Calibration Of Temperature Controlled Electrode For In Situ FTIRS And Its Study On The Electrocatalytic Oxidation Performance Of Ethanol

The current electrocatalytic activity of the catalyst for ethanol oxidation is relatively low,and the C-C bond is hard to break,so that the complete oxidation process is not easy,and the fuel utilization efficiency is greatly reduced.Increasing the temperature can increase the reaction rate and enhance the mass transport.This work uses classical electrochemical methods and electrochemical in situ FTIRS to track the electrocatalytic oxidation of ethanol at different temperatures,revealing the electrocatalytic oxidation mechanism of ethanol at different temperature,investigate whether elevated temperature is favorable for the cleavage of C-C bond.(1)In situ FTIRS at different temperatures was carried out using temp.controlled electrodes.Calibration temperature is required due to the difference between the temperature of the thin layer solution and the electrode heating temperature in the experiment,the temperature is calibrated by the "potentiometric" measurement method,electrode surface temperature was obtained by potential conversion at different temperatures in the experiment.The experimental results show that the relationship between the heating temperature Th and the surface temperature Ts is Ts=0.57Th+7.71(30?<Th?<50?);Ts=0.62Th+5.12(50?<Th?80?),through error analysis,the maximum error is 1 ?.(2)The temp.controlled electrode was used in the in situ FTIRS of electrooxidation of ethanol.Firstly,commercial Pt/C and PtRu/C catalysts in ethanol solution at different temperatures was investigated by the cyclic voltammetry.The increase of the overall oxidation current,the onset and the peak potential are negatively shifted with temperature,indicating that the thermal activation makes the oxidation reaction easier;The ratio of the first peak current to the second peak current is used to evaluate the selectivity of CO2.The commercial Pt/C catalyst has a 30%increase from 65? to 25 ?,indicating that high temperature is conducive to C-C bond cleavage for commercial Pt/C catalyst.Then the electrooxidation of ethanol was studied by in situ FTIRS.Comparing the IR at 50 ?C and 25 ?,we found that the CO2 starting potential on commercial Pt/C and PtRu/C catalysts was negatively shifted 200 mV,150 mV,respectively,indicating that high temperature provides oxygen-containing species at lower potentials;The initial potential of CH3CHO and CH3COOH did not change with temperature change,but only affected by the catalyst,the initial potential on PtRu/C catalyst was negatively shifted 150 mV compared with that on commercial Pt/C catalyst,because the binding energy of C-H bond was reduced and provide oxygen-containing species at lower potentials by the presence of Ru.The CO2 selectivity was calculated by the area of CO2 compared with the area of CH3COOH.It is found that the high temperature and low potential have the highest selectivity,indicating that high temperature is conducive to the complete oxidation of CO2 formation,but the adsorption of oxygen-containing species on the high potential surface occupied the active site,blocking the cleavage of the C-C bond.The commercial Pt/C catalyst has higher CO2 selectivity than the PtRu/C catalyst under the same conditions,it is because Ru adsorbs more-OH oxygen species favors the formation of acetic acid and hinders C-C bond cleavage.