Atomically Ordered PdCu Electrocatalysts for Selective and Stable Electrochemical Nitrate Reduction

Jeonghoon Lim; David A Cullen; Eli Stavitski; Seung Woo Lee; Marta C Hatzell

doi:10.1021/acsenergylett.3c01672

Atomically Ordered PdCu Electrocatalysts for Selective and Stable Electrochemical Nitrate Reduction

ACS Energy Lett. 2023 Oct 19;8(11):4746-4752. doi: 10.1021/acsenergylett.3c01672. eCollection 2023 Nov 10.

Authors

Jeonghoon Lim¹, David A Cullen², Eli Stavitski³, Seung Woo Lee¹, Marta C Hatzell^{1

4}

Affiliations

¹ George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.
² Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
³ National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, United States.
⁴ School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 United States.

Abstract

Electrochemical nitrate reduction (NO₃ RR) has attracted attention as an emerging approach to mitigate nitrate pollution in groundwater. Here, we report that a highly ordered PdCu alloy-based electrocatalyst exhibits selective (91% N₂), stable (480 h), and near complete (94%) removal of nitrate without loss of catalyst. In situ and ex situ XAS provide evidence that structural ordering between Pd and Cu improves long-term catalyst stability during NO₃RR. In contrast, we also report that a disordered PdCu alloy-based electrocatalyst exhibits non-selective (44% N₂ and 49% NH₄⁺), unstable, and incomplete removal of nitrate. The copper within disordered PdCu alloy is vulnerable to accepting electrons from hydrogenated neighboring Pd atoms. This resulted in copper catalyst losses which were 10× greater than that of the ordered catalyst. The design of stable catalysts is imperative for water treatment because loss of the catalyst adds to the system cost and environmental impacts.