Photocatalytic Biorefinery to Lactic Acid: A Carbon Nitride Framework with O Atoms Replacing the Graphitic N Linkers Shows Fast Migration/Separation of Charge

Abstract The rational regulation of the structure of photocatalysts with an enhanced visible‐light absorption property and rapid charge dynamics is promising and challenging. Here, a facile method was developed for preparing oxygen‐doped carbon nitride bundles with porous hollow trunk‐shaped structures (Ox@CNB) using melamine with assistance of hydrochloric acid. Experimental results and density functional theory (DFT) calculations indicated that Ox@CNB exhibited controllable bandgaps (2.20–2.60 eV) and a low photoluminescence intensity. Interestingly, Ox@CNB displayed excellent photocatalytic activity for the synthesis of lactic acid (81.4 %) and universality for the reforming of biomass‐derived monosaccharides to lactic acid. The oxidation active species of h + , ⋅OH, ⋅O 2 − and 1 O 2 all promoted the lactic acid production, and h + played a major role. A possible reaction mechanism of lactic acid synthesis was proposed by combining the experimental with the DFT results. A one‐thousand‐fold up‐scaled experiment demonstrated the significant application potential of the system for the industrial production of lactic acid.