Affiliation:
1. Institute of Materials Research Tsinghua Shenzhen International Graduate School Tsinghua University Shenzhen 518055 China
2. School of Materials and Environmental Engineering Shenzhen Polytechnic Shenzhen 518055 China
3. Faculty of Materials Science and Engineering Kunming University of Science and Technology Kunming 650093 China
Abstract
AbstractElectrochemical nitrate reduction reaction (NO3RR) is a promising approach to realize ammonia generation and wastewater treatment. However, the transformation from NO3− to NH3 involves multiple proton‐coupled electron transfer processes and by‐products (NO2−, H2, etc.), making high ammonia selectivity a challenge. Herein, a two‐phase nanoflower P‐Cu/Co(OH)2 electrocatalyst consisting of P‐Cu clusters and P‐Co(OH)2 nanosheets is designed to match the two‐step tandem process (NO3− to NO2− and NO2− to NH3) more compatible, avoiding excessive NO2− accumulation and optimizing the whole tandem reaction. Focusing on the initial 2e− process, the inhibited *NO2 desorption on Cu sites in P‐Cu gives rise to the more appropriate NO2− released in electrolyte. Subsequently, P‐Co(OH)2 exhibits a superior capacity for trapping and transforming the desorbed NO2− during the latter 6e− process due to the thermodynamic advantage and contributions of active hydrogen. In 1 m KOH + 0.1 m NO3−, P‐Cu/Co(OH)2 leads to superior NH3 yield rate of 42.63 mg h−1 cm−2 and NH3 Faradaic efficiency of 97.04% at −0.4 V versus the reversible hydrogen electrode. Such a well‐matched two‐step process achieves remarkable NH3 synthesis performance from the perspective of optimizing the tandem catalytic reaction, offering a novel guideline for the design of NO3RR electrocatalysts.
Funder
Natural Science Foundation of Guangdong Province