Construction of multifunctional highly active earth-abundant electrocatalysts on a large scale is a great challenge due to poor control over nanostructural features and limited active sites. Here, a simple methodology to tailor metal-organic frameworks (MOFs) to extract highly active multifunctional electrocatalysts on a large scale for oxygen reduction (ORR), oxygen evolution (OER), and hydrogen evolution reaction (HER) is presented. The N, S codoped Fe N decorated highly porous and defect-rich carbon nanosheets are grown using MOF xerogels, melamine, and polyvinylpyrollidone. The resulting catalyst exhibits excellent activity for ORR with an onset (0.92 V) and half-wave (0.81 V) potential similar to state-of-the-art Pt/C catalysts. The catalyst also shows outstanding OER and HER activities with a small overpotential of 360 mV in 1 m KOH and -123 mV in 0.5 m H SO at a current density of 10 mA cm , respectively. Excellent catalytic properties are further supported by theoretical calculations where relevant models are built and various possible activation sites are identified by first-principles calculations. The results suggest that the carbon atoms adjacent to heteroatoms as well as Fe -N sites present the active sites for improved catalytic response, which is in agreement with the experimental results.
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http://dx.doi.org/10.1002/smll.201803500 | DOI Listing |
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