An Efficient H<sub>2</sub>S-Tolerant Hydrogen Oxidation Electrocatalyst Enabled by a Lewis Acid Modifier for Fuel Cells.
basic_science · Level V
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- Record sourced from PubMed, PMID 39984288.
- Also identified by DOI 10.1021/acs.nanolett.4c06621.
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Abstract
Industrial hydrogen fuel typically comprises about 5 ppm of hydrogen sulfide (H<sub>2</sub>S), incurring irreversible poisoning of platinum on carbon (Pt/C) catalyst in fuel cells. For realistic use, H<sub>2</sub>S should be removed to below 4 ppb; this process, however, is challenging and costly. We describe an exceptional H<sub>2</sub>S-tolerant yet high-performing hydrogen oxidation reaction (HOR) catalyst prepared by chemical grafting of chromic oxide (Cr<sub>2</sub>O<sub>3</sub>) onto a molybdenum-nickel (MoNi<sub>4</sub>) alloy. Cr<sub>2</sub>O<sub>3</sub> as a Lewis acid enhances the specific adsorption of hydroxyl ions, which in turn prevents from S<sup>2-</sup> diffusing to the catalyst surface via electrostatic repulsion. Meanwhile, the adsorbed hydroxyl species boost HOR kinetics through improving the hydrogen-bond networks in electrical double layers. The composite catalyst achieved HOR performance comparable to that of commercial Pt/C in an alkaline electrolyte. Moreover, a fuel cell using this catalyst as anode can survive 5 ppm of H<sub>2</sub>S without deactivation, compared with rapid degradation observed over the Pt/C counterpart.