(512c) Rational Control of Co-Fe Alloy Nanoparticle Ex-Solution on Perovskites for N2o Decomposition.

Bimetallic alloy nanoparticles have received significant attention due to their distinct catalytic property and stability compared to single metals. One promising method for preparing these nanoparticles is ex-solution, which could overcome limitations such as stability due to weak support interactions. However, co-exsolution of two metals has been relatively understudied compared to single metal ex-solution. In this work, we report the controlled synthesis of Co-Fe alloy nanoparticles anchored on SrTiO₃ perovskite (SrTi_0.9Co_0.1-xFe_xO₃) through in situ ex-solution. With systematically varying the reducing conditions and Co-Fe atomic ratio, we investigated the chemical composition, size, density, and volume of the exsolved Co-Fe alloy nanoparticles. We found that higher reduction temperatures and increased Fe contents led to larger co-exsolved Co-Fe nanoparticles, while the density of particles decreased. Interestingly, no nanoparticles were observed on SrTi_0.9Fe_0.1O₃. Based on the experimental results, we applied a thermodynamic model that explains the Co-Fe alloy ex-solution and the promoting effects of Co on Fe ex-solution. Furthermore, we demonstrated the catalytic activity of our catalysts in N₂O decomposition as a model reaction due to relatively low reaction temperature compared to ex-solution process. The intimate synergy between Co-Fe alloy nanoparticles and SrTiO₃ support promotes not only the adsorption of N₂O but also the cleavage of the N-O bond. Overall, our study builds better understanding of the co-exsolution mechanism and extends its catalytic applications.