摘要
Crystalline perovskite oxides provide stability;however,their oxygen evolution reaction(OER)activity may be limited by restricted surface accessibility and active sites.Amorphous surfaces enable high activity but often lack long-term operational stability.Herein,we engineered the phase structure of the classic Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ)(BSCF)to boost OER activity and optimize operational stability.The ternary-phase BSCF demonstrates a low overpotential of 440 mV at 50 mA cm^(-2)and exceptional stability,with negligible degradation over 100 h.Within the ternary-phase structure,the hexagonal-phase BSCF readily transforms into an amorphous,catalytically active layer of(oxy)hydroxides,as demonstrated by operando Raman spectroscopy and theoretical calculations that indicate a lower formation energy.Meanwhile,the cubic-phase BSCF provides remarkable structural robustness,suppressing surface reconstruction and maintaining high stability.Importantly,the synergy between the reconstructed surface and the cubic-phase bulk markedly increases surface and bulk oxygen vacancies,thereby yielding a rapid oxygen-ion diffusion coefficient(3.04 x 10^(-12)cm^(2)s^(-1))and accelerating OER kinetics via the lattice-oxygen mechanism.Additionally,zinc-air batteries utilizing the amorphous-crystalline heterostructures with abundant oxygen vacancies exhibit a low voltage gap of 0.81 V between charging and discharging and sustain cycling stability for over 300 h at 10 mA cm^(-2).This phase engineering strategy simultaneously maximizes both bulk stability and surface reactivity,and the principles underlying this approach may be extended to other promising perovskite electrocatalysts.
基金
National Natural Science Foundation of China(No.22178144 and No.51702125)。
