Success and failure in the incorporation of gold nanoparticles inside ferri/ferrocyanide thermogalvanic cells

• Published in: Electrochemistry communications 2019-05, Vol.102, p.41-45
• Main Authors: Alzahrani, Hassan A.H., Buckingham, Mark A., Marken, Frank, Aldous, Leigh
• Format: Article
• Language: English
• Subjects: Gold nanoparticles; Thermoelectrochemistry; Thermogalvanic cells
• ISSN: 1388-2481; 1873-1902
• DOI: 10.1016/j.elecom.2019.03.007

Thermogalvanic systems represent a means to convert a temperature gradient into electricity, using only redox chemistry. However, the kinetics of electron transfer and physical mass transport of the redox couples are known limitations. In this study we present self-contained gelled thermogalvanic cells (or thermocells) containing the ferricyanide/ferrocyanide redox couple, which additionally have gold nanoparticles either immobilised at the gel/electrode interface, or distributed throughout the entire gel. Both methods of introducing the gold nanoparticles result in an apparent electrocatalytic improvement, as demonstrated by significant decreases in the electron transfer resistance. However, when used as thermogalvanic cells, only minor improvements were observed in power generation, and relatively rapid dissolution of the gold nanoparticles was observed, to yield passivating gold analogues of Prussian blue. Therefore successful preparation and short-term improvements have been demonstrated, but are offset by long-term stability issues. The relatively surprising instability of the generally inert gold nanoparticles in the presence of ferricyanide/ferrocyanide, particularly under thermogalvanic conditions, is of particular note. •Gold nanoparticles (AuNP) prepared at and in gelled thermogalvanic cells•AuNP result in electrocatalytic improvement in kinetics of [FeCN6]3−/4− redox process•However, overall improvements in thermogalvanic power produced were minor.•Poor results due to (thermogalvanic) corrosion of AuNP observed over time.