Synergistic bimetallic PdAg nanoalloy for the electrocatalytic reduction of nitrate to ammonia in a neutral solution

Abstract

The electrocatalytic reduction of nitrate to NH₃ using renewable energy sources is an effective and environmentally friendly alternative to conventional NH₃ generation methods. In the current study, a binary PdAg alloy in a face-centered cubic PdAg solid solution was obtained using electrosynthesis. Experimental evaluation revealed that the PdAg alloy had a geometrical and electronic structure that was optimal for nitrate reduction to NH₃. Owing to the significant activity of the PdAg alloy for nitrate reduction, an NH₃ yield rate of 0.683 ± 0.139 mmol h⁻¹ mg_cat⁻¹ (11.609 ± 2.368 mg h⁻¹ mg_cat⁻¹) and a high NH₃ faradaic efficiency of 97.47% ± 0.16% at −0.44 V vs. RHE were obtained. The source of NH₃ was further verified to be the nitrate through ¹⁵NO₃⁻ isotope labeling experiments. The stability of the PdAg alloy was confirmed after 10 electrocatalytic nitrate reduction cycles. The PdAg alloy exhibited promising NO₃RR activity under neutral conditions and successfully restricted the hydrogen evolution reaction activity.