Selective Production of Benzaldehyde Using Metal-Free Reduced Graphene Oxide/Carbon Nitride Hybrid Photocatalysts

Benzyl alcohol was selectively oxidized to benzaldehyde in aqueous solution, at ambient conditions of temperature and pressure, by using a photocatalytic approach, with two types of irradiation sources, namely monochromatic UV-A light (392 nm) and visible light (400-700 nm). Conversion after 4 h of reaction was more efficient under UV than under visible, with selectivity in excess of 80% for both irradiating sources. Composites of graphitic carbon nitride (g-C3N4) containing small amounts of reduced graphene oxide (rGO) (up to 1 wt.%) were used as photocatalysts. The presence of rGO was confirmed by spectroscopic and microscopic analyses. Results show that small amounts of rGO phase can considerably enhance the photocatalytic activity of g-C3N4 based catalysts, the best load being 0.10 wt.%. This improvement is attributed to the critical modification of morphological and electronic properties provided by the presence of rGO.