Photocathode chromophore-catalyst assembly via layer-by-layer deposition of a low band-gap isoindigo conjugated polyelectrolyte

• Main Authors: Leem, Gyu, Black, Hayden T., Shan, Bing, Bantang, Jose Paolo O., Meyer, Thomas J., Reynolds, John R., Schanze, Kirk S.
• Format: text
• Published: Animo Repository 2018
• Subjects: Polyelectrolytes; Photocathodes; Hydrogen evolution reaction; Polymerization; Solar energy; Chemistry
• Online Access: https://animorepository.dlsu.edu.ph/faculty_research/2965
• Institution: De La Salle University

Low band-gap conjugated polyelectrolytes (CPEs) can serve as efficient chromophores for use on photoelectrodes for dye-sensitized photoelectrochemical cells. Herein is reported a novel CPE based on poly(isoindigo-co-thiophene) with pendant sodium butylsulfonate groups (PiIT) and its use in construction of layer-by-layer (LbL) chromophore-catalyst assemblies with a Pt-based H+ reduction catalyst (PAA-Pt) for water reduction. A novel Stille polymerization/postpolymerization ion-exchange strategy was used to convert an organic-soluble CPE to the water-soluble poly(isoindigo-co-thiophene). The anionic PiIT polyelectrolyte- and polyacrylate-stabilized Pt-nanoparticles (PAA-Pt) were codeposited with cationic poly(diallyldimethylammonium) chloride (PDDA) onto inverse opal (IO), nanostructured indium tin oxide film (nITO) (IO nITO) atop fluorine doped tin oxide (FTO), by using LbL self-assembly. To evaluate the performance of novel conjugated PiIT//PAA-Pt chromphore-catalyst assemblies, interassembly hole transfer was investigated by photocurrent density measurements on FTO//IO nITO electrodes. Enhanced cathodic photocurrent is observed for the polychromophore-catalyst assemblies, compared to electrodes modified with only PiIT, pointing toward photoinduced hole transfer from the excited PilT to the IO nITO. Prolonged photoelectrolysis experiments reveal H2 production with a Faradaic yield of approximately 45%. This work provides new routes to carry out visible-light-driven water reduction using photocathode assemblies based on low band-gap CPEs. Copyright © 2018 American Chemical Society.