Conditioning of Platinum Nanoparticle Catalysts for Improved Hydrogen Generation on P3HT:PCBM Bulk Heterojunction Photocathodes

1 online resource (83 pages) : PDF

2015

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.

masters theses

Chemistry
Environmental engineering
Renewable energy sources

M.S.

Catalysis
Electrolysis
Hydrogen
Organic
Photoactive
Solar

Chemistry

Walter, Michael

Donovan-Merkert, Bernadette
Poler, Jordan
Zhang, HaiTao

Thesis (M.S.)--University of North Carolina at Charlotte, 2015.

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Ivins_uncc_0694N_10926

http://hdl.handle.net/20.500.13093/etd:941