Controlling Selectivity for Efficient Nitrogen Photo‐Fixation Over Hydrogen Evolution Using Anthracene‐Containing D–A Conjugated Polymers

Why It Matters

The breakthrough demonstrates a scalable, sacrificial‑agent‑free route to solar‑driven ammonia synthesis, addressing energy security and greenhouse‑gas reduction. It also offers a design blueprint for balancing competing photocatalytic pathways in organic materials.

Key Takeaways

• 1:1 donor:acceptor ratio yields 1645 µmol g⁻¹ h⁻¹ NH3
• Higher anthracene content boosts N2 chemisorption
• HER rate drops as NRR increases
• No sacrificial agents required
• Platform works with various electron donors

Pulse Analysis

Photocatalytic ammonia synthesis has long been hampered by weak nitrogen adsorption and the dominance of the hydrogen evolution reaction, which siphons electrons away from the desired nitrogen reduction pathway. Organic donor‑acceptor (D‑A) polymers provide a versatile scaffold where electronic structure and surface chemistry can be precisely tuned. By pairing anthracene, a strong electron donor, with dibenzothiophene sulfone (BTSO), an electron‑accepting unit, the research team created a series of conjugated polymers whose donor‑to‑acceptor ratios dictate the balance between NRR and HER activity.

The standout material, AnSO‑6, features an exact 1:1 anthracene‑to‑BTSO ratio and achieves a record‑breaking NH3 output of 1,645 µmol g⁻¹ h⁻¹ under simulated sunlight. This performance stems from three synergistic effects: enhanced N2 chemisorption on the anthracene‑rich surface, rapid electron transfer facilitated by the conjugated backbone, and prolonged charge‑carrier lifetimes due to efficient spatial separation of electrons and holes. As the anthracene proportion rises, the polymer’s affinity for nitrogen grows while its propensity to catalyze HER diminishes, offering a clear lever for selectivity control.

Beyond the laboratory, the findings have immediate relevance for sustainable fertilizer production and decentralized energy systems. The ability to achieve high‑rate ammonia synthesis without sacrificial reagents simplifies reactor design and reduces operational costs. Moreover, the demonstrated modularity—swapping anthracene for alternative donors while retaining the BTSO acceptor—suggests a broad design space for next‑generation photocatalysts tailored to specific industrial or environmental targets. Continued optimization of polymer morphology, light‑harvesting breadth, and scalability could position D‑A conjugated polymers as a cornerstone of the emerging green ammonia economy.