Solar-Powered Gram-Scale Ammonia Production from Nitrate

Area of Science:

• Renewable Energy Conversion and Storage
• Electrocatalysis
• Solar Energy Utilization

Background:

• Photoelectrochemical (PEC) methods offer potential for solar energy conversion and storage.
• Efficient solar-to-chemical energy conversion is crucial for sustainable energy solutions.
• Nitrate reduction is a key reaction for producing valuable chemicals like ammonia.

Purpose of the Study:

• To investigate the photovoltaic electrocatalytic (PV-EC) nitrate reduction reaction (NO₃^-RR) for ammonia production.
• To achieve high solar-to-ammonia conversion efficiency using silicon heterojunction solar cell technology.
• To explore the impact of tuning operation potential on product selectivity and ammonia yield.

Main Methods:

• Utilized silicon heterojunction solar cell technology for the PV-EC system.
• Employed an external resistance tuning approach to optimize the PV-EC system's operation potential.
• Systematically investigated the influence of potential tuning on product selectivity and ammonia yield.

Main Results:

• Achieved a maximum NH₃ production yield of 1.01 g L^-1 and a solar-to-ammonia conversion efficiency of 8.17%.
• Enhanced ammonia production yield by a four-fold increase (from 96 to 360 mg L^-1) through external resistance tuning.
• Successfully extracted NH₃ as NH₄Cl powder via acid stripping for chemical energy storage.

Conclusions:

• Demonstrated the feasibility of tuning product selectivity in PV-EC systems for enhanced ammonia synthesis.
• The PV-EC nitrate reduction reaction shows promise for efficient solar energy conversion and storage.
• The developed method has prospects for pilot-scale synthesis of value-added products.