In situ X‐ray Absorption Spectroscopy of Platinum Electrocatalysts

Abstract

Platinum nanocatalysts have shown high performance in a wide variety of electrocatalytic reactions, making them the focus of many studies. High quality characterization results are vital for the proper understanding of a catalyst's structure and properties, allowing for further discoveries to be made. X-ray absorption spectroscopy is a powerful characterization tool, permitting both the local structure and electronic properties to be determined for a sample of interest. This can be taken further by collecting in situ measurements, which offer the unique advantage of characterization results collected in real-time while the catalytic reaction is taking place. This review summarizes recent studies which utilized in situ X-ray absorption spectroscopy to characterize platinum nanocatalysts, highlighting the important structural parameters and electronic properties determined under the real catalytic reaction conditions. Specific examples of catalysts for use in the oxygen reduction reaction, chlorine evolution reaction, and carbon monoxide oxidation are discussed in detail. Future prospects for work in this field are also highlighted and discussed.

Isolated PdO sites on SiO2-supported NiO nanoparticles as active sites for allylic alcohol selective oxidation

“…S8, † confirms NiO as the species in our catalyst, however, overlaying the XANES region shows a more intense white line for NiO@PdO/SiO 2 relative to NiO (with the opposite observed at the Pd K edge). As Ni K-edge white line intensity inversely correlates to the degree of occupancy of the Ni 3d orbitals, 37 this increase in intensity reflects a greater degree of unoccupancy in the Ni 3d orbitals, due to the great electronegativity of Pd (2.2 vs. 1.9), which is consistent with the slightly lower than expected binding energy reported by XPS. This electron transfer between the two metals further confirms direct interaction, i.e., co-location within a single NP, while simultaneously accounting for the fit returning a small degree of Pd metal in the LCF analysis of the Pd K edge XANES.…”

Highly Dispersed Platinum Chlorine Atoms Anchored on Gold Quantum Dots for a Highly Efficient Electrocatalyst

“… Density functional theory density of states (DOS) calculations and XPS measurements were performed for the valence band to illustrate the electronic effect of individual atom formation on catalytic activity. It is worth noting that the near-Fermi level DOS in XPS valence states is highly sensitive to the local structure environment of Pt. , The intensity of the DOS near the Fermi level was determined in both chemical bonding and the kindred nearest-neighbor atom . Compared with Pt foil (Figure d), the intensity of individual Pt–Cl 2 species of PtCl 2 Au­(111)/GDY shows a dramatic decrease (−2 to 0 eV) near the Fermi level.…”

“…It is worth noting that the near-Fermi level DOS in XPS valence states is highly sensitive to the local structure environment of Pt. 10,36 The intensity of the DOS near the Fermi level was determined in both chemical bonding and the kindred nearest-neighbor atom. 35 Compared with Pt foil (Figure 2d), the intensity of individual Pt−Cl 2 species of PtCl 2 Au(111)/GDY shows a dramatic decrease (−2 to 0 eV) near the Fermi level.…”

Beginner's Guide to Raman Spectroelectrochemistry for Electrocatalysis Study

“…Understanding electrochemical processes under operating conditions requires coupling electrochemical cells with characterization methods, and the choice of technique depends on the regions of interest and the desired information. [2][3][4] For example, surface probe microscopies, such as atomic force microscopy (AFM) and scanning tunneling microscopy (STM), can provide real-time morphological details on the electrode surface; [5][6] X-ray related technologies (X-ray diffraction: XRD; Xray absorption spectroscopy: XAS; X-ray photoelectron spectroscopy: XPS) can reveal the structure and surface electronic properties; [7][8][9] mass spectroscopy can detect the electrochemically generated intermediates and products. [10] One family of the in situ technologies with particular interest is spectroelectrochemistry, which combines electrochemical studies with spectroscopic methods, such as UV-vis and infrared.…”