Graphene quantum dots as a green sensitizer for ZnO nanorod based photoanodes

Photoelectrochemical properties of ZnO nanorods have been widely investigated due to low cost, easy synthesis process and high carrier mobility. However, weak photoabsorption in visible region is the major bottleneck of ZnO for solar cell applications. To improve the photoelectrochemical behavior, it is necessary to sensitize ZnO nanorods with semiconductor quantum dots or nanoparticles. To enhance the photoresponse and photoelectrochemical behaviors graphene quantum dots (GQDs) have been utilized as green sensitizer with ZnO nanorods. GQD sensitized ZnO nanorods (GQD/ZnO) demonstrated superior photoconversion efficiency and incident photon to current conversion efficiency (IPCE) compare to pristine ZnO nanorods. GQD sensitized nanorods exhibited better photoelectrochemical properties than pristine ZnO nanorods due to higher photoabsorption and lower interfacial resistance.