Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A. This journal is The Royal Society of Chemistry 2017 Supporting information Table S1. Structural parameters of shell-by-shell fitting of the EXAFS spectrum for reduced and oxidized samples at room temperature (RT) Sample Shell N R/Å σ 2 R crys/ Å Pd/CeO 2 Reduced Pd-Pd 10.2±1.4 2.74±0.008 0.011±0.0008 2.75 (E 0 : -2.6, Red. χ 2 : 95.7) Pd-Pd 5±3.02 3.83±0.034 0.010±0.0033 3.89 Oxidized @ RT Pd-O 3.0±0.4 2.02±0.01 0.002±0.001 2.02 (E 0 : -1.7, Red. χ 2 : 83.3) Pd-Pd (Pd) 8.4±1.5 2.79±0.01 0.014±0.0012 2.75 Pd-Pd (PdO) 3.7±0.5 3.01±0.009 0.005±0.0006 3.04 Pd/MnO x-ceo 2 Reduced Pd-Pd 10.8±0.6 2.75±0.004 0.006±0.0003 2.75 (E 0 : -4.6, Red. χ 2 : 44.5) Pd-Pd 6.1±3.4 3.85±0.034 0.009±0.0035 3.89 Oxidized @ RT Pd-Pd 10.6±0.7 2.75±0.003 0.006±0.0003 2.75 (E 0 : -0.7, Red. χ 2 : 51.9) Pd-Pd 6.3±1.7 3.86±0.016 0.006±0.0016 3.89 R: Atomic distance, N: Coordination number, E 0 : Energy shift from the theoretical value, σ 2 : meansquare disorder. 1
Table S2. Structural parameters of shell-by-shell fitting of the EXAFS spectrum during He treatment and CO oxidation Sample Shell N R/Å σ 2 R crys/ Å Pd/CeO 2 He (E 0 : -2.5, Red. χ 2 : 82.3) Pd-O 4.3±0.4 1.99±0.006 0.004±0.0007 2.02 Pd-Pd 1.1±0.7 2.92±0.27 0.010±0.0048 3.04 Pd-Pd 2.9±0.6 3.36±0.01 0.006±0.0011 3.42 CO+O 2 @ RT (E 0 : 0.6, Red. χ 2 : 54.7) Pd-O 3.7±0.3 2.01±0.005 0.003±0.0006 2.02 Pd-Pd (Pd) 1.8±0.4 2.78±0.01 0.007±0.0013 2.75 Pd-Pd (PdO) 5.8±1.9 2.99±0.03 0.017±0.0033 3.04 Pd-Pd (PdO) 4.0±0.9 3.41±0.01 0.009±0.0015 3.42 @ 50 o C (E 0 : -4.1572, Red. χ 2 : 160.4) Pd-O 3.3±0.7 1.99±0.01 0.003±0.0016 2.02 Pd-Pd (Pd) 2.1±1.9 2.80±0.05 0.017±0.0069 2.75 Pd-Pd (PdO) 2.6±1.7 3.00±0.12 0.019±0.0156 3.04 Pd-Pd (PdO) 4.0±3.6 3.41±0.01 0.008±0.0056 3.42 @ 100 o C (E 0 : -3.6116, Red. χ 2 : 187) Pd-O 3.4±0.7 2.00±0.01 0.002±0.0015 2.02 Pd-Pd (Pd) 1.9±1.3 2.78±0.04 0.018±0.0062 2.75 Pd-Pd (PdO) 1.6±2.0 3.06±0.1 0.011±0.0058 3.04 Pd-Pd (PdO) 4.0±1.7 3.39±0.02 0.008±0.002 3.42 Pd/MnO x-ceo 2 He (E 0 : 0.6, Red. χ 2 :43.7) Pd-O 3.9±0.3 2.04±0.005 0.002±0.0006 2.02 Pd-Pd 4.1±0.4 3.06±0.006 0.006±0.0006 3.04 Pd-Pd 7.0±1.0 3.48±0.009 0.009±0.001 3.42 CO+O 2 @ RT (E 0 : 1.4, Red. χ 2 :61.2) Pd-O 3.6±0.2 2.05±0.004 0.001±0.0005 2.02 Pd-Pd 4.5±0.3 3.07±0.004 0.013±0.0021 3.04 Pd-Pd 6.8±1.2 3.49±0.012 0.009±0.0009 3.42 @ 50 o C (E 0 : 3.1, Red. χ 2 :166.3) Pd-O 3.4±0.5 2.06±0.010 0.002±0.0012 2.02 Pd-Pd 4.3±0.4 3.07±0.006 0.004±0.0006 3.04 Pd-Pd 6.1±2.4 3.5±0.026 0.013±0.0031 3.42 @ 100 o C (E 0 : 1.4, Red. χ 2 :61.7) Pd-O 3.9±0.4 2.04±0.007 0.003±0.0008 2.02 Pd-Pd 4.4±0.5 3.07±0.007 0.006±0.0007 3.04 Pd-Pd 7.0±1.6 3.47±0.016 0.011±0.0019 3.42 2
Counts (a.u.) X-ray Photoelectron Spectroscopy (XPS) Analysis XPS experiments were carried out on a Kratos Axid Ultra DLD XPS system equipped with a hemispherical energy analyzer. Spectra were collected using monochromatic Al Kα radiation at 1486 ev. All the spectra were calibrated to the adventitious carbon at 284.8 ev (C1s). PdO Pd/Al 2 O 3 Pd/CeO 2 Pd/MnO x -CeO 2 348 346 344 342 340 338 336 334 332 Binding Energy (ev) Figure S1. XPS analysis of Pd samples 3
Scanning Transmission Electron Microscopy (STEM) The high-resolution elemental mapping and imaging of particles were collected using a FEI Talos F200X STEM. ` Figure S2. STEM images and high-resolution elemental mapping of the calcined 1 wt% Pd/CeO2 4
Figure S3. STEM images (lower magnification) and high-resolution elemental mapping of the calcined 1 wt% Pd/MnOxCeO2 5
` Figure S4. STEM images (higher magnification) and high-resolution elemental mapping of the calcined 1 wt% Pd/MnOxCeO2 6
CO chemisorption experiments Palladium dispersion of the catalysts was carried out in the Micromeritics Auto Chem II 2920 apparatus with a thermal conductivity detector (TCD). All samples were reduced in a flow of 10% H2/Ar (50 ml/min) while ramping the temperature up to 150 o C at the rate of 10 o C/min, and then held at 150 o C for 2 h and then purged with pure Ar for 1 h before cooling to 40 o C in Ar. Afterwards loop gas of 10% CO/He was pulsed over the sample was recorded until the TCD signal peak area became stable. Pd dispersion was evaluated from the consumption of CO assuming that the ratio of CO: Pd = 1:1. The CO chemisorption experiment has been performed for two times and the results are shown in the Table S3. Table S3. Dispersion and particle size of Pd calculated from CO chemisorption experiments Dispersion (%) Size (nm) Pd/CeO2 65 1.7 48 2.3 Average 56.5 2 Pd/MnOx-CeO2 25 4.5 43 2.6 Average 34 3.55 7
Powder X-ray Diffraction (XRD) analysis Powder XRD data for samples were collected on a RigakuMiniflex II desktop diffractometer using a Cu Kα source with D/teX Ultra 250 silicon strip detector. The samples were reduced at 150 o C for 2 h and subsequently at 250 o C for additional 2 h. After reduction, the XRD profiles of the samples were collected. Figure S5. XRD analysis of reduced Pd-CeO2 and Pd-MnOx-CeO2 (Pd-MC) 8