Electrochemical NRR performances of the Pd/ACC catalyst. (a) Schematic of the NRR device. (b) Chronoamperometry curve and total electric charge after electrolysis of Pd/ACC in N2 or Ar at 0.1 V for 2 h. (c) FE and average yield rate of NH3 production at various potentials based on the indophenol blue method with an inset of an enlarged figure. (d) Nine times recycling NRR experiments of a Pd/ACC electrode tested at 0.1 V for 2 h. (e) Isotope labelling experiment. 600 M 1H NMR spectra were obtained after electrolysis in 0.1 M HCl with 15N2 and 14N2 as the feeding gas. The multiplet splitting of the peaks may because of the deuterated derivatives of ammonium.