Molybdenum carbide (Mo2C) is recognized as an alternative electrocatalyst to noble metal for the hydrogen evolution reaction (HER). Herein, a facile, low cost, and scalable method is provided for the ...fabrication of Mo2C‐based eletrocatalyst (Mo2C/G‐NCS) by a spray‐drying, and followed by annealing. As‐prepared Mo2C/G‐NCS electrocatalyst displays that ultrafine Mo2C nanopartilces are uniformly embedded into graphene wrapping N‐doped porous carbon microspheres derived from chitosan. Such designed structure offer several favorable features for hydrogen evolution application: 1) the ultrasmall size of Mo2C affords a large exposed active sites; 2) graphene‐wrapping ensures great electrical conductivity; 3) porous structure increases the electrolyte–electrode contact points and lowers the charge transfer resistance; 4) N‐dopant interacts with H+ better than C atoms and favorably modifies the electronic structures of adjacent Mo and C atoms. As a result, the Mo2C/G‐NCS demonstrates superior HER activity with a very low overpotential of 70 or 66 mV to achieve current density of 10 mA cm−2, small Tafel slope of 39 or 37 mV dec−1, respectively, in acidic and alkaline media, and high stability, indicating that it is a great potential candidate as HER electrocatalyst.
A simple, low cost, and scalable strategy for the fabrication of Mo2C‐based eletrocatalyst through spray‐drying and followed by annealing is demonstrated. As‐prepared Mo2C/G‐NCS catalyst exhibits excellent hydrogen evolution reaction performance both in acidic and alkaline media, which is attributed to synergistic effect from such an unique structure with graphene wrapping, ultrasmall Mo2C nanocrystallite, nitrogen‐dopant, and the well‐defined porous microspheres.
The development of highly efficient electrocatalysts for direct seawater splitting with bifunctionality for inhibiting anodic oxidation reconstruction and selective oxygen evolution reactions is a ...major challenge. Herein, we report a direct seawater oxidation electrocatalyst that achieves long-term stability for more than 1000 h at 600 mA/cm
@η
and high selectivity (Faraday efficiency of 100%). This catalyst revolves an amorphous molybdenum oxide layer constructed on the beaded-like cobalt oxide interface by atomic layer deposition technology. As demonstrated, a new restricted dynamic surface self-reconstruction mechanism is induced by the formation a stable reconstructed Co-Mo double hydroxide phase interface layer. The device assembled into a two-electrode flow cell for direct overall seawater electrolysis maintained at 1 A/cm
@1.93 V for 500 h with Faraday efficiency higher than 95%. Hydrogen generation rate reaches 419.4 mL/cm
/h, and the power consumption (4.62 KWh/m
H
) is lower than that of pure water (5.0 KWh/m
H
) at industrial current density.
Under the scope of “carbon neutrality” and “emissions peak,” renewable energy technologies and systems relying on electrocatalytic reactions (e.g., oxygen evolution reaction (OER), oxygen reduction ...reaction (ORR), hydrogen evolution reaction (HER), and carbon dioxide reduction reaction (CO2RR)), though kinetically slow, are attractive. To promote the efficiency of such systems, engineering of the electrocatalyst interface is an effective strategy. In the fabrication toolbox for complex surface/interface, the advanced atomic‐layer deposition (ALD) technique is superior to conventional methods, evidenced by precise control of thickness, composition, uniformity, etc. This review summarizes recent developments in ALD implementation in a variety of electrocatalytic systems, especially the electrode interface preparation and modulation. Beyond all doubt, the introduction of the ALD process could dramatically increase the number of electrocatalytic‐active sites and hence improve the performance. However, its practical application in this field is open to deliberation, while process cost and complexity are in consideration.
Advanced atomic‐layer deposition (ALD) is considered a promising technique for surface and interface engineering in competitive electrocatalysis systems. Accordingly, this review sorts out facile ALD manipulation in such a field and demonstrates representative progress. Moreover, applications of the design strategies for renewable energy are anticipated.
The commercialization of Li−S batteries is seriously hindered by polysulfides with severe shuttle effect, and the inherent insulating properties and slow reaction kinetics of insoluble Li2S products. ...Transition metal sulfides (TMSs) have a high adsorption capacity for polysulfides and have been shown to have a strong catalytic effect on polysulfide conversion reactions. This paper reviews the research on the application of Unary TMSs, heterostructures, etc. in Li−S batteries, and gives some research methods for TMD catalysts in Li−S batteries. Finally, it points out the main focuses and direction of future Li−S battery research and development. It aims to provide some insights into the design and manufacture of advanced Li−S batteries for commercial use.
The excellent theoretical performance of Li−S batteries deserves attention. However, the poor sulfur conductivity, volume change induced electrode failure and shuttle effect at the cathode limit the battery from being introduced. Among many catalysts, TMSs utilize their strong binding force to accelerate the conversion of polysulfides, making them of extraordinary research value.
Room temperature sodium-sulfur batteries are one of the most attractive energy storage systems due to their low cost, environmental friendliness, and ultra-high energy density. However, due to the ...inherent slow redox kinetics and the shuttle of polysulfides, the road of room temperature sodium-sulfur batteries to practical application is still full of difficulties. As a sulfur cathode, which is directly related to battery performance, a lot of research efforts have been devoted to it and many strategies have been proposed to solve the shuttle effect problem of sulfur cathodes. This paper analyzes the existing problems and solutions of sodium-sulfur batteries, mainly discusses and summarizes the research progress of constructing carbon-based cathode materials for sodium-sulfur batteries, and expounds the current research popular from two main directions. That is to construct advanced cathode materials based on two mechanisms of adsorption and electrocatalysis. Finally, the research direction of advanced sodium-sulfur batteries is prospected.
An efficient and durable oxygen evolution reaction (OER) electrocatalyst consisting of TiN @ Co5.47N is constructed by the integration of plasma nitriding and a delicate atomic layer deposition (ALD) ...CoxN process. Representative results of comprehensive study are: 1) the material is electrocatalytically active in universal medium. The OER overpotentials are 398, 248, and 411 mV in acidic, basic, and neutral electrolyte, respectively, at a current density of 50 mA cm−2; 2) the material records an impressive long‐term stability of continuous catalysis for 1500 h, during which the overpotential increases by only 1.3%. The synergistically electronic interaction between TiN and ALD Co5.47N, as well as a protective yet active CoTi layered double hydroxides (CoTi LDH) layer formed simultaneously at the interface/surface of TiN @ Co5.47N during the electrocatalytic process, is speculated to be responsible for the superior OER performance; 3) the surface Co atoms other than Ti of CoTi LDH, exhibit electrocatalytic activity with dramatically low overpotential based on density functional theory calculations.
Atomic layer deposition (ALD) of Co5.47N grows on the defected TiN matrix to generate an active and stable composite catalyst for oxygen evolution reaction. Both the ALD Co5.47N manipulation and self‐transformed CoTi layered double hydroxides play important roles in the performance.
Abstract
Rational design of sulfur hosts for effectively confining lithium polysulfides (LiPS) and optimizing the sluggish sulfur kinetics is still a major challenge in lithium–sulfur batteries ...(LSBs). In this work, a simple strategy of introducing single Mo–N
4
atoms into N‐doped carbon nano‐flower matrix (Mo‐N‐CNF) as sulfur host cathode materials is developed to realize high‐performance LSBs. These single Mo–N
4
atoms have been demonstrated to regulate the hydrophilic nature, Li‐ion diffusion, adsorption capacity, and catalytic conversion of polysulfides via experimental evidences and theoretical calculations. The resulting Mo‐N‐CNF with high loading content of sulfur (>72 wt.%) exhibits a high specific capacity (1248 mAh g
–1
at 0.2 C) and excellent rate capability (715 mAh g
–1
at 5 C). More importantly, the outstanding cycling performance with a low attenuation rate of only 0.004% per cycle over 400 cycles at 4.27 mA cm
–2
is achieved with the area sulfur loading of 5.1 mg cm
–2
. This work demonstrates a viable strategy for using single atoms‐based carbon materials with high exposed sites as multiple captors for LiPS and an efficient accelerator for sulfur redox kinetics toward next‐generation LSBs with boosted electrochemical performance.
Reported herein is an active and durable CoN‐containing oxygen evolution reaction (OER) electrocatalyst which efficiently functions in a neutral medium (pH ≈7). The composite material (N, S)‐RGO@CoN ...is synthesized by delicate atomic layer deposition (ALD) of CoN on a nitrogen and sulfur (N, S) co‐doped reduced graphene oxide (RGO) substrate. Representative results of the comprehensive study are: 1) The flower‐like sphere RGO substrate prepared by spray drying method features rich physical and chemical properties, which are beneficial for rapid mass/charge transfer to improve the intrinsic OER process; 2) the optimal ALD material for OER tests is afforded by tuning spray conditions and ALD parameters. Versatile structural and compositional characterizations confirm uniform growth and strong chemical coupling of nanostructured CoN on (N, S)‐RGO matrix; 3) the material is electrocatalytically active and durable in a neutral electrolyte, recording an OER overpotential of 220 mV at a current density of 10 mA cm−2 and stability of 20 h continuous catalysis at 20 mA cm−2 with nearly 100% Faradic efficiency; 4) Upon the experimental studies and density functional theory calculations, the eventual mechanism of remarkable OER activity conforms to the structural fate of ALD CoN electronic coupling to the carbon substrate.
Delicate atomic layer deposition of CoN on a nitrogen and sulfur co‐doped reduced graphene oxide substrate affords an active and durable oxygen evolution reaction electrocatalyst, which is capable in a neutral medium.
The slow sulfur oxidation–reduction kinetics are one of the key factors hindering the widespread use of lithium–sulfur batteries (LSBs). Herein, flower‐shaped NiS2‐WS2 heterojunction as the ...functional intercalation of LSBs is successfully prepared, and effectively improved the reaction kinetics of sulfur. Flower‐like nanospheres composed of ultra‐thin nanosheets (≤10 nm) enhance quickly transfer of mass and charge. Meanwhile, the heterostructures simultaneously serve as an electron receptor and a donor, thereby simultaneously accelerating the bidirectional catalytic activity of reduction and oxidation reactions in the LSBs. In addition, the adsorption experiment, chemical state analysis of elements before and after the reaction and theoretical calculation have effectively verified that NiS2‐WS2 heterojunction nanospheres optimize the adsorption capacity and bidirectional catalytic effect of polysulfides. The results show that the initial discharge capacity of NiS2‐WS2 functional intercalation is as high as 1518.7 mAh g−1 at 0.2 C. Even at a high current density of 5 C, it still shows a discharge specific capacity of 615.7 mAh g−1, showing excellent rate performance. More importantly, the capacity is 258.9 mAh g−1 after 1500 cycles at 5 C, and the attenuation per cycle is only 0.039%, and the Coulomb efficiency remains above 95%.
The flower‐like NiS2/WS2 heterojunction is designed and constructed by interface engineering and structural engineering strategy as a catalytic intercalation, which effectively alleviated the difficult problem of polysulfide bidirectional catalysis. Based on this design, the polysulfide shuttle effect is effectively inhibited, and the stable solid electrolyte interphase layer is induced to form, which significantly improves the performance of lithium–sulfur batteries.
We have successfully constructed a new type of intercalation membrane material by covalently grafting organic tris(hydroxypropyl)phosphine (THPP) molecules onto hydroxylated multi‐walled carbon ...nanotubes (CNT‐OH) as a functional interlayer for the advanced LSBs. The as‐assembled interlayer has been demonstrated to be responsible for the fast conversion kinetics of polysulfides, the inhibition of polysulfide shuttle effect, as well as the formation of a stable solid electrolyte interphase(SEI) layer. By means of spectroscopic and electrochemical analysis, we further found THPP plays a key role in accelerating the conversion of polysulfides into low‐ordered lithium sulfides and suppressing the loss of polysulfides, thus rendering the as‐designed lithium–sulfur battery in this work a high capacity, excellent rate performance and long‐term stability. Even at low temperatures, the capacity decay rate was only 0.036 % per cycle for 1700 cycles.
The organic small molecule tris(hydroxypropyl) phosphine (THPP) grafted on hydroxylated multi‐walled carbon nanotubes (CNT‐OH) as intercalation of lithium–sulfur batteries (LSBs) has been demonstrated to accelerate the catalytic conversion, effectively restrain the shuttle effect of polysulfides and reduce the formation of lithium dendrites.
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