Coupled Pd<sup>δ-</sup>-Cu<sup>δ<b>+</b></sup> Dipole for Enhanced Aqueous Nitrate Valorization at Ultralow Potentials
Nitrate <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mo>(</mml:mo><mml:msubsup><mml:mrow><mml:mi>NO</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo></mml:mrow></mml:msubsup><mml:mo>)</mml:mo></mml:math> pollution poses significant threats to water quality and the global nitrogen cycle. The electrochemical <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mrow><mml:mi>NO</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo></mml:mrow></mml:msubsup></mml:math> reduction reaction (NO<sub>3</sub>RR) emerges as a promising solution for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mrow><mml:mi>NO</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo></mml:mrow></mml:msubsup></mml:math> removal and sustainable ammonia (NH<sub>3</sub>) production. However, it suffers from an insufficient atomic hydrogen (*H) supply and poor nitrite <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mo>(</mml:mo><mml:msubsup><mml:mrow><mml:mi>NO</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo></mml:mrow></mml:msubsup><mml:mo>)</mml:mo></mml:math> adsorption at low potentials, which results in restrained <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mrow><mml:mi>NO</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo></mml:mrow></mml:msubsup></mml:math>-to-NH<sub>3</sub> conversion and notorious <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mrow><mml:mi>NO</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo></mml:mrow></mml:msubsup></mml:math> accumulation. Herein, we propose a dipole strategy that utilizes coupled divergent dual centers (Pd<sup>δ-</sup>-Cu<sup>δ+</sup>) in binder-free monolithic single-atom alloy electrodes (Pd<sub>1</sub>Cu) to overcome these challenges at ultralow potentials. In-situ experiments and theoretical simulations reveal that the polarized atomic Pd<sup>δ-</sup> dramatically enhances *H supply by facilitating water dissociation into *H, which then readily spills over to the adsorption-strengthened <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mrow><mml:mi>NO</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo></mml:mrow></mml:msubsup></mml:math> on adjacent Cu<sup>δ+</sup>, thus promoting rapid deep hydrodeoxygenation at ultralow potentials. Furthermore, the upshifted <i>d</i>-band center inhibits *H self-coupling and reduces the thermodynamic energy barrier for the *NO intermediate hydrogenation. Leveraging these advantages, the coupled Pd<sup>δ-</sup>-Cu<sup>δ+</sup> dipole achieved 100% <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mrow><mml:mi>NO</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo></mml:mrow></mml:msubsup></mml:math> removal, 100% NH<sub>3</sub> selectivity, near-zero <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mrow><mml:mi>NO</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo></mml:mrow></mml:msubsup></mml:math> accumulation, 94.4% NH<sub>3</sub> Faradaic efficiency, and an NH<sub>3</sub> yield rate of 1.98 mM h<sup>-1</sup> cm<sup>-2</sup> at just -0.2 V vs RHE, outperforming the monometallic counterparts and reported advanced catalysts. The proposed metal-dipole strategy can provide a universal principle for the rational design of electrocatalysts to valorize pollutants into valuable ammonia products.
Authors
- Zhigang Geng (ORCID: https://orcid.org/0000-0003-3183-5900)
- Jiayin Li (ORCID: https://orcid.org/0000-0003-1586-3063)
- Huihuang Chen (ORCID: https://orcid.org/0000-0002-5543-4151)
- Maohong Fan (ORCID: https://orcid.org/0000-0003-1334-7292)
- Yancai Yao (ORCID: https://orcid.org/0000-0003-2706-5560)
- Lianzhou Wang (ORCID: https://orcid.org/0000-0002-5947-306X)
- Bo Yang (ORCID: https://orcid.org/0000-0001-6739-4997)
- Bing Zhou (ORCID: https://orcid.org/0009-0002-4069-0467)
- Runze Shi
- Lizhi Zhang (ORCID: https://orcid.org/0000-0002-6842-9167)
- Yue Wu
Institutions
- University of Science and Technology of China (CN)
- University of Wyoming (US)
- Georgia Institute of Technology (US)
- The University of Queensland (AU)
- Shenzhen University (CN)
- Shanghai Jiao Tong University (CN)
- Hefei National Center for Physical Sciences at Nanoscale (CN)
- Physical Sciences (United States) (US)
- Wyoming Department of Education (US)
- Microscale (United States) (US)
Publication Details
- Journal
- ACS Nano
- Published
- 2025-08-25
- DOI
- https://doi.org/10.1021/acsnano.5c09566
- Citations
- 1
- Primary Topic
- Ammonia Synthesis and Nitrogen Reduction
- Type
- article
- Field-Weighted Citation Impact
- 0.39
Funders
- National Natural Science Foundation of China
- Science, Technology and Innovation Commission of Shenzhen Municipality