The demand for highly efficient conversion and storage of renewable energy sources calls for advanced electrocatalytic technologies. 2D graphene has long been investigated as a versatile material ...platform with flexible structure and tunable surface properties for the design of efficient electrocatalysts. In recent years, new types of graphene derivatives and analogues keep emerging and showing great potential for highly active and selective electrocatalytic applications. In this review, recent progresses on emerging graphene derivatives and analogues for electrocatalysis are summarized. This review starts from the introduction of the material requirements for efficient electrocatalysis and the advantages of 2D graphene derivatives and analogues. Then new advances on graphene derivatives for electrocatalysis are introduced, including twisted graphene superlattices, molecular‐level single‐atom catalysts, and graphene‐supported dual‐atom catalysts or atomic clusters. The next section deals with the emerging research directions of graphene analogues for electrocatalysis, including 2D metal‐free materials, metallenes, 2D transition metal borides (MBenes), and new design strategies of them. Finally, an overview on the development status of this field is provided, and perspectives on the future development of efficient electrocatalytic technologies based on 2D materials are proposed.
Graphene derivatives including twisted graphene superlattices, molecular‐level single‐atom catalysts and graphene‐supported dual‐atom catalysts, as well as graphene analogues including metal‐free materials, metallenes, and transition metal borides are reviewed with an emphasis on the structure–performance relationship of 2D electrocatalysts.
Working Zinc–Air Batteries at 80 °C Zhao, Chang‐Xin; Yu, Legeng; Liu, Jia‐Ning ...
Angewandte Chemie International Edition,
August 15, 2022, Letnik:
61, Številka:
33
Journal Article
Recenzirano
Aqueous zinc–air batteries possess inherent safety and are especially commendable facing high‐temperature working conditions. However, their working feasibility at high temperatures has seldom been ...investigated. Herein, the working feasibility of high‐temperature zinc–air batteries is systemically investigated. The effects of temperature on air cathode, zinc anode, and aqueous electrolyte are decoupled to identify the favorable and unfavorable factors. Specifically, parasitic hydrogen evolution reaction strengthens at high temperatures and leads to declined anode Faraday efficiency, which is identified as the main bottleneck. Moreover, zinc–air batteries demonstrate cycling feasibility at 80 °C. This work reveals the potential of zinc–air batteries to satisfy energy storage at high temperatures and guides further development of advanced batteries towards harsh working conditions.
The working feasibility at 80 °C and 100 °C of zinc–air batteries is demonstrated in this work. The operation of zinc–air batteries under high‐temperature working conditions is systemically investigated. The electrolyte conductivity, the cathode and anode kinetics, and the anode anti‐passivation are optimized at high temperatures, whereas declined anode Faraday efficiency originating from strengthened HER serves as the main bottleneck.
Atomic Fe in N‐doped carbon (FeNC) electrocatalysts for oxygen (O2) reduction at the cathode of proton exchange membrane fuel cells are the most promising alternative to platinum‐group‐metal ...catalysts. Despite recent progress on atomic FeNC O2 reduction, their controlled synthesis and stability for practical applications remain challenging. A two‐step synthesis approach has recently led to significant advances in terms of Fe‐loading and mass activity; however, the Fe utilization remains low owing to the difficulty of building scaffolds with sufficient porosity that electrochemically exposes the active sites. Herein, this issue is addressed by coordinating Fe in a highly porous nitrogen‐doped carbon support (≈3295 m2 g−1), prepared by pyrolysis of inexpensive 2,4,6‐triaminopyrimidine and a Mg2+ salt active site template and porogen. Upon Fe coordination, a high electrochemical active site density of 2.54 × 1019 sites gFeNC−1 and a record 52% FeNx electrochemical utilization based on in situ nitrite stripping are achieved. The Fe single atoms are characterized pre‐ and post‐electrochemical accelerated stress testing by aberration‐corrected high‐angle annular dark field scanning transmission electron microscopy, showing no Fe clustering. Moreover, ex situ X‐ray absorption spectroscopy and low‐temperature Mössbauer spectroscopy suggest the presence of penta‐coordinated Fe sites, which are further studied by density functional theory calculations.
An iron–nitrogen–carbon oxygen reduction electrocatalyst with penta‐coordinated sites and high electrochemical active sites utilization is prepared by low‐temperature Fe coordination in a porous nitrogen‐doped carbon synthetized through the ionothermal pyrolysis of 2,4,6‐triaminopyrimidine. The structure of the active site is studied by means of X‐ray absorption and Mössbauer spectroscopy and the effect of axial ligands through density functional theory calculations.
Lithium–sulfur (Li–S) batteries have extremely high theoretical energy density that make them as promising systems toward vast practical applications. Expediting redox kinetics of sulfur species is a ...decisive task to break the kinetic limitation of insulating lithium sulfide/disulfide precipitation/dissolution. Herein, we proposed a porphyrin‐derived atomic electrocatalyst to exert atomic‐efficient electrocatalytic effects on polysulfide intermediates. Quantifying electrocatalytic efficiency of liquid/solid conversion through a potentiostatic intermittent titration technique measurement presents a kinetic understanding of specific phase evolutions imparted by the atomic electrocatalyst. Benefiting from atomically dispersed “lithiophilic” and “sulfiphilic” sites on conductive substrates, the finely designed atomic electrocatalyst endows Li–S cells with remarkable cycling stablity (cyclic decay rate of 0.10% in 300 cycles), excellent rate capability (1035 mAh g−1 at 2 C), and impressive areal capacity (10.9 mAh cm−2 at a sulfur loading of 11.3 mg cm−2). The present work expands atomic electrocatalysts to the Li–S chemistry, deepens kinetic understanding of sulfur species evolution, and encourages application of emerging electrocatalysis in other multielectron/multiphase reaction energy systems.
An atomic‐scale electrocatalyst is proposed to exert atom‐efficiency electrocatalytic effects on polysulfide intermediates in working Li–S batteries. Quantifying electrocatalytic effects on multiphase evolution by kinetic characterizations reveal their unique electrocatalytic benefits on the sulfur conversion reactions, thus enabling impressive battery performances.
Rechargeable zinc–air batteries are considered as next‐generation energy storage devices because of their ultrahigh theoretical energy density of 1086 Wh kg−1 (including oxygen) and inherent safety ...originating from the use of aqueous electrolyte. However, the cathode processes regarding oxygen reduction and evolution are sluggish in terms of kinetics, which severely limit the practical battery performances. Developing high‐performance bifunctional oxygen electrocatalysts is of great significance, yet to achieve better bifunctional electrocatalytic reactivity beyond the state‐of‐the‐art noble‐metal‐based electrocatalysts remains a great challenge. Herein, a composite Co3O4@POF (POF=framework porphyrin) bifunctional oxygen electrocatalyst is proposed to construct advanced air cathodes for high‐performance rechargeable zinc–air batteries. The as‐obtained composite Co3O4@POF electrocatalyst exhibits a bifunctional electrocatalytic reactivity of ΔE=0.74 V, which is better than the noble‐metal‐based Pt/C+Ir/C electrocatalyst and most of the reported bifunctional ORR/OER electrocatalysts. When applied in rechargeable zinc–air batteries, the Co3O4@POF cathode exhibits a reduced discharge–charge voltage gap of 1.0 V at 5.0 mA cm−2, high power density of 222.2 mW cm−2, and impressive cycling stability for more than 2000 cycles at 5.0 mA cm−2.
ORR or OER: A composite bifunctional oxygen electrocatalyst was proposed to construct advanced air cathodes for rechargeable zinc–air batteries. The composite electrocatalyst demonstrates ultrahigh bifunctional oxygen reduction/evolution reaction (ORR/OER) electrocatalytic reactivity beyond the noble‐metal‐based electrocatalysts and stable cycling over 2000 cycles in rechargeable zinc–air batteries.
Coordination engineering for single‐atom sites has drawn increasing attention, yet its chemical synthesis remains a tough issue, especially for tailorable coordination structures. Herein, a molecular ...recognition strategy is proposed to fabricate single‐atom sites with regulable local coordination structures. Specifically, a heteroatom‐containing ligand serves as the guest molecule to induce coordination interaction with the metal‐containing host, precisely settling the heteroatoms into the local structure of single‐atom sites. As a proof of concept, thiophene is selected as the guest molecule, and sulfur atoms are successfully introduced into the local coordination structure of iron single‐atom sites. Ultrahigh oxygen reduction electrocatalytic activity is achieved with a half‐wave potential of 0.93 V versus reversible hydrogen electrode. Furthermore, the strategy possesses excellent universality towards diversified types of single‐atom sites. This work makes breakthroughs in the fabrication of single‐atom sites and affords new opportunities in structural regulation at the atomic level.
A coordination molecular recognition strategy is proposed to precisely regulate the local coordination structure of single‐atom sites. Specifically, utilizing five‐membered heterocycle molecules as the ligands, the coordination interaction between the guest‐host molecules induces molecular recognition and ensures further precise settlement of the heteroatoms into the local coordination structure of the metal atoms in the single‐atom sites.
The electrochemical CO2 reduction reaction (CO2RR) to value‐added chemicals with renewable electricity is a promising method to decarbonize parts of the chemical industry. Recently, single metal ...atoms in nitrogen‐doped carbon (MNC) have emerged as potential electrocatalysts for CO2RR to CO with high activity and faradaic efficiency, although the reaction limitation for CO2RR to CO is unclear. To understand the comparison of intrinsic activity of different MNCs, two catalysts are synthesized through a decoupled two‐step synthesis approach of high temperature pyrolysis and low temperature metalation (Fe or Ni). The highly meso‐porous structure results in the highest reported electrochemical active site utilization based on in situ nitrite stripping; up to 59±6% for NiNC. Ex situ X‐ray absorption spectroscopy (XAS) confirms the penta‐coordinated nature of the active sites. The catalysts are amongst the most active in the literature for CO2 reduction to CO. The density functional theory calculations (DFT) show that their binding to the reaction intermediates approximates to that of Au surfaces. However, it is found that the turnover frequencies (TOFs) of the most active catalysts for CO evolution converge, suggesting a fundamental ceiling to the catalytic rates.
Oxygen reduction reaction (ORR) constitutes the core process of many energy storage and conversion devices including metal–air batteries and fuel cells. However, the kinetics of ORR is very sluggish ...and thus high-performance ORR electrocatalysts are highly regarded. Despite recent progress on minimizing the ORR half-wave potential as the current evaluation indicator, in-depth quantitative kinetic analysis on overall ORR electrocatalytic performance remains insufficiently emphasized. In this paper, a quantitative kinetic analysis method is proposed to afford decoupled kinetic information from linear sweep voltammetry profiles on the basis of the Koutecky–Levich equation. Independent parameters regarding exchange current density, electron transfer number, and electrochemical active surface area can be respectively determined following the proposed method. This quantitative kinetic analysis method is expected to promote understanding of the electrocatalytic effect and point out further optimization direction for ORR electrocatalysis.
Lithium‒sulfur (Li–S) battery is considered as a promising energy storage system to realize high energy density. Nevertheless, unstable lithium metal anode emerges as the bottleneck toward practical ...applications, especially with limited anode excess required in a working full cell. In this contribution, a mixed diisopropyl ether‐based (mixed‐DIPE) electrolyte was proposed to effectively protect lithium metal anode in Li–S batteries with sulfurized polyacrylonitrile (SPAN) cathodes. The mixed‐DIPE electrolyte improves the compatibility to lithium metal and suppresses the dissolution of lithium polysulfides, rendering significantly improved cycling stability. Concretely, Li | Cu half‐cells with the mixed‐DIPE electrolyte cycled stably for 120 cycles, which is nearly five times longer than that with routine carbonate‐based electrolyte. Moreover, the mixed‐DIPE electrolyte contributed to a doubled life span of 156 cycles at 0.5 C in Li | SPAN full cells with ultrathin 50 μm Li metal anodes compared with the routine electrolyte. This contribution affords an effective electrolyte formula for Li metal anode protection and is expected to propel the practical applications of high‐energy‐density Li‒S batteries.
A mixed diisopropyl ether‐based (mixed‐DIPE) electrolyte was proposed to forcefully protect the lithium metal anode in working lithium–sulfur batteries with sulfurized polyacrylonitrile (SPAN) cathodes.
The development of next‐generation high‐energy‐density batteries requires advanced electrode materials. Sulfurized polyacrylonitrile (SPAN) is considered a promising sulfur cathode with the merits of ...high specific capacity and long cycling stability for high‐performance lithium–sulfur (Li–S) batteries. Nevertheless, the practical performances of SPAN cathodes are severely limited by the unfavorable electron accessibility due to the relatively low intrinsic conductivity and large particle size. Herein, a redox mediation strategy is proposed to accelerate the electron transfer processes in working Li–S batteries with SPAN cathodes. Specifically, a quinone‐based redox mediator is introduced to provide an additional redox pathway with strengthened interfacial kinetics. The redox mediator assisted SPAN cathodes exhibit higher specific capacity, improved rate performance, reduced polarization, and longer cycling lifespan with both ether‐based and carbonate‐based electrolyte. This work demonstrates the feasibility of redox mediation to promote the electron accessibility for high‐performance Li–S batteries with SPAN cathodes.
A redox mediation strategy is proposed to strengthen the interfacial kinetics of lithium–sulfur batteries with sulfurized polyacrylonitrile (SPAN) cathodes by introducing a quinone‐based redox mediator to provide an additional redox pathway. The redox mediated SPAN cathodes exhibit higher specific capacity, improved rate performance, and reduced polarization in both ether‐based and carbonate‐based electrolyte system. This work demonstrates the feasibility of redox mediation to promote the electron accessibility for Li–S batteries with SPAN cathodes.
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