Considering photocatalytic activity of Cu2+/biochar-doped TiO2 using corn straw as sacrificial agent in water decomposition to hydrogen

In this paper, a simple one-pot thermal synthesis method was used to successfully prepare Cu2+/biochar-doped TiO2 composite catalytic materials. The photocatalytic hydrogen production performance of the composites under different environmental conditions (dark, solar, and visible light irradiation) was analyzed in a biomass photocatalytic system using a corn straw suspension as a sacrificial agent. The Cu2+/biochar-doped TiO2 materials were characterized by SEM, TEM, XRD, FT-IR, XPS, and UV analysis. The photoelectric properties of the Cu2+/biochar-doped TiO2 composites were also analyzed, and the charge separation mechanism of photogenerated carriers under different environmental conditions was investigated. Compared with pure TiO2, the hydrogen production rate of Cu2+/biochar-doped TiO2 is 23.6 times higher under visible light irradiation and 16.8 times higher under simulated solar irradiation. Using density functional theory, a crystal structure model of Cu2+/biochar-doped TiO2 was established to analyze its energy band structure and density of states. An analysis of the mechanism shows that under simulated sunlight irradiation, the synergistic effect of the TiO2 doped with Cu2+ and biochar causes the formation of a potential Schottky heterojunction on the surface and induces interfacial charge transfer. Furthermore, under visible light irradiation, the photocatalytic production of hydrogen by the Cu2+/biochar-doped TiO2 composite is mainly due to the surface plasmon resonance mechanism of Cu ion-doped TiO2.