Conversion
of CO2 into value-added fuels and chemicals
faces the challenges of high overpotential, low selectivity for desired
products, and sluggish multi-electron transfer kinetics. Plasmon-mediated
electrocatalytic methods show potential for overcoming these problems.
In this work, choosing Au nanoparticles (NPs) as the dual-functional
material of the electrocatalyst and plasmonic support, methanol can
be efficiently produced from CO2 reduction. The dependences
of current density and Faradaic efficiency (FE) on the Au NP size,
light wavelength, and light density are systematically investigated.
The performance test results show that CH3OH with FE as
high as 52% can be obtained at a potential of −0.8 V (vs RHE)
when a 20.2 nm Au NP-modified glass carbon electrode is under excitation
using 520 nm light with a light density of 120 mW/cm2.
The performance results, along with the discrete dipole approximation
calculation and electrochemical characterizations, suggest that the
efficient activation of CO2 by plasmon-generated energetic
electrons accounts for the enhanced conversion rate and the high selectivity
for CH3OH production.
The electrochemical reduction of CO2 is a promising way to recycle it to produce value-added chemicals and fuels. However, the requirement of high overpotential and the low solubility of CO2 in water severely limit their efficient conversion. To overcome these problems, in this work, a new type of electrolyte solution constituted by ionic liquids and propylene carbonate was used as the cathodic solution, to study the conversion of CO2 on an Ag electrode. The linear sweep voltammetry (LSV), Tafel characterization and electrochemical impedance spectroscopy (EIS) were used to study the catalytic effect and the mechanism of ionic liquids in electrochemical reduction of CO2. The LSV and Tafel characterization indicated that the chain length of 1-alkyl-3-methyl imidazolium cation had strong influences on the catalytic performance for CO2 conversion. The EIS analysis showed that the imidazolium cation that absorbed on the Ag electrode surface could stabilize the anion radical (CO2•−), leading to the enhanced efficiency of CO2 conversion. At last, the catalytic performance was also evaluated, and the results showed that Faradaic efficiency for CO as high as 98.5% and current density of 8.2 mA/cm2 could be achieved at −1.9 V (vs. Fc/Fc+).
Two Co(II) coordination polymers, [Co(ca)(bib)] n (I) and {[Co(ca)(bibp) 1.5 ]Á 1.5H 2 O} n (II) (H 2 ca = citraconic acid, bib = 1,4-bis(1-imidazoly)benzene, bibp = 1,4-bis-[4-(imidazol-1-yl)benzyl]piperazine), were prepared by hydrothermal method and measured structurally by single-crystal X-ray diffraction, infrared spectroscopy, and elemental analysis. Complex I shows a 2D layer structure containing Cocarboxylate chains. Complex II displays a 3D metal-organic framework composed of the binuclear [Co 2 (CO 2 ) 2 ] 2+ cluster nodes through ca 2− and bibp as linkers with (4 12 Á6 3 ) topology. Complexes I and II have high thermal stabilities because their frameworks maintain good integrity before 340 C and 265 C, respectively. Both complexes show well photocatalytic activities for methylene blue degradation under UV irradiation in the presence of H 2 O 2 , which may be used as potential materials for photocatalytic dyes degradation.
K E Y W O R D Scitraconic acid, coordination polymer, photocatalytic degradation, thermal stability
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