Synergistic Performance Boosts of Dopamine-Derived Carbon Shell Over Bi-metallic Sulfide: A Promising Advancement for High-Performance Lithium-Ion Battery Anodes

Enhancing photocatalytic hydrogen evolution of carbon nitride through high-valent cobalt active sites in cobalt sulfide co-catalyst

The photocatalytic hydrogen (H2) evolution reaction driven by solar energy is one of the most promising methods to alleviate energy and environmental problems. Regrettably, the rapid recombination of photogenerated electrons and hole pairs in semiconductor catalysts leads to low solar energy conversion efficiency. To address this problem, we chose the method of co-catalyst loading. This study uses an in-situ self-assembly growth strategy to load high-valent cobalt sulfide (CoS) onto bulk carbon nitride (BCN) for photocatalytic H2 evolution. The results show that the photocatalytic H2 evolution performance of the optimal ratio of CoS and BCN composite (CoS-BCN(15%)) is 156 times that of BCN. The main reason for the performance improvement is that CoS nanoparticles act as co-catalysts to increase the carrier migration rate. Moreover, CoS nanoparticles contain mixed-valence Co3+/Co2+. During the reaction, high-valence cobalt ions become electron transfer stations, reacting with additional electrons to generate low-valence ions, reducing the recombination of carriers. Additionally, combined experiments and theoretical calculations show that the CoS surface is more conducive to the precipitation of H2 than BCN. This study provides a reference for further exploring the mechanism of action of co-catalysts.

MoSe2/Bi2Se3 Heterostructure Immobilized in N-Doped Carbon Nanosheets Assembled Flower-Like Microspheres for High-Rate Sodium Storage

A key challenge for sodium-ion batteries (SIBs) lies in identifying suitable host materials capable of accommodating large Na+ ions while addressing sluggish chemical kinetics. The unique interfacial effects of heterogeneous structures have emerged as a critical factor in accelerating charge transfer and enhancing reaction kinetics. Herein, MoSe2/Bi2Se3 composites integrated with N-doped carbon nanosheets are synthesized, which spontaneously self-assemble into flower-like microspheres (MoSe2/Bi2Se3@N-C). Electrochemical measurements and density functional theory (DFT) calculations underscore the significant improvement in reaction kinetics enabled by the interfacial effects and structural advantages of the MoSe2/Bi2Se3 composite. Remarkably, the flower-like nanosheet morphology provides more storage sites, while the uniformly distributed heterostructure can optimize carrier concentration and alter electric field distribution, thereby facilitating charge transfer and enabling additional sodium ion storage. When employed as an anode material for SIBs, MoSe2/Bi2Se3@N-C exhibits exceptional performance, delivering a reversible capacity of 521.4 mAh g-1 at 1 A g-1 for 800 cycles and 407.9 mAh g-1 at 10 A g-1 over 1400 cycles. Notably, the capacity can be fully restored to its initial level after cycling at high current densities. This study, combining experimental and theoretical insights, provides a novel perspective on interface engineering to advance the practical application of SIBs.

Three-dimensional hollow ZnS/MXene heterostructures with stable Ti-O-Zn bonding for enhanced lithium-ion storage

An effective way to improve the cycling performance of metal sulfide materials is to blend them with conductive materials. In this paper, three-dimensional (3D) hollow MXene/ZnS heterostructures (ZnSMX) were prepared via a two-step process involving hydrothermal and template methodologies. The formation of Ti-O-Zn bonds enables the firm bonding between ZnS nanoparticles and the MXene substrate at heterogeneous interfaces, which can act as "electron bridges" to facilitate electron and charge transfer. Additionally, 3D hollow ZnSMX not only enhances the conductivity of ZnS, enabling rapid charge transfer, but also effectively show restacking of MXene nanosheets to maintain structural stability during the charge/discharge process. More importantly, the 3D porous structure provides ultrafast interfacial ion transport pathways and extra surficial and interfacial storage sites, thus boosting excellent storage performances in lithium-ion battery applications. The 3D ZnSMX exhibited a high capacity of 782.1 mA h g-1 at 1 A g-1 current, excellent cycling stability (providing a high capacity of 1027.8 mA h g-1 after 350 cycles at 2 A g-1), and excellent rate performance. This indicates that 3D ZnS/MXene heterostructures can potentially be highly promising anode materials for high-multiplication lithium-ion batteries.

Cyanide Functionalization and Oxygen Vacancy Creation in Ni-Fe Nano Petals Sprinkled with MIL-88A Derived Metal Oxide Nano Droplets for Bifunctional Alkaline Seawater Electrolysis

This work investigates novel improvements in FeNi-layered double hydroxide (LDH)/MIL-88A heterocomposite for sustainable seawater electrolysis through a single-step dual functionalization process. The Fe/Ni precursor weight ratio is optimized, resulting in the formation of smaller LDH petals and nano-sized MIL-88A metal-organic framework, which transforms into clusters of Fe2O3 nanospheres within a nitrogen-functionalized carbon matrix over NiFe2O4 nano petals upon calcination. Furthermore, oxygen vacancies, and nitrogen functionalization are attained in a single step by employing thermal ammonia reduction, significantly improving the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) activities. Particularly the oxygen vacancy and nitrogen functionalization are found to accelerate the O─O coupling step in OER by lowering the activation barrier. Likewise, the dual functionalization promotes destabilizing the hydride intermediates in HER potentially facilitating faster proton-coupled electron transfer. Hence, the optimized electrode achieves current densities of 200 mA cm-2 at overpotentials of 350 and 240 mV for OER and HER respectively. The chronopotentiometry stability tests confirms the electrode's durability over 200 h at 20 mA cm-2 in alkaline seawater electrolyte. The optimized electrode, composed of cost-effective and environmentally friendly materials, demonstrates robustness in alkaline seawater electrolytes, positioning it as a strong candidate for practical and sustainable water electrolysis applications.

Optimization Design of Fluoro-Cyanogen Copolymer Electrolyte to Achieve 4.7 V High-Voltage Solid Lithium Metal Battery

Raising the charging voltage and employing high-capacity cathodes like lithium cobalt oxide (LCO) are efficient strategies to expand battery capacity. High voltage, however, will reveal major issues such as the electrolyte's low interface stability and weak electrochemical stability. Designing high-performance solid electrolytes from the standpoint of substance genetic engineering design is consequently vital. In this instance, stable SEI and CEI interface layers are constructed, and a 4.7 V high-voltage solid copolymer electrolyte (PAFP) with a fluoro-cyanogen group is generated by polymer molecular engineering. As a result, PAFP has an exceptionally broad electrochemical window (5.5 V), a high Li+ transference number (0.71), and an ultrahigh ionic conductivity (1.2 mS cm-2) at 25 °C. Furthermore, the Li||Li symmetric cell possesses excellent interface stability and 2000 stable cycles at 1 mA cm-2. The LCO|PAFP|Li batteries have a 73.7% retention capacity after 1200 cycles. Moreover, it still has excellent cycling stability at a high charging voltage of 4.7 V. These characteristics above also allow PAFP to run stably at high loading, showing excellent electrochemical stability. Furthermore, the proposed PAFP provides new insights into high-voltage resistant solid polymer electrolytes.

CoO/MoO3@Nitrogen-Doped carbon hollow heterostructures for efficient polysulfide immobilization and enhanced ion transport in Lithium-Sulfur batteries

Lithium-sulfur batteries (LSBs) have emerged as a promising energy storage system, but their practical application is hindered by the polysulfide shuttle effect and sluggish redox kinetics. To address these challenges, we have developed CoO/MoO3@nitrogen-doped carbon (CoO/MoO3@NC) hollow heterostructures based on porous ZIF-67 as separators in LSBs. CoO has a strong anchoring effect on polysulfides. The heterostructure formed after the introduction of MoO3 increases the adsorption of polysulfides. The carbon coating outside the heterostructure improves the ion transmission efficiency of the battery, leading to enhanced electrochemical performance. The modified LSB demonstrates a low-capacity decay rate of 0.092% over 500 cycles at 0.5C, with a high discharge capacity of 613 mAh g-1 at 1C. This work presents a novel approach for the preparation of hollow heterostructure materials, aiming for high-performance LSBs.