Y2O3/La2O3 electron modulation engineering of Co site for boosting oxygen electrocatalysis

Developing high-efficiency non-precious metal-based catalysts toward the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is a major task for Zinc-air batteries (ZABs). Cobalt-based catalysts have been regarded as promising catalysts owing to the multivalence characteristic of the Co element, however, there remains the agglomeration of Co particles during the high-temperature calcination process and the strong adsorption of oxygen intermediates. Herein, the synthesis of Y 2 O 3 -La 2 O 3 co-modified Co nanoparticles embedded within the porous N-doped carbon substrate derived from a metal-organic framework precursor is reported ((Y 1 La 1 )O/Co-NC). Notably, this strategy allows Y 2 O 3 -La 2 O 3 to uniformly distribute around Co nanoparticles and to form intimate Y 2 O 3 -La 2 O 3 /Co interface sites. Benefiting from Y 2 O 3 -La 2 O 3 co-modification, the synergistic effect of the heterostructures, and abundant active sites, the optimized (Y 1 La 1 )O/Co-NC catalysts exhibit a higher half-wave potential (E 1/2  = 0.845 V) than commercial Pt/C (E 1/2  = 0.828 V). In addition, the potential gap between OER and ORR potentials is 0.78 V. As a cathode catalyst for ZABs, (Y 1 La 1 )O/Co-NC achieved a specific capacity of 955.73 mAh g −1 . Theoretical calculations have also revealed that the introduction of Y₂O₃ and La 2 O 3 promotes electron transfer and increases the electron density at Co sites. The interface effect of Y 2 O 3 -La 2 O 3 /Co optimizes the adsorption strength of oxygen intermediates, significantly reduces the reaction energy barrier, and enhances oxygen electrocatalysis. This study offers significant insights into the strategy of employing rare earth metals to boost the performance of cobalt-based catalysts in ZABs.