ZIF-derived mesoporous carbon materials prepared by activation via Na2SiO3 for supercapacitor

Soluble starch-derived porous carbon microspheres with interconnected and hierarchical structure by a low dosage KOH activation for ultrahigh rate supercapacitors

The developed porous structure and high density are essential to enhance the bulk performance of carbon-based supercapacitors. Nevertheless, it remains a significant challenge to optimize the balance between the porous structure and the density of carbon materials to realize superior gravimetric and areal electrochemical performance. The soluble starch-derived interconnected hierarchical porous carbon microspheres were prepared through a simple hydrothermal treatment succeeded by chemical activation with a low dosage of KOH. Due to the formation of interconnected spherical morphology, hierarchical porous structure, reasonable mesopore volume (0.33 cm3 g-1) and specific surface area (1162 m2 g-1), the prepared carbon microsphere has an ultrahigh capacitance of 394 F g-1 @ 1 A g-1 and a high capacitance retention of 62.7 % @ 80 A g-1. The assembled two-electrode device displays good cycle stability after 20,000 cycles and an ultra-high energy density of 11.6 Wh kg-1 @ 250 W kg-1. Moreover, the sample still exhibits a specific capacitance of 165 F g-1 @ 1 A g-1 at a high mass loading of 10 mg cm-2, resulting in a high areal capacitance of 1.65 F cm-2. The strategy proposed in this study, via a low-dose KOH activation process, provides the way for the synthesis of high-performance porous carbon materials.

Recent Advances in Hierarchical Porous Engineering of MOFs and Their Derived Materials for Catalytic and Battery: Methods and Application

Hierarchical porous materials have attracted the attention of researchers due to their enormous specific surface area, maximized active site utilization efficiency, and unique structure and properties. In this context, metal-organic frameworks (MOFs) offer a unique mix of properties that make them particularly appealing as tunable porous substrates containing highly active sites. This review focuses on recent advances in the types and synthetic strategies of hierarchical porous MOFs and their derived materials. Furthermore, it highlights the relationship between the mass diffusion and transport of hierarchical porous structures and the pore size with examples and simulations, while identifying their potential and limitations. On this basis, how the synthesis conditions affect the structure and electrochemical properties of MOFs based hierarchical porous materials with different structures is discussed, highlighting the prospects and challenges for the synthetization, as well as further scientific research and practical applications. Finally, some insights into current research and future design ideas for advanced MOFs based hierarchical porous materials are presented.

Two-dimensional assembly made up of ZIF-8 particles for the high-efficient capture of the iodine and dyes

The removal of the pollutants from the environment is the need of the environmental protection. ZIF-8 is promising adsorbents, and the construction of ZIF-8 assembly is essential to boost its performance. Here, we showed the easy synthesis of two-dimensional (2D) assembly built by ZIF-8 particles (2D A-ZIF-8) for the high-efficient capture of the iodine (I₂) and dyes. The assembly was synthesized by the controllable reaction of 2-methylimidazole (2-MIM) with 2D Zn-glycerol (Zn-GL) precursor. Time-dependent experiments showed the predominant replacement of GL at outer boundary and then basic plane of the precursor by 2-MIM. The assembly can be synthesized with high output and combined the advantage of large accessible surface of 2D sheets, the plentiful pores of ZIF-8 and enhanced stability of assembly, endowing the large potential as adsorbent. The high adsorption capacity of I₂ (200 wt%) was achieved on A-ZIF-8, while it is about 128 wt% on traditional dodecahedronal ZIF-8. The assembly also showed the excellent adsorption capacity for methyl orange (MO) (46.3 mg g^-1) and methylene blue (MB) (46.5 mg g^-1) at a concentration of 50 mg L^-1. It can be easily separated for reuse benefited from the large size and enhanced stability of assembly.

Scalable CNTs/NiCoSe2 Hybrid Films for Flexible All-Solid-State Asymmetric Supercapacitors

The rapidly developing wearable flexible electronics makes the development of high-performance flexible energy storage devices, such as all-solid-state supercapacitors (SCs), particularly important. Herein, we report the fabrication of CNTs/NiCoSe₂ hybrid films on carbon cloth (CC) through a facile co-electrodeposition method based on flexible electrodes for all-solid-state SCs. The NiCoSe₂ sheets grown on CNTs uniformly with a diameter of 50-100 nm act as the active materials. The CNTs in the hybrid films act as the scaffold to offer more deposition sites for NiCoSe₂ and provide a conductive network to facilitate the transfer of electrons. Moreover, the one-step electrodeposition process avoids the usage of any organic binders. Benefiting from the high intrinsic reactivity and unique 3D architecture, the obtained CNTs/NiCoSe₂ electrode delivers high specific capacity (218.1 mA h g^-1) and satisfactory durability (over 5000 cycles). Remarkably, the CNTs/NiCoSe₂//AC flexible all-solid-state (FASS) ASC provides remarkable energy density (112.2 W h kg^-1) within 0-1.7 V and maintains 98.1% of its initial capacity after 10,000 cycles. In addition, this flexible ASC device could be fabricated at a large scale (5 × 6 cm²), and the LED arrays (>3.7 V) can be easily lighted up by three ASCs in series, showing its potential practical application.