One-Pot Synthesis of PtBi-CoX Alloys for Electrochemical Nitrate Reduction to Ammonia

The electrochemical nitrate reduction reaction (NO3RR) represents a promising strategy for wastewater remediation and sustainable ammonia (NH3) production. However, its practical application is hindered by low selectivity and competition from the hydrogen evolution reaction (HER). Herein, a series of PtBi-CoX (X = 4.9, 5.3, and 6.1) ternary alloy nanoplates was synthesized via a one-pot method with tunable Co content. Structural characterization indicates that Co incorporation does not significantly alter the hexagonal crystal structure of the PtBi phase. Electrochemical measurements reveal that the NO3RR performance varies with PtBi-CoX (X = 4.9, 5.3, 6.1), with PtBi-Co5.3 exhibiting the optimal balance of activity and selectivity among the studied samples. At −0.5 V vs. RHE, it achieves a Faradaic efficiency (FE) of 97.75 ± 0.75% and an NH3 yield rate of 9.33 ± 0.50 mg h−1 mgcat−1 under the tested conditions. In addition, the catalyst exhibits relatively suppressed HER activity compared to samples with higher Co content, along with good stability. These findings provide useful insights into the design of PtBi-based ternary alloy catalysts for efficient nitrate reduction.