Single-atom Catalyst with Hollow rod/Plate like structure for Enhanced Oxygen Reduction Reaction Performance in Zinc Air Battery
Abstract
The development of efficient and stable catalysts is critical in various energy and environmental applications. In the present study, transition metal single-atom catalysts (TM SACs) with core-shell morphology were prepared. Our In-situ polymerization approach involves the precise encapsulation of transition metal single-atoms within a nitrogen-doped carbon shell, forming robust core-shell architecture. The developed synthesis strategy is applicable for the synthesis of variety of transition metal single-atom catalysts such as Fe-N-C SAC, Co-N-C SAC, Mn-N-C SAC, and Ni-N-C SAC. Among these, Fe-N-C SAC showed the best ORR activity in both acidic and basic medium showing a half wave potential (E1/2) of 0.80 V and 0.91 V, and limiting current density (JL) of 5.96 mA cm-2 and 5.12 mA cm-2, respectively, which is higher than the state of the art 20% Pt/C catalyst. Theoretical calculation illustrated that Fe-N-C SAC has the lowest d-band center (-2.364 eV), indicating that Fe-N-C SAC is more easily to adsorb oxygen-containing intermediates and further validating excellent catalyst properties compared with Co, Mn and Ni-based catalysts. The high ORR performance is further confirmed by assembling a homemade Zinc-air battery (ZAB) using Fe-N-C SAC as a cathode, showing a high-power density of 185 mW cm-2. The enhanced performance is accredited to the novel core-shell design, which gives a favorable environment for the active sites, avert agglomeration of metal atoms, and make sure high electron conductivity. This work not only introduced a novel approach for designing advanced single-atom catalysts but also confirms their possible applications in energy transformation and storage devices.