Highly selective production of hydrogen peroxide on graphitic carbon nitride (g-C3N4) photocatalyst activated by visible light

Article abstract of DOI:10.1021/cs401208c

Photocatalytic production of hydrogen peroxide (H₂O₂) on semiconductor catalysts with alcohol as a hydrogen source and molecular oxygen (O₂) as an oxygen source is a potential method for safe H ₂O₂ synthesis because the reaction can be carried out without the use of explosive H₂/O₂ mixed gases. Early reported photocatalytic systems, however, produce H₂O₂ with significantly low selectivity (～1%). We found that visible light irradiation (λ > 420 nm) of graphitic carbon nitride (g-C ₃N₄), a polymeric semiconductor, in an alcohol/water mixture with O₂ efficiently produces H₂O₂ with very high selectivity (～90%). Raman spectroscopy and electron spin resonance analysis revealed that the high H₂O₂ selectivity is due to the efficient formation of 1,4-endoperoxide species on the g-C ₃N₄ surface. This suppresses one-electron reduction of O₂ (superoxide radical formation), resulting in selective promotion of two-electron reduction of O₂ (H₂O₂ formation).