ZHANG Zhipan, CHEN Chengzhen, WANG Qianqian, et al. Effect of halides on catalytic activity and selectivity of silver electrodes for CO2 electroreduction[J]. CIESC Journal, 2017, (2): 687-693. DOI: 10.11949/j.issn.0438-1157.20160976.
ZHANG Zhipan, CHEN Chengzhen, WANG Qianqian, et al. Effect of halides on catalytic activity and selectivity of silver electrodes for CO2 electroreduction[J]. CIESC Journal, 2017, (2): 687-693. DOI: 10.11949/j.issn.0438-1157.20160976.DOI:
Silver (Ag) is an excellent electrocatalyst for carbon dioxide (CO2) to carbon monoxide (CO) conversion in aqueous or nonaqueous electrolytes. However
polycrystalline silver needs significant overpotentials to achieve ideal selectivity and reaction rate
thus new methods are required to increase catalytic performance of polycrystalline silver. Effects of halides on silver foil for CO2 electrochemical reduction were studied by Faradaic efficiency and current density of carbon monoxide (CO) as a function of working potential with presence of Cl-
Br-
and I- in KHCO3 solution. The results showed that all of these halides increased CO selectivity and reaction rate with CO enhancement in the order of Cl- < Br- < I-. CO selectivity of I- added electrolyte was 28 times that of halide-free electrolyte at 590 mV overpotential. Besides enhancement of CO reaction rate
Cl- and Br- also improved hydrogen evolution reaction at the same time
which was not observed in I-. The remarkable catalytic performance of I- could be attributed to its strong adsorption
which might form nanoparticles on Ag surface and increase number of activity sites for CO
and its easy charge donation to Ag surface
which might enhance interaction with partially positive-charged carbon atom of CO2. In conclusion
I- was more suitable for CO2 reduction than Cl- and Br-
which could benefit industrialized CO production and maximize economic output.