A unique approach to designing resilient bi-functional nano-electrocatalysts based on ultrafine bimetallic nanoparticles dispersed in carbon nanospheres

By Nandan, Ravi; Nanda, K. K.
Published in J. Mater. Chem. A 2017

Abstract

Activity and stability are the key issues for any catalyst. Importantly, the synthesis of catalysts should be facile. Here, we report one-step facile electroless synthesis of ultrafine bimetallic PdPt nanoparticles ([similar]2 nm) dispersed in hetero-atom doped hollow carbon nanospheres (HCNSs) and PdPt nanoparticles in carbon nanostructures (CNSs) as highly active and stable electrocatalysts for electro-oxidation/-reduction of low molecular weight alcohols such as methanol and ethanol/of oxygen. HCNSs inhibit some of the electrochemical degradation pathways such as migration, agglomeration, isolation and detachment of nanoparticles. The superior mass activity of ultrafine PdPt nanoparticles for methanol/ethanol electro-oxidation (12-/8-fold), excellent operational stability, and high Jf/Jb ratio over commercially available state-of-the-art Pt-C (20 wt%) make them a potential fuel cell anode catalyst. The activity is further improved when PdPt-HCNS and PdPt-CNS are taken together suggesting a synergistic effect. Further, oxygen reduction reaction (ORR) study with embedded nanostructures exhibits a positive ORR peak potential, positive on-set potential ([capital Delta]Eon-set [similar] -50 mV) & half-wave potential ([capital Delta]E1/2 [similar] -25 mV), low Tafel slope (53 mV dec-1), enhanced current density and superior stability compared to that of Pt-C along with preferential 4e- ORR pathways. Overall, the catalyst reported here is a potential anode and cathode catalyst for direct alcohol alkaline as well as hydrogen fuel cells.

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