A Ti 3 C 2 T x MXene electrode decorated with NiO nanosheets was synthesized by a facile and cost-effective hydrothermal method. The NiO nanosheets were grown and immobilized on the carbon-supported ...TiO 2 layer which was derived from Ti 3 C 2 T x -MXene during a thermal annealing process. An electrode based on the NiO-grown derived-TiO 2 /C-Ti 3 C 2 T x -MXene nanocomposite (Ni-dMXNC) exhibited a remarkable maximum specific capacity of 92.0 mA h cm −3 at 1 A g −1 and 53.9 mA h cm −3 at 10 A g −1 . Furthermore, an asymmetric supercapacitor (ASC) device composed of Ni-dMXNC as the positive electrode and Ti 3 C 2 T x MXene as the negative electrode was demonstrated to be better with a high energy density of 1.04 × 10 −2 W h cm −3 at a power density of 0.22 W cm −3 , and cycling stability with 72.1% retention after 5000 cycles, compared to ASCs using previously reported Ti 3 C 2 T x MXene materials. The enhanced capacitive performance is attributed to the newly formed high-surface-area multilayers of the Ni-dMXNC architecture, the active surface of NiO layer, and a favourable synergetic behaviour of the Ti 3 C 2 T x MXene negative electrode.
Superfast (≤10 min) room-temperature (300 K) chemical synthesis of three-dimensional (3-D) polycrystalline and mesoporous bismuth(III) oxide (Bi2O3) nanostructured negatrode (as an abbreviation of ...negative electrode) materials, viz., coconut shell, marigold, honey nest cross section and rose with different surface areas, charge transfer resistances, and electrochemical performances essential for energy storage, harvesting, and even catalysis devices, are directly grown onto Ni foam without and with poly(ethylene glycol), ethylene glycol, and ammonium fluoride surfactants, respectively. Smaller diffusion lengths, caused by the involvement of irregular crevices, allow electrolyte ions to infiltrate deeply, increasing the utility of inner active sites for the following electrochemical performance. A marigold 3-D Bi2O3 electrode of 58 m2·g–1 surface area has demonstrated a specific capacitance of 447 F·g–1 at 2 A·g–1 and chemical stability of 85% even after 5000 redox cycles at 10 A·g–1 in a 6 M KOH electrolyte solution, which were higher than those of other morphology negatrode materials. An asymmetric supercapacitor (AS) device assembled with marigold Bi2O3 negatrode and manganese(II) carbonate quantum dots/nickel hydrogen–manganese(II)–carbonate (MnCO3QDs/NiH–Mn–CO3) positrode corroborates as high as 51 Wh·kg–1 energy at 1500 W·kg–1 power and nearly 81% cycling stability even after 5000 cycles. The obtained results were comparable or superior to the values reported previously for other Bi2O3 morphologies. This AS assembly glowed a red-light-emitting diode for 20 min, demonstrating the scientific and industrial credentials of the developed superfast Bi2O3 nanostructured negatrodes in assembling various energy storage devices.
The present study involves the synthesis of a bismuth oxide (Bi
2
O
3
) electrode consisting of an arranged nano-platelets for evolving a flower-type surface appearance on nickel-foam (Bi
2
O
3
...-Ni-F) by a simple, inexpensive, binder-free and one-step chemical bath deposition (CBD) method, popularly known as a wet chemical method. The as-prepared Bi
2
O
3
on Ni-foam, as an electrode material, demonstrates 557 F g
−1
specific capacitance (SC, at 1 mA cm
−2
), of which 85% is retained even after 2000 cycles. With specific power density of 500 kW kg
−1
, the Bi
2
O
3
-Ni-F electrode documents a specific energy density of 80 Wh kg
−1
. Furthermore, a portable asymmetric supercapacitor device,
i.e.
a pencil-type cell consisting of Bi
2
O
3
-Ni-F as an anode and graphite as a cathode in 6 M KOH aqueous electrolyte solution, confirms 11 Wh kg
−1
and 720 kW kg
−1
specific energy and specific power densities, respectively. An easy and a simple synthesis approach for manufacturing a portable laboratory scale pencil-type supercapacitor device is a major outcome of this study, which can also be applied for ternary and quaternary metal oxides for recording an enhanced performance. In addition, we presented a demonstration of lighting a light emitting diode (LED) using a home-made pencil-type supercapacitor device which, finally, has confirmed the scaling and technical potentiality of Bi
2
O
3
-Ni-F in energy storage devices.
The synthesis and asymmetric supercapacitor application of a bismuth oxide (Bi
2
O
3
) electrode consisting of arranged nano-platelets for evolving a flower-type surface appearance on nickel-foam (Bi
2
O
3
-Ni-F) are described.
The long-running Covid-19 pandemic has forced researchers across the globe to develop novel sensors and sensor materials for detecting minute quantities of biogenic viruses with high accuracy in a ...short period. In this context, MXene galleries comprising carbon/nitride two-dimensional nanolayered materials have emerged as excellent host materials in chemical gas sensors owing to their multiple advantages, including high surface area, high electrical conductivity, good thermal/chemical conductivity and chemical stability, composition diversity, and layer-spacing tunability; furthermore, they are popular in clinical, medical, food production, and chemical industries. This review summarizes recent advances in the synthesis, structure, and gas-sensing properties of MXene materials. Current opportunities and future challenges for obtaining MXene-based chemical gas sensors with high sensitivity, selectivity, response/recovery time, and chemical durability are addressed. This review provides a rational and in-depth understanding of the relationship between the gas-sensing properties of MXenes and structure/components, which will promote the further development of two-dimensional MXene-based gas sensors for technical device fabrication and industrial processing applications.
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•The MXene has an accordion-like structure that is ideal for gas sensor applications.•Recent advances in the synthesis, structure, and gas sensing property of MXenes are summarized.•The challenges and development trends of MXene based sensors are addressed.
Since the discovery of two-dimensional (2D) graphene, a new class of 2D materials with excellent electrical conductivity has recently been attracting attention in studying promising electrode ...materials in energy storage applications. Herein, bismuth oxychloride nanosheets-immobilised Ti3C2Tx MXene material (TCBOC) is synthesised by a facile and cost-effective chemical bath deposition (CBD) route. The bismuth oxychloride (BiOCl) nanosheets are grown and immobilised on surfaces of Ti3C2Tx-MXene flakes. An electrode based on the TCBOC nanocomposite exhibited a remarkably volumetric specific capacitance of 396.5 F cm-3 at 1 A g−1 and 228.0 F cm-3 at 15 A g−1. Furthermore, a symmetric supercapacitor (SSC) assembled using TCBOC material proves to have a high energy density of 15.2 Wh kg−1 at a power density of 567.4 W kg−1 compared to SSCs using previously reported Ti3C2Tx MXene materials. The SSC shows cycle life retention of 85.0% after 5000 cycles (at 5 A g−1). The enhanced capacitive performance is attributed to the increased surface area due to BiOCl nanosheets anchored on a 2D MXene surface, the activities of BiOCl sheets, and the excellent conductivity of a Ti3C2Tx MXene material.
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Porous microspheres copper cobalt carbonate hydroxides (CuxCo2⿿xCH) pseudocapacitive electrode material comprised of nanoplates via a facile hydrothermal method were presented. ...Significantly, the crystalline structure, morphology and electrochemical performance of the CuxCo2⿿xCH can be readily manipulated by varying the Cu/Co molar ratios. Among various stoichiometries of CuxCo2⿿xCH porous microspheres studied, Cu1.79Co0.21CH consisted of nanoplates with a mean thickness of ⿼35nm showed a high specific capacitance of 789Fg⿿1 at a current destiny of 1Ag⿿1 and good rate ability. Furthermore, the optimized Cu1.79Co0.21CH electrode also exhibited remarkable high cycling stability, ca 77.5% after 3000 charge/discharge cycles at current density of 5Ag⿿1. An asymmetric device was constructed from optimized Cu1.79Co0.21CH materials on nickel foam (NF) as cathode electrode and graphene on NF as anode electrode in a 6M KOH electrolyte. The asymmetric Cu1.79Co0.21CH/NF//graphene/NF supercapacitor device delivered a specific capacitance of 60.5Fg⿿1 in a potential range of 0⿿1.6V. A high energy density of 21.5Whkg⿿1 was achieved at the power density of 200Wkg⿿1. More significantly, the designed device exhibited excellent cycling stability with 73.3% capacity retention after 5000 cycles.
The bismuth (Bi
)-doped cobalt ferrite nanostructures with dual phase, i.e. cubic spinel with space group Fd3m and perovskite with space group R3c, have been successfully engineered via self-ignited ...sol-gel combustion route. To obtain information about the phase analysis and structural parameters, like lattice constant, Rietveld refinement process is applied. The replacement of divalent Co
by trivalent Bi
cations have been confirmed from energy dispersive analysis of the ferrite samples. The micro-structural evolution of cobalt ferrite powders at room temperature under various Bi
doping levels have been identified from the digital photoimages recorded using scanning electron microscopy. The hyperfine interactions, like isomer shift, quadrupole splitting and magnetic hyperfine fields, and cation distribution are confirmed from the Mossbauer spectra. Saturation magnetization is increased with Bi
-addition up to x = 0.15 and then is decreased when x = 0.2. The coercivity is increased from 1457 to 2277 G with increasing Bi
-doping level. The saturation magnetization, coercivity and remanent ratio for x = 0.15 sample is found to be the highest, indicating the potential of Bi
-doping in enhancing the magnetic properties of cobalt ferrite.
Interfacial modification (IM) plays a vital role in boosting the performance of perovskite solar cells. Herein, we demonstrate a new strategy in which zinc sulfide (ZnS) is used as an interfacial ...modifier between mesoporous-TiO2 (mp-TiO2) and a CH3NH3PbI3 absorber layer via the successive ionic layer adsorption and reaction method. The layer thickness of ZnS was optimized, and its effects on the conduction band position, interfacial charge recombination, and photovoltaic performance were investigated. Our results revealed that an ultrathin ZnS layer on mp-TiO2 helps in suppressing backflow of electrons, effectively reducing interfacial charge recombination and facilitating electron transfer. Our best performing perovskite solar cell device using the mp-TiO2-ZnS achieved a power conversion efficiency of 14.9%, with an open-circuit voltage of 1.02 V, short-circuit current density of 19.05 mA cm−2, and fill factor of 75.43%. Our simple ZnS IM approach proves that interface engineering could be a key strategy in improving the performance of perovskite solar cells.
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•Interfacial modification can improve the performance of perovskite solar cells.•Ultrathin ZnS as an interfacial modifier is deposited on the mesoporous TiO2 ETL.•The ZnS-modified TiO2 device shows a power conversion efficiency of 14.9%.•ZnS significantly reduces interfacial charge recombination and enhances charge extraction.
Using a simple hydrothermal synthesis, the crystal structure of TiO2 nanoparticles was controlled from rutile to anatase using a sugar alcohol, D-sorbitol. Adding small amounts of D-sorbitol to an ...aqueous TiCl4 solution resulted in changes in the crystal phase, particle size, and surface area by affecting the hydrolysis rate of TiCl4. These changes led to improvements of the solar-to-electrical power conversion efficiency (η) of dye-sensitized solar cells (DSSC) fabricated using these nanoparticles. A postulated reaction mechanism concerning the role of D-sorbitol in the formation of rutile and anatase was proposed. Fourier-transform infrared spectroscopy, (13)C NMR spectroscopy, and dynamic light scattering analyses were used to better understand the interaction between the Ti precursor and D-sorbitol. The crystal phase and size of the synthesized TiO2 nanocrystallites as well as photovoltaic performance of the DSSC were examined using X-ray diffraction, Raman spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and photocurrent density-applied voltage spectroscopy measurement techniques. The DSSC fabricated using the anatase TiO2 nanoparticles synthesized in the presence of D-sorbitol, exhibited an enhanced η (6%, 1.5-fold improvement) compared with the device fabricated using the rutile TiO2 synthesized without D-sorbitol.
The structure and morphology of titanium carbide (Ti
3
C
2
T
x
) MXene, a new class of two dimensional (2D) materials, are investigated and reported. Ti
3
AlC
2
MAX, treated with a hydrofluoric acid ...etching process, is used as a promising electrode material for electrochemical supercapacitor studies. The electrochemical supercapacitor performance of Ti
3
C
2
T
x
as a negatrode in a natural seawater electrolyte solution, tested in a three-electrode system, demonstrated a specific capacitance of 67.7 F g
−1
at a current density of 1 A g
−1
which is in accordance with the volumetric specific capacitance of 121.8 F cm
−3
. A symmetric supercapacitor assembled with a Ti
3
C
2
T
x
//Ti
3
C
2
T
x
electrode configuration revealed a volumetric specific capacitance of 27.4 F cm
−3
at 0.25 A g
−1
, and 96.6% capacitance retention even after 5000 cycles, which is superior to those reported previously in similar systems, suggesting the importance of abundant and cost-effective seawater as a natural electrolyte in developing energy storage devices.
A natural seawater electrolyte-mediated MXene//MXene asymmetric supercapacitor demonstrates a 27.4 F cm
−3
volumetric specific capacitance at 0.25 A g
−1
, and 96.6% capacitance retention after 5000 cycles.
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