Coupled Pd^δ--Cu^δ+ Dipole for Enhanced Aqueous Nitrate Valorization at Ultralow Potentials

Area of Science:

• Electrochemistry
• Materials Science
• Environmental Chemistry

Background:

• Nitrate pollution threatens water quality and the nitrogen cycle.
• Electrochemical nitrate reduction reaction (NO3RR) offers a path for nitrate removal and ammonia (NH3) production.
• Current NO3RR methods face challenges with insufficient hydrogen (*H) supply and poor nitrite (NO2-) adsorption, limiting efficiency and causing byproduct accumulation.

Purpose of the Study:

• To overcome limitations in NO3RR by developing a novel dipole strategy.
• To enhance *H supply and *NO2- adsorption at ultralow potentials.
• To achieve efficient nitrate removal and selective ammonia synthesis.

Main Methods:

• Fabrication of binder-free monolithic single-atom alloy electrodes with coupled divergent dual centers (Pd-Cu).
• Utilized in-situ experiments and theoretical simulations to investigate reaction mechanisms.
• Employed a dipole strategy with polarized Pd(δ-) and Cu(δ+) centers to facilitate water dissociation and *NO2- adsorption.

Main Results:

• The Pd-Cu dipole significantly enhanced *H supply via water dissociation.
• Achieved 100% nitrate removal and 100% ammonia selectivity with near-zero nitrite accumulation.
• Demonstrated high ammonia Faradaic efficiency (94.4%) and yield rate (1.98 mM h⁻¹ cm⁻²) at -0.2 V vs RHE.

Conclusions:

• The proposed metal-dipole strategy effectively addresses challenges in NO3RR at ultralow potentials.
• This approach provides a universal principle for designing advanced electrocatalysts for pollutant valorization.
• The Pd-Cu single-atom alloy electrodes show superior performance compared to monometallic counterparts and existing catalysts.