Carbonized Nanoscale Metal–Organic Frameworks as High Performance Electrocatalyst for Oxygen Reduction Reaction

Abstract

The oxygen reduction reaction (ORR) is one of the key steps in clean and efficient energy conversion techniques such as in fuel cells and metal-air batteries; however, several disadvantages of current ORRs including the kinetically sluggish process and expensive catalysts hinder mass production of these devices. Herein, we develop carbonized nanoparticles, which are derived from monodisperse nanoscale metal organic frameworks (MIL-88B-NH3), as the high performance ORR catalysts. The onset potential and the half-wave potential for the ORR at these carbonized nanoparticles is up to 1.03 and 0.92 V (vs RHE) in 0.1 M KOH solution, respectively, which represents the best ORR activity of all the non-noble metal catalysts reported so far. Furthermore, when used as the cathode of the alkaline direct fuel cell, the power density obtained with the carbonized nanoparticles reaches 22.7 mW/cm2, 1.7 times higher than the commercial Pt/C catalysts.

Design Strategies toward Advanced MOF‐Derived Electrocatalysts for Energy‐Conversion Reactions

“…By means of annealing under a controlled temperature and atmosphere, the organic units can be transformed into heteroatom-doped carbon materials, while metal-containing units are simultaneously converted into the corresponding transition-metal-based NPs supported on the as-formed carbon substrate. [24,38,41,42,44,53] More importantly, the advancement of chemical modification allows the precise manipulation of the component for the resultant composites. [41] From the view of composition, MOF-derived composites could offer strong synergistic effects between the carbon framework and metal component, which is highly preferable in enhancing electrocatalytic performance.…”

“…[42,58,[70][71][72][73] Taking MIL-88B-NH 3 (Fe 3 O(H 2 N-BDC) 3 , H 2 N-BDC = 2-aminoterephtalic acid) for example, Zhao et al prepared well-defined N-doped carbonized nanoparticles (CNPs) by pyrolyzing spindle-like MIL-88B-NH 3 NPs. [42] Notably, unlike IM-based ligands in ZIFs, which already contain N atoms in pyridine/pyrrole configurations, H 2 N-BDC only contains amino-type N atoms. Despite this difference, the results from Zhao et al found that the amino-type N in MIL-88B-NH 3 were converted into pyridine and quaternary N after carbonization.…”

“…Despite this difference, the results from Zhao et al found that the amino-type N in MIL-88B-NH 3 were converted into pyridine and quaternary N after carbonization. [42] Evidently, amino-type N atoms in organic ligands can serve as good N dopants, rather than decompose into ammonia. In another example, Zhao et al introduced N-rich ligands (1H-1,2,3-triaole) into ZIF-8 using a solventassistant-linker-exchange (SALE) approach, thereby fabricating a new MOF with rich N atoms for N doping.…”

“…When used as electrode materials in energy-conversion reactions, MOF-derived materials have displayed appealing performance in electrochemical systems, and comprehensive studies indicate that MOF-derived materials have several advantageous characteristics for electrochemical energy generation and storage. These are: 1) the carbon matrix obtained from the organic framework is able to act as a highly conductive network, promoting fast electron transfer; [31][32][33][34][35][36] 2) various heteroatoms (e.g., N, O, S, and P) contained in the organic ligands can be directly doped into the carbon framework, which can not only provide more active sites, but also create a favourable microenvironment for the growth of functional nanoparticles (NPs, e.g., transition metal carbides, nitrides, and oxides); [24,[36][37][38][39][40][41] 3) the metal atoms in MOFs can form corresponding metals and/or compounds and homogeneously distribute in the carbon network, leading to the in situ synthesis of a carbon framework decorated with transition metals and/or transition metal compounds; [24,[41][42][43] 4) a well-defined morphology, size, and structure can be obtained by adjusting synthesis parameters; [42][43][44][45] 5) many of the features (e.g., large surface area and high porosity) inherited from the MOF precursors can be preserved in the resultant materials after post-treatments. [46][47][48] Unsurprisingly, owing to the advantages discussed above, these MOF-derived materials have stimulated much interest in energy fields, [49][50][51] and have been studied as electrode materials in batteries and supercapacitors.…”

Bimetallic PtRu Nanoparticles Supported on Functionalized Multiwall Carbon Nanotubes as High Performance Electrocatalyst for Direct Methanol Fuel Cells

“…[1][2][3][4][5] Direct methanol fuel cells (DMFCs) have garnered signi¯cant attention among di®erent types of fuel cells for the several unique advantages including high energy density, the safety of storage and handling a liquid fuel and ease for miniaturization. [6][7][8] Unfortunately, the commercialization of DMFCs is still limited by lacking rational design of the anode materials, resulting in the sluggish kinetics of methanol oxidation and poisoning devitalization of electrocatalysts.…”