Isolated Iodine Single Atoms Regulating the In‐Plane Electronic Structure of G‐C3N4 for Enhanced CO2 Photoreduction

Why It Matters

The breakthrough offers a scalable, metal‑free pathway to convert CO₂ into fuels, addressing both catalyst durability and efficiency challenges in solar‑driven chemistry.

Key Takeaways

• Iodine atoms anchor to bridging nitrogen, boosting structural stability
• C‑I bonds create hole‑transfer channels, accelerating charge separation
• Orbital hybridization lowers CO₂ antibonding energy, enhancing activation
• CO yields reach 181 µmol·g⁻¹·h⁻¹ under simulated sunlight
• Visible-light CO production exceeds 90 µmol·g⁻¹·h⁻¹

Pulse Analysis

Metal‑free photocatalysts such as graphitic carbon nitride have attracted attention for CO₂ reduction because they avoid the cost and scarcity of noble metals. However, g‑C3N4 traditionally suffers from rapid photo‑induced degradation in vapor environments and limited electron‑hole separation, curbing its practical utility. Recent advances in single‑atom engineering provide a promising remedy, enabling precise tuning of electronic structures without compromising the material’s inherent advantages. By introducing isolated iodine atoms, researchers have created a new class of catalysts that combine structural robustness with tailored charge dynamics.

The iodine atoms serve a dual function: they bind to tri‑coordinated bridging nitrogen, reinforcing the C‑N‑C framework and preventing self‑decomposition, while the resulting C‑I bonds act as efficient pathways for photogenerated holes. This direct hole‑transfer channel accelerates in‑plane charge separation, reducing recombination losses. Moreover, the overlap between iodine‑modified nitrogen 2p orbitals and CO₂ 2p orbitals lowers the energy of CO₂ antibonding states, effectively priming the molecule for reduction. Such orbital hybridization is a subtle yet powerful lever that enhances catalytic activity without introducing foreign metals.

Performance metrics validate the design. Under simulated solar light the iodine‑single‑atom catalyst achieves CO production of 181 µmol g⁻¹ h⁻¹ and CH₄ generation of 16 µmol g⁻¹ h⁻¹, while visible‑light irradiation still yields over 90 µmol g⁻¹ h⁻¹ CO. These figures surpass many conventional g‑C3N4 systems and approach those of precious‑metal catalysts. The study not only expands synthetic routes for non‑metal single‑atom catalysts but also highlights the strategic importance of atomic‑scale engineering for sustainable CO₂ utilization, paving the way for greener fuel synthesis at scale.