Molecular-Level Insight into Selective Catalytic Reduction of NO x with NH 3 to N 2

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1 Supporting Information Molecular-Level Insight into Selective Catalytic Reduction of NO x with to N 2 over Highly Efficient Bifunctional V a Catalyst at Low Temperature Ying Xin, Hao Li, Nana Zhang, Qian Li, Zhaoliang Zhang,*, Xiaoming Cao,*, P. Hu, Lirong Zheng, and James A. Anderson*, School of Chemistry and Chemical Engineering, Shandong Provincial Key Laboratory of Fluorine Chemistry and Chemical Materials, University of Jinan, Jinan , China Centre for Computational Chemistry and Research Institute of Industrial Catalysis, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai , China Institute of High Energy Physics, Chinese Academy of Sciences, Beijing , China Surface Chemistry and Catalysis Group, Materials and Chemical Engineering, University of Aberdeen, AB24 3UE, United Kingdom *Corresponding authors: Zhaoliang Zhang: chm_zhangzl@ujn.edu.cn Xiaoming Cao: xmcao@ecust.edu.cn James A. Anderson: j.anderson@abdn.ac.uk S1

2 Figure S1 (a) Normalized absorption (a.u.) Mn K-edge Mn(CH 3 COO) 2 V V 0.03 Mn foil Energy (ev) (b) Mn K-edge FT magnitude (a.u.) V V R (Å) Figure S1. Normalized XANES spectra (a) and the RSF curves (b) of Mn K-edge for V a and the reference samples. S2

3 Figure S2 + Intensity (a.u.) V 0.07 V Raman shift (cm -1 ) Figure S2. Raman spectra of of,, + and V a catalysts. S3

4 Figure S3 (a) p + Intensity (a.u.) V 0.07 V 0.03 (b) p Binding energy (ev) Intensity (a.u.) + V 0.07 V 0.03 (c) Binding energy (ev) O 1s O β O α + Intensity (a.u.) O α O β V 0.07 O β O α V Binding energy (ev) Figure S3. XPS spectra of (a) p, (b) p, (c) O 1s of,, +, and V a catalysts. S4

5 Figure S4 * * * * * * (JCPDS ) Mn2 (JCPDS ) * * * Intensity (a.u.) V 0.03 V θ ( o ) Figure S4. XRD patterns of,, + and V a after SCR reactions. S5

6 Figure S5 # Mn O 4 PDF# * MnO PDF# Intensity (a.u.) # # # # # # # θ ( o ) Figure S5. The corresponding XRD patterns after H 2 -TPR test over, and. S6

7 Figure S6 (a) 0.05 (b) 0.05 Absorbance (a.u.) He-purge-250 o C He-purge-200 o C He-purge-180 o C He-purge-150 o C He-purge-120 o C He-purge-80 o C He-purge-50 o C He-purge-RT -30 m -20 m -10 m -5 m -3 m -2 m -1 m He pretreatment Absorbance (a.u.) He-purge-RT -30 m -20 m -10 m -5 m m m m He pretreatment He-purge-250 o C He-purge-200 o C He-purge-180 o C He-purge-150 o C He-purge-120 o C He-purge-80 o C He-purge-50 o C Wavenumber (cm -1 ) Wavenumber (cm -1 ) Figure S6. In situ IR spectra ( cm -1 ) of adsorption at steady-state over (a) and (b). S7

8 Figure S7 Mo m-he Absorbance (a.u.) -30 m -15 m -10 m -5 m -3 m -2 m -1 m He pretreatment Wavenumber (cm -1 ) Figure S7. In situ IR spectra of steady-state adsorption at room temperature on Mo +. S8

9 Figure S8 (a) V o C o C (b) V o C o C Absorbance (a.u.) o C o C o C m m - -5 m Absorbance (a.u.) o C o C o C m m m -He He pretreatment m -He He pretreatment Wavenumber (cm -1 ) Wavenumber (cm -1 ) Figure S8. In situ IR spectra of surface reactions between (a) pre-adsorbed and, and (b) pre-adsorbed and over. In Figure S8a, after pre-adsorbing, both NH + 4 (1440 cm -1 ) and coordinated species (1178 cm -1 ) were detected. After purging, the was introduced. A new band at 1325 cm -1 was detected. After heating over 50 o C, this band rapidly disappeared indicating the low stability. Similarly, in Figure S8b, the special band at 1327 cm -1 was also detected after introduction of to the pre-adsorbed sample. After heating over 50 o C, this band disappeared. S9

10 Figure S9 Figure S9. The bulk structure of α- (a) and top (b1) and side (b2) views of the α- (202) surface. The Mn and O atoms are displayed in purple and red, respectively. This notation will be used throughout the paper. The optimized α- (202) surface is displayed in Figure S9. The exposed Mn-O layer is shown in ball and stick styles and the others are shown in line style. Different exposed 4-fold and 5-fold coordinated Mn cations and two-fold and three-fold O anions in one unit cell are labeled as Mn I 4c, Mn II I 4c, Mn 5c, Mn II I 5c, O 2c, O II I 2c, c, O II 3c, c and O IV 3c, respectively. These illustrations are utilized throughout this paper for the results over α- (202). III, S10

11 Figure S10 Figure S10. The bulk structure of along [001] (a1) and [010] views (a2), top (b1, c1) and side (b2, c2) views of (2 01)-A (b1, b2) and (2 01)-B (c1, c2) surfaces. The Mn, V and O atoms are displayed in purple, grey and red, respectively. The only difference between (2 01)-A and (2 01)-B terminals is the existence of the exposed one-fold coordinated O 1c which is shown in pink at the (2 01)-A surface. During the preparation and reaction conditions, the surface energy of (2 01)-A is less than (2 01)-B. Hence, (2 01)-A terminal is exposed during the reaction. We refer to (2 01)-A as (2 01) hereinafter. For the (2 01) surface, the exposed Mn-V-O layer is shown in ball and stick style and the others are shown in line style. Different exposed Mn cations, V cations and O anions are labeled. These illustrations are utilized throughout this paper for the results over (2 01). S11

stable adsorption configurations of at the

Brønsted acid site (c2) and NO over (2 01)

12 Figure S11 Figure S11. Top and side (inset) views of the most stable adsorption configurations of at the Lewis acid site of the Mn cation (a1), at the Brønsted acid site (a2) and NO over (202) (b); Top and side (inset) views of the most stable adsorption configurations of at the Lewis acid site (c1), at the Brønsted acid site (c2) and NO over (2 01) (d). S12

13 The considerations for choosing the (202) and (201) facets for and, respectively, for DFT calculations. The first reason why we selected (202) and (2 01) does be based on the exposed surfaces found at our HRTEM images. Generally speaking, the thermodynamically unstable surfaces with many defect sites are really likely to be active enough to chemisorb the reactants such as strongly while these surfaces might be hard to be exposed without specially facet-controlled synthesis. Thus, even though it possessed high activity, this would become insignificant. Hence, we investigated the activity on these possibly exposed facets. Second, we also utilized PBE+U calculations to compare the adsorption energies of on reported possible facets of the prepared catalysts. For, the (001) surface with 4-fold coordinated Mn cations and the (111) surface with 5-fold coordinated Mn cations [Cheng et al. Appl. Catal. B: Environ. 2017, 204, 374] are chosen (Figure S12). The energy barriers of and NH 2 NO dehydrogenation step on (110) which was reported as one dominant crystal surface of in Ref. [Zhou et al. Chin. Phys. B 2009, 18, 5055] were also investigated. The related results and geometry structures on these surfaces were included as follows. The chemisorption energies for are 1.32 ev and 0.79 ev on (001) and (111), respectively. The results over (001) almost equal to (202) suggesting the presence of 4-fold coordinated Mn cations is important for the adsorption. The dehydrogenation barrier is as high as 1.37 ev, while the NH 2 NO dehydrogenation barrier is 0.77 ev over the (110) surface as well (Figure S13). This suggests that the performance of (2 01) is even prior to (110) once the formed NH * 2 catalyzed by migrates to. S13

14 Finally, the DFT calculations about adsorption on these exposed surfaces are really in good agreement with our IR characterization. The Lewis acid sites and negligible Brønsted acid sites characterized in could respectively correspond to the 4-fold coordinated Mn cations and the absence of one-fold coordinated oxygen anions at the surface. It is consistent with the characteristic of the (202) surface. The weaker Lewis acid sites and stronger Brønsted sites could be found at, suggesting the higher coordinated Mn cations and one-fold coordinated oxygen anions exist at the catalyst surfaces. It is also consistent with the characteristic of the (2 01) surface. Hence we think the DFT calculation results on the chosen exposed surfaces are typical for two materials, which can elucidate the mechanism of bifunctional V a materials to selectively catalyze NO x with to N 2. S14

15 Figure S12 (001) (111) Figure S12. Side views of the most stable adsorption configurations of over the Lewis acid site of 4-fold coordinated Mn cations at (001) and 5-fold coordinated Mn cations at (111). The chemisorption energies for are respectively 1.32 ev and 0.79 ev on (001) and (111). S15

16 Figure S13 -H NH 2 NO-H Figure S13. Top views of the transition state of and NH 2 NO dehydrogenation over (110). The energy barriers for and NH 2 NO dehydrogenation are respectively 1.37 and 0.77 ev. S16

17 Table S1. Adsorption energies of a or NO molecule on (202) and (2 01) surfaces. Adsorption energy (ev) Surface at Lewis acid site at Brønsted acid site NO PBE+U HSE06 PBE+U HSE06 PBE+U HSE06 (202) (2 01) S17

Supporting information. Active site identification and modification of electronic states by atomic-scale. doping to enhance oxide catalyst innovation

Supporting information. Active site identification and modification of electronic states by atomic-scale. doping to enhance oxide catalyst innovation Supporting information Active site identification and modification of electronic states by atomic-scale doping to enhance oxide catalyst innovation Ying Xin, Nana Zhang, Qian Li, Zhaoliang Zhang,*, Xiaoming