Co-phthalocyanine/Graphene Quantum Dots/TiO2 as a New Hybrid for Photocatalytic Degradation of Formic Acid Toward Hydrogen Generation

Hydrogen has been considered as one of the worthy fuels for the high potential energy and nonpolluting combustion. With increasing the concerns about fossil fuels pollution for the environment, attempts have been concentrated on the improving of new green fuels such as hydrogen. Particularly, the safe and cost-effective production of hydrogen has been widely studied, in which the catalysts deserved remarkable progresses. Herein, photocatalytic activity of cobalt-phthalocyanine/graphene quantum dots/TiO2 was investigated in the formic acid degradation under visible irradiation toward hydrogen generation. TiO2 as a semiconductor trapped photons to generate electron/hole pairs and graphene quantum dots made delay in their recombination to provide long time for promoting the hydrogen and carbon dioxide evolution reactions by electrons/holes. Cobalt (II)-phthalocyanine as a catalyst utilized the electrons in the transformation of protons to H2, while in the positive region carbon dioxide was producing. The reaction was progressed efficiently affording H2 with the rate of 3.60 mmol.h-1 and activation energy was calculated to be 16 KJ.mol-1. This three-component catalyst showed satisfying stability to run the reaction for long time. Notable catalytic activity, and employing light power for the reaction done are two significant characteristics of this hybrid.