With a simple electrochemical process, we prepared nano-architectured CuO electrodes with a 3D hierarchically porous structure and an excellent supercapacitive performance. These nano-architectured ...CuO electrodes were processed through co-deposition of a Ni–Cu layer on Ni foam, selective etching of Cu from the Ni–Cu film (leaving tentacle-like nanoporous Ni), and anodic deposition of CuO nanoribbons (NRs) on the tentacle-like nanoporous Ni/Ni foam substrate. Because of its unique nano-architecture, the prepared CuO nanoribbon-on-Ni-nanoporous/Ni foam (CNRNP) electrode shows exceptional performance of energy storage relative to a conventional version of the electrode. The CNRNP electrode has also a superior kinetic performance relative to CuO nanoflake-on-Ni foam (CNFNF) and flake-like CuO (FLC) electrodes. Besides its excellent cyclic stability, an exceptionally large specific capacitance of 880 and 800 F g −1 (deducting the substrate capacitance from the total) for the CNRNP electrode is obtained at scan rates of 10 and 200 mV s −1 , respectively. The excellent pseudocapacitive characteristics of CNRNP electrodes associated with the variation of the Cu oxidation state during charge and discharge cycles were elucidated with in situ X-ray absorption near-edge structure (XANES) spectra.
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•Pd catalysts were synthesized by an impregnation method and subsequent varied pre-treatment conditions and H2 reduction.•Pr-treatment condition is the critical step for forming small ...Pd particles.•Catalyst with small Pd size showed high activity in benzyl alcohol oxidation.•Metallic Pd is the major phase when the reaction temperature is above 100°C.
SBA-15-supported Pd catalysts were prepared by impregnation, thermal pretreatment, and H2 reduction. The pretreatment conditions have an important influence on the resulting size (from 1.3 to 10.3nm) of the Pd particles; the catalyst prepared under vacuum conditions possessed the smallest particles (size 1.3nm). X-ray absorption spectra were used to analyze the transformation of the Pd precursor in each step of the preparation. These catalysts were applied to the oxidation of benzyl alcohol by molecular oxygen; the catalyst with the smallest Pd particles exhibited the highest turnover frequency (9684h−1). The catalyst was reusable three times without loss of activity (with conversion >96%). X-ray absorption spectra were recorded ex situ to monitor the oxidation and the coordination structure of Pd at varied temperatures of reaction; when the reaction temperature was above 100°C, the Pd species were in the metallic state. This result indicates that metallic Pd might be the active phase in the oxidation of benzyl alcohol by molecular oxygen.
Direct ethanol fuel cells (DEFCs) promise the use of ethanol as a bio‐renewable and non‐toxic fuel for energy conversion through the ethanol oxidation reaction (EOR). Well dispersed Pt3Sn and Pt ...nanoparticles on graphene (denoted Pt3Sn/G and Pt/G) support electrocatalysts made with alcohol reduction were tested towards EOR. The HRTEM and XRD characterizations provide the morphology and crystal phase of the Pt3Sn alloy nanoparticles, which has a uniform particle size of 2.8±0.08 nm, as is consistent with a Pt/G catalyst as reference. According to the in‐situ quick X‐ray‐absorption near‐edge structure (QXANES) spectra during an anodic scan of CV for the EOR test to explain clearly the potential‐dependent electronic state of the prepared electrocatalysts, the white‐line intensities of the Pt L3‐edge QXANES spectra and their spectral profiles vary appreciably with the electrode voltage. Moreover, Pt3Sn/G shows a better EOR performance than Pt/G because SnO2 can improve adsorption and dissociation during the oxidation by an appropriate expansion of the lattice parameters in the PtSn alloy. This work provides insight into the reaction mechanism of dissociative adsorption of ethanol on alloyed Pt surface, which has an important role in enhancing the EOR activity for a complete ethanol oxidation.
Electrocatalysis: The Pt L3‐edge white‐line intensity of Pt3Sn/G catalysts increases with increasing electrode potential during the forward direction of the CV scan, originating from the dissociative adsorption of ethanol (Pt−CH3CH2OHads) on the Pt surface. However, the active sites of the Pt nanoparticles might be blocked by many oxides such as CO (Pt−COads) on the alloy surface to reduce the white‐line intensity of Pt L3‐edge XAS spectra of Pt3Sn/G catalysts.
Solid polymer electrolytes (SPEs) show tremendous potential for solid-state lithium metal batteries; however, challenges such as low ionic conductivity and poor mechanical strength hinder their ...progress. This study integrates Fe-MIL-101 metal organic framework into a poly(vinylidene fluoride-
co
-hexafluoro propylene) (PVdF-HFP)-based SPE system to address these limitations. The integration of Fe-MIL-101 offers two critical benefits: (1) interaction of inorganic Fe
3+
metal centers with PVdF-HFP enables fast Li
+
transport by increasing free Li
+
availability in the system through Lewis acid-base interactions. (2) Fe-MIL-101 significantly improves the mechanical strength of the SPE, boosting its structural integrity. Fe-MIL-101-integrated SPE enables excellent room temperature cycling stability in solid-state Li|LiFePO
4
(LFP) full cells, retaining ∼91% capacity after 300 cycles and ∼89% capacity after 400 cycles at 0.2 C. Advanced characteristic techniques such as synchrotron-based
in situ
X-ray diffraction and X-ray absorption spectroscopy were employed to explore structural evolutions in the LFP cathode and the Fe-MIL-101-integrated SPE during cycling. Furthermore, improved room temperature electrochemical performance is demonstrated in solid-state Li|LiNi
0.6
Mn
0.2
Co
0.2
O
2
(NMC622) batteries with Fe-MIL-101-integrated SPE, retaining 91.4% capacity after 175 cycles at 0.1 C. This work highlights the effectiveness of Fe-MIL-101 in enhancing the SPE properties, paving the way for the advancement of high-performance solid-state lithium metal batteries.
This work reports Fe-MIL-101 MOF integrated SPE for improved LMBs. The presence of Fe
3+
metal centers enhances Li
+
transfer and boosts the electrochemical properties of the SPE, enabling stable cycling at room temperature in solid-state LMBs.
► Electrodeposition of Zn was successfully demonstrnated in the water- and air-stable BMP-DCA ionic liquid. While ZnCl
2 is insoluble in the BMP-TFSI ionic liquid, it dissolves easily in the BMP-DCA. ...► Amperometric titration experiments indicated that Zn(II) probably complexed as Zn(DCA)
3- with DCA- anion. ► Chronoamperometric experiments showed that the electrodeposition of Zn on GC and Mg alloy substrates involved 3D-instantaneous nucleation/growth process. ► A lower deposition rate would bring out a more uniform and compact Zn coating layer (which is also thicker) and, consequently, this coating revealed a protection capability for the Mg substrate against corrosion.
Electrochemical reaction of Zn(II)/Zn on glassy carbon electrode(GC) and Mg alloy substrates was investigated in the room-temperature ionic liquid,
N-butyl-
N-methyl-pyrrolidinium dicyanamide (BMP-DCA) containing ZnCl
2 at 323
K. Amperometric titration experiments suggest that Zn(II) reacted with DCA anions forming Zn(DCA)
3
− complex anion, which also could be reduced to Zn metal via a single-step electron transfer process. By chronoamperometric measurements, the electrodeposition of Zn on GC and Mg alloy substrates involved three-dimensional instantaneous nucleation under diffusion control at 323
K. The Zn deposits are also systematically characterized by the techniques of powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The Zn layer deposited at a lower current density on Mg alloy substrates was more compact and uniform when compared to that deposited at a higher current density; consequently, this coating revealed a protection capability for the Mg substrate against corrosion.
In this work, we successfully fabricated 3D network vanadium oxide (VOx) and manganese oxide (MnOx) nanofibers on conductive paper (PVA–acetamide–LiClO4-graphite/paper, PGP) as electrodes linked with ...an eco-friendly PVA–acetamide–LiClO4 (PAL) deep eutectic solvent-based gel electrolyte for high-voltage wearable asymmetric supercapacitors (HVWASCs). An ecologically compatible deep eutectic solvent-based electrolyte with self-supporting electroactive species has been generally accepted as a unique type of cost-effective and green electrolyte that possibly involves a bulk concentration of the electroactive species and a large working potential window, thereby achieving a high performance. The HVWASCs are able to work with a large operating voltage of 4.2 V, and supply outstanding energy and power densities (245 W hkg−1 at 0.18 W kg−1 and 95.3 kW kg−1 at 98 W h kg−1). The HVWASCs demonstrate remarkable cycling stability and durability after 6000 cycles, including bending and twisting (capacitance retention of 91.5%). The HVWASCs are a superior prospective candidate for wearable/flexible electronic devices and Internet of Things (IoT) applications.
Large-area Co(OH)2-based supercapacitor electrodes composed of nanotube arrays grown on a 3D nickel-foam (CONTA) electrode and sucker-like nanoporous films grown on a 3D nickel-foam (COSNP) ...electrode were prepared with a facile electrochemical method for applications in energy storage. These nanoporous Co(OH)2 electrodes were fabricated with the codeposition of Cu/Ni film on the nickel foam, then etching of Cu from the Cu/Ni layer to form Ni nanotube arrays and sucker-like Ni nanoporous layers, and further cathodic deposition of Co(OH)2 on the prepared nanoporous Ni substrates. The CONTA and COSNP electrodes exhibited specific capacitances of 2500 and 2900 F/g in a voltage range of 0.65 V (capacitance of the substrates deducted from the total) at 1 A/g in a three electrode cell, respectively. The COSNP electrode demonstrated an excellent supercapacitive performance with specific capacitances 1100 F/g at 1 A/g and 850 F/g at 20 A/g in a voltage range of 1.2 V in a two electrode cell. The remarkable performance of COSNP electrodes correlated with a large conversion of the Co oxidation state during the charge/discharge cycling were examined by in situ X-ray absorption near edge structure (XANES).
Three-dimensionally ordered macroporous (3DOM) metallic Mn films have been prepared with ordered polystyrene (PS) templates on electrodeposition from an ionic liquid (IL). A 3DOM Mn core-Mn oxide ...shell film was prepared on anodizing a 3DOM Mn film in KCl aqueous solution. The varied anodization courses were confirmed to cause variations of the material characteristics of the prepared 3DOM Mn/Mn oxide electrodes and thereby in their pseudocapacitive performance. The 3DOM Mn/Mn oxide electrodes anodized with the cyclic voltammetric method showed the most promising specific capacitance, 1200 plus or minus 60 F g super(-1) (based on the mass of 3DOM Mn/Mn oxides), with a satisfactory rate capability and cycling performance. Such electrodes can be potentially applied for lithium batteries and supercapacitors.
Binary oxides with atomic ratios of Ru/Ti = 90/10, 70/30, and 50/50 were fabricated using H2O2-oxidative precipitation with the assistance of a cetyltrimethylammonium bromide (CTAB) template, ...followed by a thermal treatment at 200 °C. The characteristics of electron structure and local structure extracted from X-ray absorption spectroscopy (XAS) and transmission electron microscopy (TEM) analyses indicate that incorporation of Ti into the RuO2 lattice produces not only the local structural distortion of the RuO6 octahedra in (Ru-Ti)O2 with an increase in the central Ru-Ru distance but also a local crystallization of RuO2. Among the three binary oxides studied, (Ru70-Ti30)O2 exhibits a capacitance improvement of about 1.4-fold relative to the CTAB-modified RuO2, mainly due to the enhanced crystallinity of the distorted RuO6 structure rather than the surface area effect. Upon increasing the extent of Ti doping, the deteriorated supercapacitive performance of (Ru50-Ti50)O2 results from the formation of localized nano-clusters of TiO2 crystallites. These results provide insight into the important role of Ti doping in RuO2 that boosts the pseudocapacitive performance for RuO2-based supercapacitors. The present result is crucial for the design of new binary oxides for supercapacitor applications with extraordinary performance.
