X‐ray photoelectron spectroscopy study of neodymium niobate and tantalate precursors and thin films

Abstract

Neodymium niobate NdNbO4 (NNO) and tantalate NdTaO4 (NTO) thin films (~100 nm) were prepared by sol‐gel/spin‐coating process on Al2O3 substrate with LaNbO4/PbZrO3 interlayer and annealing at 1000°C. Surface chemistry was investigated by X‐ray photoelectron spectroscopy (XPS). The core‐level XPS studies of sol‐gel NNO and NTO were performed for the first time. The binding energy differences Δ(O―Nb) and Δ(O―Ta) were used to characterize average energies of Nb―O bonding in NNO (322.9 eV) and Ta―O bonding in NTO (504.2 eV). The XPS demonstrated single valence state of Nd (Nd3+) in precursors. Nd concentration (at. %) decreases from 22% in precursors to 7% in films considering the substrate contains C, Al, Si, Pb, and Zr elements (37%) at Nb or Ta (5%) and O (51%). The X‐ray diffraction analyses verified formation of the monoclinic (M‐NdNbO4 or M′‐NdTaO4), orthorhombic (O‐NdNbO4) and tetragonal (T‐NdTaO4) phases in precursors and films. Single valence state of Nd3+ was confirmed in these films designed for the application in environmental electrolytic thin film devices.

Electrochemical Performance Evaluation of Bimetallic Sulfide Nanocomposite with Fullerene (CeNdS/C60) for Efficient Oxygen Evolution Reaction (OER)

“…The peak fitting in the 982 eV peak yielded two peaks reduced at BE values of 977 and 973 eV, showing the presence of electron-rich states of Nd ions in the CeNdS-C 60 nanobased sulfide structure. The peak of Nd 3d 3/2 at BE ≈ 1004 eV is associated with the orbital of trivalent neodymium. , The appearance of the weak or broad peak in Figure b spectrum, leading toward the Nd 4d doublet signal, is positively varied from metallic Nd 0 (118 eV, chemical state) to 122 eV BE, which ascribed the characteristic peak of Nd–S. This peak presence showed the decreased electron density of Nd–S in the catalyst sample. − …”

“…The peak of Nd 3d 3/2 at BE ≈ 1004 eV is associated with the orbital of trivalent neodymium. 59,60 The appearance of the weak or broad peak in Figure 3b spectrum, leading toward the Nd 4d doublet signal, is positively varied from metallic Nd 0 (118 eV, chemical state) to 122 eV BE, which ascribed the characteristic peak of Nd−S. This peak presence showed the decreased electron density of Nd−S in the catalyst sample.…”

Mesoporous RE0.5Ce0.5O2–x Fluorite Electrocatalysts for the Oxygen Evolution Reaction

“…The presence and bonding state of Nd in Nd 2 Ce 2 O 7 was confirmed from the high-resolution Nd 3d spectra shown in Figure S5b, which displayed two doublets at 977.8 and 982.3 eV, corresponding to a satellite and Nd(VI) of 3d 5/2 , as well as at 1000.1 and 1004.7 eV, corresponding to a satellite and Nd(III) of 3d 3/2 . , The 4d spectra (Figure S5c) exhibited 121.1 and 124.3 eV peaks, associated with a satellite and 4d in oxides…”

“…35,36 The presence and bonding state of Nd in Nd 2 Ce 2 O 7 was confirmed from the high-resolution Nd 3d spectra shown in Figure S5b, which displayed two doublets at 977.8 and 982.3 eV, corresponding to a satellite and Nd(VI) of 3d 5/2 , as well as at 1000.1 and 1004.7 eV, corresponding to a satellite and Nd(III) of 3d 3/2 . 37,38 The 4d spectra (Figure S5c) exhibited 121.1 and 124.3 eV peaks, associated with a satellite and 4d in oxides. 39 XPS analysis of Tb 2 Ce 2 O 7 from the high-resolution Tb 3d spectrum (Figure S6b) confirmed the presence of Tb(IV), as indicated by the observed characteristic doublet peaks of 3d 5/2 and 3d 3/2 , along with their corresponding satellites at 1241.0, 1276.0, 1251.4, and 1287.0 eV, respectively.…”

Tailored (La0.2Pr0.2Nd0.2Tb0.2Dy0.2)2Ce2O7 as a Highly Active and Stable Nanocatalyst for the Oxygen Evolution Reaction

“…Doping CeO 2 with (mainly) lower valent RE 3 + cations such as Pr, Nd, Dy, and La is known to depress the concentration of Ce 3 + and introduce large amounts of oxygen vacancies resulting in a defect fluorite structure. [14,15,[29][30][31][32] Here, we again use a soft templating evaporation induced selfassembly approach (EISA) to synthesize OER fluorite catalysts with high surface area, porosity/nanoarchitecture, and varying degrees of compositional complexity, with the objective of increasing the number of exposed active sites and improving mass diffusion kinetics. [5] Furthermore, EISA is an inexpensive, highly tunable, and easily scalable synthesis approach, making it feasible for industrial manufacturing.…”