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

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 similar to 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.