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Non-precious metal electrocatalysts based on pyrolysed metal-nitrogen-carbon (MNC) are viewed as an inexpensive replacement for platinum-based electrocatalysts for the oxygen reduction reaction (ORR) in fuel cells. One of the drawbacks of all the reported procedures to synthesize MNC electrocatalysts is the inability to control the nitrogen content. Since the type of nitrogen present (pyridinic, pyrrolic, quaternary/graphitic) and their proportions both play a seminal role in deciding the ORR activity of the electrocatalyst, it is important to carefully study the effect of nitrogen content on electrocatalyst properties. In this study, selenium was used as a ligand to replace the nitrogen coordinated to the iron atom in the electrocatalyst, thereby imparting control on the nitrogen content. Upon introducing 14 at% of selenium, the N content of the catalyst dropped to 3.7 wt% and the ORR activity reached a maximum of 7.2 mA cm −2 at 0.8 V vs. RHE. We demonstrated the need for iron to complete the active site: upon complexing the iron site with bipyridine, ethylene diammine and oxalic acid in 1N H 2 SO 4 , the overpotential toward the ORR increased by ∼60 mV, ∼140 mV and ∼140 mV respectively at 2 mA cm −2 .

This paper evaluated the effect of multiwall carbon nanotube (MWCNT) on the properties of PBT/PC blends. The nanocomposites were obtained by melt blending MWCNT in the weight percentages 0.15, 0.3, and 0.45 wt% with PBT/PC blends in a high performance corotating twin screw extruder. Samples were characterized by tensile testing, dynamic mechanical analysis, thermal analysis, scanning electron microscopy, and X-ray diffraction. Concentrations of PBT and PC are optimized as 80 : 20 based on mechanical properties. A small amount of MWCNT shows better increase in the thermal and mechanical properties of the blends of PBT/PC nanocomposite when compared to nanoclays or inorganic fillers. The ultimate tensile strength of the nanocomposites increased from 54 MPa to 85 MPa with addition of MWCNT up to 0.3% and then decreased.The tensile modulus values were increased to about 60% and the flexural modulus was more than about 80%. The impact strength was also improved with 20% PC to about 60% and with 0.15% MWCNT to about 50%. The HDT also improved from 127 ∘ C to 205 ∘ C. It can be seen from XRD result that the crystallinity of PBT is less affected by incorporating MWCNT. The crystallizing temperature was increased and the MWCNT may act as a strong nucleating agent.