Campus Units

Chemical and Biological Engineering, NSF Engineering Research Center for Biorenewable Chemicals

Document Type

Article

Research Focus Area

Catalysis and Reaction Engineering

Publication Version

Submitted Manuscript

Publication Date

6-25-2021

Journal or Book Title

ACS Catalysis

Volume

11

First Page

8431

Last Page

8442

DOI

10.1021/acscatal.1c01525

Abstract

Removing excess nitrate (NO3–) from waste streams has become a significant environmental and health topic. However, realizing highly selective NO3– conversion toward N2, primarily via electrocatalytic conversions, has proven challenging, largely because of the kinetically uncontrollable NO3–-to-NO2– pathway and unfavorable N–N coupling. Herein, we discovered unique and ultra-high electrocatalytic NO3–-to-NO2–activity on oxide-derived silver (OD-Ag). Up to 98% selectivity and 95% Faradaic efficiency (FE) of NO2– were observed and maintained under a wide potential window. Benefiting from the superior NO3–-to-NO2–activity, further reduction of accumulated NO2– to NH4+ was well regulated by the cathodic potential and achieved an NH4+ FE of 89%, indicating a tunable selectivity to the key nitrate reduction products (NO2– or NH4+) on OD-Ag. Density functional theory computations provided insights into the unique NO2– selectivity on Ag electrodes compared with Cu, showing the critical role of a proton-assisted mechanism. Based on the ultra-high NO3–-to-NO2– activity on OD-Ag, we designed a novel electrocatalytic–catalytic combined process for denitrifying real-world NO3–-containing agricultural wastewater, leading to 95+% of NO3– conversion to N2 with minimal NOX gases. In addition to the wastewater treatment process to N2 and the electrochemical synthesis of NH3, NO2– derived from electrocatalytic NO3– conversion can serve as a reactive platform for the distributed production of various nitrogen products.

Comments

This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in ACS Catalysis, copyright © American Chemical Society after peer review. To access the final edited and published work see DOI: 10.1021/acscatal.1c01525. Posted with permission.

Copyright Owner

American Chemical Society

Language

en

File Format

application/pdf

Published Version

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