Fe₂N/S/N Codecorated Hierarchical Porous Carbon Nanosheets for Trifunctional Electrocatalysis

Abstract

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 Fe2N 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 H2SO4 at a current density of 10 mA cm−2, 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 Fe2–N sites present the active sites for improved catalytic response, which is in agreement with the experimental results.

Bottom‐Up Fabrication of a Sandwich‐Like Carbon/Graphene Heterostructure with Built‐In FeNC Dopants as Non‐Noble Electrocatalyst for Oxygen Reduction Reaction

“…XPS survey for FeNC/rGO unveils the presence of Fe, N, C and O elements in FeNC/rGO. As shown in Figure c, high‐resolution XPS spectra for N 1s reveal four forms of N groups: pyridinic‐N (398.5 eV), pyrrolic‐N (400.2 eV), graphitic‐N (401.1 eV) and N ‐oxide (403.2 eV) . Because of the binding energy of pyridinic‐N is very similar to FeN x group, the high content of pyridinic‐N should comprise of the contribution of FeN x group .…”

Electrocatalytic Activity of Nanocomposites of Sulphur Doped Graphene Oxide and Nanosized Cobalt Phthalocyanines

“…Theu se of heteroatom graphene oxide moieties has recently gained attention in the fieldso fs upercapacitors [1],o xygen reduction reactions [2][3][4][5][6][7][8] and electrocatalytic water oxidation [9].T he choice of graphene based materials has been mainly influenced by their high conductivity,s tability,e ase of morphology manipulation [1,2] and large specific surface area [7].D opantss uch as sulphur, nitrogen and phosphorous [10][11][12][13] have relatively similar size as carbon hence can replacec arbons ites in graphene subsequently introducing or reducing defects.T his often results in improved electrocatalytic properties,c hemical stabilitya nd surface area of the carbon sheets [10,11].…”

Laser-Assisted Fabrication of Nanostructured Substrate Supported Electrodes for Highly Active Supercapacitors

“…Moreover, no significant change in CV curve was observed upon increase in scan rate, indicating fast electrolyte diffusion through electrode materials (Mahmood et al, 2018a). The operation at large scan rate was enabled by presence of large channels in the carbon electrode which allow fast mass diffusion at higher scan rates (Mahmood et al, 2018b). Upon an increase in scan rate, capacitance of 0.87 and 0.38 mFcm −2 is obtained at scan rates of 50 and 100 mV/s, respectively.…”