Transition metal sulfides gain much attention as electrode materials for supercapacitors due to their rich redox chemistry and high electrical conductivity. Designing hierarchical nanostructures is ...an efficient approach to fully utilize merits of each component. In this work, amorphous MoS2 is firstly demonstrated to show specific capacitance 1.6 times as that of the crystalline counterpart. Then, crystalline core@amorphous shell (Ni3S4@MoS2) is prepared by a facile one‐pot process. The diameter of the core and the thickness of the shell can be independently tuned. Taking advantages of flexible protection of amorphous shell and high capacitance of the conductive core, Ni3S4@amorphous MoS2 nanospheres are tested as supercapacitor electrodes, which exhibit high specific capacitance of 1440.9 F g−1 at 2 A g−1 and a good capacitance retention of 90.7% after 3000 cycles at 10 A g−1. This design of crystalline core@amorphous shell architecture may open up new strategies for synthesizing promising electrode materials for supercapacitors.
The nanoarchitecture of crystalline core/amorphous shell particles is proposed for enhanced capacitance and cyclability for supercapacitor electrodes. Driven by the concept, uniform transition metal sulfides core/amorphous shell nanospheres with tunable sizes are produced by a facile one‐pot solution‐based method. The resulting hybrids show great potential for supercapacitor applications.
Phosphorene, monolayer or few‐layer black phosphorus (BP), has recently triggered strong scientific interest for lithium/sodium ion batteries (LIBs/SIBs) applications. However, there are still ...challenges regarding large‐scale fabrication, poor air stability. Herein, we report the high‐yield synthesis of phosphorene with good crystallinity and tunable size distributions via liquid‐phase exfoliation of bulk BP in formamide. Afterwards, a densely packed phosphorene–graphene composite (PG‐SPS, a packing density of 0.6 g cm−3) is prepared by a simple and easily up‐scalable spark plasma sintering (SPS) process. When working as anode materials of LIBs, PG‐SPS exhibit much improved first‐cycle Coloumbic efficiency (60.2%) compared to phosphorene (11.5%) and loosely stacked phosphorene–graphene composite (34.3%), high specific capacity (1306.7 mAh g−1) and volumetric capacity (256.4 mAh cm−3), good rate capabilities (e.g., 415.0 mAh g−1 at 10 A g−1) as well as outstanding long‐term cycling life (91.9% retention after 800 cycles at 10 A g−1). Importantly, excellent air stability of PG‐SPS over the 60 days observation in maintaining its high Li storage properties can be achieved. On the contrary, 95.2% of BP in PG sample was oxidized after only 10 days exposure to ambience, leading to severe degradation of electrochemical properties.
A densely packed phosphorene–graphene composite is prepared by a simple and easily upscalable spark plasma sintering process, which exhibits much improved 1st‐cycle Coulombic efficiency, high volumetric capacity, good rate capabilities as well as an outstanding cycling life, especially robust air stability in maintaining its high Li storage properties.
Lithium‐ion capacitors (LICs) are hybrid energy storage devices that have the potential to bridge the gap between conventional high‐energy lithium‐ion batteries and high‐power capacitors by combining ...their complementary features. The challenge for LICs has been to improve the energy storage at high charge−discharge rates by circumventing the discrepancy in kinetics between the intercalation anode and capacitive cathode. In this article, the rational design of new nanostructured LIC electrodes that both exhibit a dominating capacitive mechanism (both double layer and pseudocapacitive) with a diminished intercalation process, is reported. Specifically, the electrodes are a 3D interconnected TiC nanoparticle chain anode, synthesized by carbothermal conversion of graphene/TiO2 hybrid aerogels, and a pyridine‐derived hierarchical porous nitrogen‐doped carbon (PHPNC) cathode. Electrochemical properties of both electrodes are thoroughly characterized which demonstrate their outstanding high‐rate capabilities. The fully assembled PHPNC//TiC LIC device delivers an energy density of 101.5 Wh kg−1 and a power density of 67.5 kW kg−1 (achieved at 23.4 Wh kg−1), and a reasonably good cycle stability (≈82% retention after 5000 cycles) within the voltage range of 0.0−4.5 V.
A hybrid Li‐ion capacitor is developed using a pyridine‐derived porous nitrogen‐doped carbon cathode, 3D interconnected titanium carbide nanoparticle chains as the anode, and LiPF6 as electrolyte. The demonstrated high energy and power densities of such a hybrid device can bridge the gap between Li‐ion batteries and EDLCs.
Nitrogen and sulfur dual‐doped Mo2C nanosheets provide low operating potential (−86 mV for driving 10 mA cm−2 of current density). Co‐doping of N and S heteroatoms can improve the wetting property of ...the Mo2C electrocatalyst in aqueous solution and induce synergistic effects via σ‐donation and π‐back donation with hydronium cation.
Self- and peer-feedback are commonly used in higher education, and in most cases, it is assumed that students will engage with the feedback. There is, however, limited systematic exploration of how ...students use the feedback. This study proposes a structured reflective journal for students to engage with both self- and peer-feedback in the context of teamwork competencies. In total, 519 undergraduates' self- and peer-ratings and feedback and a matching number of reflective journals were coded for how students internally negotiate self- and peer-feedback on teamwork competencies. The analysis of ratings shows upward trajectories of self- and peer-ratings over time, and the analysis of journals suggests students were more effective in building their teamwork competencies when they negotiate their experiences by giving attention to positive affect, goal intention and performance. These findings highlight the importance of priming students to be reflective of self- and peer-feedback via a written and codified reflective journal.
0D transition metal phosphides (TMPs) nanocrystals (NCs)–2D ultrathin black phosphorus (BP) heterostructure (Ni2P@BP) have been synthesized via a facile sonication‐assisted exfoliation followed by a ...solvothermal process. Compared with the bare BP, the specially designed Ni2P@BP architecture can enhance the electrical conductivity (from 2.12 × 102 to 6.25 × 104 S m–1), tune the charge carrier concentration (from 1.25 × 1017 to 1.37 × 1020 cm–3), and reduce the thermal conductivity (from 44.5 to 7.69 W m–1 K–1) at 300 K, which can be considered for multiple applications. As a result, the Ni2P@BP exhibits excellent Li storage properties and high hydrogen evolution reaction electrocatalytic activities. The Ni2P@BP shows improved Li diffusion kinetics (e.g., the Li ions diffusion coefficient increases from 1.14 × 10–14 cm2 s–1 for pure BP nanosheets to 8.02 × 10–13 cm2 s–1 for Ni2P@BP). In addition, the Ni2P@BP electrode sustains hydrogen production with almost unchanged activity over 3000 cycles, which indicates its good chemical stability when operating under strong reducing environment.
A 0D–2D Ni2P nanocrystals–black phosphorus heterostructure (Ni2P@BP, the Ni2P NCs homogeneously embedded in the BP nanosheets) is prepared by a facile sonication‐assisted exfoliation and a solvothermal process, which exhibits low thermal conductivity, excellent Li storage properties, and high hydrogen evolution reaction electrocatalytic activities.
Snails are important agricultural pests difficult to control, but data regarding molluscicidal assays are scant. Stemona alkaloids are typical secondary metabolites for the taxa and have been broadly ...investigated for their pharmacological and toxicological effects. This makes it possible for us to further develop the toxicities of these compounds to snails. In this work, we tested the antifeedant properties of leaves from seven Chinese Stemona species against the land snail species Bradybaena ravida in choice and non-choice feeding assays. The tested leaves Stemona parviflora exhibited the most deterrent effects, and a further phytochemical investigation of aerial parts led to the identification of 16 alkaloids. Among them, three novel alkaloids could be identified. The alkaloidal fraction and single alkaloids were further assayed against this snail species, and the results suggest a cocktail effect because the impact of the alkaloidal fraction was higher than the effects caused by single alkaloids. The study can promote the search process of natural antimollusc products from plants to control snails.
► Using ionic liquid as pre-treatment for glucose recovery from oil palm frond. ► Detail study on biomass composition changes during pretreatment under different pretreatment conditions. ► Study the ...changes in biomass crystallinity after pretreatment. ► Study the effects of biomass changes on digestibility and glucose recovery.
The chemical and physical changes of lignocellulosic biomass after subjecting to various pretreatment conditions were investigated in this current work. Subsequently, the effects of biomass changes on digestibility of cellulose to fermentable sugar (glucose) by enzyme were studied. Oil palm frond (OPF), the chosen biomass in this study was pretreated using ionic liquid (IL) 1-butyl-3-methylimidazolium chloride (BMIMCl) at different pretreatment conditions before subjected to analysis and subsequent enzymatic hydrolysis process. The pretreatment variables studied in this work are temperature, retention time and solid loading. Results showed that OPF experienced changes in lignin, cellulose and hemicellulose content after pretreatment due to dissolution as well as depolymerization process occurring during pretreatment. In addition to that, the recalcitrance of lignocellulosic biomass was effectively disrupted by ionic liquid pretreatment at various pretreatment conditions as cellulose digestibility of OPF was largely enhanced after pretreatment.
The potential of oil palm frond (OPF) for fuel ethanol production was investigated in this current work. Pretreatment of lignocellulosic feedstock with the novel solvent ionic liquid (IL) BMIMCl was ...used to facilitate the conversion of OPF into fermentable sugar (glucose). The pretreatment was accomplished by first subjecting OPF to ionic liquid treatment, followed by regeneration of cellulose using an anti-solvent. Scanning Electron Microscopy showed a significant destruction of biomass structure after pretreatment with IL, which in turn reduced the crystallinity and improved the enzymatic digestibility of the biomass. The effects of several pretreatment variables, such as temperature, retention time and solid loading, were studied using Response Surface Methodology (RSM) based on a factorial Central Composite Design (CCD). These factors were further optimised using RSM. An optimum 100% glucose recovery was found with pretreatment conditions of 80
°C, a 15-min retention time and 10% solid loading.
► Solution–liquid–solid growth of Ge nanowires in gold-seeded porous carbon. ► Simple and highly scalable production process. ► Porous carbon matrix improve electrical conductivity and buffer volume ...change. ► Synergistic effect between porous carbon and Ge nanowires enhances capacities. ► High reversible capacity of 789mAhg−1 during the 50th cycle at a current density of 160mAg−1.
Lithium-ion batteries have been actively researched in recent years due to it being one of the most promising energy storage systems. Herein, we report a novel approach where germanium nanowires (Ge NW) are grown in gold-seeded porous carbon via the solution–liquid–solid mechanism, and the corresponding improvement observed in terms of the specific capacity of this porous carbon–germanium nanowires (PC–Ge NW) composite anode. At a current density of 160mAg−1 and voltage window of 0.001–1.5V, a specific capacity of 789mAhg−1 during the 50th cycle for PC–Ge NW is achieved as compared to 624mAhg−1 during the 50th cycle for pure Ge NW. Even though the content of the Ge is only 53.5 weight percent in the PC–Ge NW composite, it yields a better stability and higher specific capacity, indicating a synergistic effect between porous carbon and Ge nanowires. There is also potential cost savings since the use of a lower amount of Ge can bring about good cycling properties.
