Copper Selenide Nanosheet with Adjustable Cation Vacancy for Boosting Nitrogen Electroreduction

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Electrochemical nitrogen reduction reaction (NRR) is a sustainable method for ammonia synthesis.
• Vacancy engineering in catalysts enhances nitrogen-to-ammonia conversion.
• Controlling cation vacancy concentration in catalysts is challenging.

Purpose of the Study:

• To develop a method for fabricating copper selenide nanosheets with precisely tuned copper vacancy (V_Cu) concentrations.
• To investigate the effect of V_Cu concentration on NRR performance.
• To provide insights into the role of V_Cu sites in ammonia synthesis.

Main Methods:

• Combined thermal treatment and plasma approach for catalyst synthesis.
• Fabrication of copper selenide nanosheets with varying V_Cu concentrations.
• Electrochemical characterization of catalysts for NRR activity.

Main Results:

• A catalyst (p-Cu_1.8Se/Cu₂Se/C-5) with the highest V_Cu concentration showed superior NRR activity.
• Achieved an NH₃ production rate of 21.81 μg h^-1 mg_cat.^-1 at -0.7 V vs RHE, over 3-fold higher than vacancy-free.
• Identified V_Cu sites as active centers optimizing nitrogen adsorption and activation.

Conclusions:

• Precisely engineered copper vacancies significantly enhance NRR performance.
• V_Cu sites lower the energy barrier for ammonia synthesis.
• This defect engineering approach offers a new strategy for designing advanced NRR electrocatalysts.