Due to its low cost, natural abundance, non-toxicity, and high theoretical capacitance, cobalt oxide (CoO) stands as a promising candidate electrode material for supercapacitors. In this study, binder-less molybdenum doped CoO (Mo@CoO) integrated electrodes were one-step fabricated using a simple electric discharge corrosion (EDC) method. This EDC method enables the direct synthesis of Mo@CoO active materials with oxygen vacancy on cobalt substrates, without any pre-made templates, conductive additives, or chemicals. Most importantly, the EDC method enables precise control over the discharge processing parameter of pulse width, which facilitates tailoring the surface morphologies of the as-prepared Mo@CoO active materials. It was found that the fabricated Mo@CoO based symmetric supercapacitor prepared by a pulse width of 24 mu s (Mo@CoO-SCs24) achieved a maximum areal capacitance 36.0 mF cm-2 (0.15 mA cm-2), which is 1.83 and 1.97 times higher than that of Mo@CoO-SCs12 and Mo@CoO-SCs36. Moreover, the Mo@CoO-SCs24 devices could be worked at 10 V s-1, which demonstrates their fast charge/discharge characteristic. These results demonstrated the significant potential of the EDC strategy for efficiency fabricating various metal oxide binder-less integrated electrodes for various applications, like supercapacitors, batteries and sensors.

Vanadium oxides are widely used for microsupercapacitors (MSCs) due to their multiple-valence and high theoretical capacitance. A conceptually new approach of electric discharge machining (EDM) with computer-aided control is developed to one-step fabricate Mo-doped VO0.2-based electrodes and devices with designable geometry. The results demonstrate that the Mo@VO0.2 integrated interdigital MSCs (IIMSCs) with the narrowest electrode distance of 300 mu m show the best capacitive performance, which is furtherly manifested by the electric field simulation. Moreover, this work concentrates on expounding the relationships between the EDM machining current, surface morphology of Mo@VO0.2, and the capacitive behavior of Mo@VO0.2 IIMSCs. Compared to the machining current of 2 and 3 A, the machining current of 1 A facilitates synthesizing smaller Mo@VO0.2 particles with more porosity and higher surface area and thus achieving a larger capacitance value for Mo@VO0.2 IIMSCs device, which is achieving 32 mF cm(-2) at 1 mV s(-1), working well up to an ultrahigh scan rate of 30 V s(-1), and obtaining a good cyclic stability of 88.61% after 5000 cycles. Moreover, this innovative EDM approach opens a new avenue for one-step synthesis of various ceramic metal oxides for various microdevices such as microbatteries and microsensors.

Phase change materials (PCM) battery thermal management system has been studied widely because of its higher heat storage capacity, low cost, and perfect chemical stability. However, pure phase change materials such as paraffin wax has low conductivity, leading to the system failure. Hence, it is necessary to develop an easy-to- pour, high-thermal-conductive and low-density material to be applied in battery thermal management. This paper introduced a new CNT@MXene aerogel to improve the system thermal conductivity. Characterizations and battery cycling test were conducted to verify the effectiveness. It is found that the prepared material has a high thermal conductivity, good 3D porous structure and excellent thermal stability. The designed thermal management system demonstrates rapid improvement on the battery temperature distribution so that the battery aging rate is reduced, extending the lifespan by 28.13 %, 18.92 %, and 11.83 % under 4C, 3C, and 2C rate conditions, respectively. The designed battery thermal management system in this study shows great potential for application in electric vehicles and hybrid electric vehicles to prolong the life span of the battery pack.

The structure of the distribution network system in distributed grids is complex, and with the large-scale integration of power electronic devices, the issue of serious harmonics is becoming increasingly prominent, thereby affecting the power quality of the grid and severely threatening the normal operation of sensitive equipment in the distribution network. This paper proposes a unified control strategy for PV grid-connected generation and active power filters (APF). Currently, APF devices are mainly used in industrial three-phase high-power systems to eliminate harmonics, but they are costly and have a single function. Therefore, this paper, based on the harmonic current detection principle in the instantaneous reactive power theory, proposes a unified control strategy for PV grid-connected generation and APFs. Finally, the proposed reactive current and harmonic current detection method and the design method of the current loop and voltage loop controllers are validated through simulation and experiments, proving their correctness and feasibility.

Due to their advantageous electronic structures, vacancies, and synergistic effects, ceramic bimetallic oxides demonstrate great potential for microsupercapacitor (MSC) applications. Scalable and controllable synthesis of bimetallic oxides with exceptional capacitive performance remains a challenging task. In this work, 3D binderless CuMoOx ceramic microsupercapacitors (CuMoMSC) with tailorable shapes are produced using direct electric discharge writing (DEDW) with facile computer-aided design. The important finding is that the electrochemical performance of CuMoMSC could be directly adjusted by the DEDW machining parameter of pulse width for the first time. Moreover, it is interesting to find the composition of the machining electrode materials could be tailored by the material of cutting tool via DEDW, opening a new way for customizing the electrochemical performance of MSCs. The manufactured 3D CuMoMSC exhibits a capacitance of 46.2 mF cm- 2 at 1 mV s- 1, and it retained 7.3 mF cm- 2 at super-high scan rate of 10 V s- 1, and possessed a good cycling stability of 97.6 % (2000 cycles), which was beneficial from the synergistic effects of bimetallic oxides and the introduction of oxygen vacancies. The results of this investigation manifest the wide range of possibilities for utilizing the DEDW technique in automatically manufacturing various ceramic bimetallic oxides with customized structure for various applications, such as catalysts, MSC and batteries.

Maximizing the oxygen evolution reaction (OER) catalytic activity of carbon coated core-shell electrocatalysts is significant for the application of water electrolyzers and rechargeable metal-air batteries, yet the modulation of the catalytic properties through interfaces coupling remains challenging. Here, we construct Fe5C2 phase interlayered between carbon shell and Co8FeS8 core (Co8FeS8-Fe5C2@C) for enhancing the alkaline OER catalytic performance. By altering the interlayer phase with Co1_xS as the control sample (Co8FeS8-Co1_xS@C), synchrotron X-ray absorption spectroscopy analysis integrated with density functional theory calculations indicate that the induced interfacial electron coupling of Co8FeS8-Co1_xS and Co8FeS8-Fe5C2 can upshift the D-band center toward Fermi level, optimalize Gibbs free energy for oxygen-containing intermediates, facilitate electron transfer between Co8FeS8 and carbon shell. Consequently, the target Co8FeS8-Fe5C2@C catalyst with stronger interface coupling and optimal electron modulation shows an significant overpotential (eta 10) decrease by 93 mV compared with Co8FeS8@C, along with a Tafel slop of 48.9 mV dec_ 1 and a long catalytic lifetime, outperforming commercial RuO2 and other reported analogous catalysts. This work opens up further opportunities of interlayer modification in carbon caoted core-shell catalyst to effictivly tailor the D-Band centers for effectively strengthen its catalytic performance.

Developing efficient and stable electrocatalysts to speed up the slow kinetics of oxygen evolution reaction (OER) is both an opportunity and a challenge. Herein, we present a metal-organic framework (MOF)-derived highly active OER catalyst (NiFe-MOF-S@CNT) composed of Fe/NiS heterostructure-embedded nanosheets interconnected by carbon nanotubes network via a direct two-step solvothermal method. The optimized NiFe-MOFS@CNT catalyst demonstrates outstanding OER activity: it requires an ultralow overpotential of 237 mV to deliver a current density of 10 mA/cm2 (eta 10) with a small Tafel slope of 42.3 mV/dec, surpassing the commercial RuO2 (eta 10 = 295 mV) and most other transition metal catalysts. Benefiting from the mesoporous structure and large specific surface area, the MOF-derived NiFe-MOF-S@CNT nanosheets facilitate enhancing mass transfer and electrolyte penetration. Additionally, the incorporation of Fe/NiS heterostructures within the nanosheets, along with carbon nanotubes, generates interfacial effects, promoting electronic interactions and exposing more active sites, thus significantly boosting OER activity. The backbone of carbon nanotubes not only enhances conductivity but also prevents agglomeration of the metal phase, ensuring uniform dispersion of active sites. This work offers a cost-effective and green approach for synthesizing highly efficient transition metal-based sulfides and also paves the way for advancing OER electrocatalysis for various energy applications.

The shuttle effect of lithium polysulfides (LiPSs) and uncontrollable lithium dendrite growth seriously hinder the practical application of lithium-sulfur (Li-S) batteries. To simultaneously address such issues, monodispersed NbN quantum dots anchored on nitrogen-doped hollow carbon nanorods (NbN@NHCR) are elaborately developed as efficient LiPSs immobilizer and Li stabilizer for high-performance Li-S full batteries. Density functional theory (DFT) calculations and experimental characterizations demonstrate that the sulfiphilic and lithiophilic NbN@NHCR hybrid can not only efficiently immobilize the soluble LiPSs and facilitate diffusion-conversion kinetics for alleviating the shuttling effect, but also homogenize the distribution of Li+ ions and regulate uniform Li deposition for suppressing Li-dendrite growth. As a result, the assembled Li-S full batteries (NbN@NHCR-S||NbN@NHCR-Li) deliver excellent long-term cycling stability with a low decay rate of 0.031% per cycle over 1000 cycles at high rate of 2 C. Even at a high S loading of 5.8 mg cm-2 and a low electrolyte/sulfur ratio of 5.2 lL mg-1, a large areal capacity of 6.2 mA h cm-2 can be achieved in Li-S pouch cell at 0.1 C. This study provides a new perspective via designing a dual-functional sulfiphilic and lithiophilic hybrid to address serious issues of the shuttle effect of S cathode and dendrite growth of Li anode.(c) 2023 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

As photovoltaic technologies are being promoted throughout the country, the widespread installation of distributed photovoltaic systems in rural areas in rural regions compromises the safety and stability of the distribution network. Distributed photovoltaic clusters can be configured with energy storage to increase photovoltaic local consumption and mitigate the impact of grid-connected photovoltaic modes. Against this background, this paper focuses on rural areas, combines typical operation modes of distributed photovoltaic clusters, and constructs the two-stage energy storage optimization configuration model for rural distributed photovoltaic clusters. Taking a Chinese village as an example, the proposed model is optimized with an improved particle swarm optimization algorithm. Given different combinations with and without energy storage and demand response, comparative analyses are conducted on photovoltaic local consumption and the economic benefits of independent operators in various scenarios. Simulations indicate that the photovoltaic local consumption proportion of distributed photovoltaic clusters with energy storage reaches 62.64%, which is 34.02% more than the scenario without energy storage. The results indicate that configuring energy storage for rural distributed photovoltaic clusters significantly improves the photovoltaic local consumption level. Meanwhile, implementing demand response can achieve the same photovoltaic local consumption effect while reducing the energy storage configuration, and the life-cycle economic benefits are appreciable. The simulation results show that participating in demand response can reduce the energy storage system cost by 7.15% at a photovoltaic local consumption proportion of 60%. This research expands application channels of rural distributed photovoltaic clusters and provides references for investment and operation decisions of distributed photovoltaic energy storage systems.

The efficiency of electrolytic water splitting is hampered by the slow kinetics of the oxygen evolution reaction (OER). Addressing this challenge, we present a novel catalyst with rich Ni3S4/FeNi2S4 heterostructures anchored metal-organic framework-derived nanosheets interconnected by carbon nanotubes (NiFe-S@CNT). The NiFe-S@CNT electrocatalyst shows an ultralow overpotential of 246 mV at a current density of 10 mA/cm2 (eta 10), surpassing the benchmark RuO2 (eta 10 = 291 mV) as well as many reported sulfide electrocatalysts. The strong heterointerface interaction between Ni3S4 and FeNi2S4 induce synergistic effects, modifying the electronic structure of active sites and generating a large number of lattice defects. Additionally, the carbon nanotubes skeleton facilitates efficient electron transfer and enhances electrical conductivity during the catalytic process. Moreover, the metal-organic framework derivative inherits a porous structure, aiding in electrolyte penetration and efficient bubble release. This study provides a facile and scalable strategy to develop nonprecious transition-metal-based OER catalysts with abundant heterointerfaces and active sites for efficient water splitting.

Dual-single-atom catalysts are well-known due to their excellent catalytic performance of oxygen reduction reaction (ORR) and the tunable coordination environment of the active sites. However, it is still challengable to finely modulate the electronic states of the metal atoms and facilely fabricate a catalyst with dual-single atoms homogeneously dispersed on conductive skeletons with good mass transport. Herein, atomic FeNx/ZnNx sites anchored N, S co-doped nano-porous carbon plates/nanotubes material (Fe0.10ZnNSC) is rationally prepared via a facile room-temperature reaction and high-temperature pyrolysis. The as-prepared Fe0.10ZnNSC catalyst exhibits a positive onset potential of 0.956 V, an impressive half-wave potential of 0.875 V, excellent long-term durability, and a high methanol resistance, outperforming the benchmark Pt/C. The outstanding ORR performance of Fe0.10ZnNSC is due to its unique nanoarchitecture: a large specific surface area (1092.8 cm2 g-1) and well-developed nanopore structure ensure the high accessibility of active sites; the high conductivity of the carbon matrix guarantees a strong ability to transport electrons to the active sites; and the optimized electronic states of FeNx and ZnNx sites possess good oxygen intermediate adsorption/desorption capacity. This strategy can be extended to design and fabricate other non-precious dual-single-atom ORR catalysts.

It is still challenging but crucial to plumb non-noble metal-based oxygen reduction reaction (ORR) catalysts with comparable or better performance than benchmark Pt/C catalysts. Herein, we proffer an unconven-tional core-shell-structured iron-based heterostructure electrocatalyst constructed by a Fe/Fe3C hetero-structure nanoparticle core wrapped by a graphitic shell embedded on a conductive N-doped mesoporous graphite skeleton (Fe/Fe3C@NC) via facile pyrolysis of MIL-53(Fe) (MIL = Material Institute Lavoisier) and melamine. The Fe/Fe3C@NC catalyst delivers more positive half-wave potential (E1/2) of 0.86 V and a low Tafel slope of 56 mV dec-1 for ORR, outpacing the benchmark Pt/C catalyst, and it also shows remarkable long-term durability and excellent methanol tolerance. The marvelous ORR behaviors can be attributed to its distinctive morphologic structure: the heterostructure can enhance intrinsic ORR activity; the core-shell nanostructure can enhance ORR activities through unique electron transfer between iron species and their conductive carbon shells, which can also act as protective barriers to ensure long-term stability; the high-content pyridinic-N doping can be used as additional active centers; and the abundant mesopores facilitate the diffusion of electrolyte, which can further upgrade ORR activities. This study proffers a strategy to design and fabricate non-noble catalysts with well-designed nanoarchitecture and high catalytic activity.(c) 2023 Elsevier B.V. All rights reserved.

Although metal-organic frameworks (MOFs) derived nonprecious catalysts for oxygen reduction reaction (ORR) have been intensively investigated, biological metal organic frameworks (Bio-MOF) derived ORR catalysts are rarely explored. Herein, for the first time, Bio-MOF-100 derived Fe species embedded N, S-doped carbon (Fe@NSC) is prepared by a simple solution soaking and pyrolysis. The Fe@NSC catalyst shows superior ORR performance with a large half-wave potential of 0.87 V, excellent methanol resistance, and exceptional long-term durability, which even surpasses the benchmark Pt/C catalyst. The brilliant ORR catalytic activity of Fe@NSC is due to its unique nanoarchitecture: more than one type of active constituents (Fe nanoparticles and Fe-N species) anchored N, S-doped carbon skeleton provides a high intrinsic catalytic activity; the nanoporous carbon matrix with a large specific surface area (1130.97 cm2 g-1) interconnected by in-situ grown carbon nanotubes with high conductivity can not only guarantee excellent mass transfer but also facilitate electron transfer. This research presents an approach to rationally design and facilely synthesize Bio-MOF-based ORR catalyst and demonstrates that Bio-MOF-based ORR catalysts are promising for efficient and stable oxygen reduction. (c) 2022 Elsevier B.V. All rights reserved.

Lithium dendrite growth and shuttling of lithium polysulfides (LiPSs) seriously hinder the industrialization of lithium-sulfur (Li-S) batteries. Herein, elaborately designed VN quantum dots anchored N-doped carbon nano -sheets (VN@NC) is employed as a bifunctional separator. The strong absorption and catalytic conversion of polar VN quantum dots effectively suppress the shuttling effect of LiPSs, confirmed by experimental and theoretical calculations studies; moreover, lithiophilic VN@NC acts as Li-ion redistributor to regulate and redistribute the interfacial ionic flux, thus effectively inhibit the uncontrollable growth of Li dendrites. As a result, the Li-S cell with VN@NC interlayer delivers ultralong cycle life (0.036 % per cycle at 2C over 1000 cycles) and high-rate capability (752 mAh/g at 4C). Even with sulfur loading (5.4 mg cm-2) and lean electrolyte/sulfur (E/S) usage (4.6 mu L mg-1), the pouch cell can deliver an initial areal capacity of 5.16 mAh cm-2 and still retain 4.02 mAh cm-2 at 0.1C over 50 cycles. The VN@NC-based Li-Li symmetric cells demonstrate great cycling and rate per-formance in protecting the Li anode. This work offers a bi-functionally integrated interlayer strategy to simul-taneously suppress the shuttling of LiPSs and dendrite growth of Li anode for high-performance Li-S and Li-metal batteries.

For large-scale fuel cell applications, it is significant to replace expensive Pt-based oxygen reduction reaction (ORR) electrocatalysts with nonprecious metal- or metal-free carbon-based catalysts with high activity. However, it is still challenging to deeply understand the role of intrinsic defects and the origin of ORR activity in pure nanocarbon. Therefore, a novel self-assembly and a pyrolysis strategy to fabricate defect-rich mesoporous carbon nanoribbons are presented. Due to the effective regulation of nanoarchitecture, a vast number of defective catalytic sites (edge defects and holes) are exposed, which thereby enhances the electron transfer kinetics and catalytic activity. Such undoped nanoribbons display a large half-wave potential of 0.837 V, excellent long-term stability, and exceptional methanol tolerance, surpassing the most undoped ORR catalysts and the commercial Pt/C (20 wt.%) catalyst. Structural characterizations and density functional theory (DFT) calculations confirm that the zigzag edge defects and the armchair pentagon at the hole defect are responsible for outstanding ORR performance.

Development of cost-effective, efficient, and durable electrocatalysts for oxygen evolution reaction (OER) with fast kinetic reaction is highly significant, considering the elevated thermodynamic energy barrier involved in water electrolysis. To overcome such challenges, an innovative vapor phased iron-doping strategy is employed on carbon nanotubes (CNT)-interlinked metal-organic framework (MOF) nanosheets (Ni-MOF@CNT) to obtain mixed metal oxide and metal heteronanoparticles superficially implanted partially (semi)-decomposed MOF nanosheets (Ni-M@C-400). These semi-MOF nanosheets attain the structural privileges related to MOF-nanostructure, mixed metal nanoparticles synergism, interconnected-CNT assisted high conductivity, and mechanical strength. As a result, Ni-M@C-400 exhibits exceptional OER activity with overpotential as low as 229 mV to reach the benchmark current density of 10 mA/cm2 (η10) and exhibits greatly reduced thermodynamic barrier (Tafel slopes of 40.51 mV/dec) along with significant durability for ∼60 h. More importantly, this sublimated iron-doped semi-MOF (Ni-M@C-400) displays significantly better OER performance over the corresponding annealed bimetallic MOF (NiFe-M@C-400: 270 mV at η10). Moreover, the successful incorporation of vapor phased iron into variety of MOFs (Cr, Mn, Co, Ni, and Cu) approved its uniqueness and the universality. This work provides an innovative vapor phased heteroatom-doping strategy to develop cost-effective and efficient electrocatalysts for water electrolysis.

Oxygen evolution reaction (OER) plays a decisive role in electrolytic water splitting. However, it is still challengeable to develop low-cost and efficient OER electrocatalysts. Herein, we present a combination strategy via heteroatom doping, hetero-interface engineering and introducing conductive skeleton to synthesize a hybrid OER catalyst of CNTinterconnected iron-doped NiP2/Ni2P (Fe-(NiP2/Ni2P)@CNT) heterostructural nanoflowers by a simple hydrothermal reaction and subsequent phosphorization process. The optimized Fe-(NiP2/Ni2P)@CNT catalyst delivers an ultralow Tafel slope of 46.1 mV dec(-1) and overpotential of 254 mV to obtain 10 mA cm(-2), which are even better than those of commercial OER catalyst RuO2. The excellent OER performance is mainly attributed to its unique nanoarchitecture and the synergistic effects: the nanoflowers constructed by a 2D-like nanosheets guarantee large specific area and abundant active sites; the highly conductive CNT skeleton and the electronic modulation by the heterostructural NiP2/Ni2P interface and the hetero-atom doping can improve the catalytic activity; porous nano structure benefits electrolyte penetration and gas release; most importantly, the rough surface and rich defects caused by phosphorization process can further enhance the OER performance. This work provides a deep insight to boost catalytic performance by heteroatom doping and interface engineering for water splitting. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.