Title : Efficient nano-regional photocatalytic heterostructure design via the manipulation of reaction site self-quenching effect
Heterostructural photocatalysts with rationally aligned energy bands have been proved effective in diminishing the recombination of photo-induced excitons, thus leading to enhanced photocatalytic performance. Besides the enhanced photocatalytic performance with these heterostructures, most of these heterostructures observed a performance decrease when the amount of cocatalysts exceed a critical value. Although some researchers inferred that excessive nano-decorators would lead to an increased light penetration depth in the space charge layer or reaction site blocking in these heterostructures, these explanations are left unverified by experimental result, and the mechanism behind the concentration vanishment of photocatalytic performance is still in controversy. The critical role of charge carrier behaviors and their quenching pathway in determining the overall photocatalytic performance are still not fully explored, which severely hindered the development for efficient photocatalysts. As a result, there may be some omitted channels for the annihilation of photocatalytic performance in the nano-regional heterostructures, which should be further explored.
Herein, to further explore the essential principles of photocatalysis with heterostructures, a representative nano-regional photocatalytic heterostructure was constructed through uniform decoration of visible light activable BiOI nanodots on TiO2 nanorod assembled microflowers. With which as a well-known prototype of conventional heterostructures, a possible photocatalytic performance annihilation channel via reaction site self-quenching effect in photocatalytic heterostructures was experimentally evidenced for the first time. Based on our experimental results, we evidenced that excessive decoration with BiOI nanodots would result in severe self-quenching of their photocatalytic sites through highly probable charge carrier recombination between migrating electrons along TiO2 nanorods and reactive holes in adjacent BiOI nanodots. Such fundamental and experimental discovery is not limited to the current model and would shed light on the development of novel nano-regional heterostructures with high photocatalysis performance.
Audience Take Away:
- Reaction site self-quenching effect caused by excessive nano-decorators in photocatalytic heterostructures is discovered and proved by photoluminescent decay curve.
- Ultra-small BiOI nanodots (<3 nm) were synthesized via a reactant prefixing strategy, which could be used in other nano-material synthesis with uniform sizes.
- The p-n junction composed of BiOI mediated TiO2 heterostructure can significantly enhance the photocatalytic performance.
- It is expected that this work could offer guidance for the rational design of high-performance functional heterostructures in the field of photocatalysis or even photovoltaics field.