Abstract:

Controlling the dispersion of metals on supports has been widely used as a strategy for tuning catalytic functionality. However, conventional supported catalysts often face challenges associated with multisite reactivity, poorly defined active centers, and the intrinsic dynamicity of those sites under operating conditions. These complexities make it difficult to establish clear structure-function relationships that can guide rational catalyst design. As an alternative, compositionally versatile, oxygen nonstoichiometric mixed metal oxides within the perovskite family provide tunable platforms for hosting well-defined catalytically active cationic sites. Their flexible frameworks allow for control of cation composition, defect chemistry, and electronic/optical properties through structural ligation of metal cations. Moreover, the intrinsic mobility of cations within these frameworks enables reversible structural changes that can dynamically reshape catalytic function, capabilities that are difficult to access with conventional supported systems.

Through three short research vignettes, I will illustrate how cations in mixed metal oxide catalysts can be engineered to: (i) drive electron-mediated oxygen reduction and evolution with high efficiency, (ii) leverage photon-induced excitations to modulate adsorbate binding on oxide surfaces, and (iii) undergo exsolution/reincorporation through reversible cation mobility to fine tune selectivity in structure-sensitive thermal catalytic reactions. Collectively, these examples highlight how the structural complexity of nonstoichiometric mixed metal oxides can be used effectively to tune catalytic activity and product selectivity in chemical reaction through multiple, orthogonal design levers.