Abstract
Polygonal Pt nanoparticles were synthesized using ultrasonic spray pyrolysis (USP) at different precursor concentrations. Physicochemical analysis of the synthesized Pt particles involved thermogravimetric, microscopic, electron diffractive, and light absorptive/refractive characteristics. Electrochemical properties and activity in the oxygen reduction reaction (ORR) of the prepared material were compared to commercial Pt black. Registered electrochemical behavior is correlated to the structural properties of synthesized powders by impedance characteristics in ORR. The reported results confirmed that Pt nanoparticles of a characteristic and uniform size and shape, suitable for incorporation on the surfaces of interactive hosts as catalyst supports, were synthesized. It is found that USP-synthesized Pt involves larger particles than Pt black, with the size being slightly dependent on precursor concentration. Among ORR-active planes, the least active (111) structurally defined the synthesized particles. These two morphological and structural characteristics caused the USP-Pt to be made of lower Pt-intrinsic capacitive and redox currents, as well as of lower ORR activity. Although being of lower activity, USP-Pt is less sensitive to the rate of ORR current perturbations at higher overpotentials. This issue is assigned to less-compact catalyst layers and uniform particle size distribution, and consequently, of activity throughout the catalyst layer with respect to Pt black. These features are considered to positively affect catalyst stability and thus promote USP synthesis for improved properties of host-supported Pt catalysts.
Highlights
There are numerous contemporary studies dealing with the catalytic improvements of energetics-important electrochemical processes such as hydrogen evolution (HER) and the reduction and oxidation of oxygen or small organic molecules [1]
It is found that ultrasonic spray pyrolysis (USP)-synthesized Pt involves larger particles than Pt black, with the size being slightly dependent on precursor concentration
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Summary
There are numerous contemporary studies dealing with the catalytic improvements of energetics-important electrochemical processes such as hydrogen evolution (HER) and the reduction and oxidation of oxygen or small organic molecules [1]. Investigations into oxygen reduction reaction (ORR) kinetics are of the highest interest due to the ORR rate-determining characteristics for energy conversion in fuel cells (FCs) and metal–air batteries (M-O2) [2,3,4,5]. The meeting point of FCs and M-O2 (involving alkaline metal–air batteries, such as Li-O2 and Na-O2) clearly exists on the cathode side – in both FC and M–O2, the electrons for anodic oxidations are provided by ORR at the cathode [6]. New modifications of morphology and/or electronic structures of transition metal-based catalysts have offered multifunctional solutions in energy storage and conversion as well as in demanded water electrolysis applications [9]. Among various electrode materials and catalysts, such as nanostructured metals, metal oxides, hydroxides, phosphides, and chalcogenides, Pt-based catalysts are still at the forefront owing to their high activity with acceptable stability and slow chemical degradation [10,11]
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