Electrochemical reduction of CO 2 to formic acid on Bi 2 O 2 CO 3 /carbon fiber electrodes
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Electrochemical reduction of CO2 to formic acid on Bi2O2CO3/carbon fiber electrodes Lara G. Puppin1, Mohd. Khalid1, Gelson T.T. da Silva2, Caue Ribeiro3 Osmando F. Lopes4,a)
, Hamilton Varela1
,
1
Institute of Chemistry of Sao Carlos, University of Sao Paulo, Sao Carlos, SP 13560970, Brazil Embrapa Instrumentation, Rua XV de Novembro, São Carlos, SP 13560-970, Brazil 3 Embrapa Instrumentation, Rua XV de Novembro, São Carlos, SP 13560-970, Brazil; and Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research (IEK-14): Electrochemical Process Engineering, Jülich 52425, Germany 4 Institute of Chemistry of Sao Carlos, University of Sao Paulo, Sao Carlos, SP 13560970, Brazil; and Laboratory of Photochemistry and Materials Science, Institute of Chemistry, Federal University of Uberlandia, Uberlandia, MG 38400902, Brazil a) Address all correspondence to this author. e-mail: [email protected] 2
Received: 17 October 2019; accepted: 2 January 2020
Electrochemical reduction of CO2 to formic acid is a good strategy to address both environmental and energy issues. However, some drawbacks including low activity, selectivity, and stability of electrocatalysts must be overcome. We propose a method for tailoring Bi2O2CO3-coated carbon fiber electrodes with higher selectivity and stability for electrochemical CO2 reduction to formic acid. We evaluated the effect of Bi2O2CO3 and Nafion contents on the electrocatalysts performance for CO2 reduction reaction (CO2RR). All electrodes produced only HCOO− in the liquid phase with a maximum faradaic efficiency (FE) of 69%. The electrocatalysts were stable under 24 h of continuous CO2RR operation. The FE increased with the increasing electrolyte concentration and cation radius size, which indicates that the anion stabilization in solution is critical for adequate formate generation. The CO2RR mechanism was proposed with basis on the literature. The structural carbonate of Bi2O2CO3 acts as an intermediate species in the formate production from CO2.
Introduction The serious environmental problems caused by fossil fuels have stimulated the development of new economic and environmentally viable technologies for energy production [1, 2, 3, 4]. The electrochemical CO2 reduction (CO2RR) to hydrocarbons is one of the most promising strategies [5, 6, 7, 8, 9, 10, 11, 12]. Among the possible CO2RR products, formate (or formic acid) is noteworthy because it is suitable for large-scale industrial applications and is a fuel for direct formate fuel cells (DFFCs) [5, 13, 14, 15, 16, 17]. Metallic electrocatalysts (Pb, Cd, Hg, In, Sn, and Ti) are capable of reducing CO2 to formate; however, most of them are toxic heavy metals [18, 19, 20, 21]. On the other hand, Bi-based electrocatalysts have low toxicity, are cost-effective, and stable, and their act toward CO2RR, mainly producing formate, has been reported elsewhere [5, 22, 23, 24]. Bismuth subcarbonate (Bi2O2CO3) is a potential catalyst for CO2RR, especially because of its successful application as photocatalyst for organic pollutan
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