Residual ZnNx moieties in ZIF-8 derived catalysts: Protective and synergistic effects for oxygen reduction.

ORR: oxygen reduction reaction; SMSI: strong metal-support interaction; LABI: Lewis acid-base interaction. [Display omitted] • Residual Zn in various ZIF-8 derived carbons could reach ∼10 wt%. • ZnN x could act as 'spatial barriers' suppressing Pt forming ORR inactive PtN x. • ZnN x could serve as Zn source for the intermetallation of L1 0 -PtZn. • ZnN x could bring the SMSI between PtZn and support. • LABI between ZnN x and PtCl 6 2− could promote the dispersion of PtZn. ZIF-8 derived carbons demonstrate admirable application prospects in electrocatalytic fields, while ZnN x remaining in those materials are overlooked, crippling the validity of theoretic studies in researches. Herein, the residual Zn in ZIF-8 derived carbons are found could exceed 10 wt% even at carbonization temperatures over 900℃, and Zn-NCs with various Zn contents are adopted as supports to synthesize low-platinum ORR catalysts. Substantial characterizations manifest that ZnN x in Zn-NC can not only provide Zn source for L1 0 -PtZn intermetallic, but act as 'spatial barriers' to prevent the formation of inactive PtN x , elevating the active Pt proportion in catalyst by ∼104%. The resultant Zn-NC-Ar-PtZn exhibits a mass activity of 0.557 mA/g Pt and a peak density of 1.485 W/cm2. DFT calculations show the strong thermodynamic tendency of forming PtN 4 without the protection of ZnN 4 , and the superior durability and activity of Zn-NC-Ar-PtZn should be attributed to its Zn-derived ligand effects and the SMSI. [ABSTRACT FROM AUTHOR]