Enhanced photocatalytic degradation properties of a g-C₃N₄/BiVO₄ heterostructure system induced by surface and interface heterojunctions

The construction of semiconductor heterojunctions had been proven a promising strategy for improving the efficiency of photo-induced charge separation, maximizing the utilization of spectral energy, and improving redox activity for efficient environmental treatment. In this work, the PCN/BiVO₄ composites were constructed by coupling nano-layered g-C₃N₄(PCN) with co-exposed {010} and {110} planes of BiVO₄ crystals. Morphology analysis demonstrated that PCN tightly wrapped around the co-exposed {010} and {110} planes of BiVO₄ crystals. The FTIR and XPS analysis confirmed that there was interfacial interaction between PCN and BiVO₄. The PCN/BiVO₄ composites exhibited enhanced photocatalytic degradation properties for methylene blue dyes as compared to pristine PCN and BiVO₄, which was attributable to the surface and interface heterojunctions, effectively suppressing the recombination of photogenerated electro-holes pairs. Moreover, the 10-PCN/BiVO₄ composite exhibited the most efficient MB degradation removal rate and the reaction constant rate was 0.0412 min⁻¹, which reached 3.62 and 2.08 times higher than that of pure PCN and BiVO₄, respectively. EIS, i-t and PL measurements demonstrated that the 10-PCN/BiVO₄ composite presented the smallest interfacial charge-transfer resistance and extraordinary photogenerated charge separation efficiency. The present study indicated that the synergistic effect of surface heterojunction of BiVO₄ crystals and interface heterojunction between PCN and BiVO₄ was conducive to facilitating the migration and separation of photogenerated charges, thus improving the photocatalytic degradation activity.