A rotating ring disc electrode study of photo(electro)catalyst for nitrogen fixation

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Photo(electro)catalysts are crucial for nitrogen reduction to ammonia and oxidation to nitric acid.
• Advancing solar-to-fertilizer applications is hindered by slow catalyst screening methods.
• Current product analyses often rely on batch reactors and product accumulation, limiting screening efficiency.

Purpose of the Study:

• To evaluate rotating ring disk electrode voltammetry (RRDE) for detecting ammonia produced by nitrogen-fixing photo(electro)catalysts.
• To assess the feasibility of RRDE as a high-throughput screening tool for catalyst development.
• To investigate the influence of applied potential and illumination on ammonia detection using RRDE.

Main Methods:

• Utilized rotating ring disk electrode voltammetry (RRDE) to detect ammonia.
• Employed titania as a model photo(electro)catalyst known for nitrogen reduction to ammonia.
• Varied electrochemical potential and illumination levels on the disk electrode during experiments.

Main Results:

• Observed ammonia oxidation at the ring electrode strongly correlated with bulk electrolyte ammonia measurements.
• Demonstrated the potential of RRDE for real-time detection of ammonia produced by photo(electro)catalysts.
• Identified the need for an alkaline electrolyte as a limitation for the RRDE approach.

Conclusions:

• RRDE is a viable electroanalytical technique for detecting ammonia from nitrogen-fixing photo(electro)catalysts.
• This method can significantly accelerate the screening process for new catalysts in solar-to-fertilizer applications.
• Further research is needed to address limitations such as electrolyte requirements and potential interference from adventitious ammonia.