Effective Hole Utilization for Atomically Dispersed Low-Coordination Molybdenum Accelerating Photocatalytic C─H Activation.

Photocatalytic acceptorless dehydrogenation of alcohols offers a promising strategy to produce the corresponding carbonyl compounds and clean fuel H. However, the sluggish kinetics of the alkoxy C─H bond cleavage attributes to the inefficient utilization of photogenerated holes greatly restricts the photocatalytic activity. Here we develmically dispersed low-coordination Mo on ultrathin ZnInS nanosheets that can greatly accelerate photocatalytic C─H activation. An internal quantum efficiency of 45.2% at 400 nm together with 99% benzaldehyde (BAD) selectivity is achieved using benzyl alcohol (BA) as a model substrate. Extensive experimental characterizations and theoretical calculations reveal that the low-coordination Mo tunes the local atomic configuration of highest occupied molecular orbital to trap holes produced under photoexcitation within picoseconds. Moreover, the incorporated site-specific Mo greatly improves the lifetime and diffusion length of photogenerated holes and optimizes the driving force of alkoxy C─H activation, which are responsible for the excellent performance. This work marks a significant stride to enhance the utilization efficiency of holes for promoting photocatalytic C─H activation.