Tailoring electrocatalytic activity of in situ crafted perovskite oxide nanocrystals via size and dopant control

Perovskite oxides (ABO3) have been widely recognized as a class of promising noble-metal-free electrocatalysts due to their unique compositional flexibility and structural stability. Surprisingly, investigation into their size-dependent electrocatalytic properties, in particular barium titanate (BaTiO3), has been comparatively few and limited in scope. Herein, we report the scrutiny of sizeand dopant-dependent oxygen reduction reaction (ORR) activities of an array of judiciously designed pristine BaTiO3 and doped BaTiO3 (i.e., La- and Co-doped) nanoparticles (NPs). Specifically, a robust nanoreactor strategy, based on amphiphilic star-like diblock copolymers, is employed to synthesize a set of hydrophobic polymer-ligated uniform BaTiO3 NPs of different sizes (<= 20 nm) and controlled compositions. Quite intriguingly, the ORR activities are found to progressively decrease with the increasing size of BaTiO3 NPs. Notably, La- and Co-doped BaTiO3 NPs display markedly improved ORR performance over the pristine counterpart. This can be attributed to the reduced limiting barrier imposed by the formation of -OOH species during ORR due to enhanced adsorption energy of intermediates and the possibly increased conductivity as a result of change in the electronic states as revealed by our density functional theory-based first-principles calculations. Going beyond BaTiO3 NPs, a variety of other ABO3 NPs with tunable sizes and compositions may be readily accessible by exploiting our amphiphilic star-like diblock copolymer nanoreactor strategy. They could in turn provide a unique platform for both fundamental and practical studies on a suite of physical properties (dielectric, piezoelectric, electrostrictive, catalytic, etc.) contingent upon their dimensions and compositions.

Automated summary

Perovskite oxides, such as barium titanate, are considered as promising noble-metal-free electrocatalysts due to their compositional flexibility and structural stability. This study investigates the size-dependent electrocatalytic properties of BaTiO3 nanoparticles, revealing that the ORR activities decrease with increasing particle size. Additionally, doped BaTiO3 nanoparticles show enhanced ORR performance compared to pristine ones, attributed to improved adsorption energy of intermediates and possibly increased conductivity.