Templated 2D Polymer Heterojunctions for Improved Photocatalytic Hydrogen Production.

2D polymers have emerged as one of the most promising classes of organic photocatalysts for solar fuels production due to their tunability, charge transport properties and robustness. They are however difficult to process and so there have been limited studies into the formation of heterojunction materials incorporating these components. In this work w e use a novel templating approach to combine an imine-based donor polymer and an acceptor polymer formed through Knoevenagel condensation. Heterojunction formation is shown to be highly dependent on the topological match of the donor and acceptor polymers with the most active templated material found to be between 3 and 9 times more active for photocatalysis than its constituent components. Transient absorption spectroscopy reveals that this improvement is due to faster charge separation and more efficient charge extraction in the templated heterojunction. The templated material shows a very high hydrogen evolution rate of more than 20 mmol h -1 m -2 with an ascorbic acid hole scavenger but also produces hydrogen in the presence of only water and a cobalt based redox mediator. This suggested the improved charge separation interface and reduced trapping accessed through this approach could be suitable for Z-scheme formation. This article is protected by copyright. All rights reserved.