Impact of the Coordination Environment on Atomically Dispersed Pt Catalysts for Oxygen Reduction Reaction

Abstract

Because of the structural complexity and inhomogeneity, the effect of the coordination environment on the catalytic properties is underexplored in heterogeneous catalytic systems. To address this challenge, the atomically dispersed Pt is anchored on two Mo-based supports with similar morphology and particle size, that is, face-centered cubic-structured α-MoC and MoN. Spectroscopic and computational investigations demonstrate that the Pt atoms are coordinated with N atoms in Pt/MoN but with Mo atoms in Pt/α-MoC, leading to an entirely different catalytic performance in the oxygen reduction reaction (ORR). The Pt mass activity for Pt/MoN reaches 0.71 A/mg Pt at 0.9 V [vs reversible hydrogen electrode (RHE)], which is 15 times higher Pt mass activity than that of Pt/α-MoC. Density functional theory calculations correlate the better ORR performance of Pt/MoN with the weaker adsorption of OH* because of the modulation of electronic properties of Pt by the coordination with N atoms. This study highlights the importance of controlling the coordination environment of metal atoms in heterogeneous (electro)catalysis and suggests that tuning the coordination environment could be an effective strategy in catalyst development.

Recent Advances in Plasmonic Nanostructures for Enhanced Photocatalysis and Electrocatalysis

“…ORR is of great importance in multiple applications including fuel cells and metal–air batteries, which can be realized via a two‐electron pathway to produce H 2 O 2 or a four‐electron pathway to generate H 2 O. [ 163–168 ] As mentioned in Section 3.2, plasmonic metals such as Au, Ag, and Cu are able to activate O 2 through the hot electron excitation mechanism and further catalyze alkenes epoxidation reaction. Therefore, although the coinage metals are predicted to exhibit poor ORR activity, [ 169 ] introduction of light illumination is expected to make a difference.…”

Microenvironment modulation of single-atom catalysts and their roles in electrochemical energy conversion

“…The ORR follows either a two-electron (2 e − ) or four-electron (4 e − ) pathway, desirable for H 2 O 2 production or fuel cell, respectively, which has been found to depend mainly on the microenvironments of SACs. For instance, the S-coordinated single–Pt atom site (PtS 4 ) was determined to catalyze the ORR via the 2 e − pathway ( 76 ), while C-coordinated and N-coordinated single–Pt atom sites preferred the 4 e − reaction pathway ( 77 – 79 ). In the work conducted by Li et al .…”

“…In the work conducted by Li et al . ( 79 ), Pt 1 /α-MoC and Pt 1 /MoN SACs, with atomically dispersed Pt atoms anchored on α-MoC and MoN, respectively, were synthesized to study the effect of coordination environment of Pt atoms for ORR. As shown in Fig.…”

“… ( A ) Single–Pt atom catalysts supported on α-MoC and MoN for ORR, adapted with permission from Li et al . ( 79 ). ( B ) Optimized structures of single Pt atom anchored on pristine graphene (g), monovacancy graphene (g-1), and divacancy graphene (g-2), together with the associated free energy diagram for ORR, adapted with permission from Liu et al .…”

Structural Regulation and Support Coupling Effect of Single‐Atom Catalysts for Heterogeneous Catalysis

“…Furthermore, Ma and co-workers came up with a topochemical transformation strategy for tuning the coordination environment on atomically dispersed Pt catalysts, resulting in an entirely different ORR performance. [99] The single Pt atom coordinated with N on the MoN support (Pt/MoN) exhibits 15 times higher Pt mass activity than that of Pt/α-MoC in which the Pt atom is coordinated with Mo atoms (Figure 5h). The authors attributed the enhanced ORR activity to the unique Pt-N configuration in Pt/ MoN yielding a weaker adsorption of the *OH intermediates.…”