Efficient hydrogen generation by ZnAl2O4 nanoparticles embedded on a flexible graphene composite

Abstract This work reports the hydrogen generation properties of ZnAl2O4 (ZAO) powders synthesized by a combustion method, which produced carbon dots (C-dots) on the ZAO surface. These ZAO nanoparticles decorated with C-dots were incorporated into a polyacrylate matrix to form a photocatalytic membrane (named PAZO), which was subsequently attached to a flexible graphene composite (FGC) to form a FGC/PAZO (GAZO) composite. The morphological analysis by scanning electron microscopy shows embedded ZAO nanoparticles with sizes of 20–90 nm into the polymeric matrix. In addition, hydrogen generation rates of 260, 4640 and 1580 μmol g−1 h−1 were obtained for different ZAO powders annealed at 600, 700, and 800 °C, respectively. Moreover, the PAZO membrane and the GAZO composite produced hydrogen generation rates of 560 and 2860 μmol g−1 h−1, respectively. Although the GAZO composite had a lower hydrogen generation rate (≈38% less) than the best ZAO powder (annealed at 700 °C), the GAZO composite could be attached easily in the inner wall of photocatalytic reactors which facilitates its removal after hydrogen production, this advantage is not possible by using photocatalytic powders. Therefore, the GAZO composites, presented here, could be a feasible option for hydrogen generation when attached to the inner walls of photoreactors.