Promoting Visible Light Generation of Hydrogen Using a Sol-Gel-Prepared MnCo2O4@g-C3N4p-n Heterojunction Photocatalyst

Abstract

The production of hydrogen using a new type of heterogeneous photocatalyst under visible light is considered a remarkable essential pathway for sustainable, pure energy not only on the laboratory scale but also on a bigger scale. Hence, a new nanocomposite of mesoporous MnCo2O4, g-C3N4, and MnCo2O4@g-C3N4 was produced utilizing a sol-gel method with variable MnCo2O4 contents. The crystal structure of MnCo2O4 was effectively confirmed by the X-ray diffraction pattern and integrated onto the g-C3N4 structure. The MnCo2O4 nanoparticles were displayed as spherical particles by TEM images and dispersed in a uniform way inside the g-C3N4 nanosheet. The synthesized nanocomposites in the form of MnCo2O4@g-C3N4 were examined as a new effective photocatalyst against glycerol as a source for H2 production with visible light. The MnCo2O4 contents indicated a corroborative impact for the photocatalytic action related to the H2 production process. A maximum H2 production molecular value was observed (21,870 μmol·g-1·h-1) for a 1.5 wt % MnCo2O4@g-C3N4 nanocomposite as a considerable increase in its photocatalytic activity. The yields of H2 are ∼55 and 23 times higher than those of g-C3N4 and MnCo2O4, respectively. Up to five times cycles of visible lighting were the maximum number of repeated cycles by which the 1.5 wt % MnCo2O4@g-C3N4 product showed higher stability and durability.