Enhanced Electrocatalytic Oxygen Evolution in Au–Fe Nanoalloys

Abstract

Oxygen evolution reaction (OER) is the most critical step in water splitting, still limiting the development of efficient alkaline water electrolyzers. Here we investigate the OER activity of Au-Fe nanoalloys obtained by laser-ablation synthesis in solution. This method allows a high amount of iron (up to 11 at %) to be incorporated into the gold lattice, which is not possible in Au-Fe alloys synthesized by other routes, due to thermodynamic constraints. The Au Fe nanoalloys exhibit strongly enhanced OER in comparison to the individual pure metal nanoparticles, lowering the onset of OER and increasing up to 20 times the current density in alkaline aqueous solutions. Such a remarkable electrocatalytic activity is associated to nanoalloying, as demonstrated by comparative examples with physical mixtures of gold and iron nanoparticles. These results open attractive scenarios to the use of kinetically stable nanoalloys for catalysis and energy conversion.

Perspective of Surfactant‐Free Colloidal Nanoparticles in Heterogeneous Catalysis

“…The situation changes when the ablation is conducted in solvents like ethanol or acetone yielding pure AuFe alloy NPs, due to the reductive or scavenging atmosphere induced by the organic molecules suppressing oxidation processes of the metal atoms. Comprising the latter, the alloy design during LAL is controllable not just by adapting the solvent but also by tuning how the individual elemental species are ordered within the target material …”

“…Yet, compared to the physical mixture of Au NPs and Pt NPs, this activity is only twice as high which was explained with atomic mobility and intermixing during electrochemical cycling causing the formation of active surface sites (e. g. bi‐metallic AuPt) even from the nanoparticle mixture during reactive conditions . In case of laser‐generated Au−Fe NPs studied in terms of OER, Amendola and co‐workers highlighted the importance of mixing the two atomic species (here Au and Fe) on the atomic scale prior to the reaction (Figure b) . Substituting 11 % of the gold atoms with iron atoms by simple ablation of an alloy target with adjusted composition led to a significantly higher OER activity compared to the elemental nanoparticles or their mixture in a similar composition .…”

Surface Engineering of MoS2 via Laser‐Induced Exfoliation in Protic Solvents

“…The pulsed laser irradiation in liquid (PLIL) technique, usually in water or organic liquids, engages a mild laser flux to generate high temperature and pressure at the local area and thus convert a certain depth of target materials to plasma. Given the suitable reaction environment in liquid, various materials have been reformed with unique microstructures and morphologies …”

“…Using laser for the top‐down synthesis of nanomaterials has become a rapidly growing field as it can offer a simple and environment‐friendly pathway of tuning the morphology, size, composition, as well as phase under ambient conditions . The pulsed laser irradiation in liquid (PLIL) technique, usually in water or organic liquids, engages a mild laser flux to generate high temperature and pressure at the local area and thus convert a certain depth of target materials to plasma.…”

Effects of Metal Electrode Support on the Catalytic Activity of Fe(oxy)hydroxide for the Oxygen Evolution Reaction in Alkaline Media

“…Iron (oxy)hydroxide (FeO x H y ) is an earth‐abundant catalyst for the OER in alkaline media with the highest “intrinsic” activity among single‐transition‐metal (oxy)hydroxides. Its activity, however, is highly dependent on catalyst electrical conductivity, electrode substrate, and the details of the catalyst structure . When Fe is combined with NiO x H y or CoO x H y , the OER activity is further increased .…”