A hierarchical heterojunction polymer aerogel for accelerating charge transfer and separation

Abstract

A hierarchical heterojunction polymer aerogel (HPA) composed of a oxygen- and nitrogen-linked heptazine-based polymer was rationally designed as a donor–acceptor (D–A) light harvester by a facile two-step self-assembly method. The HPA features a three-dimensional (3D) continuous network of 1D holey microfibers assembled from 2D nanomesh. The collaborative engineering of the D–A homojunction and 3D hierarchical open-pore nanoarchitecture in HPA causes a narrowed bandgap, improved hydrophilicity, and dramatically increased charge transfer and separation, and therefore the synthesis of sub-1 nm ultrafine Pt cocatalysts associated with countless bonding sites. It exhibits a high H₂ evolution rate of 103.79 μmol h⁻¹ (12 times higher than that of the conventional g-C₃N₄ powder), and an excellent internal quantum yield of 29.4% at 400 nm, much higher than those of most of the aerogel-based photocatalysts reported.