Quantum dot/reduced graphene oxide (QD/rGO) hybrid photocatalysts offer a promising route to efficient, clean hydrogen production. However, the multi-step, high temperature, solvent-based syntheses typically utilized to prepare these photocatalysts can limit their scalability and sustainability. We have developed a single-enzyme, aqueous-based biomineralization route capable of producing size-controlled nanocrystalline CdS QDs centered on the enzyme-mediated turnover of L-cysteine to H2S in aqueous solutions of Cd-acetate. This same enzyme is active for the reduction of graphene oxide to rGO. These biomineralized components are then linked through a facile and efficient ligand exchange to form a highly active composite photocatalyst that is produced entirely in an aqueous environment at ambient temperature. The native L-cysteine ligand on CdS is efficiently replaced by cysteamine (CA) through a pH-controlled ligand exchange process and is confirmed by zeta potential measurements and ATR-FTIR spectroscopy. Assembly of the CA-capped CdS (CdS/CA) onto rGO was driven by electrostatic interactions between the positively charged surface of CdS/CA and the negatively charged rGO, as confirmed by UV-vis spectroscopy and HAADF-STEM imaging. The visible light hydrogen evolution rate of the resulting biomineralized CdS/CA/rGO photocatalyst is among of the highest reported (3300 μmol hr-1 g-1) for any CdS/rGO nanocomposite photocatalyst, irrespective of synthesis route. The combined green biomineralization and ligand exchange strategy offers a potentially generalizable approach to efficient synthesis of complex nanocomposite photocatalysts that offer performance comparable to, or beyond, those synthesized by typical chemical routes.

High performance, fully biomineralized CdS/rGO composite photocatalysts for hydrogen evolution

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.