CuZnAl-Oxide Nanopyramidal Mesoporous Materials for the Electrocatalytic CO<sub>2</sub> Reduction to Syngas: Tuning of H<sub>2</sub>/CO Ratio
Inspired by the knowledge of the thermocatalytic CO<sub>2</sub> reduction process, novel nanocrystalline CuZnAl-oxide based catalysts with pyramidal mesoporous structures are here proposed for the CO<sub>2</sub> electrochemical reduction under ambient conditions. The XPS anal...
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| Autores principales: | , , , , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
MDPI AG
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/5ccd035654084df5b217b8f40d85e911 |
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| Sumario: | Inspired by the knowledge of the thermocatalytic CO<sub>2</sub> reduction process, novel nanocrystalline CuZnAl-oxide based catalysts with pyramidal mesoporous structures are here proposed for the CO<sub>2</sub> electrochemical reduction under ambient conditions. The XPS analyses revealed that the co-presence of ZnO and Al<sub>2</sub>O<sub>3</sub> into the Cu-based catalyst stabilize the CuO crystalline structure and introduce basic sites on the ternary as-synthesized catalyst. In contrast, the as-prepared CuZn- and Cu-based materials contain a higher amount of superficial Cu<sup>0</sup> and Cu<sup>1+</sup> species. The CuZnAl-catalyst exhibited enhanced catalytic performance for the CO and H<sub>2</sub> production, reaching a Faradaic efficiency (FE) towards syngas of almost 95% at −0.89 V vs. RHE and a remarkable current density of up to 90 mA cm<sup>−2</sup> for the CO<sub>2</sub> reduction at −2.4 V vs. RHE. The physico-chemical characterizations confirmed that the pyramidal mesoporous structure of this material, which is constituted by a high pore volume and small CuO crystals, plays a fundamental role in its low diffusional mass-transfer resistance. The CO-productivity on the CuZnAl-catalyst increased at more negative applied potentials, leading to the production of syngas with a tunable H<sub>2</sub>/CO ratio (from 2 to 7), depending on the applied potential. These results pave the way to substitute state-of-the-art noble metals (e.g., Ag, Au) with this abundant and cost-effective catalyst to produce syngas. Moreover, the post-reaction analyses demonstrated the stabilization of Cu<sub>2</sub>O species, avoiding its complete reduction to Cu<sup>0</sup> under the CO<sub>2</sub> electroreduction conditions. |
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