Engineering plasmon-enhanced cathode for photo-electrocatalytic conversion of CO₂: Insight into the activity trends

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis
• Renewable Energy

Background:

• Photoelectrochemical CO2 reduction offers a sustainable route to convert carbon emissions into valuable fuels like syngas and formic acid.
• Current challenges include low stability, high charge recombination, and mass-transport limitations in traditional H-cell setups.
• Developing efficient photoelectrodes is crucial for advancing this technology.

Purpose of the Study:

• To design and synthesize a novel plasmonic silver-decorated Bi2WO6/ZnIn2S4 (ABZ) heterostructure photocathode.
• To systematically evaluate the performance of the ABZ photocathode for photoelectrochemical CO2 reduction under visible light.
• To investigate strategies for tailoring the selectivity towards liquid and gaseous products.

Main Methods:

• Synthesis of plasmonic Ag decorated Bi2WO6/ZnIn2S4 (ABZ) heterostructure.
• Performance testing of the ABZ photocathode under illumination (126.3 mWcm-2) with varying applied potentials.
• Electrochemical characterization, including electrochemical surface area measurements.
• In situ Diffuse Reflectance Infrared Fourier Transform (DRIFT) Spectroscopy.

Main Results:

• The Bi2WO6 component exhibited high current density (-9.14±0.4 mAcm-2) with H2 and HCOOH as major products at -0.69 V vs. RHE.
• The hydrophobic ABZ catalyst demonstrated superior performance with a large electrochemical surface area (15.4±0.3 cm2).
• The ABZ catalyst achieved approximately 100% Faradaic efficiency for CO-rich syngas production at -0.99 V vs. RHE.
• Product selectivity could be tuned by adjusting applied potentials.

Conclusions:

• The plasmonic Ag decorated ABZ heterostructure is a highly effective photocathode for CO2 reduction.
• The catalyst exhibits excellent stability and tunable selectivity for syngas and formic acid production.
• This work presents a promising strategy for visible-light-driven CO2 photo-electroreduction, contributing to carbon mitigation efforts.