Title: Porous Two-dimensional Iron-Cyano Nanosheets for High-rate Electrochemical Nitrate Reduction

Abstract

Ammonia (NH₃) is an essential ingredient in agriculture and a promising source of clean energy as a hydrogen carrier. The current major method for ammonia production, however, is the Haber–Bosch process that leads to massive energy consumption and severe environmental issues. Compared with nitrogen (N₂) reduction, electrochemical nitrate reduction reaction (NO₃RR), with a higher NH₃ yield rate and Faradaic efficiency, holds promise for efficient NH₃ production under ambient conditions. To achieve efficient NO₃RR, electrocatalysts should exhibit high selectivity and Faradaic efficiency with a high NH₃ yield rate. In this work, we developed two-dimensional (2D) iron-based cyano-coordination polymer nanosheets (Fe-cyano NSs) following in situ electrochemical treatment for high-rate NO₃RR. Owing to the strong adsorption of nitrate on Fe0 active sites generated via topotactic conversion and in situ electroreduction, 2D Fe-cyano electrocatalyst exhibits high catalytic activity with a yield rate of 42.1 mg h^–1 mgcat^–1 and a Faradaic efficiency of over 90% toward NH₃ production at –0.5 V (vs reversible hydrogen electrode, RHE). Further electrochemical characterizations revealed that superhydrophilic surface and enhanced electrochemical surface area of the 2D porous nanostructures also contributed to the high-rate NO₃RR activity. Finally, an electrolyzer toward NO₃RR and oxygen evolution reaction (OER) in a two-electrode configuration ismore » constructed based on 2D Fe-cyano, achieving an energy efficiency of 26.2%. This work provides an alternative methodology toward topotactic conversion of transition metal nanosheets for NO₃RR and reveals the often-overlooked contribution of hydrophilicity of the catalysts for high-rate electrocatalysis.« less

Authors:

Fang, Zhiwei  ^[1];

• Search DOE PAGES for author "Fang, Zhiwei"
• Search DOE PAGES for ORCID "0000-0001-8826-8834"

Jin, Zhaoyu  ^[1];

• Search DOE PAGES for author "Jin, Zhaoyu"
• Search DOE PAGES for ORCID "0000-0003-0840-3931"

Tang, Sishuang ^[1]; Li, Panpan  ^[1];

• Search DOE PAGES for author "Li, Panpan"
• Search DOE PAGES for ORCID "0000-0001-9933-0357"

Wu, Ping  ^[2];

• Search DOE PAGES for author "Wu, Ping"
• Search DOE PAGES for ORCID "0000-0003-1819-2613"

Yu, Guihua  ^[1]

• Search DOE PAGES for author "Yu, Guihua"
• Search DOE PAGES for ORCID "0000-0002-3253-0749"

---

+ Show Author Affiliations

1. Univ. of Texas, Austin, TX (United States)
2. Nanjing Normal University, Nanjing, Jiangsu (China)

Publication Date:

Fri Dec 17 00:00:00 EST 2021

Research Org.:

Univ. of Texas, Austin, TX (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); National Natural Science Foundation of China (NSFC)

OSTI Identifier:

1865383

Grant/Contract Number:  

SC0019019; 52072181

Resource Type:

Accepted Manuscript

Journal Name:

ACS Nano

Additional Journal Information:

Journal Volume: 16; Journal Issue: 1; Journal ID: ISSN 1936-0851

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; electrocatalysis; nanosheet; nanoporous; nitrate reduction; Prussian blue analogue