Tailoring Spin State of Perovskite Oxides by Fluorine Atom Doping for Efficient Oxygen Electrocatalysis

Promoting the initially deficient but economical catalysts to high-performing competitors is important for developing superior catalysts. Unlike traditional nano-morphology construction methods, this work focuses on intrinsic catalytic activity enhancement via heteroatom doping strategies to induce lattice distortion and optimize spin-dependent orbital interaction to alter charge transfer between catalysts and reactants. Experimentally, a series of different concentrations of fluorine-doped lanthanum cobaltate (F-x-LaCoO3) exhibiting excellent electrocatalytic activity is synthesized, including a low overpotential of 390 mV at j = 10 mA cm(-2) for OER and a large half-wave potential of 0.68 V for ORR. Meanwhile, the assembled rechargeable Zn-air batteries deliver an excellent performance with a large specific capacity of 811 mAh/g(Zn) under 10 mA cm(-2) and stability of charge/recharge (120 h). Theoretically, taking advantage of density functional theory calculations, it is found that the prominent OER/ORR performance arises from the spin state transition of Co3+ (Low spin state (LS, t(2g)(6)e(g)(0)) -> Intermediate spin state (IS, t(2g)(5)e(g)(1)) and the mediated d-band center upshift by F atom incorporation. This work establishes a novel avenue for designing superior electrocatalysts in perovskite-based oxides by regulating spin states.

Automated summary

Promoting the initially deficient but economical catalysts to high-performing competitors is important for developing superior catalysts. This work focuses on intrinsic catalytic activity enhancement via heteroatom doping strategies, which alter lattice distortion and optimize spin-dependent orbital interaction to improve charge transfer between catalysts and reactants. Experimental results show that fluorine-doped lanthanum cobaltate exhibits excellent electrocatalytic activity in oxygen evolution reaction and oxygen reduction reaction. Theoretical calculations reveal that the enhanced performance is attributed to the spin state transition of Co3+ and the upshift of the d-band center due to F atom incorporation.