Deciphering Competitive Kinetics in Nitrate Reduction via Mechanistic Modeling: Impact of Ru and Pd Dopants on Reaction Selectivity

Bo Li; Cheng Chen; Ouwen Peng; Mengtian Jin; Dongyang Li; Jia Liu; Mengyao Su; Lianwei Shan; Kian Ping Loh; Chun Cheng

doi:10.1021/jacs.6c05585

Deciphering Competitive Kinetics in Nitrate Reduction via Mechanistic Modeling: Impact of Ru and Pd Dopants on Reaction Selectivity

J Am Chem Soc. 2026 Jun 3;148(21):22283-22291. doi: 10.1021/jacs.6c05585. Epub 2026 May 18.

Authors

Bo Li^{1

2}, Cheng Chen¹, Ouwen Peng^{1

3}, Mengtian Jin⁴, Dongyang Li¹, Jia Liu³, Mengyao Su³, Lianwei Shan², Kian Ping Loh^{3

5}, Chun Cheng^{1

6

7}

Affiliations

¹ Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518000, China.
² Heilongjiang Provincial Key Laboratory of CO2 Resource Utilization and Energy Catalytic Materials, School of Materials Science and Chemical Engineering, Harbin University of Science and Technology, Harbin 150040, China.
³ Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
⁴ Clean Energy Research Platform (CERP), Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
⁵ Centre for Hydrogen Innovations, National University of Singapore, E8, 1 Engineering Drive 3, 117580, Singapore.
⁶ Guangdong-Hongkong-Macao Joint Laboratory for Photonic-Thermal-Electrical Energy Materials and Devices, Southern University of Science and Technology, Shenzhen 518055, China.
⁷ Guangdong Provincial Key Laboratory of Energy Materials for Electric Power, Southern University of Science and Technology, Shenzhen 518055, China.

PMID: 42149553
DOI: 10.1021/jacs.6c05585

Abstract

The electrochemical nitrate reduction reaction (NO₃RR) presents a sustainable route to ammonia (NH₃), but its practical application is hindered by competition from the parasitic hydrogen evolution reaction (HER) and the accumulation of undesired nitrite (NO₂^-) intermediates. A quantitative understanding of these competing pathways is essential for rational catalyst design, yet a comprehensive framework is currently lacking. To address this, we introduce a competitive kinetic model that explicitly couples the reaction networks of the NO₃RR and HER. Applied to Ru- and Pd-doped Fe₃C catalysts, this model is rigorously constrained by data from operando infrared spectroscopy (ATR-SEIRAS) and in situ impedance spectroscopy with distribution of relaxation times (EIS-DRT) analysis. The model successfully deconvolutes the reaction network, revealing that Ru promotes matched, high-rate kinetics for sequential deoxygenation steps, leading to high selectivity and achieving an NH₃ Faradaic efficiency of 96.3% at - 0.5 V vs RHE. Conversely, Pd induces a kinetic mismatch between sequential deoxygenation steps: upstream formation of *NO₂-related intermediates is relatively efficient, whereas their subsequent hydrogen-assisted deoxygenation/consumption is comparatively sluggish, leading to the substantial accumulation and release of the NO₂^-. By seamlessly bridging advanced operando characterization with rigorous quantitative modeling, this work provides a predictive blueprint for diagnosing kinetic bottlenecks and accelerating the rational design of highly selective electrocatalysts.