Structural revolution of atomically dispersed Mn sites dictates oxygen reduction performance

Abstract

An efficient preparation and local coordination environment regulation of isolated single-atom sites catalysts (ISASC) for improved activity is still challenging. Herein, we develop a solid phase thermal diffusion strategy to synthesize Mn ISASC on highly uniform nitrogen-doped carbon nanotubes by employing MnO 2 nanowires@ZIF-8 core-shell structure. Under hightemperature, the Mn species break free from core-MnO 2 lattice, which will be trapped by carbon defects derived from shell-ZIF-8 carbonization, and immobilized within carbon substrate. Furthermore, the poly-dispersed Mn sites with two nitrogen-coordinated centers can be controllably renovated into four-nitrogen-coordinated Mn sites using NH 3 treatment technology. Both experimental and computational investigations indicate that the symmetric coordinated Mn sites manifest outstanding oxygen reduction activity and superior stability in alkaline and acidic solutions. This work not only provides efficient way to regulate the coordination structure of ISASC to improve catalytic performance but also paves the way to reveal its significant promise for commercial application.

Thermal Migration Promotes the Formation of Manganese and Nitrogen Doped Polyhedral Surface for Boosted Oxygen Reduction Electrocatalysis

“…MnOOH rods exhibited the characteristic peaks of pure MnOOH (PDF #41-1379) with good crystallinity (Figure S4a). Moreover, the diffraction peaks at 34.9, 40.5, and 58.7° of MnO-NC and MnO were consistent with (111), (200), and (220) planes of pure MnO (PDF #07-0230), respectively (Figure a) . NCs only exhibited two broad peaks at around 25 and 41°, indicating the amorphous form of carbon.…”

“…Similarly, Wu et al. reported the synthesis of isolated single atomic Mn sites on N-doped nanotubes via a solid thermal diffusion strategy . Nonetheless, a facile thermal migration method is still lacking to construct efficient ORR catalysts for their widespread application.…”

Simultaneously Enhancing Catalytic Performance and Increasing Density of Bifunctional CuN3 Active Sites in Dopant-Free 2D C3N3Cu for Oxygen Reduction/Evolution Reactions

“… 19 − 21 Among them, the most reported SACs are limited to transition-metal atoms (Fe, Co, Ni, Cu, etc.) supported by heteroatom N-doped carbonaceous materials, which can be applied to the catalysis of a wide range of electrochemical reactions of ORR, 22 − 28 nitrogen reduction reaction (NRR), 29 − 34 carbon dioxide reduction reaction (CO 2 RR), 35 − 41 hydrogen reduction reaction (HER), 42 − 44 OER, 8 , 45 , 46 etc. The single metal atom and its coordination environment are usually modeled by a MN 4 moiety having a metal center coordinated with four N atoms.…”

Hollow microstructural regulation of single-atom catalysts for optimized electrocatalytic performance

“…It was shown that the designed hollow structure plays an important role in accelerating the kinetics and improving performance. He et al [102] synthesized a series of noble-metal (Ir, Pt, Ru, Au and Pd) single atoms immobilized on hollow nanotubes derived from a zirconiumporphyrinic MOF, which are equipped with square-planar four coordinate porphyrin units to anchor a single atom. This unique single-shell hollow structure was beneficial for fast mass diffusion.…”