Yinbing Tian,Zijie Tang,Yu Ru,Yuanyuan Wang,Liyi Dai
Main observation and conclusion Three diamines (1,8-diaminooctane/ p -phenylenediamine/biphenylenediamine) with different alkyl groups were used to synthesize the functionalized graphene networks. Pd as the common metal catalyst was used to explore the effects of alkyl types of diamines on anti-stacking, metal anchoring ability of functional graphene and hence the catalytic performance. The results were discussed by characterization of the material and its catalytic properties. All catalysts showed excellent catalytic performance on the Suzuki cross-coupling reaction with a high yield of up to 100%. The p -phenylenediamine and biphenylenediamine functionalized graphene with larger specific surface area was beneficial to improve the stability of the graphene catalyst and maintain good catalytic activity after 5 cycles. The Pd nanoparticles in 1,8-octanediamine materials have smaller size and a smaller loading with the same or even better catalytic performance than p -phenylenediamine, biphenylenediamine materials, due to the stronger electron donating ability of N of octanediamine than that of p -phenylenediamine.
MXene with excellent flexibility, metallic conductivity, and ultra-high capacitance, makes a promising electrode for flexible supercapacitor . But the serious restacking phenomenon between MXene layers undesirably limits the ion transport kinetics and substantially reduces ion storage sites, badly restricting the rate capability and storage capacity of supercapacitor. Here, we constructed a free-standing, flexible, structurally 3D-interconnected and hydronium ion penetrable MXene/Graphdiyne nanotube (MG) composite film by employing graphdiyne nanotubes (GDY-NTs) with inherent in-plane pores for horizontal-vertical intercalation among MXene layers. Benefiting from the above synergistic effect, this composite film presents a greatly-improved capacitance of 337.4 F g −1 (337.4 C g −1 ) and an obviously-enhanced rate capability of 73 %-remaining at 100 mV s −1 , which is much better than those of the pure Ti 3 C 2 T x films (230.8 F g −1 , 55 %-remaining). Based on it, we developed an asymmetric solid-state flexible supercapacitor with a high energy density of 19.7 Wh kg −1 at the power density of 750 W kg −1 and a capacitance retention of 88.2 % after 10 000 cycles at 8 A g −1 . Evidently, this work provides a new route to solve the restacking issue of MXene for high-performance flexible supercapacitor.
Two-dimensional materials, such as MXene (Ti 3 C 2 T x ), have recently garnered significant attention in the field of energy storage. However, their electrochemical performances are severely hindered by the tendency of their layered structures to restack. This study introduces an innovative strategy involving the in-situ polymerization of polypyrrole (PPy) microspheres on the surfaces of aramid nanofibers (ANFs) to form a stable PPy@ANFs core–shell structure. This structure serves as a conductive framework intercalated between Ti 3 C 2 T x nanosheets, producing an MXene/PPy@ANFs (MPA) aerogel with three-dimensional multidirectional conductive properties. The PPy@ANFs core–shell structure not only widens the ion transport pathways, but it also significantly inhibits the restacking of the Ti 3 C 2 T x layers. Additionally, the resulting interlayer spacing of the MXene effectively mitigates the swelling and pulverization of the PPy microspheres. This ternary synergistic effect endows the MPA 0.3 aerogel with a high specific capacitance of 404.9 F g −1 at 2 mV s −1 . Symmetric supercapacitors assembled with this material exhibit exceptional comprehensive performance, namely a specific capacitance of 169.84 F g −1 at 2 mV s −1 , a capacitance retention of 82 % at a high scan rate of 100 mV s −1 , and a capacity retention of 99.31 % after 10,000 cycles at a current density of 8 A g −1 . Furthermore, at a current density of 1 A g −1 , the device simultaneously achieves an energy density of 22.12 Wh kg −1 and a power density of 1280 W kg −1 . This work presents a novel three-dimensional structural design for MXene-based composites, providing valuable insights into their potential for advanced energy storage applications.
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