RESUMEN
Single Fe sites have been explored as promising catalysts for the CO2 reduction reaction to value-added CO. Herein, we introduce a novel molten salt synthesis strategy for developing axial nitrogen-coordinated Fe-N5 sites on ultrathin defect-rich carbon nanosheets, aiming to modulate the reaction pathway precisely. This distinctive architecture weakens the spin polarization at the Fe sites, promoting a dynamic equilibrium of activated intermediates and facilitating the balance between *COOH formation and *CO desorption at the active Fe site. Notably, the synthesized FeN5, supported on defect-rich in nitrogen-doped carbon (FeN5@DNC), exhibits superior performance in CO2RR, achieving a Faraday efficiency of 99% for CO production (-0.4 V vs. RHE) in an H-cell, and maintaining a Faraday efficiency of 98% at a current density of 270 mA cm-2 (-1.0 V vs. RHE) in the flow cell. Furthermore, the FeN5@DNC catalyst is assembled as a reversible Zn-CO2 battery with a cycle durability of 24 hours. In-situ IR spectroscopy and density functional theory (DFT) calculations reveal that the axial N coordination traction induces a transformation in the crystal field and local symmetry, therefore weakening the spin polarization of the central Fe atom and lowering the energy barrier for *CO desorption.
RESUMEN
SignificanceSeawater is one of the most abundant resources on Earth. Direct electrolysis of seawater is a transformative technology for sustainable hydrogen production without causing freshwater scarcity. However, this technology is severely impeded by a lack of robust and active oxygen evolution reaction (OER) electrocatalysts. Here, we report a highly efficient OER electrocatalyst composed of multimetallic layered double hydroxides, which affords superior catalytic performance and long-term durability for high-performance seawater electrolysis. To the best of our knowledge, this catalyst is among the most active for OER and it advances the development of seawater electrolysis technology.
RESUMEN
Monodisperse magnetic submicron particles were synthesized by a solvothermal reduction method. A solid phase extraction (SPE) based on the monodisperse magnetic submicron particles and high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for the determination of bisphenol A (BPA) at trace level in milk has been established. The important parameters that affect the extraction efficiency such as the solution pH, dosage of magnetic submicron particles, nature of elution solution and its volume were optimized. The optimal extraction conditions were as follows: the pH 6.0, the dosage of 3.5 mg magnetic submicron particles and 0.4 mL methanol as elution solution. BPA was analyzed by HPLC-MS/MS in negative ion mode using an Agilent XDB C18 column as analytical column. Under the optimal conditions, the calibration curves showed a good linearity in the BPA concentration range of 1.0-100.0 micro g/L. The correlation coefficient was 0. 999 3. The average recoveries of BPA at three spiked levels ranged from 85.3% to 96. 1% with the relative standard deviations (RSDs) less than 10%. The detection limit of the method was 1.0 microg/L. The method is sensitive, simple, and suitable for the rapid determination of BPA in milk.