Next-generation Energy Technologies Research Articles

In-situ probing polarization-induced stability of single-atom alloy electrocatalysts in metal-air battery via synchrotron-based X-ray diffraction

In this work, a novel single-atom alloy electrocatalyst (SAAE) was developed for enhanced electrocatalysis in next-generation energy technologies. The catalyst, composed of single-atom Rh and bulk Ni on FeV3O8 support, overcomes challenges related to stability and efficiency in electrochemical reactions. The work function difference between Rh and Ni, as confirmed by computational and synchrotron-based analysis, facilitates superior electric polarization and ohmic contact with FeV3O8. The FeV3O8@RhNi demonstrates outstanding performance in oxygen reduction reactions (ORRs) and oxygen evolution reactions (OERs), with high half-wave potential (0.90 V) and low overpotential (120 mV at 10 mA cm−2). In zinc-air batteries, it maintains a stable discharge–charge voltage gap, specific capacity of 810 mAh g−1, peak power density of 186 mW cm−2 at 320 mA cm−2, and cycle stabilities exceeding 859 h at 10 mA cm−2. The catalyst also proves its durability in flexible zinc–air batteries, indicating its potential for efficient electrocatalytic reactions in emerging energy technologies.

Leveraging Additive Manufacturing to Fabricate High Temperature Alloys With Co-Designed Mechanical Properties and Environmental Resistance

Abstract A paradigm shift in the traditional sequential design approaches is critically essential to create application-specific hierarchical and multifunctional materials with superior long-term performance for next-generation energy technologies involving extreme environments. In the current work, we aim to leverage the flexibility and geometric/compositional complexity offered by additive manufacturing to demonstrate this new approach by codesigning a compositionally graded Ni-based alloy for molten salts\sCO2 heat exchangers to enable mitigation of environmental degradation of surfaces exposed to molten halide salts, while simultaneously suppressing the consequent deterioration in mechanical stability. Thermokinetic modeling describing the underlying physics of thermally- and environmentally induced spatiotemporal compositional and microstructural evolution will be employed to predict the parameter space of material deposition processes and precisely identify the required composition gradient. Preliminary corrosion and mechanical testing of the dual material demonstrated the potential of the material to replace existing solid solution strengthened materials for this application.

One-step growth of RuNi-MOF nanoarrays on carbon felt host as a high-performance binder-free electrode for dual application: Ethanol fuel cell and supercapacitor

The future perspective is to develop high-efficient catalysts in next-generation energy technologies. Metal-organic frameworks (MOFs) offer a high degree of design flexibility which plays an important role as electrocatalysts. However, poor stability and low conductivity of MOFs are challenging to favorable electrocatalytic activity. Accordingly, a new and efficiently bimetallic RuNi-MOF is fabricated by in-situ growth of 3D nanoscale of MOFs on a 3D network of carbon felt (CF) to enhance the practical applicability of direct ethanol fuel cells (DEFCs) and supercapacitors (SCs). The RuNi-MOF/CF displays remarkable performance for SCs (the high specific capacitance of 1173.7 mF cm−2 (810.8 F g−1) at 6 mA cm−2, a high energy density of 145.9 Wh kg−1 and a power density of 6 kW kg−1 with cyclic retention of 95 %) and as an anode in DEFCs (peak current density of 84.6 mA cm−2 and power density of 70.2 mW cm−2 at 60 °C). The electron/ion transport ability and electrocatalytic performance of RuNi-MOF are enhanced due to the incorporation of Ru about 1.0 %. The success is attributed to the synergistic effects between Ru, Ni, and conductive CF. This work highlights a new understanding of using high-performance materials to improve electrocatalytic activity.

Boosted Oxygen Kinetics of Hierarchically Mesoporous Mo2C/C for High-current-density Zn-air Battery.

The high-current-density Zn-air battery shows big prospects in next-generation energy technologies, while sluggish O2 reaction and diffusion kinetics barricade the applications. Herein, the sequential assembly is innovatively demonstrated for hierarchically mesoporous molybdenum carbides/carbon microspheres with a tunable thickness of mesoporous carbon layers (Meso-Mo2C/C-x, where x represents the thickness). The optimum Meso-Mo2C/C-14 composites (≈2µm in diameter) are composed of mesoporous nanosheets (≈38nm in thickness), which possess bilateral mesoporous carbon layers (≈14nm in thickness), inner Mo2C/C layers (≈8nm in thickness) with orthorhombic Mo2C nanoparticles (≈2nm in diameter), a high surface area of ≈426m2g-1, and open mesopores (≈6.9nm in size). Experiments and calculations corroborate the hierarchically mesoporous Mo2C/C can enhance hydrophilicity for supplying sufficient O2, accelerate oxygen reduction kinetics by highly-active Mo2C and N-doped carbon sites, and facilitate O2 diffusion kinetics over hierarchically mesopores. Therefore, Meso-Mo2C/C-14 outputs a high half-wave potential (0.88V vs RHE) with a low Tafel slope (51mVdec-1) for oxygen reduction. More significantly, the Zn-air battery delivers an ultrahigh power density (272mWcm-2), and an unprecedented 100h stability at a high-current-density condition (100mAcm-2), which is one of the best performances.

WSe2-VSe2 Alloyed Nanosheets to Enhance the Catalytic Performance of Hydrogen Evolution Reaction.

Tuning the electronic structures of transition metal dichalcogenides (TMD) is essential for their implementation in next-generation energy technologies. In this study, we synthesized composition-tuned WSe2-VSe2 (W1-xVxSe2, x = 0-1) alloyed nanosheets using a colloidal reaction. Alloying the semiconducting WSe2 with VSe2 converts the material into a metallic one, followed by a 2H-to-1T phase transition at x = 0.7. Over a wide composition range, WSe2 and VSe2 are atomically immiscible and form separate ordered domains. The miscible alloy at x = 0.1 displayed enhanced electrocatalytic activity toward the hydrogen evolution reaction (HER) in an acidic electrolyte. This trend was correlated with the d-band center via a volcano-type relationship. Spin-polarized density functional theory calculations consistently predicted the atomic immiscibility, which became more significant at the 2H-1T phase transition composition. The Gibbs free energy of H adsorption on the basal planes (Se or hole sites) and the activation barriers along the Volmer-Heyrovsky reaction pathway supported the enhanced HER performance of the alloy phase, suggesting that the dispersed V-doped structures were responsible for the best HER catalytic activity. Our study demonstrates how the atomic structure of TMD alloy nanosheets plays a crucial role in enhancing catalytic activity.

Metal-Organic Frameworks for Ion Conduction.

Solid-state ionic conductors are compelling alternatives to liquid electrolytes in clean energy-harvesting and -storage technologies. The development of novel ionic conducting materials is one of the most critical challenges for next-generation energy technologies. Several advancements in design strategies, synthetic approaches, conducting properties, and underlying mechanisms for ionic conducting metal-organic frameworks (MOFs) have been made over the past five years; however, despite the recent, considerable expansion of related research fields, there remains a lack of systematic overviews. Here, an extensive introduction to ionic conducting performance for MOFs with different design strategies is provided, focusing primarily on ion mobility with the aid of hydrogen-bonding networks or solvated ionic charge. Furthermore, current theories on ion conducting mechanisms in different regimes are comprehensively summarized to provide an understanding of the underlying working principles in complex, realistic systems. Finally, challenges and future research directions at the forefront of ionic conducting MOF technologies are outlined.

Iron carbide decorated carbon nanosphere- sheet hybrid based rechargeable high-capacity non-aqueous Li–O2 batteries

High energy density carbon-neutral electrochemical systems are highly sought after for next-generation energy technologies, and lithium-oxygen (Li–O2) battery occupies a unique position in them. Here, we report the development of a high capacity (9000 mAh g−1), long-term cyclability (>60 cycles), low-cost (iron and carbon) catalyst based non-aqueous Li–O2 battery and unravel the role of the catalyst's porosity and structure in the battery performance. A scalable catalyst, named FeNxCy (S/S), is shown as the bifunctional catalyst at the cathode of the cell, where FeNxCy(S/S) has a unique structure constituted by nitrogen doped iron carbide nanoparticles decorated graphitic carbon spheres connected via graphitic sheets. The mechanism of the growth of discharged product in correlation with the high surface area and meso-porosity in FeNxCy (S/S) are studied using in situ Raman and ex situ XRD studies. The study shows the potential of Li–O2 batteries as low-cost energy systems having high energy density (2920 Wh kgLi2O2−1) and power density (18 mW cm−2) values that are close to their theoretical limits.

Eco-Friendly Triboelectric Material Based on Natural Rubber and Activated Carbon from Human Hair.

The triboelectric nanogenerator (TENG) has emerged as a novel energy technology that converts mechanical energy from surrounding environments to electricity. The TENG fabricated from environmentally friendly materials would encourage the development of next-generation energy technologies that are green and sustainable. In the present work, a green triboelectric material has been fabricated from natural rubber (NR) filled with activated carbon (AC) derived from human hair. It is found that the TENG fabricated from an NR-AC composite as a tribopositive material and a poly-tetrafluoroethylene (PTFE) sheet as a tribonegative one generates the highest peak-to-peak output voltage of 89.6 V, highest peak-to-peak output current of 6.9 µA, and can deliver the maximum power density of 242 mW/m2. The finding of this work presents a potential solution for the development of a green and sustainable energy source.

CsPbI3 Nanocrystals Go with the Flow: From Formation Mechanism to Continuous Nanomanufacturing (Adv. Funct. Mater. 6/2022)

CsPbI3 Nanocrystals In article number 2108687, Milad Abolhasani and co-workers feature a modular flow chemistry strategy for synthesis science studies of CsPbI3 nanocrystals (NCs). The reconfigurable flow reactors enable on-demand selection of the NC synthetic route and provide in-situ access to the optical properties of the in-flow synthesized NCs. Hot-injection NC synthesis in flow provides a new frontier for scalable nanomanufacturing of CsPbI3 NCs for next-generation energy technologies.

Interfacial defect engineering via combusted graphene in V2O5 nanochips to develop high‐rate and stable zinc-ion batteries

With the increasing demand of energy sources, various electrical devices have attracted considerable attention. Rechargeable aqueous zinc-ion batteries (ZIBs) represent an attractive choice in the battery industry owing to their unique properties of a high specific capacity, reliable safety, and eco-friendliness. However, the practical application of ZIBs is hindered owing to the unstable energy storing reactions of the vanadium-based cathode, which occur because of the limited electrochemical capacity and kinetics. In this study, we formulated an original strategy based on defect engineering to form interface-defective V2O5 nanochips by using combusted graphene in the electrospun polyacrylonitrile fiber template method. This framework exhibits a high specific capacity, rate capability, and long-tern cycling stability, with a high energy density of 437 W h kg−1 at a power density of 450 W kg−1. These improvements can be attributed to the acceleration of the diffusion kinetics of zinc ions and electrical conductivity of the electrode via the interfacial Vo and facilitation of the active and stable receptivity of electrochemical reactions between electrons and zinc ions through the provision of interfacial open channels. The proposed approach can promote the development of a promising cathode electrode for high‐rate and stable ZIBs as next-generation energy technologies.

Oriented Electrostatic Effects on O2 and CO2 Reduction by a Polycationic Iron Porphyrin

Next-generation energy technologies require improved methods for rapid and efficient chemical-to-electrical energy transformations. One new approach has been to include atomically positioned, electrostatic motifs in molecular catalysts to stabilize high-energy, charged intermediates. For example, an iron porphyrin bearing four cationic, o-N,N,N-trimethylanilinium groups (o-[N(CH3)3]+) has recently been used to catalyze the complex, multistep O2 and CO2 reduction reactions (ORR and CO2RR) with fast rates and at low overpotentials. The success of this catalyst is attributed, at least in part, to specific charge-charge interactions between the atomically positioned o-[N(CH3)3]+ groups and the bound substrate. However, by nature of the mono-ortho substitution pattern, there are four possible atropisomers of this metalloporphyrin and thus four unique electrostatic environments. This work reports that each of the four individual atropisomers catalyzes both the ORR and CO2RR with fast rates and low overpotentials. The maximum turnover frequencies vary among the atropisomers, by a factor of 60 for the ORR and a factor of 5 for CO2RR. For the ORR, the αβαβ isomer is the fastest and has the highest overpotential, while for the CO2RR the αααα isomer is the fastest and has the highest overpotential. The role of charge positioning is complex and can affect more than a single step such as CO2 binding. These data offer a first-of-a-kind perspective on atomically positioned charge and highlight the significance of high charge density, rather than orientation, on the thermodynamics and kinetics of multistep molecular electrochemical transformations.

Processing of tungsten through electron beam melting

Additive manufacturing (AM) presents a new design paradigm for the manufacture of engineering materials through the layer-by-layer approach combined with welding theory. In the instance of difficult to process materials such as tungsten and other refractory metals, AM offers an opportunity for radical redesign of critical components for next-generation energy technologies including fusion. In this work, electron beam powder bed fusion (EB-PBF) is applied to process pure tungsten to study the influence of process parameters on the defect density of the material. An in-situ image analysis algorithm is applied to pure tungsten for the first time, and is used to visualize the defect structure in AM tungsten. Finally, a cracking mechanism for AM tungsten is proposed, and suggestions for suppression of cracks in pure tungsten are offered.

Growth of Multiorientated Polycrystalline MoS2 Using Plasma-Enhanced Chemical Vapor Deposition for Efficient Hydrogen Evolution Reactions.

Molybdenum disulfide (MoS2) has attracted considerable attention as a promising electrocatalyst for the hydrogen evolution reaction (HER). However, the catalytic HER performance of MoS2 is significantly limited by the few active sites and low electrical conductivity. In this study, the growth of multiorientated polycrystalline MoS2 using plasma-enhanced chemical vapor deposition (PECVD) for the HER is achieved. The MoS2 is synthesized by sulfurizing a sputtered pillar-shaped Mo film. The relatively low growth temperature during the PECVD process results in multiorientated MoS2 with an expanded interlayer spacing of ~0.75 nm, which provides abundant active sites, a reduced Gibbs free energy of H adsorption, and enhanced intralayer conductivity. In HER applications, the PECVD-grown MoS2 exhibits an overpotential value of 0.45 V, a Tafel slope of 76 mV dec−1, and excellent stability in strong acidic media for 10 h. The high HER performance achieved in this study indicates that two-dimensional MoS2 has potential as an electrocatalyst for next-generation energy technologies.

Two-dimensional Metal-Organic Frameworks as Electrocatalysts for Oxygen Evolution Reaction

Oxygen evolution reaction(OER) plays an important role in many electrochemical systems. However, its sluggish kinetics severely limits the development of next-generation energy technologies. Recently, two-dimensional(2D) metal-organic frameworks(MOFs) have attracted much attention as a class of promising electrocatalysts. Their diverse components and tunable structures provide a new platform to design and explore ideal electrocatalysts. The ultrathin characteristics including high specific surface area, abundant exposed metal sites and fast electronic transfer further promote the electrocatalytic performance of 2D MOFs. Therefore, many attempts have been made in synthesizing 2D MOF-based electrocatalysts in recent years. This review focuses on the strategies to fabricate 2D MOFs with high electrocatalytic performances for OER. The discussion on challenge and development of their electrocatalytic application is also presented.

Tritium Content and Chemical Form in Nuclear Graphite from Molten Fluoride Salt Irradiations

Advanced reactor applications that use a molten fluoride salt coolant and graphite moderator are under consideration as next-generation energy technologies. For molten salts with lithium or beryllium, such as flibe (2LiF-BeF2), the production of tritium from neutron irradiation is a significant technical challenge. Understanding the expected quantities and mechanisms for tritium retention in graphite is important for designing tritium management strategies in these advanced reactors. In this work, the tritium content of IG-110U graphite from a 2013 in-core flibe irradiation experiment was measured by leaching in water and thermal desorption. Five total samples were tested, with an average measured tritium content per salt-contacting surface area of 3.83 ± 0.25 Ci/m2. The tritium measured from the thermal desorption experiments was primarily in a water-insoluble form. Compared to the overall tritium generation during the irradiation, the total amount of retention in graphite predicted by the desorption measurements is significant.

Graphene-cobalt based oxygen electrocatalysts

Increasing green energy demands and environmental concerns have promoted extensive research on the development of next-generation energy technologies with high efficiency and environmental friendliness. One big challenge of electrochemical energy conversion and storage is to facilitate the core electrocatalytic oxygen reactions, including oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), which commonly suffering from slow kinetics. In the past decade, great effort has been devoted to the development of next-generation oxygen electrocatalysts based on transition metals, among which cobalt-based compounds stand out as one of the most promising candidates for precious metals, as exhibiting highly efficiency, excellent stability, plus low-cost and earth-abundance. Here, recent progresses on the synthesis, structure and performance of various oxygen electrocatalysts of cobalt related, including metallic Co, Co-nonmetallic compounds, Co-metallic compounds and Co single-atom catalysts, are summarized, and the perspectives on the future developments are discussed.

On-chip micro/nano devices for energy conversion and storage

Abstract The evolution of next-generation energy technologies is growing in importance as the global demand for energy skyrockets. Nanotechnology and nanomaterials are critical in the creation of next-generation energy technologies. However, it is currently highly problematic to elucidate the unique properties of nanomaterials by conventional characterization methods. Hence, tailored micro/nano devices present potentially powerful opportunities as significant proof-of-principle tools for investigating the essential structures and properties of nanomaterials. Meanwhile, these devices became increasingly sophisticated in their ability to monitor individual nanomaterials under operando conditions. This review summarizes recent progress of on-chip micro/nano devices with a particular focus on their function in energy technology. Recent studies on energy conversion devices and electrochemical energy storage devices are introduced and the special design/role of these devices are emphasized. It is expected that this review will promote further research and broaden the applications potential of on-chip micro/nano devices, thus contributing to the development of energy conversion and storage technologies.

Advanced magnetic materials could drive next-generation energy technologies

Advanced magnetic materials could drive next-generation energy technologies

Self-Supported Earth-Abundant Nanoarrays as Efficient and Robust Electrocatalysts for Energy-Related Reactions

The replacement of precious-metal-based catalysts with earth-abundant alternatives for a diverse range of electrochemical applications is of great importance for next-generation energy technologies. Many self-supported earth-abundant nanoarrays have emerged as state-of-the-art electrocatalysts due to their fascinating structures and electrochemical properties. This Review presents recent advances made toward developing self-supported earth-abundant nanoarrays for a wide range of energy-conversion processes. We summarize the different synthetic methods used to construct nanoarrays and tune their compositions, morphologies, and structures. Then, we highlight their application and performance as catalysts for various energy-related reactions. We also discuss their ability to perform as bifunctional electrocatalysts in energy devices. Finally, we conclude with the challenges and prospects in this promising field, where further exploration into these materials will facilitate the development of next-generation...

Achieving high-powered Zn/air fuel cell through N and S co-doped hierarchically porous carbons with tunable active-sites as oxygen electrocatalysts

Electrochemical reduction of oxygen is the heart of the next-generation energy technologies to fuel cells and metal-air batteries, of which the reference catalysts suffer from two critical bottlenecks lying in their insufficient electroactivities and unclear active site structures. Herein, we introduce the effectively hierarchically porous carbons (HPCs) as the active-sites enriched platform for oxygen electroreduction. Three quaternized copolymers (PUB, PAADDA and PICP) with different chemical structures are used to pursue Fe/N/S-tailored ORR electrocatalysts. The most efficient one prepared by PAADDA gives the onset potential of 0.94 V and a half-wave potential of 0.85 V in basic solution, as well as superb electroactivities of low H2O2% and high electron transfer number in both alkaline and acidic medium. Surprisingly, they all display high discharge power density as applied to Zn-air fuel cells, and the HPCs-PAADDA catalyst thrillingly reaches 516.3 mW cm−2 when catalyst loading is optimized to 5.0 mg cm−2. The results elucidate that the polymer with long aliphatic chain is propitious to trap metals to create active sites and enwrap silica template to construct uniform pore structure. Only two kinds of nitrogen configuration (pyridinic-N and graphitic-N) are found with distinct structure in these HPCs, which happens to be active sites.