Mauro Malizia1 Hermenegildo Baldovi1 Kaiqi Hu2 Stuart Scott2 Laura Torrente-Murciano1 Adam Boies2 John Dennis1

1, University of Cambridge, Cambridge, , United Kingdom
2, University of Cambridge, Cambridge, , United Kingdom

There is a growing need to produce nanoparticles at a scale and cost sufficient to allow their use in industrial catalysts. A very important process is the electrolysis of water, a well-established technology making possible the production of hydrogen from water by utilizing suitably nanostructured electrocatalysts [1]. To make the process viable, these catalysts would need to be produced at low cost and with high throughput. In the present research, we have used a flexible, clean and potentially scalable method for the continuous fabrication of metal nanoparticles, based on a spark discharge process [2,3]. This method enables the mass-production of nanoparticles by striking an electrical discharge between two metal electrodes as the only precursor materials. Therefore, no wet chemical processes are needed, and there is no production of hazardous chemical waste. The nanoparticles produced are easily collected on suitable substrates and can be utilized and characterised for specific catalytic applications. Here, we demonstrate that Pt nanoparticles, produced with the spark discharge method, show excellent electrocatalytic activity in the hydrogen evolution reaction (HER) in an acidic environment [4]. The nanoparticles produced immediately after the spark ablation have a diameter of approximately 3-5 nm, and subsequently merge into larger aggregates before the eventual deposition. It was found that a loading of Pt nanoparticles on the substrates below ~100 ng/cm2 gave a high activity in the HER, with ~70 mV overpotential at 10 mA/cm2. The method of producing nanoparticles by spark discharge was found to be extremely flexible and environmentally-friendly, and was utilized as well to produce alloyed nanoparticles with tuneable size and stoichiometry. Eventually, nanoparticles produced by spark discharge could be coupled to more complex electrochemical systems such as photoelectrochemical water splitting devices or fuel cells.

[1] Roger I., Shipman M. A., Symes M. D., Nature Reviews Chemistry 1, Article number: 0003 (2017)
[2] Tabrizi N. S., Ullmann M., Vons V. A., Schmidt-Ott A., J Nanopart Res (2009) 11: 315
[3] Pfeiffer T. V., Feng J., Schmidt-Ott A., Advanced Powder Technology 25 (2014) 56–70
[4] Li X., Hao X., Abudula A., Guan G., J. Mater. Chem. A, 2016, 4, 11973