Triazole Drives Hole Localization and Superoxide Radical Formation for Enhancive Photocatalytic Cascade...

Chemocatalytic synthesis of lactic acid (LA) from biomass sugars involves heat-absorbing multistep cascade reactions mediated by different active sites, often encountering unsatisfactory selectivity. Here, a hole-localized carbon nitride-based photocatalyst (C-CNN) is constructed by covalent binding of heptazine and triazole skeleton via C─N bonds and further conjugated interaction with activated carbon, achieving the complete conversion of various biomass sugars to LA (up to 98.6% selectivity) at room temperature for 2 h. The introduced triazole electron donor in C-CNN can not only enhance the adsorption of sugar for the enhanced aldose-to-ketose isomerization over the localized hole (Lewis acid) on the triazole skeleton, but also modulate the valence band oxidation to circumvent the formation of •OH but only •O₂ ^‒ for selective C₃‒C₄ cleavage of ketose, thus realizing the exclusive synthesis of LA. Moreover, near-infrared light absorption endowed by activated carbon can supply sufficient interface photothermal effect for ambient LA production. Life cycle assessment shows that the photocatalytic system has good prospects for industrialization in terms of both energy and environment. This work offers novel insights into the multidirectional utilization of solar energy for the value-added conversion of biomass through rational modulation of photothermal active sites.