Photocatalytic conversion of biomass-based monosaccharides to lactic acid by ultrathin porous oxygen doped carbon nitride

Photocatalytic conversion of biomass-based monosaccharides to lactic acid by ultrathin porous oxygen doped carbon nitride. [Display omitted] •The Ut-OCN had controllable tunable bandgaps and lower PL intensity.•High yields of lactic acid achieved from different biomass-based monosaccharides photocatalyzed by Ut-OCN.•Catalyst was reusable for over 10 cycles without deterioration in this activity.•Good yield of lactic acid was observed from one-thousand-fold scale-up experiment. Application of photocatalysis to biorefinery conforms to the requirement of sustainable development of the society. It is of great significance, yet limited success has been achieved. Here, we report oxygen atom doped on the ultrathin porous carbon nitride (Ut-OCN) as an efficient photocatalyst for lactic acid production. The Ut-OCN photocatalyst represents an increase in the absorption range of visible-light via tunable band structure. Remarkably, the photocatalyst exhibited effective activity with lactic acid yield above 89.7 %, and this system is universal for the synthesis of lactic acid from biomass-based monosaccharides. Catalytic poisoning and recycling experiments revealed that the selectivity of ·O2− is superior to ·OH, 1O2, h+ in proper order. The photocatalyst is highly stable and recyclable. Moreover, the yield of lactic acid of one-thousand-fold scale-up experiment irradiated by sunlight retained 98.4 % of one-time experiment. It is believed that this work paves a way for the lactic acid production via photocatalysis.