Direct Z-scheme polymeric heterojunction boosts photocatalytic hydrogen production via a rebuilt extended pi-delocalized network

Carrier recombination involved in polymeric photocatalysts includes undissociated exciton decay and charge recombination, which are the major hindrance limiting their photocatalytic activities. Realizing highly efficient charge generation and separation simultaneously in one polymeric system is therefore a fundamental strategy for the potential success of solar-to-hydrogen conversion but remains a great challenge. Here, we develop a large pi-delocalized direct Z-scheme polymeric heterostructure (g-C3N4/P1Cl-T) that synergistically integrates a two-dimensional (2D) donor-acceptor conjugated polymer (P1Cl-T) with g-C3N4. We demonstrate that the intermolecular pi-pi stacking successfully rebuilds the extended pi-network over the whole polymeric heterojunction, thus facilitating full-visible-light absorption, exciton dissociation and charge transport. The combination of spectroscopic analysis and theoretical calculations reveals that both resonance energy transfer and Z-scheme charge transfer occur upon light illumination. With the intense synergy among the large pi-delocalization, pi-pi stacking interactions and internal electric field, the g-C3N4/P1Cl-T photocatalyst shows an unprecedentedly high hydrogen evolution rate of similar to 111.8 mmol h(-1) g(-1) with apparent quantum yields (AQYs) of 46.75% at 475 nm and 1.77% at 700 nm, which is about 48-fold higher than that of pristine g-C3N4 and tops those for all the previously reported polymer-based photocatalysts.

Automated summary

In this study, a large pi-delocalized direct Z-scheme polymeric heterostructure is developed, which successfully achieves enhanced full-visible-light absorption, exciton dissociation, and photocatalytic activity.