The development of versatile strategies for surface functionalization of electrodes and catalyst immobilization in photoelectrochemical water-splitting cells is crucial for the advancement of sustainable energy storage systems. A common approach for immobilizing molecular water-oxidation catalysts to electrodes is by incorporating functional groups such carboxylic acid or phosphonates into the ligand anchored catalyst. Challenges due to surface desorption and difficulty in synthetic catalyst derivatizations has limited the scope of surface-bound molecular water-oxidation catalysts. In this work, surface modification of argon-plasma fluorine tin oxide (FTO) films via UV-induced graft polymerization with acrylic acid (AAc) was carried out. The modified FTO electrode was constructed as a robust platform for the immobilization of "underivatized" molecular water-oxidation catalysts (WOCs). The metal-based water oxidation catalyst attachment procedure exploits binding to the negatively charged carboxylate groups of the UV-induced cross-linked PAA brushes. Successful immobilization is characterized via electrochemical studies and surface techniques such as X-ray fluorescence, SEM, UV-visible absorptions spectroscopy and water-contact angle measurements. Detailed studies involving surface stability, redox properties, proton-coupled-electron transfer (PCET) and water-oxidation catalysis will be further described.

Versatile strategy for wiring water-oxidation catalysts on UV-induced graft polymerized acrylic acid (AAc) onto FTO anodes

ACS Spring 2022

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