Electrochemical treatment of urea wastewater purification significantly aids in environmental protection, but it remains a considerable challenge in designing high performance anode urea oxidation electrocatalysts. Herein, we report a La-induced three-dimensional ordered macroporous (3DOM) NiO heterostructure to improve Ni sites electron density for urea electrooxidation by activating the La-O-Ni bridge. This material demonstrated exceptional performance in a membrane electrode assembly (MEA) device, characterized by a low cell voltage (1.49 V @ 80 °C) and 280 h stability test at 1 A cm-2 current density (25 °C) and displayed promising efficiency in urea wastewater purification. Permeation experiments revealed the crucial role of 3DOM morphological in facilitating mass transfer processes. A high valence nickel mechanism (HNM) on the La-O-Ni bridge during catalysis was proposed, based on various in situ characterizations and theoretical calculations. Experimentally, in situ Raman and UV-vis spectra demonstrated that Ni active species Niδ+ (δ ≥ 3) promote urea oxidation kinetics, while in situ ATR-IR proved strong adsorption of C=O with Ni sites and the enhancement of urea N-H bonds cleavage, supporting the HNM. This work enables us to underscore the critical importance of La-O-Ni electron bridge with 3DOM architectures and promising contributions to urea wastewater purification.
In order to obtain an excellent ZnS-based anode material for sodium-ion batteries (SIBs), a designed hierarchical nanostructure formed by ZnS hollow nanorods and uniform nanosheets was synthesized via hydrothermal method in the presence of carboxymethyl chitosan. The nanosheets were composed of amorphous nitrogen doped carbon and molybdenum disulfide (MoS 2 -NC). Notably, the one-dimensional tubular framework possessed low impedance characteristics. Through the way of combining it with nanosheets which had abundant defects, it could boost the charge transfer and improve the sodium storage performance effectively. When tested as the anode material of SIBs, this ZnS@MoS 2 -NC composite exhibited excellent cycling and rate performance. Moreover, it was further assembled into sodium-ion full batteries and showed good cyclic stability. This work provides a valuable option for preparing promising SIBs anode materials by combining structural design with multi-component coordination, which can be extended to other metal sulfide electrode materials.
Abstract Purpose – The purpose of this paper is to synthesise polyaniline‐SiO2 (PANI‐SiO2) composites and investigate the anticorrosion properties of polyaniline‐SiO2‐containing coating on Mg‐Li alloy. Design/methodology/approach – The PANI‐SiO2 composites were prepared by in situ chemical oxidative polymerisation in phosphoric acid medium. The PANI‐SiO2 composites were characterised by Fourier transform infrared, X‐ray diffraction and scanning electron microscopy techniques. The coating consisted of PANI‐SiO2 composites and epoxy resin was formed on Mg‐Li alloy. The anticorrosion properties were investigated by open circuit potentials (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation curves. Findings – The results indicated that the PANI‐SiO2‐containing coating on Mg‐Li alloy demonstrated good anticorrosion properties in 3.0 wt% NaCl solution. It has been found that the OCP of PANI‐SiO2‐containing coating were able to maintain more noble potential values in comparison to pure epoxy coatings in 3.0 wt% NaCl solution. EIS analysis indicated that the resistance of PANI‐SiO2‐containing coating was more than 106 Ω cm2 in 3.0 wt% NaCl solution in immersion process. Furthermore, the corrosion current of PANI‐SiO2‐containing coating on Mg‐Li alloy showed a significant reduction. Originality/value – Previous reports on PANI‐SiO2 composites were mostly focused on their conductivity and optical properties and there are few studies so far on their anticorrosion properties as protective coatings for Mg‐Li alloy.
Abstract Sodium‐ion batteries (SIBs) hold great promise for next‐generation grid‐scale energy storage. However, the highly instable electrolyte/electrode interphases threaten the long‐term cycling of high‐energy SIBs. In particular, the instable cathode electrolyte interphase (CEI) at high voltage causes persistent electrolyte decomposition, transition metal dissolution, and fast capacity fade. Here, this work proposes a balanced principle for the molecular design of SIB electrolytes that enables an ultra‐thin, homogeneous, and robust CEI layer by coupling an intrinsically oxidation‐stable succinonitrile solvent with moderately solvating carbonates. The proposed electrolyte not only shows limited anodic decomposition thus leading to a thin CEI, but also suppresses dissolution of CEI components at high voltage. Consequently, the tamed electrolyte/electrode interphases enable extremely stable cycling of Na 3 V 2 O 2 (PO 4 ) 2 F (NVOPF) cathodes with outstanding capacity retention (>90%) over 3000 cycles (8 months) at 1 C with a high charging voltage of 4.3 V. Further, the NVOPF||hard carbon full cell shows stable cycling over 500 cycles at 1 C with a high average Coulombic efficiency (CE) of 99.6%. The electrolyte also endows high‐voltage operation of SIBs with great temperature adaptability from −25 to 60 °C, shedding light on the essence of fundamental electrolyte design for SIBs operating under harsh conditions.
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