Abstract
Electronic structure engineering lies at the heart of efficient catalyst design. Most previous studies, however, utilize only one technique to modulate the electronic structure, and ...therefore optimal electronic states are hard to be achieved. In this work, we incorporate both Fe dopants and Co vacancies into atomically thin CoSe
2
nanobelts for /coxygen evolution catalysis, and the resulted CoSe
2
-D
Fe
–V
Co
exhibits much higher catalytic activity than other defect-activated CoSe
2
and previously reported FeCo compounds. Deep characterizations and theoretical calculations identify the most active center of Co
2
site that is adjacent to the V
Co
-nearest surface Fe site. Fe doping and Co vacancy synergistically tune the electronic states of Co
2
to a near-optimal value, resulting in greatly decreased binding energy of OH* (ΔE
OH
) without changing ΔE
O
, and consequently lowering the catalytic overpotential. The proper combination of multiple defect structures is promising to unlock the catalytic power of different catalysts for various electrochemical reactions.
Novel layered 2D frameworks (C3N and C2N‐450) with well‐defined crystal structures are explored for use as anode materials in lithium‐ion batteries (LIBs) for the first time. As anode materials for ...LIBs, C3N and C2N‐450 exhibit unusual electrochemical characteristics. For example, C2N‐450 (and C3N) display high reversible capacities of 933.2 (383.3) and 40.1 (179.5) mAh g−1 at 0.1 and 10 C, respectively. Furthermore, C3N shows a low hypothetical voltage (≈0.15 V), efficient operating voltage window with ≈85% of full discharge capacity secured at >0.45 V, and excellent cycling stability for more than 500 cycles. The excellent electrochemical performance (especially of C3N) can be attributed to their inherent 2D polyaniline frameworks, which provide large net positive charge densities, excellent structural stability, and enhanced electronic/ionic conductivity. Stable solid state interface films also form on the surfaces of the 2D materials during the charge/discharge process. These 2D materials with promising electrochemical performance should provide insights to guide the design and development of their analogues for future energy applications.
Layered 2D organic frameworks, C3N and C2N‐450, are evaluated as anode materials in lithium‐ion batteries for the first time, showing unusual electrochemical characteristics. New 2D structures should provide insights to guide the design and development of their analogues for future energy applications.
Atomically thin materials (ATMs) with thicknesses in the atomic scale (typically <5 nm) offer inherent advantages of large specific surface areas, proper crystal lattice distortion, abundant surface ...dangling bonds, and strong in-plane chemical bonds, making them ideal 2D platforms to construct high-performance electrode materials for rechargeable metal-ion batteries, metal-sulfur batteries, and metal-air batteries. This work reviews the synthesis and electronic property tuning of state-of-the-art ATMs, including graphene and graphene derivatives (GE/GO/rGO), graphitic carbon nitride (g-C3N4), phosphorene, covalent organic frameworks (COFs), layered transition metal dichalcogenides (TMDs), transition metal carbides, carbonitrides, and nitrides (MXenes), transition metal oxides (TMOs), and metal-organic frameworks (MOFs) for constructing next-generation high-energy-density and high-power-density rechargeable batteries to meet the needs of the rapid developments in portable electronics, electric vehicles, and smart electricity grids. We also present our viewpoints on future challenges and opportunities of constructing efficient ATMs for next-generation rechargeable batteries.
An “atomic layer‐by‐layer” structure of Co3O4/graphene is developed as an anode material for lithium‐ion batteries. Due to the atomic thickness of both the Co3O4 nanosheets and graphene, the ...composite exhibits an ultrahigh specific capacity of 1134.4 mAh g−1 and an ultralong life up to 2000 cycles at 2.25 C, far beyond the performances of previously reported Co3O4/C composites.
Developing an effective system to clean up large-scale oil spills is of great significance due to their contribution to severe environmental pollution and destruction. Superwetting membranes have ...been widely studied for oil/water separation. The separation, however, adopts a gravity-driven approach that is inefficient and discontinuous due to quick fouling of the membrane by oil. Herein, inspired by the crossflow filtration behavior in fish gills, we propose a crossflow approach via a hydrophilic, tilted gradient membrane for spilled oil collection. In crossflow collection, as the oil/water flows parallel to the hydrophilic membrane surface, water is gradually filtered through the pores, while oil is repelled, transported, and finally collected for storage. Owing to the selective gating behavior of the water-sealed gradient membrane, the large pores at the bottom with high water flux favor fast water filtration, while the small pores at the top with strong oil repellency allow easy oil transportation. In addition, the gradient membrane exhibits excellent antifouling properties due to the protection of the water layer. Therefore, this bioinspired crossflow approach enables highly efficient and continuous spilled oil collection, which is very promising for the cleanup of large-scale oil spills.
Highlights
Interface engineering of heterogeneous CoS/CoO nanocrystals and N-doped graphene composite facilitates high-performance oxygen reduction reaction and oxygen evolution reaction.
Density ...functional theory calculations and experimental results confirm the enhanced electrocatalytic performances via the proposed interface engineering.
The bifunctional oxygen electrocatalyst exhibits excellent performances in rechargeable Zn–air batteries.
Low cost and green fabrication of high-performance electrocatalysts with earth-abundant resources for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are crucial for the large-scale application of rechargeable Zn–air batteries (ZABs). In this work, our density functional theory calculations on the electrocatalyst suggest that the rational construction of interfacial structure can induce local charge redistribution, improve the electronic conductivity and enhance the catalyst stability. In order to realize such a structure, we spatially immobilize heterogeneous CoS/CoO nanocrystals onto N-doped graphene to synthesize a bifunctional electrocatalyst (CoS/CoO@NGNs). The optimization of the composition, interfacial structure and conductivity of the electrocatalyst is conducted to achieve bifunctional catalytic activity and deliver outstanding efficiency and stability for both ORR and OER. The aqueous ZAB with the as-prepared CoS/CoO@NGNs cathode displays a high maximum power density of 137.8 mW cm
−2
, a specific capacity of 723.9 mAh g
−1
and excellent cycling stability (continuous operating for 100 h) with a high round-trip efficiency. In addition, the assembled quasi-solid-state ZAB also exhibits outstanding mechanical flexibility besides high battery performances, showing great potential for applications in flexible and wearable electronic devices.
The development of oxygen reduction reaction (ORR) electrocatalysts based on earth‐abundant nonprecious materials is critically important for sustainable large‐scale applications of fuel cells and ...metal–air batteries. Herein, a hetero‐single‐atom (h‐SA) ORR electrocatalyst is presented, which has atomically dispersed Fe and Ni coanchored to a microsized nitrogen‐doped graphitic carbon support with unique trimodal‐porous structure configured by highly ordered macropores interconnected through mesopores. Extended X‐ray absorption fine structure spectra confirm that Fe‐ and Ni‐SAs are affixed to the carbon support via FeN4 and NiN4 coordination bonds. The resultant Fe/Ni h‐SA electrocatalyst exhibits an outstanding ORR activity, outperforming SA electrocatalysts with only Fe‐ or Ni‐SAs, and the benchmark Pt/C. The obtained experimental results indicate that the achieved outstanding ORR performance results from the synergetic enhancement induced by the coexisting FeN4 and NiN4 sites, and the superior mass‐transfer capability promoted by the trimodal‐porous‐structured carbon support.
A hetero‐single‐atom oxygen reduction reaction (ORR) electrocatalyst is presented, which has atomically dispersed Fe and Ni coanchored to a microsized nitrogen‐doped carbon support with unique trimodal‐porous structure configured by ordered macropores interconnected through mesopores. The achieved outstanding ORR performance results from the synergetic enhancement induced by the coexisting FeN4 and NiN4 sites, and the superior mass‐transfer capability.
Two-dimensional (2D) transition metal oxide systems present exotic electronic properties and high specific surface areas, and also demonstrate promising applications ranging from electronics to ...energy storage. Yet, in contrast to other types of nanostructures, the question as to whether we could assemble 2D nanomaterials with an atomic thickness from molecules in a general way, which may give them some interesting properties such as those of graphene, still remains unresolved. Herein, we report a generalized and fundamental approach to molecular self-assembly synthesis of ultrathin 2D nanosheets of transition metal oxides by rationally employing lamellar reverse micelles. It is worth emphasizing that the synthesized crystallized ultrathin transition metal oxide nanosheets possess confined thickness, high specific surface area and chemically reactive facets, so that they could have promising applications in nanostructured electronics, photonics, sensors, and energy conversion and storage devices.
Lithium‐ion batteries (LIBs) with higher energy density are very necessary to meet the increasing demand for devices with better performance. With the commercial success of lithiated graphite, other ...graphite intercalation compounds (GICs) have also been intensively reported, not only for LIBs, but also for other metal (Na, K, Al) ion batteries. In this Progress Report, we briefly review the application of GICs as anodes and cathodes in metal (Li, Na, K, Al) ion batteries. After a brief introduction on the development history of GICs, the electrochemistry of cationic GICs and anionic GICs is summarized. We further briefly summarize the use of cationic GICs and anionic GICs in alkali ion batteries and the use of anionic GICs in aluminium‐ion batteries. Finally, we reach some conclusions on the drawbacks, major progress, emerging challenges, and some perspectives on the development of GICs for metal (Li, Na, K, Al) ion batteries. Further development of GICs for metal (Li, Na, K, Al) ion batteries is not only a strong supplement to the commercialized success of lithiated‐graphite for LIBs, but also an effective strategy to develop diverse high‐energy batteries for stationary energy storage in the future.
Applications of graphite intercalation compounds as anodes in alkali ion batteries and as cathodes in aluminium‐ion batteries are briefly reviewed in this Progress Report. We also reach conclusions on the drawbacks, major progress, emerging challenges, and some perspectives on the development of graphite intercalation compounds for metal (Li, Na, K, Al) ion batteries.
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