Abstract: Solar fuel generation can provide a method of stable energy storage. Homogeneous photocatalysis systems benefit from rapid diffusion but are limited by poor long-term stability. Meanwhile, the efficacy of heterogeneous photocatalysis systems can be limited by mass-transfer and light-penetration. Hydrogels provide a means of bridging the gap between these two systems, providing a solid scaffold to immobilize photocatalysis components while providing diffusivity approaching the solution state. Self-assembling chromophore amphiphiles like perylene monoimide have been used to create photoactive hydrogel scaffolds, although with limited control over macroscopic morphology.

In this work, we have used common polymer systems like sodium alginate and polyacrylamides to simultaneously assemble and entrap chromophore amphiphiles in a robust, reusable scaffold. We were able to easily alter the morphology of the gels at multiple length scales to explore the role of diffusion in these materials. Then, utilizing the high-aspect ratio of the chromophore assemblies, we could create electrically conductive percolation networks that enabled us to develop 3-dimensional hydrogel photocathodes with active surface area beyond the microscale.