Contrasting Capability of Single Atom Palladium for Thermocatalytic versus Electrocatalytic Nitrate Reduction Reaction

Xuanhao Wu; Mohammadreza Nazemi; Srishti Gupta; Adam Chismar; Kiheon Hong; Hunter Jacobs; Wenqing Zhang; Kali Rigby; Tayler Hedtke; Qingxiao Wang; Eli Stavitski; Michael S Wong; Christopher Muhich; Jae-Hong Kim

doi:10.1021/acscatal.3c01285

Contrasting Capability of Single Atom Palladium for Thermocatalytic versus Electrocatalytic Nitrate Reduction Reaction

ACS Catal. 2023 May 3;13(10):6804-6812. doi: 10.1021/acscatal.3c01285. eCollection 2023 May 19.

Authors

Xuanhao Wu^{1

2}, Mohammadreza Nazemi², Srishti Gupta³, Adam Chismar³, Kiheon Hong⁴, Hunter Jacobs⁴, Wenqing Zhang⁴, Kali Rigby², Tayler Hedtke², Qingxiao Wang⁵, Eli Stavitski⁶, Michael S Wong⁴, Christopher Muhich³, Jae-Hong Kim²

Affiliations

¹ Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, China.
² Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06511, United States.
³ School for the Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, Arizona 85287, United States.
⁴ Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, United States.
⁵ Imaging and Characterization Core Lab, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia.
⁶ National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, United States.

Abstract

The occurrence of high concentrations of nitrate in various water resources is a significant environmental and human health threat, demanding effective removal technologies. Single atom alloys (SAAs) have emerged as a promising bimetallic material architecture in various thermocatalytic and electrocatalytic schemes including nitrate reduction reaction (NRR). This study suggests that there exists a stark contrast between thermocatalytic (T-NRR) and electrocatalytic (E-NRR) pathways that resulted in dramatic differences in SAA performances. Among Pd/Cu nanoalloys with varying Pd-Cu ratios from 1:100 to 100:1, Pd/Cu_(1:100) SAA exhibited the greatest activity (TOF_Pd = 2 min^-1) and highest N₂ selectivity (94%) for E-NRR, while the same SAA performed poorly for T-NRR as compared to other nanoalloy counterparts. DFT calculations demonstrate that the improved performance and N₂ selectivity of Pd/Cu_(1:100) in E-NRR compared to T-NRR originate from the higher stability of NO₃* in electrocatalysis and a lower N₂ formation barrier than NH due to localized pH effects and the ability to extract protons from water. This study establishes the performance and mechanistic differences of SAA and nanoalloys for T-NRR versus E-NRR.