Poster Presentation Royal Australian Chemical Institute National Congress 2026

Revealing Hydrogen Evolution Behaviour of Gallium–Platinum Single-Crystals using Scanning Electrochemical Cell Microscopy (#507)

Moonika Widjajana 1 , Shih-Hao Chiu 1 , Levi Tegg 2 , Bowen Wu 3 , Anju Singh 3 , Nieves Flores 1 , Anuradha Irugalbandara 3 , Kourosh Kalantar-Zadeh 1 , Kaye Minkyung Kang 3
  1. School of Chemical and Biomolecular Engineering, The University of Sydney, Sydney, New South Wales, Australia
  2. School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, New South Wales, Australia
  3. School of Chemistry, The University of Sydney, Sydney, New South Wales, Australia

Platinum (Pt) is a well-known catalyst for the hydrogen evolution reaction (HER). However, as Pt is a noble metal, reducing its cost for HER applications remains challenging. Incorporating Pt into different metals, in this case liquid metal gallium (Ga), which can also act as an electronic solvent, thereby effectively lowers Pt usage. The interaction between Pt and Ga leads to the formation of Ga–Pt alloys, and their precipitation results in crystalline phases. Ga is chosen, as during its dissolution, individual Pt atoms are proposed to be surrounded by several Ga atoms, preventing Pt aggregation1. Moreover, Ga exhibit catalytic activation comparable to Pt, making Ga a suitable choice for reducing the overall cost of Pt-based catalysts.

Once the reduced-cost Pt-based materials are successfully produced, their activity is characterized using scanning electrochemical cell microscopy (SECCM), a versatile technique for analysing localized electrochemical activity at the single micro-/nanoparticle level2. In this method, a probe containing a AgCl-coated Ag (Ag/AgCl) quasi reference counter electrodes (QRCEs) immersed in electrolyte is actuated by a piezoelectric system to localize the target area (analyte), which serves as the working electrode.  The HER on single-crystal gallium - platinum (Ga-Pt) was investigated using the SECCM method to elucidate the variations in electrochemical behaviour among individual particles.

The results show distinct HER performance across different Ga-Pt single-crystals. This variation is likely attributed to the minor differences in chemical composition as well as pore size among the crystals, as supported by the identical-location analysis via scanning electron microscope coupled with energy-dispersive spectroscopy (SEM-EDS). In conclusion, Ga–Pt single crystal was successfully fabricated and the variations in HER activity among individual particles were revealed, phenomena that bulk electrochemical measurements fail to capture. SECCM technique provides a powerful method for analysing the differences in electrochemical activity at the single-crystal level.

  1. (1) Kalantar-Zadeh, K.; Daeneke, T.; Tang, J. The atomic intelligence of liquid metals. Science 2024, 385 (6707), 372-373. DOI: 10.1126/science.adn5871.
  2. (2) Wahab, O. J.; Kang, M.; Unwin, P. R. Scanning electrochemical cell microscopy: A natural technique for single entity electrochemistry. Current Opinion in Electrochemistry 2020, 22, 120-128. DOI: 10.1016/j.coelec.2020.04.018.