Exploring the impact of Nafion modifier on electrocatalytic CO_(2) reduction over Cu catalyst

Nafion as a universal polymer ionomer was widely applied for nanocatalysts electrode preparation.However,the effect of Nafion on electrocatalytic performance was often overlooked,especially for CO_(2)electrolysis.Herein,the key roles of Nafion for CO_(2)RR were systematically studied on Cu nanoparticles(NPs)electrocatalyst.We found that Nafion modifier not only inhibit hydrogen evolution reaction(HER)by decreasing the accessibility of H_(2)O from electrolyte to Cu NPs,and increase the CO_(2)concentration at electrocatalyst interface for enhancing the CO_(2)mass transfer process,but also activate CO_(2)molecule by Lewis acid-base interaction between Nafion and CO_(2)to accelerate the formation of^(*)CO,which favor of C–C coupling for boosting C_(2)product generation.Owing to these features,the HER selectivity was suppressed from 40.6%to 16.8%on optimal Cu@Nafion electrode at-1.2 V versus reversible hydrogen electrode(RHE),and as high as 73.5%faradaic efficiencies(FEs)of C_(2)products were achieved at the same applied potential,which was 2.6 times higher than that on bare Cu electrode(~28.3%).In addition,Nafion also contributed to the long-term stability by hinder Cu NPs morphology reconstruction.Thus,this work provides insights into the impact of Nafion on electrocatalytic CO_(2)RR performance.

Microviscosity in modified Nafion membranes measured by fluorescence probes

Sodium or quaternary ammonium modified Nafion membranes in forms of Nafion-Na+, Nafion-NMe+4:, Nafion-NEt+4 and Nafion-NBu+4: have bean prepared by neutralizing Nafion-H+ membrane with NaOH or tetraalkylammonium hydroxide aqueous solution. Intramolecular excimer formation and fluorescence polarisation methods using 1,3-di(1-pyrenyl)propane and acridine orange-as probes respectively have been employed for measurements of the microviscosity within those modified Nafion membranes. Results show that the probes are located in the fluorocarbon/water interface in the cluster of the membranes and the microviscosities around the probe molecules an in the range of ca. 120–1200 cp and increase in the order of Nafion-Na+ <Nafion-NMe+4<Nafion-NEt+4<Nafion-NBu+4. Furthermore, the microviscosity values of these membranes in dry form an higher than those in wet form.

Use of microelectrodes for electrochemical measurement of nitric oxide in natural seawater

In this paper, the application of a homemade Nafion and Co(Salen) modified platinum microelec-trode and an ISO-NOPMC microsensor (World Precision Instruments, USA ) to measure nitric oxide in natural seawater is reported. These two microelectrodes are suitable for the measurement. In natural seawater, the sensitivity and stability of the ISO-NOPMC microsensor are higher than that of the homemade Nafion and Co(Salen) modified platinum microelectrode.