Water Oxidation Electrocatalysis in Acidic Media with Fe-Containing POMs/Carbon Composites
Iron-based catalysts are very appealing in terms of applications due to the low cost of Fe and to its abundance in the Earth’s crust. In the field of water oxidation, unfortunately, iron oxides cannot match the activity of Co or Ni oxides, much less than the activity of noble metal oxides (IrO2). Th...
| Authors: | , , , , , , , , |
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| Format: | article |
| Publication Date: | 2025 |
| Country: | España |
| Institution: | Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya) |
| Repository: | Recercat. Dipósit de la Recerca de Catalunya |
| OAI Identifier: | oai:recercat.cat:2072/482444 |
| Online Access: | http://hdl.handle.net/2072/482444 https://doi.org/10.1021/acs.inorgchem.4c04422 |
| Access Level: | Open access |
| Keyword: | Química 54 |
| Summary: | Iron-based catalysts are very appealing in terms of applications due to the low cost of Fe and to its abundance in the Earth’s crust. In the field of water oxidation, unfortunately, iron oxides cannot match the activity of Co or Ni oxides, much less than the activity of noble metal oxides (IrO2). The activity of transition metals to promote the oxygen evolution reaction (OER) can be tuned and enhanced by their incorporation into polyoxometalate frameworks (POMs). In comparison with metal oxides, POMs offer a controlled, discrete structure and a tailor-made environment. Fe-POMs still show a low OER activity in neutral or basic media when compared to Co-POMs. When moving to highly acidic media, we have found an unexpected electrochemical response in carbon paste electrodes containing salts of the [Fe4III(H2O)2(PW9O34)2]6– (Fe4) polyanion. In oxidative conditions, these electrodes showed lower onset potentials and higher current densities than their Co-based analogues, contrary to computational expectations. Careful analyses have shown the excellent stability of the Fe4 in these pH < 1 conditions, but a poor selectivity. CO2 is the dominant product, in addition to O2. The capability of Fe4 to oxidize amorphous carbon under acidic conditions appears to be unique since it is not found in Fe oxides or simple Fe salts. Thus, Fe-POMs, in acidic conditions, are still modest OER catalysts, but exhibit a unique performance when electrochemically oxidizing carbon. |
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