Phase Evolution of Multi-Metal Dichalcogenides With Conversion-Alloying Hybrid Mechanism for Superior Lithium Storage.

Traditional lithium-ion battery (LIB) anodes, whether intercalation-type like graphite or alloying-type like silicon, employing a single lithium storage mechanism, are often limited by modest capacity or substantial volume changes. Here, the kesterite multi-metal dichalcogenide (CZTSSe) is introduced as an anode material that harnesses a conversion-alloying hybrid lithium storage mechanism. Results unveil that during the charge-discharge processes, the CZTSSe undergoes a comprehensive phase evolution, transitioning from kesterite structure to multiple dominant phases of sulfides, selenides, metals, and alloys. The involvement of multi-components facilitates electron transport and mitigates swelling stress; meanwhile, it results in formation of abundant defects and heterojunctions, allowing for increased lithium storage active sites and reduced lithium diffusion barrier. The CZTSSe delivers a high specific capacity of up to 2266 mA h g-1 at 0.1 A g-1; while, maintaining a stable output of 116 mA h g-1 after 10 000 cycles at 20 A g-1. It also demonstrates remarkable low-temperature performance, retaining 987 mA h g-1 even after 600 cycles at -40 °C. When employed in full cells, a high specific energy of 562 Wh kg-1 is achieved, rivalling many state-of-the-art LIBs. This research offers valuable insights into the design of LIB electrodes leveraging multiple lithium storage mechanisms.

Manipulating coordination environment for a high-voltage aqueous copper-chlorine battery.

Aqueous copper-based batteries have many favourable properties and have thus attracted considerable attention, but their application is limited by their low operating voltage originating from the high potential of copper negative electrode (0.34 V vs. standard hydrogen electrode). Herein, we propose a coordination strategy for reducing the intrinsic negative electrode redox potential in aqueous copper-based batteries and thus improving their operating voltage. This is achieved by establishing an appropriate coordination environment through the electrolyte tailoring via Cl- ions. When coordinated with chlorine, the intermediate Cu+ ions in aqueous electrolytes are successfully stabilized and the electrochemical process is decoupled into two separate redox reactions involving Cu2+/Cu+ and Cu+/Cu0; Cu+/Cu0 results in a redox potential approximately 0.3 V lower than that for Cu2+/Cu0. Compared to the coordination with water, the coordination with chlorine also results in higher copper utilization, more rapid redox kinetics, and superior cycle stability. An aqueous copper-chlorine battery, harnessing Cl-/Cl0 redox reaction at the positive electrode, is discovered to have a high discharge voltage of 1.3 V, and retains 77.4% of initial capacity after 10,000 cycles. This work may open up an avenue to boosting the voltage and energy of aqueous copper batteries.

Rational Design of Electron Transfer Kineties of CdS/Zn(impim) Dots-on-Rods for Efficient Visible-Light Reduced C-X Bond.

Halogenated organic compounds are a kind of common environmental pollutants. Photocatalytic dehalogenation of C-halogen (C-X) bonds to C-H bonds can not only control environmental pollution but also realize important organic conversion reactions. However, the electron transfer kinetics of photocatalytic reduction of the C-X bond for semiconductor/MOF composites has remained unexplored. Herein, we successfully synthesized CdS/Zn(impim) (MOF) dots-on-rods composite photocatalyst under mild conditions. Zn(impim) MOF consists of Zn(µ-N)4 clusters and imidazole derivative ligands. Zn(impim), as a carrier, is beneficial to the dispersion of CdS nanoparticles and avoiding the agglomeration of CdS nanoparticles. The photocatalytic performance of CdS/Zn(impim) composites for the reduction of the C-X bond is much higher than that of pure CdS or Zn(impim). This high activity is due to the high electron separation efficiency of CdS assisted by Zn(impim). Under visible light irradiation, Zn(impim) is not excited due to its wide band gap of 3.26 eV. Through metal-to-ligand charge transfer of Zn(µ-N)4 clusters, Zn(impim) accepts excited electrons from CdS because the Fermi energy level of CdS is more negative by Kelvin probe force microscopy. Moreover, fluorescence spectrum and femtosecond transient absorption spectroscopy reveal the related electron transfer kinetics in detail. In addition, the inherent porous structure of MOFs is beneficial to the adsorption of halogenated hydrocarbons, providing a suitable environment for the dehalogenation reaction, thus improving the activity. This work can further understand the electron transfer mechanism in semiconductor/MOF composites for photocatalytic halide dehalogenation.

Unlocking High-Performance Ammonium-Ion Batteries: Activation of In-Layer Channels for Enhanced Ion Storage and Migration.

Ammonium-ion batteries, leveraging non-metallic ammonium ions, have arisen as a promising electrochemical energy storage system; however, their advancement has been hindered by the scarcity of high-performance ammonium-ion storage materials. In this study, an electrochemical phase transformation approach is proposed for the in situ synthesis of layered VOPO4 ·2H2 O (E-VOPO) with predominant growth on the (200) plane, corresponding to the tetragonal channels on the (001) layers. The findings reveal that these tetragonal in-layer channels not only furnish NH4 + storage sites but also enhance transfer kinetics by providing rapid cross-layer migration pathways. This crucial aspect has been largely overlooked in previous studies. The E-VOPO electrode exhibits exceptional ammonium-ion storage performance, including significantly increased specific capacity, enhanced rate capability, and robust cycling stability. The resulting full cell can be stably operated for 12 500 charge-discharge cycles at 2 A g-1 for over 70 days. The proposed approach offers a new strategy for meticulously engineering electrode materials with facilitated ion storage and migration, thereby paving the way for developing more efficient and sustainable energy storage systems.

Encapsulating polyaniline within porous MIL-101 for high-performance corrosion protection.

The metal corrosion possesses a serious threat to the safety and loss of property. The anticorrosion study on metal-organic frameworks (MOFs) remains rarely reported. Therefore, it is desirable to build MOFs-based anticorrosion coating with long-term corrosion resistance. Herein, we prepared a novel MOF-polymer anticorrosion composite PANI@MIL-101 by encapsulating polyaniline (PANI) within the pores of MIL-101 with in-situ polymerization of aniline monomer. The N2 adsorption-desorption and transmission electron microscopy (TEM) of PANI@MIL-101 illustrate that PANI is successfully encapsulated in the pores of MIL-101 with in-situ polymerization. PANI@MIL-101 was dispersed in epoxy resin (EP) to prepare anti-corrosive coatings. The Tafel potentiodynamic polarization measurements and electrochemical impedance spectroscopy show that PANI@MIL-101/EP coating system has superior corrosion protection with the lowest icorr value and the highest |Z|0.01 value compared with MIL-101/EP coating, PANI/EP coating and EP coating. A possible anticorrosion mechanism of PANI@MIL-101 was discussed. This work reveals that MOF-polymer composite materials are superb candidates for high-performance corrosion protection.

The sandwich-like structures of polydopamine and 8-hydroxyquinoline coated graphene oxide for excellent corrosion resistance of epoxy coatings.

A novel sandwich-like structure material was exploited for the fabrication of an effective corrosion resistance system. An environmentally friendly composite material was synthesized by installing 8-hydroxyquinoline (8-HQ) on the surface of graphene oxide (GO). In order to prevent leakage of corrosion inhibitor 8-HQ, GO/8-HQ was modified by polydopamine (PDA), denoted as GO/8-HQ/PDA. A sandwich-like structure (GO/8-HQ/PDA) enables long-term stable storage of corrosion inhibitor in the protective matrix. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were utilized to verify the sandwich-like structure of GO/8-HQ/PDA. The electrochemical tests in a 3.5 wt% NaCl solution showed that the addition of well-dispersed GO/8-HQ/PDA into epoxy system (GO/8-HQ/PDA-EP) remarkably improved corrosion protection of AZ31b magnesium alloy compared with pure epoxy (EP) coating. The sandwich structure protects the activity and structural integrity of the corrosion inhibitor (8-HQ). The corrosion inhibitor (8-HQ) of the GO/8-HQ/PDA sandwich structure cuts off the ion exchange between the metal alloy and the electrolyte solution, which hinders the electrochemical corrosion of the metal. A possible corrosion resistance mechanism of GO/8-HQ/PDA is fully discussed. This study provides feasibilities for the immobilization of corrosion inhibitors on the metal surface.

Excellent Efficacy of MOF Films for Bronze Artwork Conservation: The Key Role of HKUST-1 Film Nanocontainers in Selectively Positioning and Protecting Inhibitors.

Development of metal-organic framework (MOF) films for selectively positioning inhibitors in metallic anticorrosion applications remains a substantial challenge due to the difficulty of controlling the arrangement of inhibitor molecules in MOF pores. Cetyltrimethyl ammonium bromide (CTAB), which contains hydrophobic and hydrophilic tails, was chosen as a prototypical inhibitor and was selectively located in the pores of the classic HKUST-1 thin film on a metallic surface. Experimental results reveal that the prepared CTAB@HKUST-1 film displays good metallic anticorrosion performances, especially for bronze conservation. A possible anticorrosion mechanism of CTAB@HKUST-1 is proposed and fully discussed. The study provides an avenue for developing MOF-based thin films for metallic anticorrosion applications to address the environmental development issues related to corrosion.