The electrocatalytic nitrate reduction reaction represents a promising technology for wastewater treatment while enabling electrochemical ammonia (NH3) synthesis. However, electrostatic repulsion between nitrate (NO3-) and the cathode impedes NO3- diffusion into the electric double layer, thereby hindering the reaction. Herein, the diffusion limitation is mitigated by introducing a trace CsOH additive to the electrolyte, and the underlying mechanism is systematically elucidated. CsOH not only weakens the static repulsion between NO3- and the cathode but also enhances the selectivity of NH3 by preventing the formation of adsorbed H+ on the electrode. Remarkably, the addition of CsOH enables an NH3 production rate of 456.2 μmol cm-2 h-1 at 150 mA cm-2 with a faradaic efficiency of 65.2% in 20 mM NO3-. Furthermore, the Zn-NO3 battery with a CsOH additive achieves a peak power density of 30.16 mW cm-2. This work not only provides fundamental insights of additive-enhanced NO3- reduction but also successfully demonstrates a Zn-NO3 battery capable of simultaneous high-efficiency NH3 synthesis and electric power generation.
Luo et al. (Sun,) studied this question.