Conditioning of Platinum Nanoparticle Catalysts for Improved Hydrogen Generation on P3HT:PCBM Bulk Heterojunction Photocathodes
1 online resource (83 pages) : PDF
University of North Carolina at Charlotte
This work aims to design, develop, and investigate the capacity of a metal catalyst-coated organic photoelectrode to produce molecular hydrogen when illuminated in acidic media. 3-5 nm platinum nanoparticles (PtNPs) were synthesized, treated to remove bound surface ligands and subsequently found to function as improved catalysts for the hydrogen evolution reaction (HER). Thermal processing of the catalyst was the most successful removal method. The exchange current density decreased only slightly while the Tafel slope decreased considerably from 74.1 ± 1.0 mV dec-1 to 41.5 ± 1.1 mV dec-1 following heat treatment at 200 oC. The low Tafel slope indicates that catalysis on the NP surface proceeds by a Vollmer-Heyrovsky Mechanism. An attempt was made to utilize the characterized PtNPs as embedded electrocatalysts on a bulk heterojunction (BHJ) blend of poly(3-hexylthiophene): [6,6]-phenyl C61-butyric acid methyl ester (P3HT:PCBM). In solution, the bare (no catalyst) BHJ photoelectrode showed good light response, achieving an open circuit voltage of 414 mV and short-circuit current density of 0.013 mA cm-2, resulting in an overall solar-to-hydrogen efficiency of 0.016%. However, the catalyst-sensitized BHJ appeared to function only as a dark catalyst, demonstrating almost no response to light. While further investigations are needed, we believe steps must ultimately be taken to prevent direct touching of the platinum nanoparticle layer with the organic film while maintaining electrical contact across the semiconductor, catalyst, and solution interfaces.
Donovan-Merkert, BernadettePoler, JordanZhang, HaiTao
Thesis (M.S.)--University of North Carolina at Charlotte, 2015.
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