Crystal facet engineering has attracted worldwide attention, particularly in facet manipulation of titanium dioxide (TiO2) surface properties. An improved synthesis by solvothermal route has been ...employed for the formation of TiO2 with highly exposed 001 facets decorated on reduced graphene oxide (RGO) sheets. The RGO-TiO2 composite could be produced with high yield by following a stringently methodical yet simple approach. Field emission scanning electron microscope and high resolution transmission electron microscope imaging reveal that the structure consists of TiO2 nanoparticles covered with TiO2 nanosheets of exposed 001 facets on a RGO sheet. The photocurrent response of the RGO-TiO2 composite was discovered to outperform that of pure TiO2, as a ~10-fold increase in photocurrent density was observed for the RGO-TiO2 electrodes. This may be attributed to rapid electron transport and the delayed recombination of electron-hole pairs due to improved ionic interaction between titanium and carbon.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Hydrogel materials are receiving increasing research interest due to their intriguing structures that consist of a crosslinked network of polymer chains with interstitial spaces filled with solvent ...water. This feature endows the materials with the characteristics of being both wet and soft, making them ideal candidates for electrolyte materials for flexible energy storage devices, such as supercapacitors that are under intensive studies nowadays. In this study, hybrid poly (N, N-dimethylacrylamide) (PDMA) hydrogels were prepared through free radical mechanism. Ammonium persulfate was used as a free radical initiator while sodium montmorillonite was used as a crosslinker. Magnesium trifluoromethanesulfonate (MgTf2) and cobalt oxide (Co3O4) nanoparticles were added to provide the conduction pathway. The synthesized hydrogels were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), and field emission scanning electron microscopy (FESEM). The presence of Co3O4 nanoparticles in the hybrid hydrogel was confirmed using energy dispersive X-ray spectroscopy (EDX). The ionic conductivity study was performed using electrochemical impedance spectroscopy (EIS). The ionic conductivity study revealed that hydrogel containing MgTf2 and Co3O4 nanoparticles (DMA3) has the highest ambient ionic conductivity (9.4 × 10−3 S cm−1, respectively), dielectric permittivity, and lowest activation energy (0.094 eV). Transference number of hydrogel electrolyte was measured which described the movement of ions due to the presence of salt ions and nanoparticles. Furthermore, electrochemical performance of the synthesized hydrogels in electric double layer capacitor (EDLC) was examined using activated carbon electrode. The electrochemical studies such as cyclic voltammetry (CV) and galvanic charge-discharge (GCD) revealed that hydrogel containing MgTf2 and Co3O4 nanoparticles (DMA3) hydrogel showed maximum specific capacitance of 26.1 F g−1 at 3 mV s−1 and 29.48 F g−1 at 30 mA g−1, respectively. Additionally, it was able to withstand 97.4% of capacitance from its initial capacitance value over 8000 cycles at a current density of 200 mA g−1. The fabricated device revealed the successful light up of light emitting diode (LED). Hence, it can be said that the synthesized hydrogel electrolyte has significant potential for smart, light weight, and flexible electronic devices.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The synergistic effect of two metals with a mixed crystal structure of an electrode material can enhance the electrochemical performance of the electrochemical energy storage device. Herein, mixed ...metal (nickel and cobalt) phosphates are synthesized by the facile sonochemical method followed by calcination. X-ray diffraction (XRD) confirmed the successful synthesis of pure and mixed metal phosphates with crystalline and amorphous phases, supplemented by Fourier transform infrared spectroscopy (FTIR). The field emission scanning electron microscopy (FESEM) micrograph revealed the flake-like morphology of mixed metal phosphates with a rough surface, confirmed by transmission electron microscopy (TEM). The surface area of mixed metal phosphate was estimated by Brunauer-Emmett-Teller (BET). The electrochemical performance of the prepared materials through a three-electrode cell revealed that 75:25 (Ni:Co) possesses excellent electrochemical performance compared to its counterparts. An asymmetric device (supercapattery) is fabricated to investigate the performance Ni:Co 75:25 used as a positive electrode. The supercapattery gave energy and power density values of 33.6Wh/kg and 730W/kg at 1A/g, respectively. The cyclic stability test reveals high capacity retention of 84.1% after 4000 cycles. The excellent electrochemical performance is ascribed to the two different metal phosphates with mixed crystalline phases.
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•Mixed phosphate of cobalt and Nickel is prepared by sonochemical method.•The concentration of Nickel and cobalt ions is optimized to get the best composition•All characterizations confirmed the successful synthesis of mixed phosphates•The mixed crystalline and amorphous structure is responsible for good performance•The composition Ni:Co 75:25 gave an excellent electrochemical performance.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•High density and morphological uniformity of taper-free Ni3Si2 nanowires.•Solid-phase diffusion-control growth mechanism of Ni3Si2 nanowires.•High densely packed with thin, straight, and long ...morphologies of Ni3Si2 NWs increase the redox active reaction sites.•Large surface area of single crystalline Ni3Si2 NWs electrode demonstrated a very high specific capacitance and excellent rate capability.
Lithium-ion batteries and supercapacitors unable to satisfy the growing energy needs of the world due to their distinct energy storage capacity and rate capability. Hence, asymmetric supercapacitor which can be another alternative of energy storage device however its performance greatly depending on the electrode materials. In this work, nickel silicide nanowires (Ni3Si2 NWs) grown on Ni-coated Ni foam substrate via chemical vapor deposition technique. Structure and morphology studies revealed the material is a single-crystalline structure with the average NWs length and diameter of 12.5 ± 0.3 µm and 13 ± 2 nm, respectively, with a high the aspect ratio of 923. These physical characteristics are beneficial in asymmetric supercacitor as electrons are permitted to travel efficiently along each nanowire. In addition, the material has a large surface area (5.184 × 1011 NWs/cm2), thus, allowing high number of electrolyte ions to diffuse throughout the electrode to promote the redox reaction. Ni3Si2 NWs and activated carbon are assembled into an asymmetric supercapacitor and the device exhibited a maximum specific capacity of 578.3 C/g and specific energy of 62.24 Wh/kg at specific power of 387.5 W/kg, and good cyclic stability with 76% capacity retention after 3,000 cycles.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
NASICON-type Na3Zr2(SiO4)2PO4 (NZSP) has garnered increasing attraction as a solid electrolyte owing to its high thermal stability and ionic conductivity. In this study, NaH2PO4 was selected as a new ...phosphate source to synthesize NZSP using solid-state reaction (SSR) method. The samples were ball-milled at different durations (i.e. 5, 12, 24 and 36 h) to study the effect of milling duration on their microstructure and conductivity properties. Structural and morphological studies revealed that the milling duration leads to the formation of different types of ZrO2 which have been the cause of the different ionic conductivities. Among all samples, NZSP ball-milled for 24 h achieved the highest maximum total (bulk + grain-boundary) ionic conductivity at room temperature (9.66 × 10−4 S cm−1). The increment in ionic conductivity is contributed by the maximum amount of NASICON phase content and the least pore areas in the sample. The conductivity mechanism has been discussed, promising its potential to be employed as a solid electrolyte of sodium-ion battery.
•Na3Zr2(SiO4)2PO4 solid electrolytes have been synthesized successfully using new phosphate source.•The synthesized NZSP samples have NASICON-type crystal structure.•Different milling duration has greatly influenced the microstructure and ionic conductivity mechanism.•24 h-milled NZSP samples displayed the highest total ionic conductivity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Blending two different polymers through a physical blending is a wise alternative to create a new polymer with desired properties showing a synergistic effect of the individual polymers. In this ...work, polyacrylonitrile (PAN) and poly (1-vinylpyrrolidone-co-vinyl acetate) P(VP-co-VAc) were blended in a fixed amount of binary organic solvent of ethylene carbonate and propylene carbonate. The weight ratios were varied to 30:70, 50:50 and 70:30 wt%, respectively. Polymer electrolytes in a gel and solid form are safer than liquid ones. Thus 50:50PP and 70:30PP samples were selected and incorporated with iodide/triiodide redox mediators such as sodium iodide salt, 1-methyl-3-propylimidazolium iodide (MPII) ionic liquid and iodine for dye-sensitized solar cells (DSSC) application. Polymer electrolytes containing 50 wt.% of both PAN and P(VP-co-VAc) with iodide/triiodide redox mediator (50:50PP-IL) has achieved maximum ionic conductivity, short-circuit (JSC) current and power conversion efficiency (PCE, η) of 6.10 ×10−3 S cm−1, 11.1 mA cm−1 and 5.35%, respectively.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Manganese phosphate (Mn
3
(PO
4
)
2
) particles decorated polyaniline (PANI) have been proposed as a promising electrode material for supercapacitors. Mn
3
(PO
4
)
2
particles were synthesized via ...the sonochemical method followed by calcination. The size of the particles was optimized by varying the sonication times: 30, 60, and 90 min which were labeled as M30, M60, and M90. The optimized Mn
3
(PO
4
)
2
(M90) was blended with presynthesized PANI to form PANI-Mn
3
(PO
4
)
2
composite (PANI-M90). The phase structure and purity of the synthesized materials were authenticated via X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The morphological studies through field emission scanning electron microscopy (FESEM) showed that M90 particles are firmly anchored on branched-structured PANI which is beneficial for the quick transfer of charges. The electrochemical performance of M30, M60, M90, and PANI-M90 was investigated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) in 1 M KOH electrolyte. PANI-M90 exhibited significantly improved specific capacity (347 C/g) than M90 (88 C/g) at 1 A/g due to the augmentation of redox active sites and the synergistic effect between the conductive PANI and Mn
3
(PO
4
)
2
. Furthermore, the hybrid supercapacitor (activated carbon//PANI-M90) achieved a maximum energy density of 14.7 Wh/kg and a power density of 378 W/kg with 80% of capacity retention after 3000 charge-discharge cycles.
Graphical abstract
Graphical abstract for the morphology and the cyclic voltammogram of M30, M60, M90, and PANI-M90 performed in 1 M KOH
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
•Novel TiO2 aerogel/Co-MOF composites were synthesized successfully.•The incorporation of Co-MOF was confirmed by XRD, EDS and elemental mapping.•The composites were used as supercapattery electrodes ...for the first time.•Remarkably, the composite-based electrodes possessed high specific capacity.•Excellent capacity retention (93%) after 5000 cycles was achieved for the supercapattery.
Three-dimensional hierarchical nanostructured porous TiO2 aerogel/Co-MOF composites were synthesized via a one-step modified sol-gel method. The composite materials were used as an electrode material for supercapattery and their electrochemical performances were assessed. The obtained results showed that the addition of Co-MOF improved the specific capacity; achieved a maximum value of 111.2 C/g at 0.8 A/g which is higher than pure TiO2 aerogel (66.4 C/g) and is relatively high compared with other TiO2/carbon composites. The improved performance of the composite-based electrode is because of the synergistic effects of enriched electroactive site, high surface area, reduced pore size, low internal resistance and good mechanical stability offered by the incorporation of MOF. Further, a supercapattery (TiO2 aerogel/Co-MOF composite//activated carbon) was fabricated and delivered a high specific power of 1875 W/kg with an impressive capacity retention of 93% after 5000 charge-discharge cycles.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Battery type binder-free MnCoS3/NF electrode synthesized.•The incorporation of Mn and Cu into optimized CoS3/NF.•Excellent capacity retention (91%) after 7500 cycles at 1 A/g.
The intermittent ...nature of renewable energy needs ideal storage device to balance the electricity demand and supply. Specific energy, specific power, and stability of electrode play a critical role to increase better performance of supercapattery. Here, we account a unique cobalt sulfide (CoS) binder-free electrode which was modified with different metals (i.e. manganese (Mn) and copper (Cu), fabricated by hydrothermal technique on the nickel foam (NF). The morphological features portray uniform distribution of flakes with different textures after the incorporation of Mn and Cu with the optimised cobalt sulfide system, respectively. Among all electrodes, Mn-CoS-3/NF exhibits a significant boost in the rate capability at 74% compared to CoS-3/NF (75%) and Cu-CoS-3/NF (59%) electrodes with maximum specific capacitance of 2379 F/g at 1 A/g. Mn-CoS-3/NF also shows capacitance retention about 65% after 5500 cycles compared to CoS-3/NF (48%) and Cu-CoS-3/NF (55%) when performed as three electrode system configurations. The outstanding performance of Mn-CoS-3/NF as compared to the other electrodes is contributed to its high surface area, flake-like nanostructure, valence state of metal, and low internal resistance. In order to evaluate the real time performance of Mn-CoS-3/NF, supercapattery device was fabricated in a configuration of Mn-CoS-3/NF//AC/NF. Mn-CoS-3/NF//AC/NF delivered a specific energy (17.94 Wh/kg at 806 W/kg) and specific power (6405 W/kg at 4.66 Wh/kg). The capacity decayed slowly to 92% after 9000 cycles together with a coulombic efficiency of 99%, indicating good stability of the device.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Solid-phase diffusion controlled growth of nickel silicide nanowires.•NiSi nanowires growth is dependent on the Nickel film thickness.•NiSi nanowires densities increase with the ...increasing of Ni film thickness.•Specific capacitance enhancement of high density NiSi nanowires on Ni foil substrates is demonstrated.
This work reports on the influence of nickel (Ni) thickness on the growth of nickel silicide nanowires (NiSi NWs) using a solid-phase diffusion controlled growth treatment. The NiSi NWs were grown on two different substrates (i.e. crystal silicon (c-Si) and Ni foil) which were coated with Ni film with different thicknesses; 110 ± 5 and 220 ± 5 nm. FESEM images revealed that the shape, the size and the density of NiSi on both substrates were strongly dependent on the thickness of Ni film. These NWs exhibited morphology of straight NWs with diameter and length of between 16 to 23 nm and 2.9 to 3.9 µm, respectively. The NWs showed a single-crystalline Ni3Si2 phase with a preferred orientation in the (1 0 0) plane. XRD diffractogram proved that the formation of Ni-rich NiSi NWs is strongly dependent on the Ni film’s thickness rather than on the types of substrates. NiSi NF220 demonstrated the highest specific capacity with a maximum value of 313.3 C/g. This is attributed from the high density of NWs which endows more redox reaction and the high conductivity of Ni foil substrate that facilitated the high charge transfer kinetics. The fabricated NiSi NWs//activated carbon-based asymmetric supercapacitor exhibited the maximum energy density of 13.37 W h/kg at 200 W/kg and good cyclic stability with 79% capacity retention after 3000 cycles.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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