One-step hydrothermal synthesis of CdxInyS(x+1.5y) for photocatalytic oxidation of biomass-derived 5-hydroxymethylfurfural to 2, 5-diformylfuran under ambient conditions

The Cd x In y S ( x +1.5 y ) catalysts with gradient Cd:In ratios were controllably synthesized via an one-step hydrothermal approach. Particularly, the hydrothermal synthesis conferred those Cd x In y S ( x +1.5 y ) catalysts with Cd:In ratios over 1:2 with a one-dimensional–three-dimensional heterojunction structure composed of CdS nanorods and cubic-phase CdIn 2 S 4 . Our characterization evidences reflected that the CdS nanorods effectively promoted the separation of photoexcited electron–hole pairs in Cd x In y S ( x +1.5 y ) and enabled transboundary transfer of photogenerated carriers. Spectroscopic and experimental results were further employed to develop a detailed catalytic mechanism, in which the superoxide anion (•O 2 − ) plays an important role in the catalytic oxidation of HMF to DFF by Cd x In y S ( x +1.5 y ) . Unlike other photocatalysts with •O 2 − as the main active species, Cd 1.5 In 2 S 4.5 gives an excellent performance in HMF conversion. This shows the great potential of cadmium–indium sulfides as photocatalysts for biomass conversion under ambient conditions.