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Open AccessArticle

Galvanic Exchange as a Novel Method for Carbon Nitride Supported CoAg Catalyst Synthesis for Oxygen Reduction and Carbon Dioxide Conversion

Department of Chemical Engineering, Qatar University, P.O. Box 2713, Doha, Qatar, Qatar
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Catalysts 2019, 9(10), 860; https://doi.org/10.3390/catal9100860
Received: 23 September 2019 / Revised: 6 October 2019 / Accepted: 8 October 2019 / Published: 16 October 2019
(This article belongs to the Special Issue Synthesis and Applications of Nano-Catalytic Materials)
A bimetallic alloy of CoAg nanoparticles (NPs) on a carbon nitride (CN) surface was synthesized using a galvanic exchange process for the oxygen reduction reaction (ORR) and carbon dioxide electrocatalytic conversion. The reduction potential of cobalt is ([Co2+(aq) + 2e → Co(s)], −0.28 eV) is smaller than that of Ag ([Ag+(aq) + e → Ag(s)], 0.80 eV), which makes Co(0) to be easily replaceable by Ag+ ions. Initially, Co NPs (nanoparticles) were synthesized on a CN surface via adsorbing the Co2+ precursor on the surface of CN and subsequently reducing them with NaBH4 to obtain Co/CN NP. The Co NPs on the surface of CN were then subjected to galvanic exchange, where the sacrificial Co atoms were replaced by Ag atoms. As the process takes place on a solid surface, only the partial replacement of Co by Ag was possible generating CoAg/CN NPs. Synthesized CoAg/CN bimetallic alloy were characterized using different techniques such as powder x-ray diffraction (PXRD), x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and electron diffraction spectroscopy (EDS) to confirm the product. Both the catalysts, Co/CN and CoAg/CN, were evaluated for oxygen reduction reaction in 1M KOH solution and carbon dioxide conversion in 0.5 M KHCO3. In the case of ORR, the CoAg/CN was found to be an efficient electrocatalyst with the onset potential of 0.93 V, which is comparable to commercially available Pt/C having Eonset at 0.91 V. In the electrocatalytic conversion of CO2, the CoAg/CN showed better performance than Co/CN. The cathodic current decreased dramatically below −0.9V versus Ag/AgCl indicating the high conversion of CO2. View Full-Text
Keywords: carbon nitride; galvanic exchange; AgCo catalyst; oxygen reduction reaction; carbon dioxide conversion carbon nitride; galvanic exchange; AgCo catalyst; oxygen reduction reaction; carbon dioxide conversion
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Nazir, R.; Kumar, A.; Ali, S.; Saad, M.A.S.; Al-Marri, M.J. Galvanic Exchange as a Novel Method for Carbon Nitride Supported CoAg Catalyst Synthesis for Oxygen Reduction and Carbon Dioxide Conversion. Catalysts 2019, 9, 860.

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