Semi-carbonized nanostructures of carbohydrate for highly efficient photocatalysts

Abstract

We demonstrate that the semi-carbonized nanostructures of carbohydrate (cellulose and glucose as precursors) show high performance as photocatalysts directly for selective oxidation of cis-cyclooctene with air as an oxidant. Three dimensionally macroporous carbon spheres (3DMPCS) prepared from cellulose carbonized at 500 °C yielded the highest conversion of cis-cyclooctene (32.6%) and a high selectivity of 2-hydroxycyclooctanone (90.4%) after 24 h reaction, while cellulose carbonized at lower heat treatment temperatures (HTTs) (0–400 °C) or higher (600–900 °C) gave lower cis-cyclooctene conversion. The 3DMPCS synthesized from glucose carbonized at 600 °C shows higher performance in selective oxidation of cis-cyclooctene (12.2% conversion of cis-cyclooctene and 75.4% selectivity of 2-hydroxycyclooctanone) than glucose carbonized at other HTTs (200–500 °C and 700–900 °C) as catalysts. The results indicate that the semi-carbonized nanostructures of carbohydrates are highly efficient photocatalysts.