MOF Structure Engineering to Synthesize CoNC Catalyst with Richer Accessible Active Sites for Enhanced Oxygen Reduction

Abstract

Single‐atom cobalt‐based CoNC are promising low‐cost electrocatalysts for oxygen reduction reaction (ORR). However, further increasing the single cobalt‐based active sites and the ORR activity remain a major challenge. Herein, an acetate (OAc) assisted metal–organic framework (MOF) structure‐engineering strategy is developed to synthesize hierarchical accordion‐like MOF with higher loading amount and better spatial isolation of Co and much higher yield when compared with widely reported polyhedron MOF. After pyrolysis, the accordion‐structured CoNC (CoNC (A)) is loaded with denser CoN4 active sites (Co: 2.88 wt%), approximately twice that of Co in the CoNC reported. The presence of OAc in MOF also induces the generation of big pores (5–50 nm) for improving the accessibility of active sites and mass transfer during catalytic reactions. Consequently, the CoNC (A) catalyst shows an admirable ORR activity with a E1/2 of 0.89 V (40 mV better than Pt/C) in alkaline electrolytes, outstanding durability, and absolute tolerance to methanol in both alkaline and acidic media. The CoNC‐based Zn‐air battery exhibits a high specific capacity (976 mAh g−1Zn), power density (158 mW cm−2), rate capability, and long‐term stability. This work demonstrates a reliable approach to construct single atom doped carbon catalysts with denser accessible active sites through MOF structure engineering.

Metal–organic framework derived carbon-encapsulated hollow CuO/Cu2O heterostructure heterohedron as an efficient electrocatalyst for hydrogen evolution reaction

“…Significantly, the D-band originates from crystal lattice defects and disordered graphitic carbon, and the G-band is due to ordered sp 2 graphitic carbon atoms. 42 This indicates the existence of a disordered carbon structure (Fig. 4f).…”

Exploiting the Synergistic Electronic Interaction between Pt‐Skin Wrapped Intermetallic PtCo Nanoparticles and Co‐N‐C Support for Efficient ORR/EOR Electrocatalysis in a Direct Ethanol Fuel Cell

“…Briefly, the Co-N-C support with rich atomically dispersed Co single-atom site was first synthesized from Zn, Co-centered zeolitic imidazole frameworks (ZnCo-ZIF), following a previously reported strategy. [26,27] The highly porous structure Co-N-C support has a Brunauer-Emmett-Teller (BET) surface area up to 908.2 m 2 g −1 (Figure S1, Supporting Information), which contains abundant accessible Co sites for the subsequent anchor and growth of Pt-based nanoparticles by adsorption of [PtCl 6 ] 2− on Co-N-C followed with annealing. During the annealing process, the adsorbed [PtCl 6 ] 2− would be reduced and alloyed with inactive Co nanoparticle residue on Co-N-C, forming the IMC PtCo, that is, PtCo/Co-N-C hybrid.…”

Synthetic strategies for MOF-based single-atom catalysts for photo- and electro-catalytic CO2 reduction

“…MOFs have poor stability under relatively harsh chemical conditions and poor electrical conductivity, which limits its application in electrocatalysis. However, through a high-temperature pyrolysis under the protection of inert gases, the organic components are carbonized to form carbon-based materials doped with heteroatoms such as nitrogen and oxygen (Gao et al, 2021;Zhou et al, 2021b). The graphite-like structure significantly improves the electrical conductivity of the materials, whereas the retention of spatial topology in the pyrolysis process makes the MOF-derived material still has good mass transfer performance (Li et al, 2020b).…”