Harnessing Surface-Tuned Ag/Cu Interfaces in Ag/Ag2O/CuO for High-Efficiency Ammonia Synthesis and Co-Electricity Generation in Zn-Nitrate Batteries

Abstract

This study presents a hierarchical silver/silver oxide/copper oxide (Ag/Ag2O/CuO) composite with high electrocatalytic efficiency for the nitrate (NO3-) reduction reaction (NO3RR). The Ag/Ag2O/CuO composite is synthesized using a single-pot pulsed laser ablation in liquid method. The incorporation of Ag/Ag2O nanoparticles enhances the conductivity of the Ag/Ag2O/CuO composite electrocatalyst, enabling a maximum Faradaic efficiency (FE) of 92.2% for NH4+ production with a yield rate of 6.4 mg<middle dot>h(-1)<middle dot>cm(-2) during the NO3RR at a reduction potential of -0.3 V versus reversible hydrogen electrode. In-depth analysis of the NO3RR kinetics using in situ and ex situ spectroscopic techniques reveals surface-tuning of the metallic Ag/Cu interface on the Ag/Ag2O/CuO composite electrocatalyst during the NO3RR, which plays a vital role in enhancing the NO3RR performance, further supported by density functional theory. Remarkably, a Zn-nitrate battery fabricated using the Ag/Ag2O/CuO composite cathode and a Zn anode demonstrates an open-circuit voltage of 1.48 V, achieving impressive NO3- to NH4+ conversion with an FE of 93.5% at a current density of 8 mA<middle dot>cm(-2). This study not only presents a novel methodology for developing a Ag/Ag2O/CuO composite but also provides insights into its superior NO3RR performance in Zn-nitrate batteries for green NH3 synthesis and co-electricity generation.