Single-atom Catalysis Using Pt/Graphene Achieved through Atomic Layer Deposition

Abstract

Platinum-nanoparticle-based catalysts are widely used in many important chemical processes and automobile industries. Downsizing catalyst nanoparticles to single atoms is highly desirable to maximize their use efficiency, however, very challenging. Here we report a practical synthesis for isolated single Pt atoms anchored to graphene nanosheet using the atomic layer deposition (ALD) technique. ALD offers the capability of precise control of catalyst size span from single atom, subnanometer cluster to nanoparticle. The single-atom catalysts exhibit significantly improved catalytic activity (up to 10 times) over that of the state-of-the-art commercial Pt/C catalyst. X-ray absorption fine structure (XAFS) analyses reveal that the low-coordination and partially unoccupied densities of states of 5d orbital of Pt atoms are responsible for the excellent performance. This work is anticipated to form the basis for the exploration of a next generation of highly efficient single-atom catalysts for various applications.

Influence of Carbon Support on Electronic Structure and Catalytic Activity of Pt Catalysts: Binding to the CO Molecule

“…4 Using X-ray absorption fine structure analyses, they showed that the low-coordination and partially unoccupied densities of states of the Pt 5d orbitals are responsible for the excellent performance. Therefore, CO adsorption energy on atom-type Pt catalysts is generally greater than that on Pt particles and their corresponding extended surfaces.…”

“…Single atom catalysts, by providing single active sites at the solid surface, exhibit many fascinating characteristics, such as high activity, selectivity, and maximum atomic utilization as compared to conventional metal catalysts. [4][5][6] In a Pt/C catalyst, the carbon support plays an important role in determining the size and degree of catalyst dispersion. Due to high surface-to-volume ratio (theoretical value of 2630 m 2 /g), graphene is a promising candidate as a substrate for stabilizing metal nanoparticles in heterogeneous catalysis.…”

A highly active, stable and synergistic Pt nanoparticles/Mo2C nanotube catalyst for methanol electro-oxidation

“…It is generally understood that the anodic peak in the reverse scan to be linked to the removal of incompletely oxidized carbonaceous species accumulated on the catalyst surface during the forward anodic scan. 2,36 CO is an intermediate species of methanol oxidation and can poison the Pt catalyst, leading to a lower fuel cell potential and energy conversion efficiency. 2 Therefore, the ratio of the forward anodic peak current density to the backward anodic peak current density (I f /I b ) can be used to indicate the CO tolerance of the catalyst.…”

“…2,36 CO is an intermediate species of methanol oxidation and can poison the Pt catalyst, leading to a lower fuel cell potential and energy conversion efficiency. 2 Therefore, the ratio of the forward anodic peak current density to the backward anodic peak current density (I f /I b ) can be used to indicate the CO tolerance of the catalyst. [36][37][38][39] A low I f /I b value usually indicates poor oxidation of methanol to CO 2 during the forward anodic scan and excessive accumulation of residual carbon species (for example, CO) on the catalyst surface.…”

“…[1][2][3] Despite these advantages, a few technological obstacles remain to be circumvented before commercial applications can be achieved. One main challenge is the poor electrocatalytic activity in the methanol oxidation reaction (MOR); another is the occurrence of serious carbon monoxide (CO) poisoning at the anode of the Pt catalyst.…”