Tailoring the Porous Structure of Mono‐dispersed Hierarchically Nitrogen‐doped Carbon Spheres for Highly Efficient Oxygen Reduction Reaction

Abstract

The search for a low‐cost metal‐free cathode material with excellent mass transfer structure and catalytic activity in oxygen reduction reaction (ORR) is one of the most challenging issues in fuel cells. In this work, nitrogen‐rich m‐phenylenediamine is introduced into the synthesis of porous carbon spheres to tune the pore structure and nitrogen‐doped active sites. As a result, more pyridinic N and pyrrolic N functional species were observed at the interior and surface of the carbon spheres. The introduction of m‐phenylenediamine also regulated the nucleating of precursors, an urchin‐like mesoporous surface structure ensures point contact and less agglomeration between each particle was obtained. With optimized proportion of micropores/mesopores and improved nitrogen‐contained functional species, the ORR activity can be remarkably improved. The half‐wave potential of this catalyst could achieve to 0.81 V (versus RHE) which is only 42 mV lower than commercial Pt/C catalyst. Furthermore, the optimized cathode catalyst achieved a 69 mW cm−2 maximum power density when operated in direct methanol fuel cells at room temperature.

Rational Design of High‐Performance Bilayer Solar Evaporator by Using Waste Polyester‐Derived Porous Carbon‐Coated Wood

“…PC‐ x ( x = 0.5, 1, 2 and 3) exhibits the combination of type I/IV physisorption isotherms and displays a type‐H4 hysteresis loop at P / P 0 = 0.2 − 0.95 with a sharp N 2 uptake at P / P 0 > 0.8, confirming the formation of abundant mesopores and macropores (Figure 2h and i). [ 46 ] The micropore size distribution of PC‐ x ( x = 0.5, 1, 2, and 3) calculated by using DFT model is centered on 0.5 nm, smaller than that of PC‐0 (0.65 nm), implying the positive effect of ZnO on the formation of smaller micropores. To expound the catalytic effect of ZnO during the carbonization of PET, model carbonization experiments were conducted, in which PET or PET/ZnO mixture (the ZnO/PET mass ratio=1) was heated at 350 °C for 30 min.…”

Hierarchical Porous Carbon Anchored Atomic/Clustered Cobalt for Boosting Oxygen Reduction Electrocatalysis

“…Hierarchical porous carbon has emerged as an ideal support material for energy applications in recent years. [30][31][32] Due to the large surface area provided for active sites, together with the facilitated reactant diffusion via the micro/mesopores, hierarch-ical porous carbon has great significance in boosting the ORR. [33][34][35] For instance, Cu, N-doped hierarchical porous carbon (CuÀ NÀ C) shows excellent ORR performance, with an improved half-wave potential (~16 mV) compared to a commercial Pt/C catalyst.…”

“…Hierarchical porous carbon has emerged as an ideal support material for energy applications in recent years [30–32] . Due to the large surface area provided for active sites, together with the facilitated reactant diffusion via the micro/mesopores, hierarchical porous carbon has great significance in boosting the ORR [33–35] .…”

High-Rate-Capacity Cathode Based on Zn-Doped and Carbonized Polyacrylonitrile-Coated Na4MnV(PO4)3 for Sodium-Ion Batteries

“…Meanwhile, the Zn 2p spectrum (Figure d) exhibits two conspicuous peaks at 1022.2 and 1045.2 eV, corresponding to Zn 2p 3/2 and Zn 2p 1/2 , respectively. The result shows that Zn is bivalent. − The C 1s spectrum (Figure e) exhibits three peaks corresponding to the C–C bond (284.8 eV), C–O bond (286.4 eV), and O–CO bond (288.6 eV). ,, The N 1s XPS spectrum (Figure f) shows the peaks for three different states of N, including pyridinic nitrogen (398.6 eV), pyrrolic nitrogen (400.8 eV), and graphitic nitrogen (402.4 eV) . The presence of N is mostly attributed to PAN. , The disorder states of nitrogen provide more defects and vacancies for the carbonized PAN layer.…”