Abstract
The development of Pt-based atomic layer alloy and Pt-based single atom alloy (SAA) catalysts for oxygen reduction reaction (ORR) has received extensive attention. A comprehensive insight into how Pt distribution on nanoparticle surface affects ORR kinetics is still unclear. Here, we employ density functional theory calculation, current–potential polarization curve simulations and Wulff construction principle to study ORR on a series of Au@PtnL nanoparticles with diverse Pt loading from three atomic layers to dilute concentration of single-atom (n = 3, 2, 1, 1/4, 3/16, 1/8, 1/16). The ORR rate-determining step and activity of Au@PtnL nanoparticles can be described by a three-dimensional volcano plot spanned by the adsorption free energies of ΔG(O2*) and ΔG(OH*), where high density Pt SAA (Au@Pt1/4L) presents highest Pt atom catalytic efficiency. The simulations reveal that thinner Pt atomic layers on Au@PtnL possess higher d-band energy level due to stretch strain, leading the stronger OH* intermediate binding and suppressed protonation kinetics of OH*, in good agreement with available experimental data. When Pt atoms become isolated by Au host on Au@PtnL, Pt single-atom is converted into a free atom-like electronic structure due to the ligand effect of Au full coordination. A much narrower d band of Pt single-atom results in more filling of the σ* anti-bond, which brings about a much weakened OH* adsorption strength and superior ORR activity of Pt SAA. An excessive diluter concentration of Pt SAA suffers from declined ORR kinetics impeded by O2 adsorption as the rate-determining step. This work shed light on the adjustment mechanism of the coordination environment of Pt active sites on ORR activity and attributed it to a combined ligand effect and geometry strain effect, which provides guidance for the future engineering of Pt-based nanoparticles with high Pt atom catalytic efficiency.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
