Hidden oxide layer boosts gold's catalytic power, study reveals
Researchers discovered that gold electrodes treated to form a subsurface oxide layer—not visible on the surface—deliver superior catalytic performance. The finding explains why oxide-derived metals outperform standard metals in industrial catalysis and could guide design of cheaper, more efficient catalysts for hydrogen production and chemical manufacturing.
Originaltitel: Multi-spectroscopic study of electrochemically-formed oxide-derived gold electrodes
<p>Oxide-derived metals are produced by reducing an oxide precursor. These materials, including gold, have shown improved catalytic performance over many native metals. The origin of this improvement for gold is not yet understood. In this study, <em>operando</em> non-resonant sum frequency generation (SFG) and <em>ex situ</em> high-pressure X-ray photoelectron spectroscopy (HP-XPS) have been employed to investigate electrochemically-formed oxide-derived gold (OD-Au) from polycrystalline gold surfaces. A range of different oxidizing conditions were used to form OD-Au in acidic aqueous medium (H<sub>3</sub>PO<sub>4</sub>, pH = 1). Our electrochemical data after OD-Au is generated suggest that the surface is metallic gold, however SFG signal variations indicate the presence of subsurface gold oxide remnants between the metallic gold surface layer and bulk gold. The HP-XPS results suggest that this subsurface gold oxide could be in the form of Au<sub>2</sub>O<sub>3</sub> or Au(OH)<sub>3</sub>. Furthermore, the SFG measurements show that with reducing electrochemical treatments the original gold metallic state can be restored, meaning the subsurface gold oxide is released. This work demonstrates that remnants of gold oxide persist beneath the topmost gold layer when the OD-Au is created, potentially facilitating the understanding of the improved catalytic properties of OD-Au.</p>