Authors:

Hannah Oberg

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About Paper:

Large-scale overfertilization of crops elicits major ecological consequences, as runoff ammonia reacts with ground water, poisoning water sources with nitrate, leading to algal blooms that create aquatic dead-zones. Electrocatalytic nitrate reduction has been of specific interest because of its ability to transform nitrate into nitrogen gas. Specifically, this reduction on copper electrodes has drawn special attention due to copper's abundance and low cost regarding its relative activity, however the specific mechanism is not well-understood, preventing commercial use. Polycrystalline copper, Cu(100), Cu(110), and Cu(111) electrodes were studied to understand their respective selectivities and activities. Mass spectrometry data was collected using an in situ Electrochemical Mass Spectrometer (EC-MS) to measure gaseous products. A potential program was used to characterize at which potentials certain products formed, comparing this with charge balances to determine reaction mechanisms. Examining these data sets gives insights into possible non-gaseous products formed and non-faradaic reactions occurring. Inductively coupled plasma optical emissions spectroscopy (ICP-OES) was used to qualitatively determine copper dissolution and relative stability of each copper electrode. Key observations include the formation of gaseous NO on all facets at open circuit potential and significant amounts of N2O formed on Cu(110). Overall, these findings suggest that each facet has specific activities, selectivities, and stabilities at varying potentials. These results have major implications on how metallic configurations yield diverse results; depending on preferred product, the electrode with highest efficiency could be selected. Additionally, this can be applied to nanostructured catalysts when determining size and shape to design efficient nitrate remediation systems.

Source:

Purdue University / 2023

Topics:

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Co-authors:

Hannah Oberg