant and compound pollution using an effective n-ZnO@p-LaFeO3/3DOM SiO2 photocatalyst

To confront the complex challenges of removing trace and compound pollutants from wastewater, this research presents a novel photocatalyst, n-ZnO@p-LaFeO3/3DOM SiO2. Powered by visible light, this catalyst combines lanthanum ferrite and zinc oxide within a three-dimensional ordered macroporous silica framework. The 3DOM structure’s high surface area and porosity effectively concentrate pollutants, enhancing their interactions with reactive oxygen species (ROS) and notably reducing the ROS diffusion path. Impressively, it achieves over 96.5 % removal rates for both bisphenol A (BPA) and hexavalent chromium (Cr(VI)) at concentrations as low as 0.2 mg·L−1 within an hour. This study also discovers a synergistic effect in simultaneously oxidizing BPA and reducing Cr(VI). Moreover, it investigates the underlying mechanism, focusing on ROS generation and the crucial role of adsorption in the photocatalytic process. This study positions the presented photocatalyst as a promising solution to the intricate challenges of advanced oxidation processes (AOPs), showcasing an efficient strategy for comprehensive wastewater treatment.

Optically Mediated Nonvolatile Resistive Memory Device Based on Metal-Organic Frameworks.

Metal-organic frameworks (MOFs), characterized by tunable porosity, high surface area, and diverse chemical compositions, offer unique prospects for applications in optoelectronic devices. However, the prevailing research on thin-film devices utilizing MOFs has predominantly focused on aspects such as information storage and photosensitivity, often neglecting the integration of the advantages inherent in both photonics and electronics to enhance optical memory. This work demonstrates a light-mediated resistive memory device based on a highly oriented porphyrin-based MOFs film, in which the resistance state of the memristor is modulated by light, realizing the integration of the perception and storage of optical information. The memristor shows excellent performance with a wide light range of 405-785nm and a persistent photoconductivity phenomenon up to 8.3 × 103 s. Further mechanistic studies have revealed that the resistive switching effect in the memristor is primarily associated with the reversible formation and annihilation of Ag conductive filaments.

Investigation of the impact of the flow mode in all-vanadium-redox-flow battery using macroporous and mesoporous carbon electrodes

Energy storage in vanadium redox flow batteries (VRFBs) is significantly impacted by both the cell design and the kinetics of electron transfer at the electrode/electrolyte interfaces. In this work, a novel VRFB flow field was designed and evaluated, allowing a portion of the flow to go through the porous electrodes in the direction of current flow. It was found that, when using standard carbon paper electrodes with moderate hydrophilicity, as compared to flow-by or only flow-through, concurrent 50 % flow-through and 50 % flow-by mode decreased the voltage loss by 46 % and increased the voltage efficiency from 74 % to 80 % compared to flow-by only (flow rate of 60 ml s−1). The voltage efficiency and energy efficiency were also enhanced to 82 % and 68 %, respectively, in the flow-through mode. This was likely due to enhanced mass transfer and increased utilization of the internal electrode surface area, in turn lowering the overpotential during both charging and discharging. To further determine the benefits of flow-through conditions, the effect of a binder-free, hydrophilic, and mesoporous carbon scaffold electrode (NCS85) was also investigated under flow-through mode and compared with the standard carbon paper electrodes with moderate hydrophilicity. NCS 85 has monodisperse, 3-D interconnected 85 nm pore diameters and thus a much higher surface area, resulting in a further increase in voltage and energy efficiency to 86 and 65 %, respectively. Heat treatment of the NCS85 to graphitize it and thus lower its resistance showed further improvements when using the flow-through mode, giving a voltage efficiency of 94 % and energy efficiency of 72 %. These improvements show the benefits that can be realized by optimizing both flow mode and carbon electrode porosity and permeability on VRFB performance.

Boosting the activity of BiVOx via vanadium-promotion for highly selective oxidation of biomass-derived xylose toward formic acid

Formic acid is a versatile and promising value-added chemical derived from the chemoselective transformation of renewable biomass resources. However, achieving a high production rate of formic acid remains a pivotal and enormous challenge. Herein, we synthesized a sequence of BiVOx catalysts based on vanadium-promotion by a facile and cost-effective strategy for selective oxidation of biomass-derived xylose in water under O2 atmosphere. Particularly, the resultant Bi1V2Ox exhibited a remarkably enhanced catalytic activity, higher selectivity toward formic acid, and excellent recyclability, giving a yield of 75.8 % and a production rate of formic acid (9.22 mol FA molV−1h−1) at 170 °C within only 20 min. Such pronounced improved performance was largely attributed to the synergistic effect between V and Bi species, with higher surface area, abundant surface acidity, as well as stronger adsorption energy, meanwhile efficiently suppressing the formation of undesired by-products. This study demonstrates that the promotion of V in BiVOx leads to more efficient catalytic oxidation of xylose to formic acid, and with further driven research that proved great potential for generating formic acid from renewable biomass resources for future industrial application.

Structural, optical, and gas sensing characteristics of synthesized environmentally friendly ZnO-ZnAl2O4 nanocomposites

In this study, we synthesized ZnO-ZnAl2O4 composites from orange peel extract by using an environmentally friendly approach. ZnO-ZnAl2O4 composites with different Al content, namely 30, 40, 50, 60, and 70 at%, were successfully synthesized, and they were characterized in detail using advanced techniques to study their structures, phases, morphologies, and electrical and optical properties. Gas sensing measurements for H2S gas showed that the sensor with 70 at% Al had the best response at 350 °C along with long-term stability. We attribute this high response to the high specific surface area (48.8 m2·g−1), the formation of ZnO-ZnO homojunctions and ZnO-ZnAl2O4 heterojunctions, and the high intrinsic sensing properties of the ZnO phase. This study is expected to contribute to the development of green approaches for the synthesis of environmentally friendly gas sensing materials.

Predicting and refining acid modifications of biochar based on machine learning and bibliometric analysis: Specific surface area, average pore size, and total pore volume

Acid-modified biochar is a modified biochar material with convenient preparation, high specific surface area, and rich pore structure. It has great potential for application in the heavy metal remediation, soil amendments and carrying catalysts. Specific surface area (SSA), average pore size (APS) and total pore volume (TPV) are the key properties that determine its adsorption capacity, reactivity, and water holding capacity, and an intensive study of these properties is essential to optimize the performance of biochar. But the complex interactions among the preparation conditions obstruct finding the optimal modification strategy. This study collected dataset through bibliometric analysis and used four typical machine learning models to predict the SSA, APS, and TPV of acid-modified biochar. The results showed that the extreme gradient boosting (XGB) was optimal for the test results (SSA R2 = 0.92, APS R2 = 0.87, TPV R2 = 0.96). The model interpretation revealed that the modification conditions were the major factors affecting SSA and TPV, and the pyrolysis conditions were the major factors affecting APS. Based on the XGB model, the modification conditions of biochar were optimized, which revealed the ideal preparation conditions for producing the optimal biochar (SSA = 727.02 m2/g, APS = 5.34 nm, TPV = 0.68 cm3/g). Moreover, the biochar produced under specific conditions verified the generalization ability of the XGB model (R2 = 0.99, RMSE = 12.355). This study provides guidance for optimizing the preparation strategy of acid-modified biochar and promotes its potentiality for industrial application.

ZIF-derived "cocoon"-like in-situ Zn/N-doped carbon as high-capacity anodes for Li/Na-ion batteries

Owing to the unique structure and physicochemical properties, including high specific surface area, self-doped N atoms, open pore structure and good chemical stability, zeolitic imidazolate frameworks (ZIFs) and their derivatives have been widely used in the field of energy storage. Here, a new type of "cocoon"-like Zn/N doped ZIF-derived porous carbon (Zn@N-C-800) is synthesized as an anode for lithium-ion batteries (LIBs) and sodium ion batteries (SIBs) through a one-step carbonization process using a novel Zn-ZIF as the precursor. In Zn@N-C-800, the "cocoon"-like disordered carbon skeleton is conducive to electrolyte infiltration, while the Zn/N doping can provide additional active sites for ion storage. Benefiting from these unique structural characteristics, Zn@N-C-800 achieves excellent electrochemical performances as anode for both LIBs and SIBs: an ultrahigh rate capability of 352 mAh g−1 can be delivered at 12.8 A g−1 for LIBs; an outstanding long-term cycling stability (312 mAh g−1 at 1 A g−1 after 2000 cycles) can be achieved for SIBs. This paper provides new ideas for the design and preparation of high-performance anodes for LIBs and SIBs.

On the design of manifolds for parallel channel systems

In the design of high-performance heat and mass transfer devices such as liquid-cooled heat sinks, catalytic reactors, and catalytic convertors, parallel mini/microchannels are favored owing to their special potentials. Offering low pressure drop, providing high transfer surface area to volume ratio, and being easy to manufacture and optimize have been drawing thermal and chemical engineers attention to parallel channels for past decades. When working with parallel channels, the challenge of flow maldistribution is commonly faced which decreases their efficiency significantly. System total pressure drop and flow uniformity are two parameters that determine the system performance. In the present study, a variety of practical ideas, aiming to enhance parallel channels performance, are studied numerically. Inventive manifold designs with high hydraulic performance are created through the course of this study. The results of these designs are compared with basic conventional designs which show substantial enhancement. Analyzing less successful designs lead us to deep understanding of fluid dynamics in parallel channel heat and mass transfer devices.

BaTaO2N and quantum dots-based CuO nanocomposites for HER by solar electrochemical water splitting

Barium tantalum oxynitride (BaTaO2N) has been demonstrated to be an attractive catalyst for photo-electrochemical water splitting, especially oxygen evolution reactions. However, the hydrogen production rates and charge transfer resistances of BTN leave much to be desired from a practical standpoint. In fact, it has never been reported for photocathode applications. On the other hand, CuO has been reported for hydrogen evolution reactions. Given this, here nanocomposites of BaTaO2N and copper oxide quantum dots (CuO QDs), where the latter are digestively ripened, are reported for photoelectrochemical water splitting on a carbon paper substrate. To assess the role of ultra-small quantum dots, composites of commercially available CuO nanoparticles with BaTaO2N were also tested. BaTaO2N and CuO QD nanocomposites performed well and showed a high photocurrent density of 3.1 mA cm−2 at 0 V vs RHE. This was also accompanied by reduced charge transfer resistance (225.4 Ω) due to the high interfacial surface area provided by nanoscopic CuO on BaTaO2N.

Engineered Mesoporous Silica-Based Nanoparticles: Characterization of Surface Properties.

Mesoporous silica-based nanomaterials have emerged as multifunctional platforms with applications spanning catalysis, medicine, and nanotechnology. Since their synthesis in the early 1990s, these materials have attracted considerable interest due to their unique properties, including high surface area, tunable pore size, and customizable surface chemistry. This article explores the surface properties of a series of MSU-type mesoporous silica nanoparticles, elucidating the impact of different functionalization strategies on surface characteristics. Through an extensive characterization utilizing various techniques, such as FTIR, Z-potential, and nitrogen adsorption porosimetry, insights into the surface modifications of mesoporous silica nanoparticles are provided, contributing to a deeper understanding of their nanostructure and related interactions, and paving the way to possible unexpected actionability and potential applications.