Modulation of Photocatalytic CO₂ Reduction by n-p Codoping Engineering of Single-Atom Catalysts

Area of Science:

• Materials Science
• Catalysis
• Computational Chemistry

Background:

• Transition metal single-atom catalysts (TM SACs) are crucial for photocatalytic CO2 reduction.
• Optimizing TM SACs requires strategies to enhance their stability and electronic properties.
• Defect engineering in 2D materials offers a pathway to tune catalyst performance.

Purpose of the Study:

• To investigate the effect of n-p codoping on the photocatalytic CO2 reduction activity of TM SACs on a 2D bismuth-oxyhalide cathode.
• To elucidate the mechanism by which n-p codoping enhances catalyst performance using first-principles calculations.
• To identify stable dopant-defect configurations and their impact on electronic structure and catalytic efficiency.

Main Methods:

• First-principles calculations were employed to study n-p codoping in bismuth-oxyhalide-based cathodes.
• Formation energies of charged defects were calculated to determine stable dopant-defect pair configurations.
• Electronic structure analysis, including d-orbital alignment and d-band center shifts, was performed.

Main Results:

• Stable n-p codoped dopant-defect pairs (P0 for Fe, Co, Ni; P-1 for Cu) were identified.
• N-p codoping enhances TM SAC stability and electron accumulation via Coulombic interactions.
• Electron accumulation modifies d-orbital alignment, shifting the d-band center towards the Fermi level and improving CO2 reduction capacity.

Conclusions:

• N-p codoping is an effective strategy to enhance the performance of TM SACs for photocatalytic CO2 reduction.
• The Cu SAC-based P-1 configuration shows particular promise due to further electron accumulation and d-band center upshift.
• Limitations due to Cl multivacancies highlight the importance of defect control in achieving optimal catalytic activity.