Gold catalysts supported on Y-modified ceria for CO-free hydrogen production via PROX

Au/TiO2-CeO2 Catalysts for Photocatalytic Water Splitting and VOCs Oxidation Reactions

“…The Au/TiO 2 sample (red line) showed the same bands of bare TiO 2 (black line). In the TiO 2 -10%CeO 2 sample (green line) the signal at 466 cm´1 was associated with the cubic phase of the CeO 2 fluorite [52][53][54] and the small component at 600 cm´1 was assignable to intrinsic O vacancies in ceria as a result of its non-stoichiometric composition due to the presence of Ce 3+ in the lattice [54,55]. Interestingly, over the Au/TiO 2 -10%CeO 2 sample, the peak associated with cubic CeO 2 was less intense, broader and shifted to lower frequencies compared to over the TiO 2 -10%CeO 2 sample (Figure 3b, orange and green lines, respectively).…”

“…This can be related to the replacement of Ti 4+ cations by Ce 4+ or Ce 3+ cations in the TiO 2 network [51,54,58]. Moreover, looking at the DRS spectra of the investigated samples in the visible region ( Figure 5), it can be seen that all gold-loaded samples (Au/TiO 2 , Au/CeO 2 and Au/TiO 2 -10%CeO 2 ) exhibit a clear absorbance band at around 550 nm, attributed to the plasmon resonance of gold nanoparticles [59].…”

Gold Catalysts on Y-Doped Ceria Supports for Complete Benzene Oxidation

“…On the basis of a combined density functional and IR spectroscopy investigation, the authors reported a stronger carbonate bond with the ceria surface having oxygen vacancies as compared to the surface free of vacancies. In our study, vacancy formation is caused by Y 3+ -doping; moreover, the vacancy generation by IM is mainly at the surface because this method of support preparation leads to the predominant surface modification of ceria [15]. The obtained TGA/QM data of the CO2 evolution could satisfactorily explain why the air treatment at 200 °C is enough for the cleaning of carbonates of the bare ceria surface but in the case of Y-doping a better effect appears after heating at the higher temperature.…”

“…The X-ray diffractograms of all catalysts ( Figure 4, upper section) were similar, showing only the diffraction lines of the cubic crystal structure of ceria and very weak reflections at 2Θ = 38.2˝, typical of metallic Au (1 1 1). A second phase of Y 2 O 3 was not visible; however, the presence of Y 2 O 3 crystals not detectable by XRD for the IM-prepared supports was evidenced by measuring the interplanar distances in selected HRTEM images [15]. The estimated average size of ceria crystallites was in the range of 4-8 nm (Table 1), without a clear dependence on the support preparation method and the Y amount.…”

“…Gold over undoped CeO 2 was used as a reference. Very recently, the catalytic performance in the preferential CO oxidation in the H 2 reach stream (PROX) was studied over this type of gold catalyst [15]. In order to avoid the ordering of oxygen vacancies established in the literature for heavy yttrium doping ( [16][17][18] and references therein), a low-extent Y modification of ceria (up to 7.5 wt.…”