Streptavidin activated hydroxyl radicals enhanced photocatalytic and photoelectrochemical properties of membrane-bound like CaMoO₄:Eu³⁺ hybrid structures

Recently, organic-inorganic hybrid structures have gained significant interest and are considered as an innovative alternative for the development of multifunctional materials. Herein, we report highly reliable and reproducible protein-inorganic hybrid CaMoO₄:Eu³⁺ microstructures as a novel photocatalyst for decontamination of environments using an energy-efficient and cost-effective green synthesis. In this synthesis process, streptavidin (SA) serves as an organic scaffold and builds covalent bonds with the amine groups of the CaMoO₄:Eu³⁺ surface, which leads to the formation of membrane-bound-like structures. Because of the well overlapped absorption bands of tyrosine residues and CaMoO₄:Eu³⁺, SA acts as a sensitizer and transfers more UV energy to the MoO₄ moieties of CaMoO₄:Eu³⁺, resulting in an enhanced emission intensity along with a blue shifted absorption spectrum. Compared to the commercial TiO₂, the CaMoO₄:Eu³⁺ host and SA modified CaMoO₄:Eu³⁺ microstructures exhibit 145 and 207% higher dye removal efficiencies for methylene blue, signifying their light absorption efficiency and higher number of surface-active sites. After hybridization with SA, the CaMoO₄:Eu³⁺ sample offers more photo-generated electrons to improve the photocatalytic activity along with an enhanced photocurrent density of 0.72 μA cm^-2, which is about 1.5 times higher than that of the CaMoO₄:Eu³⁺ host. Moreover, the SA modified CaMoO₄:Eu³⁺ sample displayed excellent photocatalytic stability after 6 reusability cycles. Our synthesis strategy for protein-inorganic hybrid CaMoO₄:Eu³⁺ opens a new avenue for the production of cutting-edge materials for industrial-scale catalysis and solid-state lighting applications.