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 H2. However, the sluggish kinetics of the alkoxy C–H bond cleavage attributes to the inefficiency utilization of photogenerated holes greatly restricts the photocatalytic activity. Here we develop atomically dispersed low‐coordination Mo on ultrathin ZnIn2S4 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 calculation reveal that the low‐coordination Mo tunes the local atomic configuration of highest occupied molecular orbital to trap holes produced under photoexcitation within picosecond. 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.