Potential-Controlled Deposition of Multilayer CO₂ Reduction Catalyst Films onto Silicon Photoelectrodes Demonstrates...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Hybrid photoelectrode architectures combining molecular catalysts and semiconductors are crucial for CO2 reduction.
• Polymeric molecular catalyst films offer higher loading densities than monolayers for improved solar fuel production rates.

Purpose of the Study:

• To investigate the effect of catalyst film thickness on the photocatalytic performance of CO2 reduction.
• To establish a method for controllably attaching multilayered molecular catalyst films to semiconductor surfaces.

Main Methods:

• Photoassisted diazonium electrografting was used to attach multilayered Re(apbpy)(CO)3Cl catalyst films to p-type silicon (pSi).
• Ellipsometry, XPS, and ICP-MS were employed for film characterization.
• Controlled-potential electrolysis was used to assess photocatalytic performance.

Main Results:

• Catalyst loading increased with more negative grafting potentials (Vgraft).
• CO evolution rates were enhanced with increasingly negative applied potentials (Vapp), with thicker films showing greater enhancement.
• Thicker films demonstrated increased CO-to-H2 production ratios, indicating improved selectivity.

Conclusions:

• Controllable electrografting allows for the creation of thicker catalyst films on semiconductor photoelectrodes.
• Film thickness is a critical parameter for optimizing both the rate and selectivity of CO2 reduction.
• These findings advance the development of efficient solar fuel production technologies.