Publications by authors named "Deepak Dubal"

Herein, NaCl-templated mesoporous hard carbons (NMCs) have been designed and engineered with tunable surface properties as anode materials for potassium-ion batteries (KIBs) and hybrid capacitors (KICs). By utilizing "water-in-oil" emulsions, the size of NaCl templates is precisely modified, leading to smaller particles that enable the formation of primary carbon structures with reduced particle size and secondary structures with 3D interconnected mesoporosity. These features significantly enhance electrode density, reduce particle-to-particle resistance, and improve electrolyte wettability.

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Exploration of innovative strategies aiming to boost energy densities of supercapacitors without sacrificing the power density and long-term stability is of great importance. Herein, highly porous nitrogen-doped carbon spheres (NPCS) are decorated onto the graphite sheets (GSs) through a hydrothermal route, followed by a chemical activation. The capacitive performance of the NPCS is then enhanced by hydroquinone sulfonic acid (HSQA) incorporation in both cathodic electrolyte and electrode materials.

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Lead-free double perovskites (DPs) will emerge as viable and environmentally safe substitutes for Pb-halide perovskites, demonstrating stability and nontoxicity if their optoelectronic property is greatly improved. Doping has been experimentally validated as a powerful tool for enhancing optoelectronic properties and concurrently reducing the defect state density in DP materials. Fundamental understanding of the optical properties of DPs, particularly the self-trapped exciton (STEs) dynamics, plays a critical role in a range of optoelectronic applications.

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As reserves of non-renewable energy sources decline, the search for sustainable alternatives becomes increasingly critical. Next-generation energy materials play a key role in this quest by enabling the manipulation of properties for effective energy solutions and understanding interfaces to enhance energy yield. Studying these interfaces is essential for managing charge transport in optoelectronic devices, yet it presents significant challenges.

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Flexible all-solid-state asymmetric supercapacitors (FAASC) represent a highly promising power sources for wearable electronics. However, their energy density is relatively less as compared to the conventional batteries. Herein, a novel ultra-high energy density FAASC is developed using nickel-cobalt sulfide (NiCoS)/polyaniline (PANI)/manganese dioxide (MnO) ternary composite on carbon fiber felt (CF) as positive and N, S-co-doped carbon nanofibers (CNF)/CF as negative electrode, respectively.

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Lithium-ion batteries are commonly used for energy storage due to their long lifespan and high energy density, but the use of unsafe electrolytes poses significant health and safety concerns. An alternative source is necessary to maintain electrochemical efficacy. This research demonstrates new safe glyme-based electrolytes for silica/carbon (SiO/C) nanocomposite derived from Australian rice husk (RH).

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Electric cars are desirable for their environmental and economic benefits yet face limitations in range in cold weather due to the increased energy demands for cabin heating. To provide efficient heating for vehicles, flexible composite electrothermal heaters offer a viable solution owing to their lightweight design, efficiency, and adaptability for use within and beyond vehicle interiors. The current study aims to improve electrothermal heater stability and performance by understanding the impact of the polymer structure on composite properties.

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Battery-type materials with ultrahigh energy density show great potential for hybrid supercapacitors (HSCs). In this work, we have developed a nickel selenide (NiSe)/reduced graphene oxide (rGO)/graphitic carbon nitride (g-CN) ternary composite as a promising positive electrode for hybrid supercapacitors (HSCs). The extended π-conjugated planar layers of g-CN promote strong interconnectivity with rGO, which further enhances surface area, surface free energy, and efficient electron/ionic path.

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Article Synopsis
  • Metal-organic frameworks (MOFs) are innovative materials known for their hierarchical porosity, active metal centers, and large surface area, which make them attractive for various applications.
  • Among these, zirconium-based MOFs, particularly NU-1000 synthesized at Northwestern University, excel in chemical and thermal stability, positioning them well for energy and environmental uses.
  • The review discusses synthesis methods for NU-1000, its unique surface properties, applications in areas like catalysis and gas storage, and highlights ongoing challenges in practical implementation, suggesting future research directions.
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Urea oxidation reaction (UOR) is one of the promising alternative anodic reactions to water oxidation that has attracted extensive attention in green hydrogen production. The application of specifically designed electrocatalysts capable of declining energy consumption and environmental consequences is one of the major challenges in this field. Therefore, the goal is to achieve a resistant, low-cost, and environmentally friendly electrocatalyst.

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Ultra-high energy density battery-type materials are promising candidates for supercapacitors (SCs); however, slow ion kinetics and significant volume expansion remain major barriers to their practical applications. To address these issues, hierarchical lattice distorted α-/γ-MnS@Co S core-shell heterostructure constrained in the sulphur (S), nitrogen (N) co-doped carbon (C) metal-organic frameworks (MOFs) derived nanosheets (α-/γ-MnS@Co S @N, SC) have been developed. The coordination bonding among Co S , and α-/γ-MnS nanoparticles at the interfaces and the π-π stacking interactions developed across α-/γ-MnS@Co S and N, SC restrict volume expansion during cycling.

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High-energy-density battery-type materials have sparked considerable interest as supercapacitors electrode; however, their sluggish charge kinetics limits utilization of redox-active sites, resulting in poor electrochemical performance. Here, the unique core-shell architecture of metal organic framework derived N-S codoped carbon@Co S micropetals decorated with Nb-incorporated cobalt molybdate nanosheets (Nb-CMO @C S NC) is demonstrated. Coordination bonding across interfaces and π-π stacking interactions between CMO @C S and N and, S-C can prevent volume expansion during cycling.

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Current energy and environmental challenges demand the development and design of multifunctional porous materials with tunable properties for catalysis, water purification, and energy conversion and storage. Because of their amenability to de novo reticular chemistry, metal-organic frameworks (MOFs) have become key materials in this area. However, their usefulness is often limited by low chemical stability, conductivity and inappropriate pore sizes.

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Metal-organic gels (MOGs) emerged as a novel class of functional soft materials in which the scaffolding framework is fabricated by metal-ligand coordination in combination with other supramolecular interactions (for example, hydrogen bonding or π-π stacking). Through the combination of organic and inorganic (metal/metal-oxo clusters) building blocks, significant steps forward have been made in the development of new electrochemical sensors, superhydrophobic materials and ion storage devices, among others. These leaps forward are to some extend induced by the intrinsic hierarchical microporous/mesoporous pore structure of these metal-organic materials.

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Rapid progress on developing smart materials and design of hybrids is motivated by pressing challenges associated with energy crisis and environmental remediation. While emergence of versatile classes of nanomaterials has been fascinating, the real excitement lies in the design of hybrid materials with tunable properties. Metal-organic frameworks (MOFs) are the key materials for gas sorption and electrochemical applications, but their sustainability is challenged by limited chemical stability, poor electrical conductivity, and intricate, inaccessible pores.

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We are reporting on the impact of air annealing temperatures on the physicochemical properties of electrochemically synthesized cadmium selenium telluride (CdSeTe) samples for their application in a photoelectrochemical (PEC) solar cell. The CdSeTe samples were characterized with several sophisticated techniques to understand their characteristic properties. The XRD results presented the pure phase formation of the ternary CdSeTe nanocompound with a hexagonal crystal structure, indicating that the annealing temperature influences the XRD peak intensity.

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The conversion of nitrogen to ammonia offers a sustainable and environmentally friendly approach for producing precursors for fertilizers and efficient energy carriers. Owing to the large energy density and significant gravimetric hydrogen content, NH is considered an apt next-generation energy carrier and liquid fuel. However, the low conversion efficiency and slow production of ammonia through the nitrogen reduction reaction (NRR) are currently bottlenecks, making it an unviable alternative to the traditional Haber-Bosch process for ammonia production.

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The increased demand of energy due to the recent technological advances in diverse fields such as portable electronics and electric vehicles is often hindered by the poor capability of energy-storage systems. Although supercapacitors (SCs) exhibit higher power density than state-of-the art batteries, their insufficient energy density remains a major challenge. An emerging concept of hybrid supercapacitors (HSCs) with the combination of one capacitive and one battery electrode in a single cell holds a great promise to deliver high energy density without sacrificing power density and cycling stability.

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Supercapacitors (SCs) are considered promising energy storage systems because of their high power output and long-term cycling stability; however, they usually exhibit poor energy density. The hybrid supercapacitor (HSC) is an emerging concept in which two dissimilar electrodes with different charge storage mechanisms are paired to deliver high energy without sacrificing power output. This Perspective highlights the features of transition-metal phosphides (TMPs) as the positive electrode in HSCs.

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Nickel chalcogenide (S and Se) based nanostructures intrigued scientists for some time as materials for energy conversion and storage systems. Interest in these materials is due to their good electrochemical stability, eco-friendly nature, and low cost. The present review compiles recent progress in the area of nickel-(S and Se)-based materials by providing a comprehensive summary of their structural and chemical features and performance.

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Silicon anodes are considered as promising electrode materials for next-generation high capacity lithium-ion batteries (LIBs). However, the capacity fading due to the large volume changes (∼300%) of silicon particles during the charge-discharge cycles is still a bottleneck. The volume changes of silicon lead to a fracture of the silicon particles, resulting in recurrent formation of a solid electrolyte interface (SEI) layer, leading to poor capacity retention and short cycle life.

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The efficient utilization of solar energy has received tremendous interest due to the increasing environmental and energy concerns. The present paper discusses the efficient integration of a plasmonic photocatalyst (Ag/AgCl) with an iron-based metal-organic framework (MIL-88A(Fe)) for boosting the visible light photoreactivity of MIL-88A(Fe). Two composites of Ag/AgCl@MIL-88A(Fe), namely MAG-1 and MAG-2 (stoichiometric ratio of Fe to Ag is 5 : 1 and 2 : 1), were successfully synthesized via facile in situ hydrothermal methods followed by UV reduction.

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In this work, the covalent attachment of an amine functionalized metal-organic framework (UiO-66-NH  = Zr O (OH) (bdc-NH ) ; bdc-NH  = 2-amino-1,4-benzenedicarboxylate) (UiO-Universitetet i Oslo) to the basal-plane of carboxylate functionalized graphene (graphene acid = GA) via amide bonds is reported. The resultant GA@UiO-66-NH hybrid displayed a large specific surface area, hierarchical pores and an interconnected conductive network. The electrochemical characterizations demonstrated that the hybrid GA@UiO-66-NH acts as an effective charge storing material with a capacitance of up to 651 F g , significantly higher than traditional graphene-based materials.

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Metal halide perovskites (MHPs) have excellent optoelectronic and photovoltaic applications because of their cost-effectiveness, tunable emission, high photoluminescence quantum yields, and excellent charge carrier properties. However, the potential applications of the entire MHP family are facing a major challenge arising from its weak resistance to moisture, polar solvents, temperature, and light exposure. A viable strategy to enhance the stability of MHPs could lie in their incorporation into a porous template.

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Potassium-ion storage devices are attracting tremendous attention for wide-ranging applications on account of their low cost, fast charge transport in electrolytes, and large working voltage. However, developing cost-effective, high-energy electrodes with excellent structural stability to ensure long-term cycling performance is a major challenge. In this contribution, we have derived two different forms of carbon materials from almond shells using different chemical treatments.

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