Confined Synthesis of Amorphous Al2 O3 Framework Nanocomposites Based on the Oxygen-Potential Diagram as Sulfur Hosts for Catalytic Conversion

In Situ Phosphorization for Constructing Ni5P2-Ni Heterostructure Derived from Bimetallic MOF for Li-S Batteries

Heterostructured materials commonly consist of bifunctions due to the different ingredients. For host material in the sulfur cathode of lithium-sulfur (Li-S) batteries, the chemical adsorption and catalytic activity for lithium polysulfides (LiPS) are important. This work obtains a Ni5P2-Ni nanoparticle (Ni5P2-NiNPs) heterostructure through a confined self-reduction method followed by an in situ phosphorization process using Al/Ni-MOF as precursors. The Ni5P2-Ni heterostructure not only has strong chemical adsorption, but also can effectively catalyze LiPS conversion. Furthermore, the synthetic route can keep Ni5P2-NiNPs inside of the nanocomposites, which have structural stability, high conductivity, and efficient adsorption/catalysis in LiPS conversion. These advantages make the assembled Li-S battery deliver a reversible specific capacity of 619.7 mAh g- 1 at 0.5 C after 200 cycles. The in situ ultraviolet-visible technique proves the catalytic effect of Ni5P2-Ni heterostructure on LiPS conversion during the discharge process.

Hyphae Carbon Coupled with Gel Composite Assembly for Construction of Advanced Carbon/Sulfur Cathodes for Lithium-Sulfur Batteries

The design and fabrication of novel carbon hosts with high conductivity, accelerated electrochemical catalytic activities, and superior physical/chemical confinement on sulfur and its reaction intermediates polysulfides are essential for the construction of high-performance C/S cathodes for lithium-sulfur batteries (LSBs). In this work, a novel biofermentation coupled gel composite assembly technology is developed to prepare cross-linked carbon composite hosts consisting of conductive Rhizopus hyphae carbon fiber (RHCF) skeleton and lamellar sodium alginate carbon (SAC) uniformly implanted with polarized nanoparticles (V2O3, Ag, Co, etc.) with diameters of several nanometers. Impressively, the RHCF/SAC/V2O3 composites exhibit enhanced physical/chemical adsorption of polysulfides due to the synergistic effect between hierarchical pore structures, heteroatoms (N, P) doping, and polar V2O3 generation. Additionally, the catalytic conversion kinetics of cathodes are effectively improved by regulating the 3D carbon structure and optimizing the V2O3 catalyst. Consequently, the LSBs assembled with RHCF/SAC/V2O3-S cathode show exceptional cycle stability (capacity retention rate of 94.0% after 200 cycles at 0.1 C) and excellent rate performance (specific capacity of 578 mA h g-1 at 5 C). This work opens a new door for the fabrication of hyphae carbon composites via fermentation for electrochemical energy storage.

Constructing ion-transport blockchain by polypyrrole to link CoTi-ZIF-9 derived carbon materials for high-performance seawater desalination

The instability and poor electronic conductivity of carbon materials derived from bimetallic zeolite imidazolate frameworks (ZIFs) pose significant challenges for utilizing these carbon materials as direct electrodes for achieving rapid electron transfer and high-performance capacitive deionization (CDI). However, modifying ZIFs through conductive polymers is a wise tool to enhance the target characteristics of ZIFs. Herein, a strategy is proposed to use polypyrrole (PPy) to interlink the carbon units derived from CoTi-ZIF-9 to construct a blockchain network system with high capacity and fast electrochemical kinetics for high performance CDI. In this system, PPy serves as a branched link connecting each carbon unit, so that the ions in the electrolyte can achieve low barrier and fast transmission in the three-dimensional network structure between the unit structures. As expected, with the improved charge transfer efficiency between electrode materials and electrolyte, the CDI cell exhibits excellent desalination capacity (77.3 mg g-1). In addition, density functional theory calculations also indicate that the introduction of PPy results in a higher electron density near the fermi surface of carbon material, which is conducive to electron transport and reaction kinetics. This work may provide important concepts for the design of CDI electrodes with high-conductivity and high-performance.