Ammonia synthesis and energy harvesting from nitrate via laser-engineered interface-tuned Pd@Cu catalysts

Abstract

Electrocatalytic conversion of nitrate to ammonia via the nitrate reduction reaction (NO3RR) is a sustainable method for ammonia production with simultaneous electricity generation. The electrocatalytic NO3RR is not only a versatile and scalable method but also a strategic option for next-generation electric vehicles. Herein, we report the development of palladium-decorated copper (Pd@Cu) composite microspheres via pulsed laser irradiation in liquid, and their application as electrocatalysts for the NO3RR. The Pd@Cu-3 composite achieved a maximum NH3 yield rate of 13100 mu g h-1 cm-2 and a Faradaic efficiency of 92.5 % at-0.4 V vs. the reversible hydrogen electrode. In-depth analysis of the NO3RR kinetics using in situ micro-Raman, ex situ XRD, and ex situ Fourier transform infrared spectroscopy revealed information on reaction intermediates and confirmed the excellent electrochemical activity of the Pd@Cu-3 composite. A Zn-nitrate battery assembled with a Pd@Cu-3 composite as the cathode and a zinc plate as the anode exhibits an open-circuit voltage of 1.33 V and an ultralong cycling stability of 100 hat 10 mA cm-2. The high NH3 yield rate and excellent stability of the Pd@Cu-3 composite demonstrate its potential for real-world applications.