Nitrate Reduction Provides Insights into Evolving Electrode Structures

JACS Spotlights April 19, 2022

Wastewater treatments that reduce nitrate to form ammonia not only remove nitrate pollutants, but the resulting ammonia can be used in a variety of industrially useful reactions. William Tarpeh and colleagues recently studied the interacting effects of electrochemical nitrate reduction and the evolving structure and performance of titanium electrodes during the reaction, and they found a way to characterize the two phenomena separately (DOI: 10.1021/jacs.2c01274).

Titanium is an inexpensive, robust electrocatalyst, but the reasons for its catalytic performance have not been fully explained. Electrochemical nitrate reduction reconstructs titanium electrode surfaces and forms a water-stable titanium hydride surface layer that changes as the reaction proceeds. The researchers studied titanium hydride formation on titanium electrodes under controlled nitrate reduction reaction conditions and found that the presence or absence of an initial hydride layer produced no appreciable differences in the reaction rate or selectivity. As the reaction progressed, near-surface X-ray characterization and density functional theory modeling showed that increasing the applied electrical potential and duration of the reaction quantitatively increases the formation of near-surface titanium hydride on the titanium electrode. This insight will be useful for research into the design and operation of other electrocatalytic reactions.

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