On the electrocatalytic activity of transition metal nitroso-R complexes towards the reduction of CO2

Abstract

In this study the electrochemical reduction of CO2 using the electrocatalytic systems which consists of four types of surface-modified fluorine-doped tin oxide coated glass electrodes (FTO) and three kinds of transition metal (Co2+ Ni2+ Fe2+) nitroso–R complexes was investigated By reducing the CO2 into methanol it can not only eliminate the excess emission of CO2 in atmosphere but also generate an alternative energy to solve both severe greenhouse effect and the energy crisis The four types of surface-modified FTO electrodes include bare FTO Prussian blue modified FTO (FTO|PB) Platinum (Pt) modified FTO (FTO|Pt) and Prussian blue modified FTO|Pt (FTO|Pt|PB) electrodes The PB thin film prepared by electrodeposition acts as the electron transfer mediator in this work whereas the transition metal nitroso-R complexes was used as the electrocatalysts electrocatalyzing the electrochemical reduction of CO2 It was found that the electrocatalytic system containing cobalt nitroso-R complex showed best electrocatalytic activity towards the reduction of CO2; methanol production was noticed for all the four types of electrodes and the maximal Faradaic efficiency of 52 83 ± 17 10% can be achieved using FTO|Pt|PB The electrocatalyst system containing ferrous nitroso-R complex exhibited second best activity; the maximal Faradaic efficiency of 11 50 ± 12 14% can be achieved using FTO|Pt|PB The electrocatalyst system containing nickel nitroso-R complex didn’t exhibit any activity towards the electrochemical reduction of CO2 into methanol These results is quite different from the previous work done by Ogura group in 1980s in which they employ Pt|PB as the working electrode and ferrous nitroso-R complex showed the best activity to methanol production with a Faradaic efficiency of 83% The lower or ignorable activity of electrocatalytic systems containing ferrous nitroso-R complex and nickel nitroso-R complex could be attributed to the fact that the instability of these two complexes under cathodic conditions or other byproducts which cannot be detected and quantified using gas chromatography formed during the electrochemical reduction of CO2

Date of Award	2016 Jul 28
Original language	English
Supervisor	Chia-Yu Lin (Supervisor)