Gram-Level Production of Atomic-Scale and Photoresponsive Two-Dimensional Self-Folded Monolayer Polymeric Sheets

Self-folding 1D polymers into atomic-scale and stimuli-responsive 2D polymeric nanomaterials with a scalable production and tailored functions offers an unprecedented and challenging strategy for the construction of innovative free-standing sub-1 nm 2D materials for heterogeneous catalysis. Herein, self-folded monolayer polymeric sheets (SFMPSs) with a thickness of 7.2 ± 2.2 Å and a lateral size of several hundreds of μm² are produced in a grams-level using the solution self-assembly of alternating azocopolymers, exemplifying the thinnest 2D self-assembled polymeric materials. A phototriggered reversible structural transformation from 2D SFMPSs to spherical micelles (SMs, ∼32 nm) is rendered by the photoisomerization of azobenzene units. A series of SFMPS-based single-atom catalysts (SACs) is yielded using the coordination interaction between Pt ions and distinct nitrogenous ligands. The resulting photocontrollable electrocatalytic activity highly depends on the presence of the Pt element, structural characteristics of supports, and metal–support interaction. Among them, Pt-based hybrid SACs using porphyrin-modified SFMPSs as support display a favorable electrocatalytic capacity with an overpotential of ∼22 mV at a current density of 10 mA cm^–2, whose mass activity is ∼159 times larger than commercial Pt/C catalysts. Our work proposes a significant approach to fabricating a scalable production of atomic-scale 2D macromolecular materials with controllable HER catalytic performance.