Fig. 4: In-situ DEMS and ATR-FTIR characterization of electrocatalytic NO₃RR on ZnPc MDE(H).

a In-situ DEMS measurements for electrocatalytic NO₃RR at −0.7 V over four continuous cycles. The mass signals increased rapidly upon application of the reduced potential and gradually decreased to the baseline after the potential was removed. b In-situ DEMS of NH₂OH changes with applied potential in LSV. Scan rate of LSV: 1.0 mV s⁻¹. The abbreviation “arb. units” refers to “arbitrary units”. R_u = 12.9 ± 1.1 Ω. c The electrocatalytic NO₃RR pathway in our experiment, derived from our in-situ DEMS experiment results. d In-situ ATR-FTIR spectra of the electrocatalytic NO₃RR. As the spectra were background corrected, the downward peak change in the blue region indicates the consumption of NO₃⁻, and the upward peak change in the yellow region signifies the formation of NH₂OH. R_u = 11.1 ± 0.1 Ω. All in-situ characterization experiments were conducted in an Ar-saturated 1.0 M KOH + 1.0 M KNO₃ electrolyte. Resistances were measured by three individual measurements, and the average (mean) values with the standard deviation are presented.