various noble metal catalysts, such as Au, Ag, and Pd have demonstrated impressive potential for yielding CO through CO 2 RR. [2] Furthermore, Ir/Au [1a] and 3D Pd nanosheets [3] offer sufficient performances for Zn-CO 2 batteries. These electrocatalysts are, however, expensive and often require high overpotentials to generate desired products. In addition, the Faradaic efficiency (FE) for CO 2 RR in Zn-CO 2 batteries, particularly for CO 2-to-CO conversion, is typically below 50% at relatively high discharge currents (e.g., 5 mA cm −2). [4] As an alternative to noble metal catalysts, nitrogen-coordinated single-metal active sites anchored within porous carbon (M-N-C) have been recently identified as a new class of efficient CO 2 RR catalysts to enable CO 2-to-CO conversion, because of their abundance, high electrical conductivity, and good durability. [5] Among various M-N-C catalysts, Fe-N-C presents a low onset potential for CO production, whereas its CO Faradaic efficiency (FE CO) and partial current density (J CO) are not high, particularly for concentrated electrolytes, [6] owing to the strong binding of *CO on the single Fe-N x site. [7] Strategies such as modifying the morphology and pore structure of the carbon substrate, [6a,8] and adjusting the coordination structure as well as the local environment of the metal center, [4b,5f,9] were employed to enhance CO 2 RR performance. In addition to the single Fe-N x sites, nonmetal moieties in the carbon plane of M-N-C, such as N-doped sites and intrinsic defects, may additionally contribute to CO 2 RR (Figure S1, Supporting Information). Pyridinic and hydrogenated nitrogen species in Fe-N-C was demonstrated to exhibit preferential adsorption for CO 2 and acted as active sites for CO 2 RR. [5h,10] Moreover, the intrinsic carbon defects could also act as sole metal-free active sites for CO 2 RR, stemming from the electron redistribution around the defects, and consequently, form partially positive C atoms, as demonstrated very recently in certain studies. [11] For example, defectrich and metal-free mesoporous carbon materials exhibited enhanced CO generation from CO 2 RR, whereas the competing HER was suppressed. When an overpotential of 490 mV was applied, the FE CO was ≈80%, with a J CO of −2.9 mA cm −2. [11b] A positive correlation was also observed between the content of intrinsic carbon defects and the CO 2 RR performance of carbon-based catalysts. [11a] Despite these achievements, the J CO for the reported carbon catalysts containing intrinsic defects remained below 7 mA cm −2. [11] Considering that such catalysts Manipulating the in-plane defects of metal-nitrogen-carbon catalysts to regulate the electroreduction reaction of CO 2 (CO 2 RR) remains a challenging task. Here, it is demonstrated that the activity of the intrinsic carbon defects can be dramatically improved through coupling with single-atom Fe-N 4 sites. The resulting catalyst delivers a maximum CO Faradaic efficiency of 90% and a CO partial current density of 33 mA cm −2 in 0.1 m KHCO 3. The ...

by judiciously adjusting the structure of ILs. ILs have been intensively studied as a "green" alternative to organic solvents for synthesis, catalysis, extraction, and separation. [2] They are also safe and versatile electrolytes for electrochemistry and energy-related applications. [3] However, their viscosities are generally two or three orders of magnitude higher than those of conventional organic solvents (molecular liquids), which inevitably lead to handling difficulties (e.g., infiltration, decantation, and dissolution), low reaction rates, competitive unimolecular side reactions, sluggish ionic transport, and significantly reduced ionic conductivity. [4] For the potential application of ILs, such high viscosities have to be deliberately avoided by choosing alternative anions such as bis (trifluoromethanesulfonimide) (TFSI − ) and dicyanamide anions with high charge delocalization [4b,5] or introducing ether groups that pack less efficiently and provide more available free volume to enable low viscosity. [6] Nevertheless, the disadvantageous high viscosities of ILs can become advantageous for special applications that require viscous materials, such as adhesion, sealing, and gelation. [7] Particularly, adhesion is the attraction between two different condensed phases when they are in contact to construct a robust joint. Adhesion involves not only the molecular interactions at the interface of two individual surfaces but also the energy within the deformed material when pulling them apart. Adhesives have been acknowledged as indispensable chemicals in daily life and in many industries ranging from packaging, labeling, housing construction, and automobile manufacturing to soft robots, wearable devices, and aerospace. [7a,b,8] Along with conventional resins and gum-based adhesives, many musselinspired and catechol-based polymeric materials had been developed as modern adhesives in the past. [9] Nevertheless, they possess inherent drawbacks such as irreversible oxidizing crosslinking, tedious synthesis, and poor cycling performance. [10] We recently reported a series of noncatechol adhesive materials produced by water-triggered supramolecular polymerization of crown ether-containing monomers, but the synthesis of such specific monomers involves complicated functionalization, which is difficult to scale up. [11] The presence of water in these supramolecular adhesives also becomes an obvious disadvantage as they cannot bear ultra-high vacuum adhesion.Adhesive materials have wide applications in diverse fields, but the development of a novel and multipurpose adhesive is a great challenge. This study demonstrates that conventional poly(ionic liquid)s (PILs) can be designed as highly efficient adhesives by simply introducing alkoxy moieties into the cationic backbone of PILs containing bis(trifluoromethanesulfonimide) (TFSI − ) anions. The incorporated flexible alkoxy chain not only reduces the glass transition temperature of PILs but also endows these materials with strong hydrogen bonding interactions, w...

In this study, aligned porous lead zirconate titanate (PZT) ceramics with high pyroelectric figures-of-merit were successfully manufactured by freeze casting using water-based suspensions. The introduction of aligned pores was demonstrated to have a strong influence on the resultant porous ceramics, in terms of mechanical, dielectric, and pyroelectric properties. As the level of porosity was increased, the relative permittivity decreased, whereas the Curie temperature and dielectric loss increased. The aligned porous structure exhibited improvement in the compressive strength ranging from 19 to 35 MPa, leading to easier handling, better processability and wider applications for such type of porous material. Both types of pyroelectric harvesting figures-of-merit (F E and F 0 E ) of the PZT ceramics with a porosity level of 25-45 vol% increased in all porous ceramics, for example, from 11.41 to 12.43 pJ/m 3 / K 2 and 1.94 to 6.57 pm 3 /J, respectively, at 25°C, which were shown to be higher than the dense PZT counterpart.

Regulating the electrical double layer (EDL) structure via electrolyte additives is a promising strategy to improve the cycle stability of Zn anodes, but there are no general disciplines that can...

The booming of portable electronics has stimulated great interest in developing flexible Zn-ion hybrid supercapacitors (Zn HSCs) that feature low cost and high operational safety. However, the commercial applications of Zn HSCs are greatly hindered by low energy density due to the low capacity of the cathode and also the invalid weight of the flexible current collector. Here, a free-standing cathode is developed by patterning redox-active polydopamine (PDA) with abundant quinone groups on the porous carbon cloth substrate via a hydrothermal polymerization process. Unlike the traditional carbon cloth-based electrode, the carbon cloth adopted here is activated by the air calcination process, which is beneficial for the loading of PDA and absorption of Zn2+ ions. Benefiting from the hybrid mechanism of Zn2+–quinone group coordination and electrical double layer absorption, the polydopamine-coated porous carbon cloth (PDA@PCC) delivers a high area capacity of 1.25 mA h cm–2 and a high capacity retention of 100% after 10,000 cycles at a current density of 10 mA cm–2. Moreover, when assembled into flexible Zn HSCs, PDA@PCC still displays a high capacity of 0.92 mA h cm–2, and the flexibility and operation safety have also been demonstrated by several extreme condition tests, such as cutting and sewing tests. This work may promote new opportunities for next-generation flexible Zn HSCs.