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

Abstract

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.