Optimizing dual-active-site electrocatalysts for adsorption and hydrogenation for efficient nitrate-to-ammonia

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Electrochemical nitrate reduction reaction (NO3RR) to ammonia (NH3) is crucial but hindered by multi-step reaction kinetics.
• Cobalt-based catalysts show promise but suffer from poor nitrate adsorption and slow intermediate transfer.

Purpose of the Study:

• To design and investigate a novel dual-active-site catalyst for efficient electrochemical NO3RR.
• To understand the synergistic effects of Fe and Co sites in FeCo-NC nanocubes for NH3 synthesis.

Main Methods:

• Synthesis of FeCo hollow nanocubes (FeCo-NC) with dual active sites.
• In-situ electrochemical spectra measurements.
• Density functional theory (DFT) calculations.

Main Results:

• Fe sites enhanced NO3- adsorption and activation; Co sites facilitated water dissociation and hydrogenation.
• Fe doping reduced the energy barrier for the rate-determining step (*NO to *HNO).
• FeCo-NC achieved a high ammonia production rate (14.1 mg h-1 cm-2) and Faradaic efficiency (94.5%) at -0.6 V, outperforming Co-NC.
• Demonstrated excellent cycling stability (20 h) and a Zn-NO3- battery power density of 8.98 mW cm-2.

Conclusions:

• Dual-active-site design with synergistic Fe-Co interactions is effective for high-performance NO3RR.
• FeCo-NC offers a promising pathway for efficient and stable ammonia synthesis via electrocatalysis.
• The study provides insights into catalytic mechanisms for NO3RR and advanced catalyst development.