XPS study of the SnO₂ films modified with Rh

Abstract

In this paper, we have analyzed the effect of the rhodium surface modification on the surface state of SnO2 films. SnO2 films, subjected for the surface modification, were deposited by spray pyrolysis, while Rh was deposited by using a microelectron beam evaporation. The thickness of the Rh coating varied in the range 0 to 0.1 monolayer. An explanation of the observed effects was proposed. Basing on the results of X‐ray photoelectron spectroscopy, it was assumed that at a small thickness of the rhodium covering, Rh was in a the well‐dispersed state, close to atomically dispersed state. The growth in the size of the nanoparticles began mainly when the thickness of the Rh covering exceeeded 0.01 monolayer. The size of clusters did not exceed 0.5 to 1.0 nm.

Quasi-Hexagonal to Lepidocrocite-like Transition in TiO2 Ultrathin Films on Cu(001)

“…Figure a reports the Ti 2p XPS region for the clean Cu(001) surface (bottom) and two different surface coverages (0.8 ML and 1.8 ML), showing the progressive increase in the Ti 2p signal. Figure b shows that the ratio between the areas of Ti 2p and Cu 2p signals increases linearly with the deposition time, suggesting that TiO 2 islands maintain a similar and uniform thickness during the film growth process, thus excluding a Volmer–Weber growth . The fit of the Ti 2p XPS spectrum reported in Figure c shows the main contribution (blue) at 459.2 eV attributable to Ti IV species .…”

“…Figure 1b shows that the ratio between the areas of Ti 2p and Cu 2p signals increases linearly with the deposition time, suggesting that TiO 2 islands maintain a similar and uniform thickness during the film growth process, thus excluding a Volmer−Weber growth. 36 The fit of the Ti 2p XPS spectrum reported in Figure 1c shows the main contribution (blue) at 459.2 eV attributable to Ti IV species. 37 Their relative spin−orbit coupling component (Ti 2p 1/2 ) is shifted by 5.7 eV in line with previous reports.…”

Characteristics of Copper and Tin-Based Rhodium Bimetallic Electrodes for Highly Selective Ammonia Yield in Electrochemical Denitrification

“…Increasing the degree of Rh coverage increased the metallic phase, in other words, the transition from state of Rh(III) to Rh(0) likely occurred in the Rh cluster. 34 The BE of Sn 3d 5/2 peak at 486.2 eV corresponded to an oxidized Sn(II) state on the RhSn/Ni electrode, 35 which was also ascribed to the thermodynamically spontaneous disproportionation of Sn by rhodium salt, i.e., 3Sn 0 + 2Rh 3+ + 6H 2 O ⇌ 3Sn(OH) 2 + 2Rh 0 + 6H + ; ΔG 0 = −479.6 kJ mol −1 (Figure 1k). When extending the Rh plating time to 10 min, a metallic Sn at 485 eV along with a shift of tin oxide to dioxide (Sn(IV) at 487.2 eV) implied an autocatalytic reduction of tin hydroxide, i.e., 2Sn(OH) 2 ⇌ Sn 0 + SnO 2 + 2H 2 O.…”

Rhodium as efficient additive for boosting acetone sensing by TiO2 nanocrystals. Beyond the classical view of noble metal additives

“…Much less attention has been paid to another noble metal group element such as rhodium. Only few examples are known of Rh addition to Ga2O3 [7], SnO2 [8,9], In2O3 [10], WO3 [11]. Interestingly, it has been recently pointed out [12,13] that the effectiveness of Rh addition is due to Fermi level control upon contact of SnO2, In2O3 and WO3 host with Rh nanoparticles oxidized to Rh2O3.…”