Amphiphilic block copolymer poly (isoprene-b-acrylic acid) (PI-b-PAA) stabilized exfoliated graphene in water and allowed the immobilization of semiconductor CdS nanoparticles forming CdS•PI-b-PAA/graphene. Characterization with HR-TEM and EDX justified the success of preparation and revealed the presence of spherical CdS. Moreover, UV-Vis and photoluminescence assays suggested that electronic interactions within CdS•PI-b-PAA/graphene exist as evidenced by the significant quenching of the characteristic emission of CdS by exfoliated graphene. Photoillumination of CdS•PI-b-PAA/graphene, in the presence of ammonium formate as quencher for the photogenerated holes, resulted on the generation of hydrogen by water splitting, monitored by the reduction of 4-nitroaniline to benzene-1,4-diamine (> 80±4% at 20 min; 100% at 24 min), much faster and efficient as compared when reference CdS•PI-b-PAA was used as photocatalyst (< 30±3% at 20 min; 100% at 240 min). Moreover, Rhodamine B was photocatalytically degraded by CdS•PI-b-PAA/graphene, with fast kinetics under visible light illumination in the presence of air. The enhancement of both photocatalytic processes by CdS•PI-b-PAA/graphene was rationalized in terms of effective separation of holes–electrons, contrary to reference CdS•PI-b-PAA, in which rapid recombination of the hole–electron pair is inevitable due to the absence of exfoliated graphene as suitable electron acceptor.
