Heterogeneous Assembly of Pt-Clusters on Hierarchical Structured CoOx@SnPd2@SnO2 Quaternary Nanocatalyst Manifesting Oxygen Reduction Reaction Performance
Rational design and synthesis of heterogeneous interfaces with tailored structural and functional properties are highly sought to realize green energy technologies. In the present study, quaternary metallic heterogeneous nanocatalysts (NCs) consisting of Pt-clusters decorated CoO2-SnPd2-SnO2 hierarchical structure (namely CSPP) are proposed with improved heteroatomic interactions for oxygen reduction reaction (ORR) in alkaline medium (0.1 M KOH). The CSPP NCs have been synthesized in different Pt contents (1, 2 and 14 wt.%) by using wet chemical reduction method on carbon nanotube (CNT) support with simultaneous heterogeneous and homogenous nucleation. Of special relevance, mass activity (MA) of CSPP-1 (~1.0 wt.% Pt) and CSPP-2 (~2.0 wt.% Pt) NCs is 2146.2 mAmg-1 and 1555.7 mAmg-1, which is ~32 and ~23-folds increased, respectively, as compared to that of commercial J.M.-Pt/C catalyst (20 wt.% Pt) at 0.85 V vs RHE. Through intensive analysis of microscopic and spectroscopic results, we demonstrated that such enhanced ORR activities for the ultra-low dosage of Pt are mainly dominated by incorporation of Pt atoms into defect sites of Co-Sn-Pd surface. These Pt-atoms lowering down the adsorption strength for oxygenated species via electron confinement from adjacent sites, resulting in enhanced splitting and relocation kinetics of subsequent oxygen molecules on NC surface and thus ORR performance.