PdAg Alloy Nanocatalysts: Toward Economically Viable Nitrite Reduction in Drinking Water

Nitrite (NO2-) is the primary reduction product of nitrate (NO3-), which is the most predominant contaminant in global freshwater. Both species present major environmental challenges; NO2- is also highly toxic to humans. Available technologies for the removal of NO3- and NO2- from potable water are hampered by a number of issues, which limit their widespread usage. Catalytic degradation of NO3- and NO2- is a potentially disruptive technology. However, the high cost of palladium metal required for this process is a significant economic barrier. Herein, we report the synthesis of scalable catalyst materials based on randomly alloyed palladium-silver nanoparticles. These catalysts significantly lower the overall catalyst cost and simultaneously achieve a 3.4-times increase in the catalytic activity for NO2- hydrogenative reduction. Density functional theory (DFT) studies reveal that alloying Pd with Ag creates more favorable surface binding sites, which is the origin of the increased catalytic activity. The catalysts are also highly selective toward the production of nitrogen gas over ammonia.