Interfacial engineering of a magnetic zein-modified ZIF-67 metal-organic framework hybrid nanocomposite for photocatalytic dehydrogenation of formic acid

The development of multifunctional catalysts with well-defined surface and interfacial properties is crucial for efficient light-assisted hydrogen generation from liquid hydrogen carriers. Herein, a magnetic hybrid nanocomposite consisting of zein–modified Fe₃O nanoparticles decorated onto the surface of ZIF-67 was rationally designed as a support for the immobilization of Au3+Pd2+ species for the photocatalytic dehydrogenation of formic acid (FA). The zein biopolymer acts as a bio-derived interfacial modifier, improving surface dispersion and interfacial compatibility between Fe₃O₄ and ZIF-67, while preserving the porosity of the MOF framework. Au3+Pd2+ species are introduced in their ionic form and confined within the porous structure via an impregnation strategy, avoiding the use of external chemical reducing agents. The resulting composite exhibits enhanced photocatalytic activity toward FA dehydrogenation under light irradiation with a TOF value of 536 h⁻¹. The improved performance was attributed to the synergistic interfacial interactions among the Au³⁺Pd²⁺ active sites, the ZIF-67 framework, and the zein-modified magnetic support, which promoted visible-light absorption and interfacial charge transfer. Furthermore, scavenger experiments revealed that photogenerated holes (h⁺) are the dominant active species involved in the photocatalytic hydrogen generation process. In addition, the magnetic nature of the catalyst enabled facile recovery and reuse, demonstrating the potential of this interfacial engineering strategy for the development of sustainable and efficient photocatalytic systems for hydrogen production from formic acid.