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Electrochemical conversion of nitrate offers an efficient solution to nitrate pollution and a sustainable strategy for ammonia generation. Cu and Fe bimetallic electrocatalysts exhibit excellent electrochemical reduction of nitrate (NO3RR) reactivity but the conventional preparation strategy is complex and time‐consuming and this reaction is still suffers from unsatisfied kinetic and unidentified mechanisms. Herein, in situ electrodeposition strategy is employed to induce Cu to modify the Fe active sites of iron‐based N‐doping carbon nanofiber electrode (Fe/Fe3C@NCNFs) during NO3RR in Cu‐contained nitrate solution. Benefiting from the synergistic effect between Cu and Fe sites of Cu─Fe/Fe3C@NCNFs electrode, superior activity of rate‐determining reaction (*NO3 to *NO2) and reduced energy barriers of the following deoxidation and hydrogenation steps are achieved. Compared with Fe/Fe3C@NCNFs‐500, the pseudo‐first‐order (PFO) rate constant for NO3RR by Cu─Fe/Fe3C@NCNFs demonstrates nearly two‐fold improvement with high current efficiencies over wide pH and voltage range. Furthermore, the maximum NO3─N removal capacity and N2 selectivity of Cu─Fe/Fe3C@NCNFs reach 15593.8 mg N g−1 Fe and ca. 92% after twenty cycles. This work offers an avenue for highly active bimetallic electrode design, paving more insights into the interactions between active site construction and NO3RR performance. [ABSTRACT FROM AUTHOR]

Mining wastewater with heavy metals poses a serious threat to the ecological environment. However, the acute single and combined ecological effects of heavy metals, such as chromium (Cr) and nickel (Ni), on freshwater ostracods, and the development of relevant prediction models, remain poorly understood. In this study, Heterocypris sp. was chosen to investigate the single and combined acute toxicity of Cr and Ni. Then, the quantitative structure-activity relationship (QSAR) model was used to predict the combined toxicity of Cr and Ni. The single acute toxicity experiments revealed high toxicity for both Cr and Ni. In addition, Cr exhibited greater toxicity compared to Ni, as evidenced by its lower 96-hour half-lethal concentration (LC50) of 1.07 mg/L compared to 4.7 mg/L for Ni. Furthermore, the combined acute toxicity experiments showed that the toxicity of Cr-Ni was higher than Ni but lower than Cr. Compared with the concentration addition (CA) and independent action (IA) models, the predicted results of the QSAR model were more consistent with the experimental results for the Cr-Ni combined acute toxicity. So, the high accuracy of QSAR model identified its feasibility to predict the toxicity of heavy metal pollutants in mining wastewater. [ABSTRACT FROM AUTHOR]

This study proposes a new Pr 0.25 Nd 0.25 Ca 0.5 MnO 3-δ (PNCM) cathode material for protonic ceramic fuel cells (PCFCs). As demonstrated by first-principles calculations, the Ca-doping strategy can promote oxygen vacancy formation and accelerate the oxygen reduction reaction (ORR) compared to the conventional Sr-doping method. Additional experiments reveal the doping of Ca can enhance the proton and oxygen diffusion abilities compared with the traditional Sr-doped material. Consequently, the PCFC with single-phase PNCM cathode produces a high peak power density of 1232 mW cm-2 at 700 °C, which is significantly greater than the cell with Sr-doped cathode, which only produces 749 mW cm-2 under the same testing conditions. The PNCM cathode inherits the excellent stability of manganate cathodes, allowing the fuel cell to exhibit good stability under operational conditions. PNCM is a new and promising cathode material for PCFCs due to its excellent fuel cell performance and stability. [ABSTRACT FROM AUTHOR]

Sintering aids are commonly used to improve the sinterability of proton-conducting oxides, whereas the sintering aid elements are being used alone in previous research. In this study, a high-entropy design method for the BaCe 0.4 Zr 0.4 Y 0.2 O 3 (BCZY) proton-conducting oxides sintering aid is proposed. In contrast to the use of sintering aids such as Ni, Fe, Cu, Co, and Zn alone, the high-entropy design allows for the simultaneous use of all five elements, resulting in the new composition BaCe 0.4 Zr 0.4 Y 0.15 Ni 0.01 Cu 0.01 Co 0.01 Fe 0.01 Zn 0.01 O 3 (HE-BCZY). Compared to conventional BaCe 0.4 Zr 0.4 Y 0.15 M 0.05 O 3 (BCZYM, M = Ni, Cu, Co, Fe, Zn) materials, the sinterability of the new HE-BCZY material is significantly greater than that of BCZYM, despite the fact that the concentration of sintering aids is the same. Following sintering at 1300 °C, the HE-BCZY electrolyte membrane is completely dense. In addition, the HE-BCZY electrolyte has a higher conductivity than BCZYM. The low sintering temperature allows the successful preparation of proton ceramic fuel cells (PCFCs) with the HE-BCZY electrolyte, and the fuel cell reaches a high peak power density of 1218 mW cm−2 at 700 °C, which is much higher than that of PCFCs using BCZY-based electrolytes. In addition, the excellent chemical stability of HE-BCZY is maintained under both H 2 O and CO 2 conditions. Consequently, a fuel cell employing the HE-BCZY electrolyte operates without detectable degradation for 200 h. This study demonstrates that although the high-entropy design is seldom used for sintering aids of proton-conducting oxides, it is an intriguing and promising strategy for creating high-performance electrolyte materials with good sinterability, high conductivity, and excellent stability. [ABSTRACT FROM AUTHOR]