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Sodium-ion batteries (SIBs) have garnered significant interest in energy storage due to their similar working mechanism to lithium ion batteries and abundant reserves of sodium resource. Exploring facile synthesis of a carbon-based anode materials with capable electrochemical performance is key to promoting the practical application of SIBs. In this work, a combination of petroleum pitch and recyclable sodium chloride is selected as the carbon source and template to obtain hard carbon (HC) anode for SIBs. Carbonization times and temperatures are optimized by assessing the sodium ion storage behavior of different HC materials. The optimized HC exhibits a remarkable capacity of over 430 mA·hg−1 after undergoing full activation through 500 cycles at a density of current of 0.1 A·g−1. Furthermore, it demonstrates an initial discharge capacity of 276 mAh·g−1 at a density of current of 0.5 A·g−1. Meanwhile, the optimized HC shows a good capacity retention (170 mAh·g−1 after 750 cycles) and a remarkable rate ability (166 mAh·g−1 at 2 A·g−1). The enhanced capacity is attributed to the suitable degree of graphitization and surface area, which improve the sodium ion transport and storage. [ABSTRACT FROM AUTHOR]

Mesoporous ZSM-5 zeolite (MZ) was used as support for Cu and Ce species, and the effects of structure and physical-chemical properties on selective catalytic reduction of NO with NH3 (NH3-SCR) were investigated. The characterization and experimental results show that the high activity of the Cu-Ce/MZ catalyst could be due to its high surface area, more and uniformly distributed active sites, and abundant oxidative species. Compared with the conventional ZSM-5 and SBA-15, the Cu-Ce/MZ possesses large amount of mesopores, and more accessible active sites, which are beneficial to accelerate the diffusion and improve the internal mass transfer in the denitration process. The Cu-Ce/MZ catalyst shows higher activity than Cu-Ce/ZSM-5 and Cu-Ce/SBA-15 at 200 °C. [ABSTRACT FROM AUTHOR]

Highlights: A freestanding MXene-derived defect-rich TiO2@reduced graphene oxides (M-TiO2@rGO) foam electrode was fabricated. M-TiO2@rGO presents fast Na+ storage kinetics due to capacitive contribution. M-TiO2@rGO foam electrode displays a capacity retention of 90.7% after 5000 cycles.Sodium ion batteries and capacitors have demonstrated their potential applications for next-generation low-cost energy storage devices. These devices's rate ability is determined by the fast sodium ion storage behavior in electrode materials. Herein, a defective TiO2@reduced graphene oxide (M-TiO2@rGO) self-supporting foam electrode is constructed via a facile MXene decomposition and graphene oxide self-assembling process. The employment of the MXene parent phase exhibits distinctive advantages, enabling defect engineering, nanoengineering, and fluorine-doped metal oxides. As a result, the M-TiO2@rGO electrode shows a pseudocapacitance-dominated hybrid sodium storage mechanism. The pseudocapacitance-dominated process leads to high capacity, remarkable rate ability, and superior cycling performance. Significantly, an M-TiO2@rGO//Na3V2(PO4)3 sodium full cell and an M-TiO2@rGO//HPAC sodium ion capacitor are fabricated to demonstrate the promising application of M-TiO2@rGO. The sodium ion battery presents a capacity of 177.1 mAh g−1 at 500 mA g−1 and capacity retention of 74% after 200 cycles. The sodium ion capacitor delivers a maximum energy density of 101.2 Wh kg−1 and a maximum power density of 10,103.7 W kg−1. At 1.0 A g−1, it displays an energy retention of 84.7% after 10,000 cycles. [ABSTRACT FROM AUTHOR]

This paper provides an overview of recent advances in urea electro-oxidation. Urea sources are abundant from human urine, urea-containing wastewater, and industrial urea, thus becoming an attractive option as anodic fuel for the application in direct urea fuel cells (DUFCs). Besides, as a hydrogen-rich chemical fuel, urea can also be electrolyzed to produce hydrogen for energy storage in the near future. The exact mechanisms of urea decomposition are pretty different in alkaline or neutral mediums and are separately discussed in detail. More importantly, the development of anodic electro-catalysts is of great significance for improving the electrochemical performance of both DUFCs and urea electrolysis cells, which is systematically summarized in our review. Challenges and prospects on the future development of urea electro-oxidation are particularly proposed. [ABSTRACT FROM AUTHOR]

NiMoO4 has attracted intensive attention as one of the promising ternary metal oxides because of its high specific capacitance and electrical conductivity compared to traditional transition-metal oxides. In this study, NiMoO4 nanorods uniformly decorated on graphene nanosheets (G-NiMoO4) are synthesized through a facile hydrothermal method. The prepared G-NiMoO4 composite exhibits a high specific capacitance of 714 C·g−1 at 1 A·g−1 and an excellent rate capability, with a retention ratio of 57.7% even at 100 A·g−1. An asymmetric supercapacitor (ASC) fabricated with the G-NiMoO4 composite as the positive electrode and Fe2O3 quantum dot-decorated graphene (G-Fe2O3-QDs) as the negative electrode delivers an ultrahigh energy density of 130 Wh·kg−1, which is comparable to those of previously reported aqueous NiMoO4-based ASCs. Even when the power density reaches 33.6 kW·kg−1, an energy density of 56 Wh·kg−1 can be maintained. The ASC device exhibits outstanding cycling stability, with a capacitance retention of 113% after 40,000 cycles. These results indicate that the G-NiMoO4 composite is a promising candidate for ASCs with ultrahigh energy density and excellent cycling stability. Moreover, the present work provides an exciting guideline for the future design of high-performance supercapacitors for industrial and consumer applications via the simultaneous use of various pseudocapacitive materials with suitable potential windows as the positive and negative electrodes. [ABSTRACT FROM AUTHOR]

A facile hydrothermal synthetic method, followed by in situ reduction and galvanic replacement processes, is used to prepare PtCo-modified CoO nanosheets (PtCo/CoO NSs) supported on Ni foam. The prepared nanomaterial is used as an electrocatalyst for NaBH oxidation in alkaline solution. The morphology and phase composition of PtCo/CoO NSs are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The catalytic performance of PtCo/CoO NSs is investigated by cyclic voltammetry (CV) and chronoamperometry (CA) in a standard three-electrode system. Current densities of 70 and 850 mA·cm were obtained at-0.4 V for Co/CoO and PtCo/CoO NSs, respectively, in a solution containing 2 mol·L NaOH and 0.2 mol·L NaBH. The use of a noble metal (Pt) greatly enhances the catalytic activity of the transition metal (Co) and CoO. Besides, both Co and CoO exhibit good B-H bond breaking ability (in NaBH), which leads to better electrocatalytic activity and stability of PtCo/CoO NSs in NaBH electrooxidation compared to pure Pt. The results demonstrate that the as-prepared PtCo/CoO NSs can be a promising electrocatalyst for borohydride oxidation. [ABSTRACT FROM AUTHOR]

Flexible and binder-free multi-walled carbon nanotube (MWNT)-modified sponge-based nickel (Ni) is employed as the electrode material for methanol (CHOH) electrooxidation. The nano-spherical Ni is electrodeposited on the surface of the MWNTs which are assembled on the skeleton of a commercial sponge. The as-prepared MWNT-modified sponge-based Ni electrode (MSNi) is characterized by scanning electron microscopy, transmission electron microscope, and X-ray diffractometer. The catalytic activity of the MSNi electrode for CHOH electrooxidation is investigated by means of cyclic voltammetry, chronoamperometry, and electrochemical impedance spectra. The preparation process of the flexible MSNi electrode does not use any binder and it exhibits a unique three-dimensional (3D) network-porous structure. The MSNi exhibits a high electrocatalytic performance of 23 mA (cm mg) in 0.5 mol dm CHOH at 0.5 V. [ABSTRACT FROM AUTHOR]

Cetyltrimethylammonium bromide (CTAB) was used as surfactants to modify the crystallization of β-Ni(OH) via a simple ammonia-evaporation/CTAB-induced method onto nickel foam by using a mixed aqueous solution of nickel nitrate, CTAB, and ammonia. Their structure and surface morphology are characterized by X-ray diffraction and scanning electron microscopy. The SEM images show changes in the microstructure of β-Ni(OH), and the XRD patterns exhibit a much higher relative diffraction intensity of (1 0 0) peaks with the addition of CTAB. The effects of CTAB content on the electrochemical behaviors of β-Ni(OH) are investigated by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy. The results demonstrate that the modified β-Ni(OH) electrode has better electrochemical performance, such as better reaction reversibility, higher proton diffuse coefficient, higher specific capacity, and better cyclic stability. Importantly, when the CTAB content in the initial solution was 0.03 g, the results show a drastic improvement in the capacitive characteristics of β-Ni(OH) with a specific capacitance increases from 386 to 1,019 F g at a high charging/discharging current density of 6 A g. [ABSTRACT FROM AUTHOR]

In this research, the effect of the different concentrations of NaSnO as the electrolyte additive in 0.7 mol L NaCl solution on the electrochemical performances of the magnesium-8lithium (Mg-8Li) electrode are investigated by methods of potentiodynamic polarization, potentiostatic current-time, electrochemical impedance technique, and scanning electron microscopy (SEM). The corrosion resistance of the Mg-8Li electrode is improved when NaSnO is added into the electrolyte solution. The potentiostatic current-time curves show that the electrochemical behaviors of the Mg-8Li electrode in the electrolyte solution containing 0.20 mmol L NaSnO is the best. The electrochemical impedance spectroscopy results indicate that the polarization resistance of the Mg-8Li electrode decreases in the following order with the concentrations of NaSnO: 0.05 mmol L > 0.00 mmol L > 0.30 mmol L > 0.10 mmol L > 0.20 mmol L. The scanning electron microscopy studies indicate that the electrolyte additive prevents the formation of the dense oxide film on the alloy surface and facilitates the peeling off of the oxidation products. [ABSTRACT FROM AUTHOR]

FeOOH nanowires were prepared and characterized with X-ray diffraction spectroscopy and scanning electron microscopy. A composite electrode consisting of FeOOH and Ni foam (FeOOH/Ni-foam) was fabricated, and its catalytic performance for oxygen evolution reaction (OER) was evaluated and compared with nanowire NiCoO/Ni-foam electrode. The mass current density of OER on FeOOH/Ni-foam is around three times of that on NiCoO/Ni-foam. Ni foam played a key role for the high activity of the FeOOH/Ni-foam. A synergistic mechanism of FeOOH and Ni was proposed to account for the superior catalytic performance of the FeOOH/Ni-foam electrode. Considering the low cost, abundant resource and environment-benign property of FeOOH, the FeOOH/Ni-foam electrode would be a promising anode for OER. [ABSTRACT FROM AUTHOR]

Fe-N-C catalysts were prepared through metal-assisted polymerization method. Effects of carbon treatment, Fe loading, nitrogen source, and calcination temperature on the catalytic performance of the Fe-N-C for HO electroreduction were measured by voltammetry and chronoamperometry. The Fe-N-C catalyst shows optimal performance when prepared with pretreated active carbon, 0.2 wt.% Fe, paranitroaniline (4-NA) and one-time calcination. The Fe-N-C catalyst displayed good performance and stability for electroreduction of HO in alkaline solution. An Al-HO semi-fuel cell was set up with Fe-N-C catalyst as cathode and Al as anode. The cell exhibits an open-circuit voltage of 1.3 V and its power density reached 51.4 mW cm at 65 mA cm. [ABSTRACT FROM AUTHOR]

Composites of CoO/graphene nanosheets are prepared and characterized by X-ray diffraction and scanning electron microscopy. Their electrochemical behavior as anode materials of lithium-ion rechargeable batteries is investigated by galvanostatic discharge/charge measurements and cyclic voltammetry. The composite is composed of CoO nanorods (around 20-40 nm in diameter) and nanoparticles (around 10 nm in diameter) distributed within the graphene matrix. The specific capacity of the composite is higher than both CoO and graphene nanosheets. The cycling stability of CoO is obviously enhanced by compositing with graphene. After 100 cycles, the discharge and charge capacity of the composite is 1,005 and 975 mAh g, respectively, and the irreversible capacity loss is less than 3%. [ABSTRACT FROM AUTHOR]