Graphene-supported CoS2 particles: an efficient photocatalyst for selective hydrogenation of nitroaromatics in visible light

Abstract

CoS₂/graphene composites fabricated by a facile hydrothermal method exhibit excellent photocatalytic performance for selective hydrogenation of nitroaromatics to the corresponding aniline employing molecular hydrogen as a reducing agent under visible light irradiation (400–800 nm). The rate constant of the composite catalyst for nitrobenzene hydrogenation can achieve as high as 35.50 × 10⁻³ min⁻¹ with a selectivity of 100% toward the target product under mild conditions (30 °C and 0.25 MPa pressure of H₂). The catalyst also shows high recyclability, and there is no decrease in the catalytic activity after five successive cycles. There exists a synergistic effect between the graphene support and the CoS₂ particles: conductive graphene as the support can rapidly extract the photoexcited electrons and effectively suppress the recombination of photogenerated charges in CoS₂ particles, and then improve the photocatalytic performance. The photocatalytic reduction of nitrobenzene over the CoS₂/graphene catalyst to aniline occurs through the direct pathway in the presence of H₂.