Insights into formation of Pt species in Pt/CeO2 catalysts: Effect of treatment conditions and metal-support interaction

Fine-tuned local coordination environment of Pt single atoms on ceria controls catalytic reactivity

“…2c , the band below 400 nm on CeO 2 and Pt/CeO 2 -X catalysts (X = 550, 700, and 800) could be attributed to the charge transfer for O 2p → Ce 4f transition 42 . Interestingly, after the deposition of Pt, an additional strong absorption assigned to the absorption tail or Urbach tail was observed at 400–600 nm, which was related to the band gap smearing induced by defect accumulation 43 . For Pt/CeO 2 -X catalysts, such absorption tail could be due to the structural disorders induced by the highly dispersed Pt species.…”

“…The indirect band gap was also calculated by Davis and Mott equation for further understanding the interaction between Pt species and CeO 2 support within Pt/CeO 2 -X catalysts (Fig. 2d and Table 1 ) 43 , 47 . The band gap for Pt/CeO 2 -X catalysts was much lower than that for CeO 2 support (3.23 eV), indicating the insertion of metal levels between the valence and conduction bands of CeO 2 as well as the strong interaction through Pt–O–Ce linkage 48 .…”

Single‐Phase Formation of Rh2O3 Nanoparticles on h‐BN Support for Highly Controlled Methane Partial Oxidation to Syngas

“…The UV‐vis‐NIR spectra of Rh/h‐BN calcined at 300 °C for 5 h showed two absorption bands centered at 320 and 450 nm corresponding to the allowed transitions 1 A 1g → 1 T 1g and 1 T 2g of the Rh 3+ species [29] . These bands exhibited an evident red‐shift, and the overall absorption intensity monotonously increased at elevated calcination temperatures, implying the incorporation of density of states between the valence and conduction bands of h‐BN due to enhanced Rh 2 O 3 and h‐BN interactions [30] . The rhodium oxide species in Rh/h‐BN, which were calcined at various temperatures for a short time (1 min), showed a negligible change in their Rh−O bond strength and their interaction with h‐BN (Figure S14 and Figure S15).…”

Single‐Phase Formation of Rh2O3 Nanoparticles on h‐BN Support for Highly Controlled Methane Partial Oxidation to Syngas

“…[29] These bands exhibited an evident red-shift, and the overall absorption intensity monotonously increased at elevated calcination temperatures,i mplying the incorporation of density of states between the valence and conduction bands of h-BN due to enhanced Rh 2 O 3 and h-BN interactions. [30] Ther hodium oxide species in Rh/h-BN,w hich were calcined at various temperatures for as hort time (1 min), showed an egligible change in their RhÀOb ond strength and their interaction with h-BN (Figure S14 and Figure S15). This implies that there is aprerequisite step for inducing stronger interactions between the Rh 2 O 3 and h-BN supports.T his can be attributed to the formation of oxidized boron species by the desorption of terminal BÀOH and BÀNH 2 groups from h-BN for bonding to rhodium species,a sc onfirmed by in situ DRIFT and XPS analyses (Figure S16 and Figure S17).…”