Quantifying Electrochemical Driving Force for Exsolution in Perovskite Oxides by Designing Graded Oxygen Chemical Potential

Metalnanoparticles exsolved and anchored at the parent perovskiteoxide surfaces can greatly enhance the activity and antisinteringstability for high-temperature (electro-) chemical catalytic reactions.While exsolution of nanoparticles triggered by using conventionalhigh-temperature thermal reduction suffers from slow kinetics, usingan electrochemical driving force can promote the exsolution rate.However, a quantitative correlation between the applied electrochemicaldriving force and the spatial density of exsolved nanoparticles remainsunknown. In this work, we use a specially designed electrochemicaldevice to induce a spatially graded voltage in a La0.43Ca0.37Ti0.94Ni0.06O3-& delta; electrode, in order to systematically investigate the effect ofelectrochemical switching on exsolution. With increasing driving force,which leads to decreasing oxygen chemical potential, the density ofnanoparticles was observed to increase dramatically, while the averageparticle size remained roughly constant. We further identified oxygenvacancy pairs or clusters as the preferential nucleation sites forexsolution. Our work provided a high-throughput platform for the systematicstudy of exsolution of perovskite oxides targeted for fuel electrodematerials with improved electrocatalytic performance and stability.

Automated summary

Metal nanoparticles exsolved and anchored at the parent perovskite oxide surfaces can enhance the activity and stability for high-temperature chemical catalytic reactions. In this work, an electrochemical device is used to investigate the effect of electrochemical switching on exsolution. Increasing driving force leads to an increase in nanoparticle density and oxygen vacancy pairs or clusters are identified as the preferential nucleation sites for exsolution.