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

• Published in: ChemistrySelect (Weinheim) 2018-07, Vol.3 (28), p.8070-8081
• Main Authors: Lima, Maria J., Pastrana‐Martínez, Luisa M., Sampaio, Maria J., Dražić, Goran, Silva, Adrián M. T., Faria, Joaquim L., Silva, Cláudia G.
• Format: Article
• Language: English
• Subjects: benzaldehyde; carbon nitride; photocatalysis; reduced graphene oxide; sustainable chemistry
• ISSN: 2365-6549; 2365-6549
• DOI: 10.1002/slct.201800962

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. Hybrid materials of graphitic carbon nitride (g‐C3N4) containing small amounts (up to 1.00 wt.%) of reduced graphene oxide (rGO) were successfully used as photocatalysts for the synthesis of benzaldehyde (BAL) from benzyl alcohol (BA), with simultaneous production of H2, under both UV and visible light irradiation. The introduction of rGO reduces the recombination of electron and holes, increasing the efficiency of the photocatalytic process.