Ni nanoparticles modified Cu nanowires for enhanced electrocatalytic nitrate removal

Cu-based materials have been extensively studied for nitrate removal as an inexpensive and abundant electrocatalyst for water purification via the nitrate reduction reaction (NO3RR). But it typically suffers from nitrite accumulation due to the high selectivity towards nitrite formation. To address this issue, we herein report a strategy of modifying Cu nanowires with Ni nanoparticles to improve the NO3RR performance. The Ni nanoparticles both facilitate electron transfer from Ni to Cu and enhance the conversion of nitrite, thereby improving the overall removal of nitrate with a minimal yield of nitrite. Through a facile liquid phase deposition process, the loading amount of Ni nanoparticles can be easily tailored by simply changing the concentration of precursors, and the best Cu/Ni molar ratio for nitrate removal performance is 20. Under this ratio, the material simultaneously delivers a high nitrate removal rate of 92.2% and a low nitrite selectivity of only 2.2% at –0.9 V vs. reversible hydrogen electrode, accompanied with superior stability for a continuous NO3RR. This study thus offers an efficient, stable, and low-cost Cu-Ni bimetallic catalyst for NO3RR.