Photosensitization of CdS by acid red-94 modified alginate: Dual ameliorative effect upon photocatalytic hydrogen evolution

Photosensitization is a potential candidate for improving photocatalytic performance of inorganic semiconductors in water splitting. Given many photosensitizers are organic dyes bearing strong hydrophobicity, simple combination of dye and inorganic material, however, still suffers limited access of the photocatalyst to water and consequently presents compromised activity. Herein, we exploited aminated acid red-94 (RB-NH2) to prepare dye chemically modified alginate (RB-NH-HA) via dialysis method, which was further employed to incorporate with CdS (RB-NH-HA@CdS). According to the water contact angles (CA(water)) and photoelectrochemical detection, though simply integrated CdS with RB-NH2 (RB-NH2@CdS) expectantly enhanced the transient photocurrent over CdS, yet the CA(water) was apparently emaciated from 53.56 degrees to 86.12 degrees, even leading to a slightly attenuated photocatalytic performance in hydrogen evolution under visible light. In contrast, introducing hydrophilic HA into RB-NH-HA@CdS is able to reclaim the CA(water) to 50.22 degrees. Moreover, owning to the cooperative effects proffered by the significantly increased contacts between the reactant (H2O) and the composite, as well as the fluorescent feature that improves the photocatalysts visible-light absorption and simultaneously suppresses the recombination of photo-induced carriers, the hydrogen production rate was advanced to 475 mu mol.h(-1) H-2, about 4.5 and 5.7 times that of CdS and RB-NH2@CdS, respectively. Our work provides an efficient method to ameliorate the sensitization technique aiming to improve the photocatalytic performance of inorganic semiconductors.