Non-redox doping boosts oxygen evolution electrocatalysis on hematite
| Autor: | Mabel de Fez-Febré, Huu Chuong Nguyen, Núria López, Felipe A. Garcés-Pineda, José Ramón Galán-Mascarós |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Materials science
Electrolysis of water Inorganic chemistry Oxygen evolution Oxide 02 engineering and technology General Chemistry Hematite Overpotential 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 7. Clean energy Redox 0104 chemical sciences 3. Good health Catalysis Chemistry chemistry.chemical_compound chemistry visual_art visual_art.visual_art_medium Proton-coupled electron transfer 0210 nano-technology |
| Zdroj: | Chemical Science RECERCAT (Dipòsit de la Recerca de Catalunya) Recercat. Dipósit de la Recerca de Catalunya instname |
| ISSN: | 2041-6520 |
| DOI: | 10.1039/c9sc05669f |
| Popis: | The oxygen evolution reaction (OER) is the major bottleneck to develop viable and cost-effective water electrolysis, a key process in the production of renewable fuels. Hematite, all iron α-Fe2O3, would be an ideal OER catalyst in alkaline media due to its abundance and easy processing. Despite its promising theoretical potential, it has demonstrated very poor OER activity under multiple experimental conditions, significantly worse than that of Co or Ni-based oxides. In the search for improving hematite performance, we have analysed the effect of doping with redox vs. non-redox active species (Ni or Zn). Our results indicate that Zn doping clearly outperforms Ni, commonly accepted as a preferred dopant. Zn-doped hematite exhibits catalytic performances close to the state-of-the-art for alkaline water splitting: reaching 10 mA cm−2 at just 350 mV overpotential (η) at pH 13, thus twenty times that of hematite. Such a catalytic enhancement can be traced back to a dramatic change in the reaction pathway. Incorporation of Ni, as previously suggested, decreases the energetic barrier for the OER on the available centres. In contrast, Zn facilitates the appearance of a dominant and faster alternative via a two-site reaction, where the four electron oxidation reaction starts on Fe, but is completed on Zn after thermodynamically favoured proton coupled electron transfer between adjacent metal centres. This unique behaviour is prompted by the non-redox character of Zn centres, which maintain the same charge during OER. Our results open an alternative role for dopants on oxide surfaces and provide a powerful approach for catalytic optimisation of oxides, including but not limited to highly preferred all-iron oxides. The distinct beneficial effect of Zn-doping on the OER alkaline activity of Fe-based catalysts points towards an alternative and faster two-site mechanism. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|