Isolated Lewis Acid Site Enables Electrocatalytic Chlorine Evolution at Low-concentration Chloride Electrolyte

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Industrial chlorine production relies on electrolysis, but the chlorine evolution reaction (CER) faces selectivity issues due to the competing oxygen evolution reaction (OER).
• This competition is particularly problematic in low-concentration chloride and high pH electrolytes, limiting efficient chlorine production.

Purpose of the Study:

• To engineer an isolated site strategy to improve CER selectivity by suppressing OER.
• To develop a silicon-doped platinum-ruthenium (PtRuSi) catalyst for enhanced chlorine evolution.

Main Methods:

• Engineered isolated silicon (Si) sites within a platinum-ruthenium (PtRu) catalyst structure.
• Utilized operando characterizations to analyze intermediate binding and electrochemical tests to evaluate catalyst performance.
• Investigated catalyst behavior in low-concentration NaCl electrolytes and natural seawater.

Main Results:

• The isolated Si sites preferentially captured oxygen evolution reaction intermediates (OH*), suppressing their interference with chlorine adsorption.
• PtRuSi demonstrated significantly improved CER selectivity, achieving nearly 100% in 1.5 M NaCl and 69.1% in natural seawater.
• The engineered catalyst outperformed the undoped PtRu catalyst, especially in challenging low-concentration and high pH conditions.

Conclusions:

• Isolated site engineering with Si doping is an effective strategy to enhance CER selectivity by mitigating OER.
• The PtRuSi catalyst offers a promising solution for efficient chlorine production in diverse and challenging aqueous environments.
• This approach advances catalyst design for industrial electrolysis reactions beyond traditional highly concentrated brine conditions.