Core/Shell PDA@UiO-66 Metal–Organic Framework Nanoparticles for Efficient Visible-Light Photodegradation of Organic Dyes

In this study, bio-inspired polydopamine nanoparticles (PDA NPs) were utilized as a starting template to fabricate a well-defined zirconium-based MOF (UiO-66, PDA@MOF) core/shell heteronanostructures for visible light-emitting diode (LED) light-assisted photocatalytic applications. The selected PDA substrate provided a multifunctional starting platform for one-pot nucleation growth of metal–organic frameworks (MOF) shell layer with regular spherical morphologies (∼350 nm in size), as well as monodisperse size distribution. The obtained band properties of PDA@MOF (ECB = −1.10 eV and EVB = 1.85 eV vs normal hydrogen electrode (NHE)) revealed that the synthesized nanostructures could promote the reduction of oxygen to superoxide anions (O2•–) and the formation of HO• for effective visible LED-light-irradiated photocatalytic degradation of MB. To accelerate the photocatalytic decolorization of MB, an electron acceptor (i.e., H2O2) was utilized, which effectively surpassed the electron–hole recombination by trapping electron and producing more hydroxyl radicals. Therefore, a remarkable photocatalytic performance was recorded using PDA@MOF, in which ∼99% of MB was decolorized within 80 min under visible LED light illumination thanks to the well-defined core/shell structure, high surface area, convenient band gap, effective molecular sieving due to the regular/identifiable morphology, as well as good dispersity in reaction medium. Owing to the advantages of PDA@MOF nanoparticles, the photoelectrochemical (PEC) water splitting performance with highest photocurrent density was obtained as 1.53 mA/cm2 at low potential 0.28 V vs RHE under visible LED illumination, which is ∼20-fold higher than dark conditions (0.07 mA/cm2). This study mainly highlighted the great potential of MOF-based core/shell nanostructures with uniform/regular morphologies as a next generation of visible-light-responsive catalysts for various environmental applications.