Facile and Scalable Synthesis of Self-Supported Zn-Doped CuO Nanosheet Arrays for Efficient Nitrate Reduction to Ammonium

CuO has been regarded as a promising catalyst for the electrochemical reduction of nitrate (NO3–RR) to ammonium (NH3); however, the intrinsic activity is greatly restricted by its poor electrical property. In this work, self-supported Zn-doped CuO nanosheet arrays (Zn–CuO NAs) are synthesized for NO3–RR, where the Zn dopant regulates the electronic structure of CuO to significantly accelerate the interfacial charge transfer and inner electron transport kinetics. The Zn–CuO NAs are constructed by a one-step etching of commercial brass (Cu64Zn36 alloy) in 0.1 M NaOH solution, which experiences a corrosion–oxidation–reconstruction process. Initially, the brass undergoes a dealloying procedure to produce nanosized Cu, which is immediately oxidized to the Cu2O unit with a low valence state. Subsequently, Cu2O is further oxidized to the CuO unit and reconstructed into nanosheets with the coprecipitation of Zn2+. For NO3–RR, Zn–CuO NAs show a high NH3 production rate of 945.1 μg h–1 cm–2 and a Faradaic efficiency of up to 95.6% at −0.7 V in 0.1 M Na2SO4 electrolyte with 0.01 M NaNO3, which outperforms the majority of the state-of-the-art catalysts. The present work offers a facile yet very efficient strategy for the scale-up synthesis of Zn–CuO NAs for high-performance NH3 production from NO3–RR

Stabilizing Lithium-Metal Host Anodes by Covalently Binding MgF₂ Nanodots to Honeycomb Carbon Nanofibers

Constructing lithiophilic carbon hosts has been regarded as an effective strategy for inhibiting Li dendrite formation and mitigating the volume expansion of Li metal anodes. However, the limitation of lithiophilic carbon hosts by conventional surface decoration methods over long-term cycling hinders their practical application. In this work, a robust host composed of ultrafine MgF2 nanodots covalently bonded to honeycomb carbon nanofibers (MgF2/HCNFs) is created through an in situ solid-state reaction. The composite exhibits ultralight weight, excellent lithiophilicity, and structural stability, contributing to a significantly enhanced energy efficiency and lifespan of the battery. Specifically, the strong covalent bond not only prevents MgF2 nanodots from migrating and aggregating but also enhances the binding energy between Mg and Li during the molten Li infusion process. This allows for the effective and stable regulation of repeated Li plating/stripping. As a result, the MgF2/HCNF-Li electrode delivers a high Coulombic efficiency of 97% after 200 cycles, cycling stably for more than 2000 h. Furthermore, the full cells with a LiFePO4 cathode achieve a capacity retention of 85% after 500 cycles at 0.5C. This work provides a strategy to guide dendrite-free Li deposition patterns toward the development of high-performance Li metal batteries

General Metal-Ion Mediated Method for Functionalization of Graphene Fiber

Graphene fibers (GFs) are attractive materials for wearable electronics because of their lightness, superior flexibility, and electrical conductivity. However, the hydrophobic nature and highly stacked structure endow GFs similar characteristics in nature to solid carbon fibers. Therefore, the interior functionalization of GFs so as to achieve synergistic interaction between graphene nanosheets and active materials thus enhance the performance of hybrid fibers remains a challenge. Herein, a general metal-ion mediated strategy is developed to functionalize GFs and nanoparticles of Cu, Fe₂O₃, NiO, and CoO are successfully incorporated into GFs, respectively. As proof-of-concept applications, the obtained functionalized GFs are used as electrodes for electrochemical sensors and supercapacitors. The performances of thus-devised fiber sensor and supercapacitor are greatly improved