Laser-controlled tandem catalytic sites of CuNi alloys with ampere-level electrocatalytic nitrate-to-ammonia reduction activities for Zn–nitrate batteries

Abstract

The clean production of electric energy and ammonia (NH₃) is an inevitable requirement of modern industrial development. In this work, we synthesized CuNi alloy nanoparticles on a Cu foil (CuNi NPs/CF) by a facile and fast laser irradiation method as the integral cathode for efficient electrocatalytic reduction of nitrate (NO₃⁻) into NH₃ (NIRR). As a result, the obtained CuNi NPs/CF with tandem catalytic sites exhibits ampere-level NIRR performance with the highest NH₃ yield rate of 94.57 mg h⁻¹ cm⁻² and a faradaic efficiency (FE) of ∼97.03% at −0.48 V vs. RHE, along with good stability in an ultrahigh NO₃⁻ concentration of 44.3 g L⁻¹. The tandem configuration of the optimized NO₃⁻ binding energy on Cu and sufficient active hydrogen on Ni sites are vital for the NIRR. Furthermore, benefiting from the high NIRR activity, a galvanic Zn–NO₃⁻ battery with the highest reported power density of 70.7 mW cm⁻² was constructed with the CuNi NPs/CF as the cathode. This work not only reveals the catalytic mechanism of bimetallic alloys for NO₃⁻ reduction but also realizes an efficient Zn–NO₃⁻ battery for NH₃ synthesis and electric energy output.