Sculpting In‐plane Fractal Porous Patterns in Two‐Dimensional MOF Nanocrystals for Photoelectrocatalytic CO2 Reduction

Abstract Herein, by choosing few‐nm‐thin two‐dimensional (2D) nanocrystals of MOF‐5 containing in‐planner square lattices as a modular platform, a crystal lattice‐guided wet‐chemical etching has been rationally accomplished. As a result, two attractive pore patterns carrying Euclidean curvatures; precisely, plus(+)‐shaped and fractal‐patterned pores via ⟨100⟩ and ⟨110⟩ directional etching, respectively, are regulated in contrast to habitually formed spherical‐shaped random etches on MOF surface. In agreement with the theoretical calculations, a diffusion‐limited etching process has been optimized to devise high‐yield of size‐tunable fractal‐pores on the MOF surface that tenders for a compatibly high payload of catalytic ReI‐complexes using the existing large edge area once modified into a free amine‐group‐exposed inner pore surface. Finally, on benefiting from the long‐range fractal opening in 2D MOF support structure, while loaded on an electrode surface, a facilitated cross‐interface charge‐transportation and well‐exposure of immobilized ReI‐catalysts are anticipated, thus realizing enhanced activity and stability of the supported catalyst in photoelectrochemical CO2‐to‐CO reduction.