Design of Hybrid Zeolitic Imidazolate Framework-Derived Material with C-Mo-S Triatomic Coordination for Electrochemical Oxygen Reduction

Efficient removal of neonicotinoid by singlet oxygen dominated MoSx/ceramic membrane-integrated Fenton-like process

Removal of neonicotinoids (NEOs) from contaminated water is of great importance for both ecological environment and human health. However, conventional Fenton process might be insufficient for NEOs removal due to short lifetime for generated HO^• and limited Fe³⁺/Fe²⁺ redox cycle. Advancing Fenton process to produce singlet oxygen can be an effective route to improve its efficacy for NEOs removal. Herein, we developed a molybdenum sulfide modified ceramic membrane-integrated Fenton-like system to achieve efficient catalytic removal of NEOs. The reduced Mo⁰ and Mo⁴⁺ could promote the reduction process of Fe³⁺ to Fe²⁺, improving the activation efficiency of hydrogen peroxide (H₂O₂) and the generation of superoxide radical (O₂^•-). Consequently, the coexisting Mo⁶⁺ reacted with O₂^•- to generate ¹O₂. The membrane enabled the pollutants to adequately contact oxidants due to the enhanced convective mass transfer. The functionalized membrane exhibited stable catalytic performance for clothianidin (CLO, a kind of NEOs, 10 mg/L) removal (degradation efficiency > 85%). The presence of ¹O₂ enabled the dechlorination and hydroxylation of CLO and thus reduced the toxicity of wastewater. Our work sheds light on the use of functionalized ceramic membrane integrated catalytic Fenton system for effective environmental remediation.

Active Sites In Situ Implanted Hybrid Zeolitic Imidazolate Frameworks for a Water Oxidation Catalyst

Metal-organic frameworks (MOFs) have been a focus of research because of their unique porous structure, but they are usually not directly for electrocatalysis. Herein, we prepared a special class of Fe/Zn/Mo-based trimetallic hybrid zeolitic imidazolate frameworks by in situ solvothermal synthesis that have the potential to act directly as highly efficient oxygen evolution reaction electrocatalysts. This work provides a foundation for the preparation of multimetal MOFs and expands the investigation of electrocatalysts.

In-Plane Mott-Schottky Effects Enabling Efficient Hydrogen Evolution from Mo5 N6 -MoS2 Heterojunction Nanosheets in Universal-pH Electrolytes

Cost-effective electrocatalysts for the hydrogen evolution reaction (HER) spanning a wide pH range are highly desirable but still challenging for hydrogen production via electrochemical water splitting. Herein, Mo₅ N₆ -MoS₂ heterojunction nanosheets prepared on hollow carbon nanoribbons (Mo₅ N₆ -MoS₂ /HCNRs) are designed as Mott-Schottky electrocatalysts for efficient pH-universal HER. The in-plane Mo₅ N₆ -MoS₂ Mott-Schottky heterointerface induces electron redistribution and a built-in electric field, which effectively activates the inert MoS₂ basal planes to intrinsically increase the electrocatalytic activity, improve electronic conductivity, and boost water dissociation activity. Moreover, the vertical Mo₅ N₆ -MoS₂ nanosheets provide more activated sites for the electrochemical reaction and facilitate mass/electrolyte transport, while the tightly coupled HCNRs substrate and metallic Mo₅ N₆ provide fast electron transfer paths. Consequently, the Mo₅ N₆ -MoS₂ /HCNRs electrocatalyst delivers excellent pH-universal HER performances exemplified by ultralow overpotentials of 57, 59, and 53 mV at a current density of 10 mA cm^-2 in acidic, neutral, and alkaline electrolytes with Tafel slopes of 38.4, 43.5, and 37.9 mV dec^-1 , respectively, which are superior to those of the reported MoS₂ -based catalysts and outperform Pt in overall water splitting. This work proposes a new strategy to construct an in-plane heterointerface on the nanoscale and provides fresh insights into the HER electrocatalytic mechanism of MoS₂ -based heterostructures.

In Situ Architecting Endogenous Heterojunction of MoS2 Coupling with Mo2 CTx MXenes for Optimized Li+ Storage

Endogenous heterojunction of 2D MXenes with unique structure shows inspiring potential in energy applications, which is impeded by complex synthesis method and finite MAX materials. Herein, an in situ hydrothermal strategy is implemented to successfully synthesize unique endogenous hetero-MXenes of amorphous MoS₂ coupling with fluoride-free Mo₂ CT_x (hetero-Mo₂ C) directly from Mo₂ Ga₂ C MAX. The distinctive morphology and heterojunction structure caused by the introduction of MoS₂ endow the hetero-MXenes with extraordinary structural stability and optimized Li⁺ storage mechanism with improved charge transport and lithium ion adsorption capabilities. As a result, hetero-Mo₂ C exhibits excellent electrochemical performance with a high discharge specific capacity of 1242 mAh g^-1 at 0.1 A g^-1 and long cycle stability of 683.9 mAh g^-1 after 1200 cycling. This work provides new insights into rational design of novel MXenes heterojunctions, practically important for the development of MXenes and their applications in high-performance energy storage systems.

Popcorn-like Co3O4 Nanoparticles Confined in Three-Dimensional Hierarchical N-doped carbon nanotubes Networks as Highly Efficient Trifunctional Electrocatalyst for Zinc-Air Batteries and Water Splitting Device

A novel unique popcorn-like three-dimensional (3D) hierarchical structural electrocatalyst is synthesized by the pyrolysis of ZIF-8/ZIF-67 and polyacrylonitrile fibers composites, where popcorn-like Co3O4 nanoparticles coated with nitrogen-doped amorphous carbon anchor...

Recent Advances on Transition Metal Dichalcogenides for Electrochemical Energy Conversion

Transition metal dichalcogenides (TMDCs) hold great promise for electrochemical energy conversion technologies in view of their unique structural features associated with the layered structure and ultrathin thickness. Because the inert basal plane accounts for the majority of a TMDC's bulk, activation of the basal plane sites is necessary to fully exploit the intrinsic potential of TMDCs. Here, recent advances on TMDCs-based hybrids/composites with greatly enhanced electrochemical activity are reviewed. After a summary of the synthesis of TMDCs with different sizes and morphologies, comprehensive in-plane activation strategies are described in detail, mainly including in-plane-modification-induced phase transformation, surface-layer modulation, and interlayer modification/coupling. Simultaneously, the underlying mechanisms for improved electrochemical activities are highlighted. Finally, the strategic evaluation on further research directions of TMDCs in-plane activation is featured. This work would shed some light on future design trends of TMDCs-based functional materials for electrochemical energy-related applications.

A hybrid zeolitic imidazolate framework-derived ZnO/ZnMoO4 heterostructure for electrochemical hydrogen production

Sustainable hydrogen fuel supply through electrochemical water splitting requires highly efficient, low-cost and robust electrocatalysts. Interface engineering is of key importance to improve the catalytic performance in a heterogeneous electrocatalytic system. Herein, a porous microcubic framework composed of a ZnO/ZnMoO₄ heterostructure (ZnO@ZnMoO₄) is prepared by a hybrid zeolitic imidazolate framework-derived oxidation method, and it shows much enhanced hydrogen evolution reaction (HER) activity in alkaline media. The overpotential (at 10 mA cm^-2) for ZnO@ZnMoO₄ is significantly reduced by 30% and 20% compared with those for virgin ZnO (v-ZnO) and polycrystalline zinc molybdenum oxide (PZMO), respectively. The enhanced electrocatalytic activity should be attributed to the ZnO/ZnMoO₄ heterostructure, which can synergistically facilitate the charge transport. This work provides a more structured design strategy for electrocatalysts for future electrochemical energy conversion systems.