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There are huge prospects for environmental remediation using semiconductor photocatalysts that decompose toxic pollutants under the illumination of light. This review article offers ...an outline of the applications of BiOI photocatalyst for the efficient decomposition of pollutants exist in the aqueous ecosystem. In addition, methods for synthesizing and modifying BiOI are emphasized to provide strategies for improving their photocatalytic activity. Furthermore, recent research progress and future predictions for BiOI photocatalyst are also summarized. This review will offer vision into the fabrication of novel and highly active BiOI-based photocatalysts in a green manner at low operational cost.
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•Nanosized SnO2 photocatalysts were prepared with a precipitation method.•SnO2 nanoparticles displayed high photocatalytic activities for the MB degradation.•OH radicals are the main ...active species in photocatalysis on the SnO2 nanoparticles.
Nanosized SnO2 photocatalysts were prepared with a precipitation method and were characterized by performing transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and X-ray absorption spectroscopy (XAS). The powder XRD results revealed that the SnO2 nanoparticles have a typical tetragonal rutile (cassiterite) structure and the average crystallite size was found to be approximately 4.5nm by using the Debye–Scherrer equation. The prepared SnO2 nanoparticles consist of agglomerated particles with a mean diameter of around 4–5nm according to the analysis of TEM images. The XAS data confirmed that the prepared samples have cassiterite structures with tin oxidation state of +4. The prepared SnO2 nanoparticles were found to exhibit approximately 3.8 times higher activity than bulk SnO2 in the photodegradation of methylene blue. On the basis of a trapping experiment, we developed a possible mechanism for the photodegradation on SnO2 nanoparticles.
•Advanced integrated technique of pulsed laser irradiation and sonochemical processes.•Hybrid technique utilized for the production of highly surface-active materials.•Facile strategy employed for ...the production of Pd, NiPd, ZnO, and Ag/GO composites.•NiPd spheres displayed good HER activity in a 1 M KOH solution.
The development of highly surface-active nano-sized and submicron particles with well-defined features is a promising approach in regulating various physicochemical properties of materials for different applications. A new hybrid technique involving pulsed laser irradiation and sonochemical processes for the production of Pd nanoparticles, NiPd alloys, and ZnO and Ag/graphene oxide (GO) composites was developed herein. An unfocused pulsed laser (neodymium-doped yttrium aluminum garnet Nd:YAG laser pulse with a wavelength of 532 nm) was used to irradiate a mixture of colloidal Ni solution obtained by ablation and PdCl2, resulting in the formation of highly surface-active NiPd under continuous sonication at 40 kHz. The physicochemical properties of the synthesized materials were analyzed by X-ray diffraction (XRD), ultraviolet–visible (UV–vis) spectroscopy, field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy (HR-TEM), and dynamic light scattering (DLS). To investigate their potential uses, the alloys were employed as electrocatalysts in the hydrogen evolution reaction (HER). Notably, the NiPd synthesized by the integrated process exhibited higher HER activity in a 1 M KOH solution (overpotential of 38 mV at 1 mA/cm2) than the material obtained via pulsed laser irradiation alone (44 mV). The enhanced HER performance of the NiPd alloy was attributed to the synergistic effects of the integrated pulsed laser irradiation and sonochemical processes, affording NiPd particles displaying active surface defects and shape homogeneity. These features resulted in high electronic conductivity and low internal resistance of the material. The proposed hybrid technique could be utilized in the upscaling production of various functional materials with controlled properties.
•Recent progress in MXene based supercapacitive energy storage is reviewed.•Top-down and bottom-up MXene synthesis methods are discussed.•Unique properties of MXenes have been reviewed.•Charge ...storage mechanism of various MXene based supercapacitors are dsicused.
In the past few decades, with the advancement of technology, there has been an increasing demand for high-capacity energy storage devices having durability, low production cost, and flexibility. MXene, a layered 2D transition metal carbide, nitride or carbonitride, exfoliated from its parent MAX phase by selective chemical etching of covalently bonded A layer has become the most emerging material today for energy storage applications. The 2D layered structure, atomic layer thickness, high conductivity, tunable surface functional groups, superior hydrophilicity, good mechanical properties, excellent electrochemical nature, flexibility, and the ease of preparation of MXene has made it the most demanding material today among 2D families. Starting from gas and biosensors, water purification, water splitting, photo and electrocatalysis, transparent conductors in electronics, antibacterial film, electromagnetic interference shielding, and in batteries and supercapacitors, MXene have a wide range of applications. The special properties of MXene have made scientists work on its further theoretical and experimental developments. This article mainly reviews the recent advances of MXene for fabricating durable, pliable, and highly efficient electrochemical energy storage devices using supercapacitors as its power source. The structure of MXene, different synthesis methods, and their unique properties have been deeply studied, as well as the effect of various factors like size and shape of MXene sheets, design of electrode architecture, nature of electrolyte, etc. on the electrochemical performance and charge storage mechanism of MXene based supercapacitors have been emphasized. This article also throws light on state-of-the-art recent progress in MXene composite-based supercapacitors. Finally, its challenges and future advances have been discussed.
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•Multiscale design of 3D MOF (M−BTC, M: Cu, Co, Ni) was demonstrated via PLAL.•Studied intrinsic properties on electrocatalytic active-states for overall water splitting.•Co-BTC ...achieve low η10 of 437 and 370 mV for HER and OER, respectively.•Require only 2.03 V @ 10 mA/cm2 for Co–BTC ∥ Co–BTC full electrolysis system.•Electronic effect implying on structural stability and long-term durability.
Multiscale structural engineering of high-performance bifunctional electrocatalysts to influence hydrogen and oxygen evolution reactions (HER and OER) has a significant role in overall water splitting. Thus, we successfully designed a new strategy and synthesized transition-metal-based 3D metal–organic framework (MOF) materials having various architectures, namely, Cu–BTC, Co–BTC, and Ni–BTC, by pulsed laser ablation in dimethylformamide. The coordination between the metal and carboxylate moieties of the ligand, crystalline structure, phase purity, morphology, thermal stability, and oxidation states were illustrated using physical characterization techniques. Further, intrinsic properties of the MOF materials were studied using electrocatalytic reactions toward HER and OER in an alkaline medium. Among the synthesized MOF materials, the Co–BTC electrocatalyst showed a very low overpotential of 437 mV toward HER at a constant current density of 10 mA cm−2 in 1.0 M potassium hydroxide. The derived Tafel slope and Rct values are 115.1 mV dec−1 and 2.77 Ω cm−2, respectively. Similarly, OER studies reveal that the Co–BTC MOF showed robust activity with low overpotential of 370 mV at 10 mA cm−2. Finally, the optimal Co–BTC MOF electrode required 2.03 V of cell potential to deliver 10 mA cm−2 in a dielectrode (Co–BTC ∥ Co–BTC) electrolysis system with long-run stability. The present report reveals a new possibility for the innovation in robust HER and OER bifunctional electrocatalysts using nonprecious metallic MOF materials.
Herein, the authors produce Co‐based (Co3(PO4)2, Co3O4, and Co9S8) electrocatalysts via pulsed laser ablation in liquid (PLAL) to explore the synergy of anion modulation on phase‐selective active ...sites in the electrocatalytic hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Co3(PO4)2 displays an ultralow overpotential of 230 mV at 10 mA cm−2 with 48.5 mV dec−1 Tafel slope that outperforms the state‐of‐the‐art Ir/C in OER due to its high intrinsic activity. Meanwhile, Co9S8 exhibits the highest HER performance known to the authors among the synthesized Co‐based catalysts, showing the lowest overpotential of 361 mV at 10 mA cm−2 with 95.8 mV dec−1 Tafel slope in the alkaline medium and producing H2 gas with ≈500 mmol g−1 h−1 yield rate under −0.45 V versus RHE. The identified surface reactive intermediates over in situ electrochemical–Raman spectroscopy reveal that cobalt(hydr)oxides with higher oxidation states of Co‐cation forming under oxidizing potentials on the electrode–electrolyte surface of Co3(PO4)2 facilitate the OER, while Co(OH)2 facilitate the HER. Notably, the fabricated two‐electrode electrolyzers using Co3(PO4)2, Co3O4, and Co9S8 electrocatalysts deliver the cell potentials ≈2.01, 2.11, and 1.89 V, respectively, at 10 mA cm−2. This work not only shows PLAL‐synthesized electrocatalysts as promising candidates for water splitting, but also provides an underlying principle for advanced energy‐conversion catalysts and beyond.
Co‐based electrocatalysts fabricated via the pulsed laser ablation in liquid process for water splitting are presented. The fabricated two‐electrode water electrolyzers using Co3(PO4)2, Co3O4, and Co9S8 can deliver the cell potentials of 2.01, 2.11, and 1.89 V, respectively.
•SnO2–CNT nanocomposites were prepared with thiolated CNTs.•SnO2–CNTs displayed high photocatalytic activities for MB and MO degradation.•The incorporated CNTs acted as electrical conductors.•A ...plausible photocatalytic mechanism is proposed.
Tin oxide–carbon nanotube (SnO2–CNT) nanocomposites were prepared by depositing SnO2 nanoparticles onto thiolated CNT surfaces to develop highly efficient photocatalysts. The structure of SnO2–CNTs was characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of the sample was benchmarked using the photodegradation of methylene blue (MB) and methyl orange (MO) in aqueous solution under UV–vis light irradiation. The SnO2–CNTs exhibited enhanced photocatalytic activities compared with bulk SnO2, SnO2 nanoparticles, and commercial P25 TiO2. The enhanced activity was ascribed to the CNT addition. The presence of CNTs effectively suppressed an electron–hole recombination and favored a reactant and product mass transport. A plausible photocatalytic mechanism is proposed.
The demand for sustainable energy storage and production is vital and continues to grow with increasing human population. Energy utilization and environmental protection demand urgent attention in ...the development of energy devices, including the expansion and assessment of earth abundant and inexpensive materails. Recently, two-dimensional (2D) structured graphene has emerged as an outstanding energy material due to its excellent physicochemical properties, for example, high thermal and electrical conductivity, high surface area, strong mechanical strength, and an excellent chemical stability. However, pure graphene has a band gap of zero significantly limiting its application as a material. Among the various approaches used to alter the properties of graphene is doping with a heteroatom, which has been shown to be an efficient process in tailoring the properties of 2D-graphene. Heteroatom-doped graphene has several improved physicochemical properties, making graphene a favorable material for application in various fields. In this review, we report the usage and advancement of heteroatom-doped graphene materials in various energy conversion and storage technologies, including supercapacitors, batteries, dye-sensitized solar cells, and hydrogen production from electrocatalytic water splitting. Furthermore, we have also highlighted the recent developments made to date and systematically discuss physicochemical mechanisms, and the precise advantages obtained by the doping of heteroatoms. Finally, the challenges and future perspectives for heteroatom-doped graphene materials are outlined. The information provided in this review should be useful to any researchers involved in the field of graphene research for wide-ranging applications, and structural-oriented (morphology, structure, size and composition) research.
•Progression of heteroatom-doped graphene materials in energy fields is overviewed.•Synergistic effects of heteroatoms with graphene are highlighted in energy application.•Developments on synthetic strategies for the fabrication of materials are described.•Challenges for heteroatom-doped graphene in energy fields are mentioned.•Effective electrochemical properties and future perspectives are discussed.
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•Critical overview on progression of sonoelectrochemistry in energy and environment.•Importance of ultrasound with electrochemical process is highlighted.•Challenges that remain for ...sonoelectrochemistry in energy/environment applications.•Experimental parameters of sonoelectrochemistry and future perspectives discussed.
Sonoelectrochemistry is the study of the effects and applications of ultrasonic waves on electrochemical processes. The integration of ultrasound and electrochemistry offers many advantages: fast reaction rates, enhanced surface activation, and increased mass transport at an electrode. Significant progress has been made in advancing basic and applied aspects of sonoelectrochemical techniques, which are herein reviewed by addressing the development and applications of sonoelectrochemical processes in energy and environmental areas. This review examines the experimental procedures that are used in various sonoelectrochemical techniques generally used for the synthesis of energy related materials (e.g., fuel cell electrocatalysts and materials for hydrogen production) and for the degradation of various organic compounds/pollutants. The challenges that remain for the sonoelectrochemical production of energy materials, the degradation of organic pollutants, and their associated reaction pathway mechanism(s) are also discussed. This review also highlights the significant improvements made to date. The provided information in this review may be helpful to scientists working in the research areas of environmental remediation, energy exploitation and exploration, as well as synthetic process-oriented research.
High‐entropy oxides (HEO) have recently concerned interest as the most promising electrocatalytic materials for oxygen evolution reactions (OER). In this work, a new strategy to the synthesis of HEO ...nanostructures on Ti3C2Tx MXene via rapid microwave heating and subsequent calcination at a low temperature is reported. Furthermore, the influence of HEO loading on Ti3C2Tx MXene is investigated toward OER performance with and without visible‐light illumination in an alkaline medium. The obtained HEO/Ti3C2Tx‐0.5 hybrid exhibited an outstanding photoelectrochemical OER ability with a low overpotential of 331 mV at 10 mA cm−2 and a small Tafel slope of 71 mV dec−1, which exceeded that of a commercial IrO2 catalyst (340 mV at 10 mA cm−2). In particular, the fabricated water electrolyzer with the HEO/Ti3C2Tx‐0.5 hybrid as anode required a less potential of 1.62 V at 10 mA cm−2 under visible‐light illumination. Owing to the strong synergistic interaction between the HEO and Ti3C2Tx MXene, the HEO/Ti3C2Tx hybrid has a great electrochemical surface area, many metal active sites, high conductivity, and fast reaction kinetics, resulting in an excellent OER performance. This study offers an efficient strategy for synthesizing HEO‐based materials with high OER performance to produce high‐value hydrogen fuel.
Herein, a high‐entropy oxide (HEO) anchored 2D Ti3C2Tx MXene (HEO/Ti3C2Tx) hybrid via impregnation and microwave‐heating methods is developed. The attained HEO/Ti3C2Tx‐0.5 hybrid achieved a comparable oxygen evolution reactions (OER) performance with the commercial IrO2 catalyst with/without visible‐light illumination. Furthermore, the fabricated water electrolyzer with HEO/Ti3C2Tx‐0.5 hybrid as anode required a low potential of 1.62 V to drive 10 mA cm‐2 under visible‐light illumination.
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