Plasmon photothermal-promoted solar photocatalytic hydrogen production over a CoCr2O4/g-C3N4 heterojunction

Abstract

It is an effective method to promote the activity of photocatalysts by exploiting their own photothermal effects to increase the temperature of the reaction center and thus accelerate the kinetic process of photocatalysis. In this study, for the first time, a CoCr₂O₄/g-C₃N₄ composite photocatalyst is designed through the construction of CoCr₂O₄ nanoparticles decorated tremella-like porous g-C₃N₄. On the one hand, the type-II heterostructure can be formed and effectively improves the separation efficiency of photogenerated carriers. On the other hand, the photothermal effect of plasmonic CoCr₂O₄ nanoparticles can significantly increase the temperature of the reaction system, thereby enhancing the photocatalytic efficiency. CoCr₂O₄ nanoparticles exhibit a broad-band strong absorption in the near-infrared region. Under full spectrum illumination for 300 s, their surface temperature can be increased by 113 °C, demonstrating excellent photothermal properties. Although the bare CoCr₂O₄ nanoparticle sample does not show the photocatalytic activity of water splitting for hydrogen evolution, the optimized g-C₃N₄/CoCr₂O₄ heterostructure composite exhibits an average hydrogen production rate as high as 1525.1 μmol g⁻¹ h⁻¹ under UV-Vis-IR illumination, which is 4.0 and 5.8 times higher than that of bare g-C₃N₄ under UV-Vis-IR and UV-Vis light illumination, respectively. This work provides a new guide for designing novel photothermal-assisted photocatalytic composite materials.