Abstract

The efficient electrocatalysis of converting nitrate (NO₃^-) to ammonia (NH₃) represents a promising strategy for achieving net-zero carbon emissions and sustainable environmental practices. In this study, we introduce a rational design of pulsed laser-synthesized Pd nanoparticle-decorated Co nanodendrites (Pd/Co NDs) as a highly efficient and selective electrocatalyst. This system demonstrates a Faradaic efficiency (FE) of 92.35% and a yield of 9.03 mg h^-1 cm^-2, with long-term stability lasting 300 h during nitrate reduction (NO₃RR). Both mechanistic in situ and ex situ analyses reveal dynamic surface reconstructions that occur during NO₃RR. The pristine Co NDs transform into a CoOOH@Co structure with Pd, and the synergistic performance of the Pd/CoOOH@Co NDs remarkably enhances NO₃RR performance, as supported by theoretical calculations. Furthermore, a Zinc-NO₃^- battery using Pd/Co NDs as the cathode achieves an open-circuit voltage of 1.506 V and a NO₃RR conversion FE of 68.78% at a current density of 4 mA cm^-2 the long-term stability of 500 h. This study highlights the importance of surface reconstructions in the Pd/CoOOH@Co ND electrocatalysis for NO₃RR and the performance of Zn-NO₃^- batteries, providing valuable insights for designing advanced electrocatalysts aimed at sustainable ammonia synthesis from nitrate pollutants.