Authors:

Michael Vullo

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Due to the increased demand for energy, hydrogen as a fuel source has been highly regarded as a potential alternative for decades. The hydrogen evolution reaction (HER) has been a sought-after method for producing clean and zero-emission hydrogen gas. Alloys in previous works have been reported as having good catalytic properties for HER. Alloys containing five or more components are referred to as High Entropy Alloys (HEAs). HEAs have been shown to have exceptional strength, thermal resistance, and toughness. HEAs also have tunable properties depending on the combination of metals used. Therefore, HEAs have been used as catalysts for many different reactions. Here, we took advantage of a method named nanodroplet-mediated electrodeposition to electrodeposit a HEA nanoparticle onto a glassy carbon surface. The method consists of an emulsion solution, where equal concentrations of the metal salt precursors of Au, Ag, Pt, Pb, and Pd were confined in aqueous nanodroplets suspended in 1,2-dichloroethane. These nanodroplets collide directly onto the electrode surface, allowing the synthesis of HEAs via electrochemical reduction. Chronoamperometry at - 0.6 V vs. Ag/AgCl was used to electrodeposit the HEA nanoparticles. The morphology of our nanoparticles was observed via a scanning electron microscope, and elemental composition was confirmed via energy-dispersive X-ray. Rotating disc electrode voltammetry was used to demonstrate the electrocatalytic activity of the HEA for HER. The synthesized HEA nanoparticles showed long-term stability for over two hours. Hydrogen evolution activity was 11 mV lower compared to Pt, while using 1/5 the amount of Pt. This opens new avenues for HEAs and their role in energy conversion systems.

Source:

Purdue University / 2023

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Co-authors:

Michael Vullo