Asymmetrically Coordinated Cu–N₁C₂ Single‐Atom Catalyst Immobilized on Ti₃C₂T_x MXene as Separator Coating for Lithium–Sulfur Batteries

Abstract

(2 of 12)electrodes, low Coulombic Efficiency, and severe capacity decay. Therefore, developing remarkable components of batteries for addressing these challenges is significantly urgent. Separators, as the bridge between cathode and anode presented on electrolyte, exhibit considerable potential in simultaneously retarding the negative effect of LiPSs to cathode and anode. [11][12][13][14] Nevertheless, it is difficult for the traditional polypropylene (PP) separator to promote the adsorption and conversion of LiPSs, which is ascribed to its electronic insulativity. [15] Impressively, the introduction of active materials with outstanding catalytic performance as separator coatings can boost the kinetical conversion between LiPSs and Li 2 S 2 /Li 2 S, and propel adsorption to LiPSs for relieving shuttle effect, which is regarded as a suitable route to construct high-performance Li-S batteries.Single-atom catalysts (SACs) play a vital role in the energy and catalysis fields as they are characterized to be almost 100% atomic utilization and unique electronic structure, showing great prospect in high-performance Li-S batteries. [16][17][18][19][20][21][22] The catalytic performance of SACs is extremely dependent on the local microenvironments of central metal, that is, the local coordination configuration involving coordination atoms species, number, and bond length. [23][24][25] Up to now, the reported SACs to improve Li-S batteries mainly focus on the conventional metal-nitrogen-carbon catalysts supported on carbon-based supports; however, the nonpolar metal-N 4 coordination is difficult to efficiently absorb LiPSs. [10,15] Recently, both theoretical and experimental reports suggest that asymmetrically coordinated environment of SACs may highly influence the catalytic performance, which is attributed to the disordered electronic redistribution and irregular geometric structure optimizing the adsorption and conversion for intermediates. [26][27][28] However, the tunable asymmetrical coordination of central metal atoms to kinetically accelerate LiPSs conversion and strengthen LiPSs adsorption for ultrastable Li-S batteries has barely been reported. Thus, the delicate construction of isolated metal sites on ideal supports with asymmetrically coordinated configuration to meet high-efficiency requirement is promising but challenging for Li-S batteries.MXenes, emerging 2D materials, represent the novel family of transition metal carbides, nitrides, or carbon nitrides. [29][30][31] The general formula of MXenes is M n+1 X n T x , where M means the transition metal, X represents the C and/or N elements, and T x represents the surface groups (O, OH, F, and so on), reflecting its compositional variability. [32][33][34][35] Benefitting from

Regulating the Local Electronic Structure of Copper Single Atoms with Unsaturated B,O-Coordination for Selective 1O2 Generation

“…43−47 Therefore, on the one hand, the introduction of Ti 3 C 2 T x MXene can provide a diverse coordination environment different from M-N x sites; on the other hand, the electronic structure of the metal sites can be further modulated by doping Ti 3 C 2 T x MXene with heteroatoms of different electronegativities, which can reveal the catalytic activity and structure−activity relationship of SACs in Fentonlike reactions. 48,49 Herein, density functional theory calculations (DFT) were first used to predict 1 O 2 generation trends over a series of Cu-O 3 sites with different electronegative heteroatomic coordina-…”

“…Heteroatom doping is regarded as an effective strategy to modulate the electronic structure of SACs by altering the coordinated atoms of the metal center. − Ti 3 C 2 T x MXene was proved to be a promising support for the dispersion and immobilization of single-atom sites through surface negatively charged O terminals, exhibiting excellent catalytic activity for PMS activation. − Moreover, the tunable functional groups and interlayer structure on the surface of Ti 3 C 2 T x MXene are more favorable for coordination modulation and dispersion of metal sites. − Therefore, on the one hand, the introduction of Ti 3 C 2 T x MXene can provide a diverse coordination environment different from M-N x sites; on the other hand, the electronic structure of the metal sites can be further modulated by doping Ti 3 C 2 T x MXene with heteroatoms of different electronegativities, which can reveal the catalytic activity and structure–activity relationship of SACs in Fenton-like reactions. , …”

Single-atom site catalysis in Li–S batteries

“…191,192 Among these functional materials, SASCs with excellent conductivity are the most promising candidates, as they exhibit high LiPS catalytic activity and promote Li + diffusion, among other advantages (Table 2). 112,132,193–198…”

Electrocatalytic nitrate-to-ammonia conversion on CoO/CuO nanoarrays using Zn–nitrate batteries

“…Transition metals have garnered significant interest in electrochemical redox reactions owing to their advantages of low price, abundance, and adjustable activity. 20–32 In particular, Cu-based catalysts have been widely studied as NO 3 RR electrocatalysts owing to their high conductivity and efficient inhibiting effect on hydrogen evolution. 33–37 Unfortunately, Cu-based catalysts have drawbacks of low activity and unsatisfactory stability for NO 3 RR.…”