Photocatalytic Glucose Reforming for Formic Acid on 2D Amorphous MoO3-x/TNTs Heterojunction in Pure Water.

Formic acid is a promising hydrogen-storage material and biohydrogen production intermediate, offering sustainable biomass-derived alternative processes. Herein, a two-dimensional amorphous molybdenum oxide/titanium oxide nanotubes (MoO3-x/TNTs) heterojunction with amorphous/crystalline interfaces, is designed and fabricated by supercritical CO2, with which the photocatalytic reforming of glucose for formic acid is realized in pure water. The HCOOH yields of 14.8% for glucose and 22% for glycerol are achieved in pure water at room temperature with 2 bars O2 atmosphere within 6 hours under 365 nm light with 5 mW/cm2. The photoinduced Mo6+-catalyzed ligand-to-metal charge transfer (LMCT) and the enhanced adsorption energy of glucose molecules on the MoO3-x surface in the MoO3-x/TNTs heterojunction facilitate the cleavage of C-C bonds in polyhydric alcohol skeletons, leading to the formation of HCOOH. Under light excitation, MoO3-x transfers electrons to TNTs due to defect state, synergizing with the generated •OH radicals in the system. This results in reversible cycling between Mo6+ and Mo5+, thereby ensuring catalytic persistence. Therefore, this study demonstrates a photocatalytic strategy for the sustainable production of value-added chemicals from biomass under eco-friendly conditions, using easily recyclable heterogeneous catalysts in pure water.