Hollow carbon nanoreactors integrating NiFe-LDH nanodots with adjacent La single atom for efficient oxygen electrocatalytic reactions

Abstract

Simultaneous optimization of the mass transport and the electronic structure of the active component is of interest to obtain electrocatalysts with superior oxygen evolution reaction (OER) performance. Herein, we miniaturized the classical NiFe-layered double hydroxide (NiFe-LDH) and integrated them into S/N co-doped hollow hierarchical porous carbon (SNHPC) loaded with rare-earth La single aotms (La SAs) to obtain nanoreactors. The unique carbon framework induced uniform deposition of LDH nanodots and ensuring adequate exposure during electrocatalysis. The advantages of carbon carrier for the local electric field and interfacial OH- layer density in the catalytic process were confirmed by finite element simulations. The well-designed NiFe-LDH@La SNHPC obtained satisfactory activity (overpotential of 251 mV at 10 mA cm-2) and stability in alkaline media exceeding that of commercial RuO2. Impressively, a cathode catalyst combining NiFe-LDH@La SNHPC with Pt/C can be stabilized in rechargeable zinc-air batteries (ZABs) for more than 350h. Theoretical calculations indicated that the introduction of La SAs modified the electronic structures of NiFe-LDH nanodots, activated lattice oxygen activity, optimized adsorption stength of intermediates, and reduced rate-determining step energy barriers in OER. This study provided guidance for the preparation of sub-microreactor design and strong electron interaction effects induced by rare earth.