Synergistic catalytic conversion of nitrate into ammonia on copper phthalocyanine and FeNC two-component catalyst

Cu-based catalysts have been extensively studied to enhance the performance of the electrochemical nitrate reduction reaction (NO3-RR), while it is still a challenge to balance high ammonia (NH3) current density and Faradaic efficiency. Here, we incorporated nitrogen coordinated iron single atom catalyst (FeNC) with copper phthalocyanine (CuPc), denoted as CuPc/FeNC, for NO3-RR. Compared with the two individual catalysts, this two-component catalyst increases NH3 Faradaic efficiency and current density at low overpotentials, achieves efficient synergistic catalytic conversion. Experiments and theoretical calculations reveal that the enhanced electrochemical performance of CuPc/FeNC catalyst comes from the tandem process, in which NO2- is produced on CuPc and then transferred to FeNC and further reduced to NH3. In this exceptional tandem catalyst system, an outstanding NH3 Faradaic efficiency close to 100% was achieved at potentials greater than -0.35 V vs. RHE, coupled with a peak NH3 partial current density of 273 mA cm-2 at -0.57 V vs. RHE, effectively suppressing NO2- production across the entire potential range. This strategy provides a design platform for the continued advancement of NO3-RR catalysts. Published by Elsevier B.V. All rights reserved.