Efficient Nitrate to Ammonia Conversion on Bifunctional IrCu4 Alloy Nanoparticles

Electrochemical nitrate reduction (NO3RR) to ammonia presents a promising alternative strategy to the traditional Haber-Bosch process. However, the competitive hydrogen evolution reaction (HER) reduces the Faradaic efficiency toward ammonia, while the oxygen evolution reaction (OER) increases the energy consumption. This study designs IrCu4 alloy nanoparticles as a bifunctional catalyst to achieve efficient NO3RR and OER while suppressing the unwanted HER. This is achieved by operating the NO3RR at positive potentials using the IrCu4 catalyst, which allows a Faradaic efficiency of 93.6% for NO3RR. When applied to OER catalysis, the IrCu4 alloy also shows excellent results, with a relatively low overpotential of 260 mV at 10 mA cm-2. Stable ammonia production can be achieved for 50 h in a 16 cm2 flow electrolyzer in simulated working conditions. Our research provides a pathway for optimizing NO3RR through bifunctional catalysts in a tandem approach.Electrochemical nitrate reduction (NO3RR) to ammonia presents a promising alternative strategy to the traditional Haber-Bosch process. However, the competitive hydrogen evolution reaction (HER) reduces the Faradaic efficiency toward ammonia, while the oxygen evolution reaction (OER) increases the energy consumption. This study designs IrCu4 alloy nanoparticles as a bifunctional catalyst to achieve efficient NO3RR and OER while suppressing the unwanted HER. This is achieved by operating the NO3RR at positive potentials using the IrCu4 catalyst, which allows a Faradaic efficiency of 93.6% for NO3RR. When applied to OER catalysis, the IrCu4 alloy also shows excellent results, with a relatively low overpotential of 260 mV at 10 mA cm-2. Stable ammonia production can be achieved for 50 h in a 16 cm2 flow electrolyzer in simulated working conditions. Our research provides a pathway for optimizing NO3RR through bifunctional catalysts in a tandem approach.