Reconstruction of Interfacial Charge Topology in S‐Scheme Heterojunction for Enhanced CO2 Photoreduction

Why It Matters

By reengineering charge flow, the Au‑based system pushes CO₂ photoreduction efficiency beyond traditional band‑alignment limits, offering a scalable route for solar‑driven carbon capture technologies.

Key Takeaways

• Au nanoparticles reconstruct charge topology in S‑scheme heterojunction
• CO evolution reaches 115.4 µmol g⁻¹ h⁻¹, 57.7× BiOCl
• Au lowers *CO2→*COOH barrier by 0.36 eV
• Electron flow redirects from Cs3Bi2Br9 to BiOCl conduction band
• Multi‑site hole utilization improves overall photocatalytic efficiency

Pulse Analysis

The S‑scheme heterojunction has emerged as a promising architecture for photocatalysis because it separates electrons and holes while preserving strong redox potentials. However, its performance is traditionally capped by fixed band alignments and the built‑in electric field, which restricts how efficiently charge carriers can be directed to reactants. Introducing plasmonic metals adds a new dimension: localized surface plasmon resonance can generate hot electrons that alter the interfacial energetics, effectively rewriting the charge‑transfer map rather than merely boosting carrier density.

In the reported Au/Cs3Bi2Br9/BiOCl system, gold nanoparticles serve dual functions. Experimentally, they raise the CO evolution rate to 115.4 µmol g⁻¹ h⁻¹, a 57.7‑fold increase over bare BiOCl and a 2.3‑fold gain versus the binary S‑scheme. Theoretical calculations reveal that Au injects hot electrons into BiOCl’s conduction band, shifting the primary CO₂ reduction site from the quantum dots to the BiOCl lattice. Simultaneously, Au lowers the Gibbs free energy of the rate‑limiting *CO₂→*COOH step by 0.36 eV, accelerating the formation of carbon‑oxygen intermediates and enabling multi‑site hole utilization for improved overall efficiency.

The broader impact extends to the renewable‑energy landscape. By demonstrating that plasmonic metals can actively redesign charge pathways, this work opens a general strategy for surpassing the intrinsic limits of existing photocatalytic platforms. Scaling such ternary heterojunctions could accelerate solar‑driven CO₂ conversion, providing a viable feedstock for synthetic fuels and chemicals. Future research will likely explore other plasmonic metals, tunable nanoparticle geometries, and integration with industrial‑scale reactors, positioning plasmon‑engineered S‑scheme systems as a cornerstone of next‑generation carbon‑neutral technologies.