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

Abstract

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.