N-Co-S Single-Atom Electronic Bridge Enables a Z-Scheme Heterojunction for Room-Temperature Photocatalytic Hydrogen Production From Ammonia Decomposition.

Ammonia (NH3) decomposition to hydrogen (H2) offers a sustainable route for clean energy generation, benefiting from abundant feedstocks, ease of storage and zero-carbon cycle. Conventional NH3 decomposition, however, relies on Ru-based noble metal catalysts and requires temperatures above 400°C, resulting in high cost and limited scalability. The development of efficient, low-cost catalysts that operate under mild conditions is therefore imperative. Here, we report a novel Z-scheme photocatalyst composed of Co-doped CdS quantum dots anchored on NH2-MIL-53(Al) (Co-CdS QDs/MIL) via an interfacial N-Co-S single atom electron bridge (Co-SAEB). By precisely steering the separation and migration of photogenerated charges, this architecture drives efficient photocatalytic NH3 decomposition at ambient temperature. The catalyst achieves an exceptional H2 evolution rate of 18 µmol·g-1·s-1, surpassing existing photocatalytic systems and approaching the performance of photothermal NH3 decomposition processes. Combined characterization and theoretical analyses reveal that the Co-SAEB is pivotal in establishing a direct Z-scheme charge-transfer pathway, which suppresses carrier recombination and enhances both redox capability and photocatalytic durability. This work advances the fundamental understanding of Z-scheme electron transfer and provides a design strategy for highly active, stable and adaptable photocatalytic materials.