A novel Pt nanoparticle (Pt NP) embedded aminoclay/Nafion (Pt/AC/N) nanocomposite catalyst film was prepared for oxygen reduction reaction by sol-gel method. The prepared nanocomposite films were surface characterized using XRD and TEM and thermal stability was studied by TGA. The prepared film has firmly bound Pt NP and could exhibit an improved electro-reduction activity compared to vulcan carbon/Nafion supported Pt NP (Pt/VC/N). Moreover, the Pt/AC/N film possessed good stability in the acidic environment. The limiting current density of the Pt/AC/N film with 35.4 μg/cm(2) of Pt loading was found to be 4.2 mA/cm(2), which is 30% higher than that of the Pt/VC/N. The maximum H2O2 intermediate formation was found to be ∼1.6% and the reaction found to follow a four electron transfer mechanism. Accelerated durability test for 2000 potential cycles showed that ca. 78% of initial limiting current was retained. The results are encouraging for possible use of the Pt/AC/N as the free-standing electrocatalyst layer for polymer electrolyte membrane fuel cells.

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Pt 3 M (M: Co, Ni and Fe) bimetallic alloy nanoclusters were synthesized by a novel and simple chemical reduction approach, and employed as the promising electrocatalyst to accelerate the kinetics of oxygen reduction reaction (ORR) for polymer electrolyte membrane fuel cells. From XRD, the positive shift of diffraction angle confirms the alloy formation between Pt and M and the elemental composition was confirmed by energy dispersive X-ray spectroscopy analysis. The nanocluster morphology and particle size was determined using scanning and transmission electron microscopy analysis. The ORR kinetic parameters for Pt-M electrocatalysts were calculated and compared with reported Pt/C catalysts. Among the Pt-M electrocatalysts, Pt-Co was found to be the most efficient catalyst having the higher mass and specific activity (at 0.9 V vs. RHE) of 0.44 mA/μg and 0.69 mA/cm 2 , respectively. The accelerated durability test reveals that the Pt-M bimetallic alloy nanoclusters retain appreciable surface area and mass activity after 8000 potential cycles confirms good long-term durability, and also competing with the reported benchmark ORR catalysts.

Self-stabilized Pt–Rh nanoclusters (NCs) were prepared by formic acid reduction and used as the durable electrocatalyst for ORR.

Self-supported silver nanoflowers (AgNFs) and unmodified multi-walled carbon nanotube (MWCNT) supported silver nanostructures (Ag/MWCNT) were synthesized by an environmentally amicable slow chemical reduction method using ascorbic acid at room temperature. Structural morphologies were analyzed by scanning and transmission electron microscopic techniques and crystallinities were determined by X-ray diffraction method. Electrocatalytic activities for oxygen reduction reaction (ORR) were investigated for both Ag NF and Ag/MWCNT catalysts using cyclic voltammetry (CV) and linear sweep voltammetry (LSV). From CV profiles the electrochemically active surface areas of Ag NF and Ag/MWCNT were estimated to be 87.7 m2/g and 19.8 m2/g respectively. The LSV showed the maximum limiting current densities of 4.7 and 3.76 mA/cm2 at the electrode rotation rate of 2400 rpm with specific activities of 1.26 and 1.06 mA/cm2 measured at −0.1 V for Ag NF and Ag/MWCNT, respectively, confirmed their high ORR activities in 0.5 M KOH medium. Accelerated durability tests revealed that Ag/MWCNT possessed an excellent stability, that is, it has retained nearly 83% of its initial activity after 3000 potential cycles, which is much higher than modified MWCNT supported Ag catalyst reported in literature.