Activating Montmorillonite for Light-Driven Hydrogen Evolution with the Coupling of Fe Species

Abstract

Montmorillonite (MMT), a layered hydrated aluminum silicate mineral, emerges as a promising catalyst support due to its substantial specific surface, ion storage capacity, thermal stability, and cost-effectiveness. Despite the success of MMT-based photocatalysts in degrading compounds, their potential for the photocatalytic hydrogen evolution reaction (HER) is underexplored. Furthermore, the reliance on noble metals and dye sensitization in MMT-based photocatalysts leads to elevated costs. This study introduces an MMT-based photocatalyst modified with Fe species (denoted as Fe@MMT) for photocatalytic HER without the reliance on noble metals and dye sensitization. The incorporation of Fe species has a dual impact, expanding the light harvesting region of MMT and modulating the aluminum-silicate framework. Simultaneously, it facilitates the exfoliation of individual sheets from stacked MMT layers, generating abundant active sites and inner electronic fields that can promote the separation of photoexcited electrons and enhance the photon-to-electron conversion. In comparison to pristine MMT, Fe@MMT exhibits a 43% reduction in the charge transfer resistance in the dark and a 52% reduction under illumination. Additionally, the majority carrier density within the space charge region increased by 33%. Due to these advantages, the photocatalytic HER efficiency over Fe@MMT was improved, approximately 2.9 times that of pristine MMT.