Anion and cation substitution is an effective way in modulating electrochemical properties of electrode materials to achieve enhanced performance. Herein, we report our finding in the fabrication of ...advanced binder-free supercapacitor electrodes of hierarchical anion- (phosphorus-) and cation- (zinc- and nickel-) substituted cobalt oxides (denoted as ZnNiCo-P) architectures assembled from nanosheets grown directly on Ni foam. In contrast to the reference Co-P systems, the as-prepared electrode manifests a markedly improved electrochemical performance with a high specific capacity of ~ 958 C g−1 at 1 A g−1 and an outstanding rate capability (787 C g−1 at 20 A g−1) due to its compositional and structural advantages. Density functional theory calculations confirm that the Co species partially replaced by Zn/Ni and O species by P can simultaneously improve the charge transfer behavior and facilitate the OH- adsorption and deprotonation/protonation reaction process. Moreover, an aqueous hybrid supercapacitor based on self-supported ZnNiCo-P nanosheet electrode demonstrates a high energy density of 60.1 Wh kg−1 at a power density of 960 W kg−1, along with a superior cycling performance (89% of initial specific capacitance after 8000 cycles at 10 A g−1 is retained). These findings offer insights into the rational design of transition metal compounds with multi-components and favorable architectures by manipulating the cations and anions of metal compounds for high-performance supercapacitors.
A high-performance mix-metal phosphide nanosheet electrode enables excellent capacity, rate capability, and cycle stability of hybrid supercapacitors. The electrode is composed of hierarchical Zn and Ni co-substituted Co phosphide nanosheet arrays grown on porous Ni foam. Display omitted
•Hierarchical ZnNiCo-P nanosheet arrays grown directly on Ni foam are constructed for the first time.•The resultant binder-free electrodes manifest outstanding electrochemical performances.•The synergetic contribution and structural features together contribute to outstanding electrochemical performance.•The assembled ZnNiCo-P//PPD-rGOs hybrid supercapacitor achieved a high energy density of 60.1 W h kg−1 at a power density of 960 W kg−1.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Elective home education is a significant aspect of the UK educational system, yet dedicated research on this topic is limited. This study, employing Appreciative Inquiry, explored the best practices ...perceived by 90 UK home-educating parents. It uncovered diverse strategies, emphasising the importance of resources such as technology, curricula, and collaborative efforts within home education co-operatives. Parents stressed the value of flexible learning environments and strong family commitment, envisioning a future with an enhanced home learning atmosphere and government and school support. They recommended concrete guidance for prospective home-educating parents, focusing on comprehensive child development. Ultimately, families aspired to shape a future for home education that prioritises enriched learning environments, broader societal recognition, and practical support for those embarking on the home education journey. The study’s findings have implications for children’s development, facilitating collaboration between homes and schools, as well as partnerships between families and educators.
Nanoscale surface‐engineering plays an important role in improving the performance of battery electrodes. Nb2O5 is one typical model anode material with promising high‐rate lithium storage. However, ...its modest reaction kinetics and low electrical conductivity obstruct the efficient storage of larger ions of sodium or potassium. In this work, partially surface‐amorphized and defect‐rich black niobium oxide@graphene (black Nb2O5−x@rGO) nanosheets are designed to overcome the above Na/K storage problems. The black Nb2O5−x@rGO nanosheets electrodes deliver a high‐rate Na and K storage capacity (123 and 73 mAh g−1, respectively at 3 A g−1) with long‐term cycling stability. Besides, both Na‐ion and K‐ion full batteries based on black Nb2O5−x@rGO nanosheets anodes and vanadate‐based cathodes (Na0.33V2O5 and K0.5V2O5 for Na‐ion and K‐ion full batteries, respectively) demonstrate promising rate and cycling performance. Notably, the K‐ion full battery delivers higher energy and power densities (172 Wh Kg−1 and 430 W Kg−1), comparable to those reported in state‐of‐the‐art K‐ion full batteries, accompanying with a capacity retention of ≈81.3% over 270 cycles. This result on Na‐/K‐ion batteries may pave the way to next‐generation post‐lithium batteries.
Surface‐amorphized and defect‐rich black niobium oxide@graphene nanosheets are constructed as anode materials for sodium and potassium storage, delivering a high‐rate Na/K storage capacity (123 and 73 mAh g−1, respectively at 3 A g−1) and long‐term cycling stability. Na/K full batteries based on the prepared anodes also demonstrate high energy and power densities.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
This article investigates the classical entropy generation in cooled slabs. Two types of materials are assumed for the slab: homogeneous material and FGM (functionally graded material). For the ...homogeneous material, the thermal conductivity is assumed to be a linear function of temperature, while for the FGM slab the thermal conductivity is modeled to vary in accordance with the rule of mixtures. The boundary conditions are assumed to be convective and radiative concurrently, and the internal heat generation of the slab is a linear function of temperature. Using the DTM (differential transformation method) and resultant temperature fields from the DTM, the local and total entropy generation rates within slabs are derived. The effects of physically applicable parameters such as the thermal conductivity parameter for the homogenous slab, beta , the thermal conductivity parameter for the FGM slab, gamma , gradient index, j, internal heat generation parameter, Q, Biot number at the right side, Nc2Nc2, conduction-radiation parameter, Nr2Nr2, dimensionless convection sink temperature, delta , and dimensionless radiation sink temperature, eta , on the local and total entropy generation rates are illustrated and explained. The results demonstrate that considering temperature- or coordinate-dependent thermal conductivity and radiation heat transfer at both sides of the slab have great effects on the entropy generation.
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To ensure a long-term quantum computational advantage, the quantum hardware should be upgraded to withstand the competition of continuously improved classical algorithms and ...hardwares. Here, we demonstrate a superconducting quantum computing systems Zuchongzhi 2.1, which has 66 qubits in a two-dimensional array in a tunable coupler architecture. The readout fidelity of Zuchongzhi 2.1 is considerably improved to an average of 97.74%. The more powerful quantum processor enables us to achieve larger-scale random quantum circuit sampling, with a system scale of up to 60 qubits and 24 cycles, and fidelity of FXEB=(3.66±0.345)×10-4. The achieved sampling task is about 6 orders of magnitude more difficult than that of Sycamore Nature 574, 505 (2019) in the classic simulation, and 3 orders of magnitude more difficult than the sampling task on Zuchongzhi 2.0 arXiv:2106.14734 (2021). The time consumption of classically simulating random circuit sampling experiment using state-of-the-art classical algorithm and supercomputer is extended to tens of thousands of years (about 4.8×104 years), while Zuchongzhi 2.1 only takes about 4.2 h, thereby significantly enhancing the quantum computational advantage.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Smartly designed nanoarchitectures with effective hybridization of transition metal oxides/hydroxides are promising to realize high performance electrodes for energy storage devices. To promote the ...applications of high-power supercapacitors, a seed-assisted method is firstly applied to prepare mesoporous Ni–Co–Mn hydroxide nanoflakes (NCMH) on nickel foam with practical mass loadings (higher than 5 mg cm −2 ). Further mechanism study reveals that the Ni(OH) 2 nanorod arrays, which are firstly prepared by a hydrothermal process, serve as seeds for the successful deposition of NCMH nanoflakes. Through this convenient and cost effective method, this design results in a more orderly spatial distribution, lower intrinsic resistance and shorter electron transport pathways. The proof-of-concept application of NCMH as a binder-free supercapacitor electrode reveals an impressive specific capacity of 1043.1 μA h cm −2 at a high mass loading of 5.2 mg cm −2 . The NCMH//activated carbon asymmetric device delivered a maximum energy density of 55.42 W h kg −1 at a power density of 750 W kg −1 , exhibiting great potential as an energy storage device and shedding light on the structural design of nanomaterials.
Quantum walks are the quantum mechanical analog of classical random walks and an extremely powerful tool in quantum simulations, quantum search algorithms, and even for universal quantum computing. ...In our work, we have designed and fabricated an 8x8 two-dimensional square superconducting qubit array composed of 62 functional qubits. We used this device to demonstrate high fidelity single and two particle quantum walks. Furthermore, with the high programmability of the quantum processor, we implemented a Mach-Zehnder interferometer where the quantum walker coherently traverses in two paths before interfering and exiting. By tuning the disorders on the evolution paths, we observed interference fringes with single and double walkers. Our work is an essential milestone in the field, brings future larger scale quantum applications closer to realization on these noisy intermediate-scale quantum processors.
How leaders influence followers have been a hot topic in both research and practice. Yet, prior studies have primarily focused on the impact of one leadership style, while overlooking how a ...leadership role may influence behavioral expressions of leaders. Particularly, being a leader means having to face time demands and workload pressure, and thus, busyness becomes a common phenomenon for leaders. Focused on perceived leader busyness, we had examined how it may influence employee interactions with leaders and how those interactions influenced leader evaluations of the performance of followers. Based on sensemaking theory, we propose that when followers have a high level of perspective taking, they are more likely to take avoidance behavior when perceiving leaders as of high busyness. Further, when followers engage in interaction avoidance behavior, leaders may consider followers as hiding errors or intentionally concealing their work process, which reduces positive evaluations (i.e., task performance and conscientiousness evaluation) while enhancing negative evaluation (i.e., deviance behavior) toward followers. We conducted two studies. Study one was conducted with a 25 participants interview and data of 297 employees to show scale validity of perceived leader busyness. Study two was conducted with 377 employees and their direct supervisors. Applying the complex modeling method, we found that followers with low-level perspective taking are less likely to engage in interaction avoidance behavior, even when perceiving leaders as high busyness; interaction avoidance behavior of followers has a positive relationship with counterproductive behavior evaluation of leaders, but a negative relationship with conscientiousness behavior evaluation. This study enriches the dyadic interactions between leaders and followers. In addition, it also shows the burden of perspective taking.
Entropy generation rate is directly related to exergy destruction and is therefore to useful energy. This study investigates temperature distribution and local and total entropy generation rates ...within a composite hollow cylinder with temperature-dependent thermal conductivity and internal heat generation. The internal heat generation is considered constant but different for inner and outer materials. Two cases are examined: (a) constant temperature boundary conditions and (b) asymmetric convective cooling boundary conditions for inside and outside surfaces. The general solution for the system of equations is analytically found, and constant parameters are numerically calculated for each case. Moreover, complete analytical solution is performed for cases with temperature-independent thermal conductivities. For the first case, temperature distribution and entropy generation depend on eight parameters, and for the second case, the reported data depend on ten thermophysical parameters. After verifying the solution procedure, a comprehensive study is performed for temperature distribution and total entropy generation rate with various values for different parameters. Thus, the new proposed data and graphs in this study provide a remarkable tool and at the same time retain suitable simplicity for engineers. The results should be useful in a number of engineering applications and considerably ease the processes of choosing geometrical parameters together with environment temperature or heat transfer coefficient when dealing with composite hollow cylinders with two-layer materials for less entropy generation, that is, less exergy destruction.
•Local and total entropy generation rates in composite hollow cylinders are investigated.•Both constant temperature and convective asymmetric boundary conditions are considered.•A combined numerical–analytical technique is used and verified against exact solution.
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Developing of inexpensive, high-efficient, and earth-abundant bifunctional catalysts for water splitting is of great significance for green and sustainable energy development. Herein, a bifunctional ...hybrid electrocatalyst of Ni3ZnC0.7 nanodots in-situ grown on nitrogen-doped carbon nanotube (Ni3ZnC0.7/NCNT) arrays is synthesized by a one-step template strategy with 1, 3, 5-triamino-2, 4, 6-trinitrobenzene serving as carbon/nitrogen sources, ZnO nanorods as template and zinc source, and nickel foam as substrate and nickel source. Benefiting from the introduction of Ni3ZnC0.7 nanodots and nitrogen doping to the carbon nanotubes, the Ni3ZnC0.7/NCNT-700 arrays exhibit superior hydrogen evolution reaction and oxygen evolution reaction catalytic activity in terms of low overpotential (203 mV and 380 mV vs RHE at 10 mA cm−2 for hydrogen evolution reaction and oxygen evolution reaction, respectively). When the Ni3ZnC0.7/NCNT-700 is served as both anode and cathode catalysts for overall water splitting, a potential of 1.66 V is needed to deliver a current density of 10 mA cm−2, and it also displays negligible degradation after 24 h of operation in alkaline solution. The present work not only provides an efficient bifunctional electrocatalyst for overall water splitting, but also offers a new strategy to design and synthetize the bimetallic carbide.
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