Two-step tandem catalysis for high-efficiency ammonia synthesis via nitrate reduction on anion-intercalated CoNi LDH and Cu/Cu2O

Lin, Changzheng, Li, Weijia, Chen, Hao, Feng, Jiangtao, Zhu, Mengyuan, Shi, Jinwen, Li, Mingtao, Hou, Bo ORCID: https://orcid.org/0000-0001-9918-8223, Wang, Zhenyu, Chen, Xin, Liu, Jia and Yan, Wei 2025. Two-step tandem catalysis for high-efficiency ammonia synthesis via nitrate reduction on anion-intercalated CoNi LDH and Cu/Cu2O. Advanced Science , 2502262. 10.1002/advs.202502262

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Abstract

Ammonia is essential across industry, agriculture, and as a future carbon-free energy carrier. Electrocatalytic nitrate reduction (NitRR) offers a sustainable path for removing nitrate contaminants from wastewater and groundwater while using abundant nitrate ions as nitrogen sources under eco-friendly conditions. However, the NitRR pathway, which involves sequential reactions, poses challenges in synchronizing the rate of nitrate-to-nitrite conversion with the subsequent reduction of nitrite to ammonia, particularly as the initial reduction step is rate-limiting. This study presents a CoNi layered double hydroxide (LDH) approach to finely control hydrogen radical (*H) supply, paired with Cu/Cu2O redox coupling, to achieve optimal rate matching. CoNi LDH is engineered with various anion intercalations (NO3−, Cl−, SO42−, MoO42−, WO42−) to regulate *H capacity. By integrating Cu/Cu2O and CoNi LDH, tandem kinetic descriptors, including a volcano curve, are employed to predict rate constants, facilitating ideal kinetic matching for efficient ammonia synthesis. The optimized MoO4-CoNi LDH/CuO NW/CF electrode demonstrated exceptional performance, achieving a 99.78% Faraday efficiency, a yield of 1.12 mmol cm−2 h−1 at −0.2 V vs. RHE, and robust 14-h stability. The model descriptors effectively elucidated the kinetic pathway, linking reaction rates and factors impacting ammonia production.

Item Type:	Article
Date Type:	Published Online
Status:	In Press
Schools:	Schools > Physics and Astronomy
Publisher:	Wiley
ISSN:	2198-3844
Funders:	Royal Society, EPSRC and Leverhulme Trust
Date of First Compliant Deposit:	15 April 2025
Date of Acceptance:	2 April 2025
Last Modified:	29 Apr 2025 07:51
URI:	https://orca.cardiff.ac.uk/id/eprint/177715

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