02389nas a2200217   4500008004100000022001400041245015200055210006900207260000800276300001400284490000600298520158300304653001901887653001501906653001801921653002601939653003001965100002701995700002402022856012502046       2020                        eng d  a2196-021600aCo (9) S (8) nanoparticle-supported nitrogen-doped carbon as a robust catalyst for oxygen reduction reaction in both acidic and alkaline conditions0 aCo 9 S 8 nanoparticlesupported nitrogendoped carbon as a robust   cJUL  a3123-31340 v73 a<p>The present work illustrates the synthesis of an efficient and durable catalyst for electrochemical oxygen reduction reaction (ORR) which is active both in the alkaline and acidic conditions by dispersing few-layer graphitic carbon coated Co(9)S(8)nanoparticles on the nitrogen-doped carbon (NVC-G) support (Co9S8/NVC-G). The size of the Co(9)S(8)nanoparticles is nearly 7-8 nm and the particles are found to be dispersed homogeneously on the NVC-G support. The few-layer graphitic carbon formed on the surface of Co(9)S(8)nanoparticles is assisting to accomplish their small size and it also prevents agglomeration of the nanoparticles. The ORR activity of the obtained material was analyzed in both 0.1 M KOH and 0.5 M H(2)SO(4)solutions. Co9S8/NVC-G displays nearly 70 mV overpotential compared to thestate-of-the-artPt/C in 0.1 M KOH solution. The half-wave potential (E-1/2) difference of the present system is nearly 75 mV with the commercial Pt/C. Co9S8/NVC-G displays promising ORR activity in the acidic conditions as well with nearly 140 mV overpotential compared to its Pt/C counterpart. The system shows about 170 mV lowerE(1/2)value with Pt/C. The system shows good stability both in acidic and basic conditions compared to the Pt/C system. Finally, testing of a single cell of a polymer electrolyte membrane fuel cell (PEMFC) was performed by employing Co9S8/NVC-G as the cathode catalyst and Nafion-212 as the proton exchange membrane. The system displays a maximum power density of 245 mW cm(-2)in H-2-O(2)and 115 mW cm(-2)in H-2-air feeding conditions.</p>
10acobalt sulfide10afuel cells10aNanoparticles10anitrogen-doped carbon10aoxygen reduction reaction1 aIllathvalappil, Rajith1 aKurungot, Sreekumar  uhttp://library.ncl.res.in/content/co-9-s-8-nanoparticle-supported-nitrogen-doped-carbon-robust-catalyst-oxygen-reduction02909nas a2200265   4500008004100000022001400041245014100055210006900196260000900265300001400274490000700288520197300295653001902268653002102287653002302308653002802331653002102359100002702380700002402407700002702431700002102458700001802479700002402497856012202521       2020                        eng d  a0947-653900aHierarchical nanoflower arrays of Co9S8-Ni3S2 on nickel foam: a highly efficient binder-free electrocatalyst for overall water splitting0 aHierarchical nanoflower arrays of Co9S8Ni3S2 on nickel foam a hi  cJUN   a7900-79110 v263 a<p>Hydrogen production is vital for meeting future energy demands and managing environmental sustainability. Electrolysis of water is considered as the suitable method for H-2 generation in a carbon-free pathway. Herein, the synthesis of highly efficient Co9S8-Ni3S2 based hierarchical nanoflower arrays on nickel foam (NF) is explored through the one-pot hydrothermal method (Co9S8-Ni3S2/NF) for overall water splitting applications. The nanoflower arrays are self-supported on the NF without any binder, possessing the required porosity and structural characteristics. The obtained Co9S8-Ni3S2/NF displays high hydrogen evolution reaction (HER), as well as oxygen evolution reaction (OER), activities in 1 m KOH solution. The overpotentials exhibited by this system at 25 mA cm(-2) are nearly 277 and 102 mV for HER and OER, respectively, in 1 m KOH solution. Subsequently, the overall water splitting was performed in 1 m KOH solution by employing Co9S8-Ni3S2/NF as both the anode and cathode, where the system required only 1.49, 1.60, and 1.69 V to deliver the current densities of 10, 25, and 50 mA cm(-2), respectively. Comparison of the activity of Co9S8-Ni3S2/NF with the state-of-the-art Pt/C and RuO2 coated on NF displays an enhanced performance for Co9S8-Ni3S2/NF both in the half-cell as well as in the full cell, emphasizing the significance of the present work. The post analysis of the material after water electrolysis confirms that the surface Co(OH)(2) formed during the course of the reaction serves as the favorable active sites. Overall, the activity modulation achieved in the present case is attributed to the presence of the open-pore morphology of the as formed nanoflowers of Co9S8-Ni3S2 on NF and the simultaneous presence of the surface Co(OH)(2) along with the highly conducting Co9S8-Ni3S2 core, which facilitates the adsorption of the reactants and subsequently its conversion into the gaseous products during water electrolysis.</p>
10acobalt sulfide10aelectrocatalysts10aHydrogen evolution10aoverall water splitting10aoxygen evolution1 aIllathvalappil, Rajith1 aWalko, Priyanka, S.1 aKanheerampockil, Fayis1 aBhat, Suresh, K.1 aDevi, Nandini1 aKurungot, Sreekumar  uhttp://library.ncl.res.in/content/hierarchical-nanoflower-arrays-co9s8-ni3s2-nickel-foam-highly-efficient-binder-free