Electrodeposition of polyaniline on high electroactive indium tin oxide nanoparticles-modified fluorine doped tin oxide electrode for fabrication of high-performance hybrid supercapacitor

In this study, hierarchical polyaniline (PANI) nanosheets were electrochemically deposited on indium tin oxide nanoparticles coated fluorine-doped tin oxide glass (ITONPs-FTO) substrate from an aqueous solution containing 0.5 M aniline and 1 M H₂SO₄. The ITONPs provide efficient support with high electroactive surface area in the electrochemical deposition of PANI and produce excellent PANI films. The developed PANI film deposited on the ITONPs-FTO electrode was characterized via field-emission scanning-electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. A hybrid supercapacitor (HSC) was fabricated using the developed PANI deposited ITONPs-FTO as a positrode and the jute sticks derived activated carbon nanosheets coated FTO (JAC-FTO) as a negatrode. Because of its high capacitive performance, unique structures of electrode materials, and optimum operating potential window, the fabricated PANI-ITONPs-FTO//JAC-FTO HSC performed excellently in 0.1 M HCl aqueous electrolyte, delivering a high areal capacitance of 318 mF/cm² at a 1.0 mA/cm² current density and exhibit a high energy density of 28 µWh/cm² at a high power density of 400 µW/cm². Moreover, the HSC exhibits excellent cyclic stability with ～ 87% Coulombic efficiency and ～ 91% capacitance retention after 1000 charge–discharge cycles.     

Three‐Dimensional NiMoO4 Nanosheets Supported on a Carbon Fibers@Pre‐Treated Ni Foam (CF@PNF) Substrate as Advanced Electrodes for Asymmetric Supercapacitors

Herein, we report a nanoarchitectured nickel molybdate/carbon fibers@pre‐treated Ni foam (NiMoO₄/CF@PNF) electrode for supercapacitors. The synthesis of NiMoO₄/CF@PNF mainly consists of a direct chemical vapor deposition (CVD) growth of dense carbon fibers (CFs) onto pre‐treated Ni foam (PNF) as the substrate, followed by in situ growth of NiMoO₄ nanosheets (NSs) on the CF@PNF substrate by means of a hydrothermal process. The NiMoO₄/CF@PNF electrode exhibits a high areal capacitance (5.14 F cm^?2 at 4 mA cm^?2) and excellent cycling stability (97 % capacitance retention after 2000 cycles at 10 mA cm^?2). Furthermore, we have successfully assembled NiMoO₄ NSs//activated carbon (AC) asymmetric supercapacitors, which can achieve an energy density of 45.6 Wh kg^?1 at 674 W kg^?1, and excellent stability with 93 % capacitance retention after 2000 cycles at 5 mA cm^?2. These superior properties hold great promise for energy‐storage applications.     

Mesoporous PtPb Nanosheets as Efficient Electrocatalysts for Hydrogen Evolution and Ethanol Oxidation

Using a one-pot hydrothermal method with ethylenediamine, we have synthesized mesoporous PtPb nanosheets that exhibit exceptional activity in both hydrogen evolution and ethanol oxidation. The resulting PtPb nanosheets have a Pt-enriched structure with up to 80 % atomic content of Pt. The synthetic method generated a significant mesoporous structure, formed through the dissolution of Pb species. These advanced structures enable the mesoporous PtPb nanosheets to achieve a current density of 10 mA cm⁻² with an extreme low overpotential of 21 mV for hydrogen evolution under alkaline conditions. Furthermore, the mesoporous PtPb nanosheets exhibit superior catalytic activity and stability for ethanol oxidation. The highest catalytic current density of PtPb nanosheets is 5.66 times higher than that of commercial Pt/C. This research opens up new possibilities in designing mesoporous, two-dimensional noble-metal-based materials for electrochemical energy conversion with excellent performance.     

Selective oxidation of alcohols by porphyrin-based porous polymer-supported manganese heterogeneous catalysts

A series of porphyrin-based porous polymers to support Mn heterogeneous catalysts (Mn/TFP-DPM, Mn/TFP-DPM-2, Mn/TFP-DPM-3, and Mn/TFP-DPM-4) in the selective oxidation of alcohols were designed. TFP-DPM and TFP-DPM-2 demonstrated micro/nanoscale spherical morphology, whereas TFP-DPM-3 and TFP-DPM-4 exhibited nanosheets structure. According to surface area and porosity analysis results, the specific surface areas of these catalysts were less than 300 m² g^–1. Thermogravimetric analysis indicated that the synthesized catalysts maintain their stability even at 300 °C. Catalysts Mn/TFP-DPM and Mn/TFP-DPM-3, which had the smallest and largest specific surface area among the four catalysts, respectively, were used to perform selective oxidation reaction of alcohols, with experimental results indicating that both have excellent catalytic performance. As these catalysts possess good catalytic performance despite their low specific surface area, we suggest that porphyrin-based porous polymer-supported Mn heterogeneous catalysts are promising materials for selective oxidation of alcohols.     

Synthesis of Two‐dimensional Microporous Carbonaceous Polymer Nanosheets and Their Application as High‐performance CO2 Capture Sorbent

The synthesis of two‐dimensional (2D) polymer nanosheets with a well‐defined microporous structure remains challenging in materials science. Here, a new kind of 2D microporous carbonaceous polymer nanosheets was synthesized through polymerization of a very low concentration of 1,4‐dicyanobenzene in molten zinc chloride at 400–500 °C. This type of nanosheets has a thickness in the range of 3–20 nm, well‐defined microporosity, a high surface area (～537 m² g^?1), and a large micropore volume (～0.45 cm³ g^?1). The microporous carbonaceous polymer nanosheets exhibit superior CO₂ sorption capability (8.14 wt % at 298 K and 1 bar) and a relatively high CO₂ selectivity toward N₂ (25.6). Starting from different aromatic nitrile monomers, a variety of 2D carbonaceous polymer nanosheets can be obtained showing a certain universality of the ionothermal method reported herein.     

Heteroatom‐Doped Porous Carbon Nanosheets: General Preparation and Enhanced Capacitive Properties

High‐performance electrical double‐layer capacitors (EDLCs) require carbon electrode materials with high specific surface area, short ion‐diffusion pathways, and outstanding electrical conductivity. Herein, a general approach combing the molten‐salt method and chemical activation to prepare N‐doped carbon nanosheets with high surface area (654 m² g^?1) and adjustable porous structure is presented. Owing to their structural features, the N‐doped carbon nanosheets exhibited superior capacitive performance, demonstrated by a maximum capacitance of 243 F g^?1 (area‐normalized capacitance up to 37 μF cm^?2) at a current density of 0.5 A g^?1 in aqueous electrolyte, high rate capability (179 F g^?1 at 20 A g^?1), and excellent cycle stability. This method provides a new route to prepare porous and heteroatom‐doped carbon nanosheets for high‐performance EDLCs, which could also be extended to other polymer precursors and even waste biomass.     

High-performance Pt-NiO nanosheet-based counter electrodes for dye-sensitized solar cells

High-performance counter electrodes for dye-sensitized solar cells (DSSCs) are fabricated with platinum-nickel oxide (Pt-NiO) nanosheets as catalytic materials. Firstly, the Pt-Ni nanosheets are synthesized via galvanic replacement reaction between pre-synthesized Ni nanosheets and an aqueous H₂PtCl₆ solution. Secondly, after thermal treatment in air, the Pt-Ni alloys are turned to Pt-NiO nanosheets. The related data of cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel polarization reveal that Pt-NiO counter electrodes show highly catalytic activity and low charge transfer resistance. The DSSC with Pt-NiO counter electrode exhibits power conversion efficiency (PCE) of 8.40 %, which is lower than that of the DSSC containing commercial available Pt counter electrode (9.15 %) under full sunlight illumination (100 mW cm^?2, AM1.5G). However, owing to the extremely high transparency of Pt-NiO counter electrode, when putting an Ag mirror behind the back side of the DSSC, the reflected light can bring great enhanced PCE (11.27 %).     

Molten-Salt-Assisted Synthesis of Bismuth Nanosheets for Long-term Continuous Electrocatalytic Conversion of CO2 to Formate

Two-dimensional (2D) monometallic pnictogens (antimony or Sb, and bismuth or Bi) nanosheets demonstrate potential in a variety of fields, including quantum devices, catalysis, biomedicine and energy, because of their unique physical, chemical, electronic and optical properties. However, the development of general and high-efficiency preparative routes toward high-quality pnictogen nanosheets is challenging. A general method involving a molten-salt-assisted aluminothermic reduction process is reported for the synthesis of Sb and Bi nanosheets in high yields (>90 %). Electrocatalytic CO₂ reduction was investigated on the Bi nanosheets, and high catalytic selectively to formate was demonstrated with a considerable current density at a low overpotential and an impressive stability. Bi nanosheets continuously convert CO₂ into formate in a flow cell operating for one month, with a yield rate of 787.5 mmol cm⁻² h⁻¹. Theoretical results suggest that the edge sites of Bi are far more active than the terrace sites.     

Activating surface atoms of high entropy oxides for enhancing oxygen evolution reaction

High entropy oxides (HEOs) have attracted extensive attention of researchers due to their remarkable properties. The electrocatalytic activity of electrocatalysts is closely related to the reactivity of their surface atoms which usually shows a positive correlation. Excellenet stability of HEOs leads to their surface atoms with relative poor reactivity, limiting the applications for electrocatalysis. Therefore, it is significant to activate surface atoms of HEOs. Constructing amorphous structure, introducing oxygen defects and leaching are very effective strategies to improve the reactivity of surface atoms. Herein, to remove chemical inert, low-crystallinity (Fe, Co, Ni, Mn, Zn)₃O₄ (HEO-Origin) nanosheets with abundant oxygen vacancies was synthesized, showing an excellent catalytic activity with an overpotential of 265 mV at 10 mA/cm², which outperforms as-synthesized HEO-500°C-air (335 mV). The excellent catalytic performance of HEO-Origin can be attributed to high activity surface atoms, the introduction of oxygen defects efficiently altered electron distribution on the surface of HEO-Origin. Apart from, HEO-Origin also exhibits an outstanding electrochemical stability for oxygen evolution reaction (OER).     

Reduced Graphene Oxide‐Supported TiO2 Fiber Bundles with Mesostructures as Anode Materials for Lithium‐Ion Batteries

Although the synthesis of mesoporous materials is well established, the preparation of TiO₂ fiber bundles with mesostructures, highly crystalline walls, and good thermal stability on the RGO nanosheets remains a challenge. Herein, a low‐cost and environmentally friendly hydrothermal route for the synthesis of RGO nanosheet‐supported anatase TiO₂ fiber bundles with dense mesostructures is used. These mesostructured TiO₂‐RGO materials are used for investigation of Li‐ion insertion properties, which show a reversible capacity of 235 mA h g^?1 at 200 mA g^?1 and 150 mA h g^?1 at 1000 mA g^?1 after 1000 cycles. The higher specific surface area of the new mesostructures and high conductive substrate (RGO nanosheets) result in excellent lithium storage performance, high‐rate performance, and strong cycling stability of the TiO₂‐RGO composites.     

一步法合成的FeOOH/黑磷纳米复合材料协同实现体系优异的析氧性能

通过水热法,在黑磷(BP)纳米片表面生长FeOOH纳米材料,制备出FeOOH/BP纳米复合材料。作为电化学析氧反应(OER)催化剂,该复合材料在20 mA·cm^-2时的过电位仅为191 mV,Tafel斜率为49.9 mV·dec^-1;在循环1 000圈后,过电位仅仅增加了3 mV,且循环过程中元素价态不变,表现出优秀的稳定性。纳米FeOOH负载于BP表面,客观上能隔断氧气对BP的氧化,保护BP的载流子传导性能。同时,生长的FeOOH颗粒尺度小,结晶性弱,这有利于丰富其活性位点,增大活性面积。     

一步法合成的FeOOH/黑磷纳米复合材料协同实现体系优异的析氧性能

通过水热法,在黑磷(BP)纳米片表面生长FeOOH纳米材料,制备出FeOOH/BP纳米复合材料。作为电化学析氧反应(OER)催化剂,该复合材料在20 mA·cm^-2时的过电位仅为191 mV,Tafel斜率为49.9 mV dec^-1;在循环1 000圈后,过电位仅仅增加了3 mV,且循环过程中元素价态不变,表现出优秀的稳定性。纳米FeOOH负载于BP表面,客观上能隔断氧气对BP的氧化,保护BP的载流子传导性能。同时,生长的FeOOH颗粒尺度小,结晶性弱,这有利于丰富其活性位点,增大活性面积。     

一步法合成的FeOOH/黑磷纳米复合材料协同实现体系优异的析氧性能

通过水热法，在黑磷(BP)纳米片表面生长FeOOH纳米材料，制备出FeOOH/BP纳米复合材料。作为电化学析氧反应(OER)催化剂，该复合材料在20 mA·cm^-2时的过电位仅为191 mV，Tafel斜率为49.9 mV dec^-1；在循环1 000圈后，过电位仅仅增加了3 mV，且循环过程中元素价态不变，表现出优秀的稳定性。纳米FeOOH负载于BP表面，客观上能隔断氧气对BP的氧化，保护BP的载流子传导性能。同时，生长的FeOOH颗粒尺度小，结晶性弱，这有利于丰富其活性位点，增大活性面积。     

Hierarchical Mesoporous SnO2 Nanosheets on Carbon Cloth: A Robust and Flexible Electrocatalyst for CO2 Reduction with High Efficiency and Selectivity

Electrochemical reduction of CO₂ into liquid fuels is a promising approach to achieve a carbon‐neutral energy cycle. However, conventional electrocatalysts usually suffer from low energy efficiency and poor selectivity and stability. A 3D hierarchical structure composed of mesoporous SnO₂ nanosheets on carbon cloth is proposed to efficiently and selectively electroreduce CO₂ to formate in aqueous media. The electrode is fabricated by a facile combination of hydrothermal reaction and calcination. It exhibits an unprecedented partial current density of about 45 mA cm⁻² at a moderate overpotential (0.88 V) with high faradaic efficiency (87±2 %), which is even larger than most gas diffusion electrodes. Additionally, the electrode also demonstrates flexibility and long‐term stability. The superior performance is attributed to the robust and highly porous hierarchical structure, which provides a large surface area and facilitates charge and mass transfer.     

Three‐Dimensional Macroassembly of Sandwich‐Like,Hierarchical, Porous Carbon/Graphene Nanosheets towards Ultralight,Superhigh Surface Area,Multifunctional Aerogels

A new, ultralight, superhigh surface area, multifunctional aerogel, which is macroassembled from sandwich‐like, hierarchical, porous carbon/graphene nanosheets, is described. The multifunctional aerogel was characterized by means of XRD, SEM, TEM, Raman spectroscopy, and UV/Vis absorption spectroscopy. The multifunctional aerogel had an ultralow density of 8 mg cm^?3 and a superhigh surface area of 2650 m² g^?1. The multifunctional aerogel was thermal stability and compressible. Meanwhile, the multifunctional aerogel exhibited high capacity for the adsorption of oils and organic solvents, unexpectedly high hydrogen adsorption and good electrochemical performance.     

Ultrafine molybdenum carbide nanoparticles supported on nitrogen doped carbon nanosheets for hydrogen evolution reaction

Nitrogen doped carbon nanosheets supported molybdenum carbides nanoparticles (Mo_xC/NCS) have been synthesized by tuning the mass ratio of melamine and ammonia molybdate. The Mo₂C/NCS-10 exhibits superior electrocatalytic performance and stability for HER, which was attributed to N-doped carbon nanosheets, small particle size, mesoporous structure, and large electrochemical active surface area.     

Enhanced Catalytic Activity in Liquid‐Exfoliated FeOCl Nanosheets as a Fenton‐Like Catalyst

A facile liquid‐phase exfoliation method to prepare few‐layer FeOCl nanosheets in acetonitrile by ultrasonication is reported. The detailed exfoliation mechanism and generated products were investigated by combining first‐principle calculations and experimental approaches. The similar cleavage energies of FeOCl (340 mJ m^?2) and graphite (320 mJ m^?2) confirm the experimental exfoliation feasibility. As a Fenton reagent, FeOCl nanosheets showed outstanding properties in the catalytic degradation of phenol in water at room temperature, under neutral pH conditions, and with sunlight irradiation. Apart from the increased surface area of the nanosheets, the surface state change of the nanosheets also plays a key role in improving the catalytic performance. The changes of charge density, density of states (DOS), and valence state of Fe atoms in the exfoliated FeOCl nanosheets versus plates illustrated that surface atomistic relationships made the few‐layer nanosheets higher activity, indicating the exfoliation process of the FeOCl nanosheets also brought about surface state changes.     

Carnation‐like CuO Hierarchical Nanostructures Assembled by Porous Nanosheets for Nonenzymatic Glucose Sensing

Carnation‐like CuO hierarchical nanostructures assembled by ultrathin porous nanosheets were successfully fabricated via a facile solvothermal route followed with heat treatment. As‐prepared CuO nanostructures exhibited excellent catalytic activity toward glucose oxidation in the absence of any enzymes. Under the optimized conditions, the CuO‐based enzymeless glucose sensor showed high sensitivity of 3.15 mA mM^?1 cm^?2, low limit of detection (98 nM, S/N=3), good reproducibility, excellent selectivity and long‐time stability. The superb nonenzymatic glucose sensing performance of the CuO hierarchical nanostructures was attributed to the highly catalytically active sites at the edges and basal planes of the CuO nanosheets, facile transportation of analytes through the abundant mesopores and macropores, robust and stable hierarchical structure. Moreover, the CuO‐based enzymeless glucose sensor showed high accuracy and reliability in comparison with clinical glucometer for quantitative determination of glucose in human blood serum samples.     

In situ constructing of ultrastable ceramic@graphene core-shell architectures as advanced metal catalyst supports toward oxygen reduction

The changeable structure of 2 D graphene nanosheets makes the Pt-based nanoparticles(NPs) possess a low efficiency toward oxygen reduction reaction(ORR) and a short lifetime for proton exchange membrane fuel cells. Thus, a unique Ti C@graphene core-shell structure material with low surface energy is designed and prepared by an in situ forming strategy, and firstly applied as a stable support of Pt NPs.The as-prepared Pt/GNS@Ti C catalyst presents a high activity. Especially, its ORR stability is remarkably improved. Even after 15000 potential cycles, the half-wave potential and mass activity toward ORR have almost no change. This can be attributed to that the graphene nanosheet existing in a sphere shape effectively avoids the restacking or folding caused by the giant surface tension in 2 D graphene nanosheets,impeding the decrease of the triple-phase boundary on Pt NPs. Significantly, the power density of fuel cells with our novel catalyst reaches 853 m V cm~(–2) under a low Pt loading(0.25 mg Pt cm~(–2)) and H_2/Air conditions. These indicate the new ceramic@graphene core-shell nanocomposite is a promising application in fuel cells and other fields.     

Highly Sensitive Nonenzymatic Glucose Sensor Based on 3D Ultrathin NiFe Layered Double Hydroxide Nanosheets

As a promising electrode material, Ni‐based nanomaterials exhibit a remarkable electrochemical catalytic activity for nonenzymatic glucose sensors. In this paper, Nickel–Iron layered double hydroxide (NiFe‐LDH) film electrode with ultrathin nanosheets and porous nanostructures was synthesized directly on Ni foam (NF) by a one‐step hydrothermal method. The as‐obtained NiFe‐LDH electrode was adopted for glucose detection without further treatment. As an integrated binder‐free electrode for glucose sensor, the NiFe‐LDH/NF hybrid exhibits a superior sensitivity of 3680.2 μA mM⁻¹ cm⁻² with a low limit of detection (0.59 μM, S/N=3) as well as fast response time (<1 s). An excellent selectivity from potential interference species such as ascorbic acid, uric acid and Cl⁻ ions and acceptable stability were also achieved. The outstanding performance can be ascribed to the abundant electrochemistry active sites, facilitative diffusion of the electrolyte, high electron transfer rate and reliable stability architecture. Therefore, the NiFe‐LDH nanosheets demonstrate potential application in non‐enzymatic sensory of glucose.