Surface Segregation and Reactivity in Alloy Catalysts

Alloy catalysts combine two or more metallic elements to tune surface composition, electronic structure and catalytic performance. Surface segregation—the preferential migration of one element to the outermost layer—plays a central role in determining active‐site availability, reaction selectivity and long‐term stability. By modulating surface segregation via bulk composition, temperature, gas atmosphere and applied potential, researchers can tailor adsorption energies, activation barriers and reaction pathways. Advances in atomic‐scale characterisation, in situ spectroscopy and first-principles modelling have revealed how dynamic shifts in surface composition under reaction conditions influence processes such as oxygen activation, hydrogen evolution, carbon monoxide oxidation and selective hydrogenation. The global significance of this work spans sustainable energy technologies, emission control, chemical manufacturing and environmental remediation. Understanding the interplay between thermodynamic driving forces for segregation and kinetic limitations allows for the rational design of robust catalysts with maximised activity and resistance to deactivation. Emerging strategies include single-atom alloying, core–shell architectures and surface-skin formation, each exploiting controlled segregation to create new active sites or protective layers. Collectively, these developments promise more efficient routes to clean energy conversion and low-emission industrial processes.

Research from Nature Portfolio

Recent studies have demonstrated that adjoining single-atom iron sites on an oxide host form diatomic Fe–O–Fe motifs, markedly enhancing molecular oxygen activation and lowering the energy barrier for CO oxidation. Experimental and computational investigations of Cu–Au(111) alloys have revealed spontaneous gold enrichment at the surface, establishing a protective Au skin that impedes deep oxidation and improves high-temperature stability. Complementary work using hyperthermal oxygen beams and synchrotron X-ray photoelectron spectroscopy on Cu3Pd(111) and Cu3Pt(111) surfaces shows that subsurface Pd or Pt mobility governs the onset of Cu oxide formation; tuning interfacial charge transfer controls whether CuO or Cu₂O predominates, demonstrating how selective segregation underpins oxide growth and catalytic resilience.

Surface Segregation and Reactivity in Alloy Catalysts publication trend

The graph below shows the total number of articles in surface segregation and reactivity in alloy catalysts across all publications each year (not limited to Nature Index journals).

Technical terms

Surface segregation: preferential migration of one alloy component to the surface, driven by differences in surface energy and environmental conditions.

Alloy catalyst: a multimetallic system in which compositional tuning and atomic arrangement optimise catalytic properties.

Single-atom catalyst: a catalyst containing isolated metal atoms dispersed on a support, providing uniform and maximally efficient active sites.

d-band centre: the average energy level of d-electrons in a transition metal, correlating with adsorbate binding strength and reactivity.

Activation barrier: the minimum energy required for reactants to transform into products via a specific reaction pathway.

References

1. Adjacent single-atom irons boosting molecular oxygen activation on MnO2. Nature Communications (2021).
2. Experimental and Theoretical Studies on Oxidation of Cu-Au Alloy Surfaces: Effect of Bulk Au Concentration. Scientific Reports (2016).
3. Interface atom mobility and charge transfer effects on CuO and Cu2O formation on Cu3Pd(111) and Cu3Pt(111). Scientific Reports (2021).
4. Ab Initio Investigation of the Adsorption and Dissociation of O2 on Cu-Skin Cu3Au(111) Surface. Catalysts (2022).