Ultrathin Metal-Organic Framework Nanosheets with Ultrahigh Loading of Single Pt Atoms for Efficient Visible-Light-Driven Photocatalytic H₂ Evolution

A surfactant-stabilized coordination strategy is used to make two-dimensional (2D) single-atom catalysts (SACs) with an ultrahigh Pt loading of 12.0 wt %, by assembly of pre-formed single Pt atom coordinated porphyrin precursors into free-standing metal-organic framework (MOF) nanosheets with an ultrathin thickness of 2.4±0.9 nm. This is the first example of 2D MOF-based SACs. Remarkably, the 2D SACs exhibit a record-high photocatalytic H₂ evolution rate of 11 320 μmol g^-1 h^-1 via water splitting under visible light irradiation (λ>420 nm) compared with those of reported MOF-based photocatalysts. Moreover, the MOF nanosheets can be readily drop-casted onto solid substrates, forming thin films while still retaining their photocatalytic activity, which is highly desirable for practical solar H₂ production.