SUPPORTING INFORMATION. Additive-Free Dehydrogenation of Formic Acid at. Room Temperature

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1 SUPPORTING INFORMATION MnO x -Promoted PdAg Alloy Nanoparticles for the Additive-Free Dehydrogenation of Formic Acid at Room Temperature Ahmet Bulut, Mehmet Yurderi, Yasar Karatas, Zafer Say, Hilal Kivrak, Murat Kaya, Mehmet Gulcan, Emrah Ozensoy, Mehmet Zahmakiran *, Nanomaterials and Catalysis (NanoMatCat) Research Laboratory, Department of Chemistry, Yüzüncü Yıl University, 65080, Van, Turkey; Department of Chemistry, Bilkent University, 06800, Ankara, Turkey; Department of Chemical Engineering, Yüzüncü Yıl University, 65080, Van, Turkey; Department of Chemical Engineering and Applied Chemistry, Atılım University, 06836, Ankara, Turkey * Corresponding author: zmehmet@yyu.edu.tr

2 Figure S1. XPS survey spectrum of PdAg-MnO x /N-SiO 2 catalyst in the range of ev.

3 Figure S2. TEM image of metal-free amine-grafted SiO2 support material (N-SiO2).

4 Figure S3. XRD patterns of (1) MnO x /N-SiO 2, (2) Ag/N-SiO 2, (3) Pd/N-SiO 2, (4) PdAg- MnO x /N-SiO 2.

5 Figure S4. DR-UV-Vis spectra of (1) Ag/N-SiO 2, (2) Ag-MnO x /N-SiO 2, (3) PdAg-MnO x /N- SiO 2.

6 Figure S5. TEM images and the particle size distributions of (a) Pd/N-SiO 2, (b) Pd Mn0.55 /N-SiO 2, (c) Pd 0.42 Ag 0.58 /N-SiO 2 (scale bars in the TEM images correspond to 10 nm). Here, the term particles represents PdAg and/or MnO x clusters.

7 Figure S6. Plot for the volume of the generated gas (i.e. CO 2 +H 2 ) versus time corresponding to the additive-free dehydrogenation of FA ([FA(aq)] = 0.25 M, V FA(aq) = 10 ml) at 313 K in the presence of (i) Pd 0.44 Ag Mn 0.37 /N-SiO 2 ( ), (ii) Pd 0.42 Ag 0.58 /N-SiO 2 ( ), (iii) the physical mixture of Pd 0.41 Ag 0.59 /N-SiO 2 and Mn 0.37 /N-SiO 2 ( ) and (iv) the physical mixture of (Pd 0.45 /N-SiO 2 + Ag 0.21 /N-SiO 2 + Mn 0.34 /N-SiO 2 ) ( ).

8 Figure S7. The volume of generated gas (CO 2 +H 2 ) versus time graph for Pd 0.44 Ag Mn 0.37 /N-SiO 2 -catalyzed additive-free dehydrogenation of FA ([FA(aq)] = 0.25 M, V FA(aq) = 10 ml) with and without NaOH trap (i.e. [NaOH(aq)]=10.0 M) at 313 K. Inset: GC traces of the generated gas without the trap (blue), reference gas containing 5 % CO(g) in He (black) and generated gas after purification with the NaOH trap (red).

9 Figure S8. Arrhenius plot (y = x and R 2 = 0.98) for Pd 0.44 Ag Mn 0.37 /N-SiO 2 (2.69 mm) catalyzed additive-free dehydrogenation of aqueous FA solution (0.25 M in 10.0 ml H 2 O) at different temperatures.

10 Figure S9. Eyring plot (y = x and R 2 = 0.97) for Pd 0.44 Ag Mn 0.37 /N-SiO 2 (2.69 M) catalyzed additive-free dehydrogenation of aqueous FA solution (0.25 M in 10.0 ml H 2 O) at different temperatures.

11 Figure S10. Plot of the gas generation rate versus the catalyst concentration (both in logarithmic scale; y = x and R 2 = 0.97) for the additive free dehydrogenation of FA (0.25 M in 10 ml aqueous solution) starting with different Pd 0.44 Ag Mn 0.37 /N-SiO 2 concentrations at 298 K.

12 Figure S11. The gas (CO 2 +H 2 ) generation rate versus the amount of surface-grafted amine groups (mmol/g) for Pd 0.41 Ag Mn 0.39 /SiO 2 (-NH 2 free), Pd 0.45 Ag Mn 0.35 /N-SiO 2 ([-NH 2 ] = 0.47 mmol/g), Pd 0.44 Ag Mn 0.37 /N-SiO 2 ([-NH 2 ] = 1.00 mmol/g), Pd 0.44 Ag Mn 0.38 /N- SiO 2 ([-NH 2 ] = 1.81 mmol/g) and Pd 0.46 Ag Mn 0.35 /N-SiO 2 ([-NH 2 ] = 3.87 mmol/g)- catalyzed additive-free dehydrogenation of FA ([FA(aq)] = 0.25 M, V FA(aq) = 10 ml) at 313 K. The mean particle size value for each catalyst is given in brackets. Here, the term particles represents PdAg and/or MnO x clusters.

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14 Figure S12. (a) TEM image of Pd0.41Ag0.20-Mn0.39/SiO2 (-NH2 free); scale bar equals to 20 nm (b) size histogram of Pd0.41Ag0.20-Mn0.39/SiO2 (-NH2 free), (c) TEM image of Pd0.45Ag0.20-Mn0.35/N-SiO2 ([-NH2] = 0.47 mmol/g); scale bar equals to 50 nm (d) size histogram of Pd0.45Ag0.20-Mn0.35/N-SiO2 ([-NH2] = 0.47 mmol/g), (e) TEM image of Pd0.44Ag0.18-Mn0.38/N-SiO2 ([-NH2] = 1.81 mmol/g), scale bar equals to 10nm, (f) size histogram of Pd0.44Ag0.18Mn0.38/N-SiO2 ([-NH2] = 1.81 mmol/g), (g) TEM image of Pd0.46Ag0.19-Mn0.35/N-SiO2 ([-NH2] = 3.87 mmol/g); scale bar equals to 50 nm, (h) size histogram of Pd0.46Ag0.19-Mn0.35/N-SiO2 ([-NH2] = 3.87 mmol/g) catalysts.

15 Figure S13. Gas generation rate (ml/min) and conversion as a function of the type of the support material for the additive free dehydrogenation of FA ([FA(aq)] = 0.25 M, V FA(aq) = 10 ml) catalyzed by Pd 0.44 Ag Mn 0.37 /N-SiO 2, Pd 0.40 Ag Mn 0.40 /C, Pd 0.37 Ag Mn 0.46 /Al 2 O 3, Pd 0.38 Ag Mn 0.32 /TiO 2 at 313 K.

16 Figure S14. TEM images of (a) Pd 0.40 Ag Mn 0.40 /C, (b) Pd 0.37 Ag Mn 0.46 /Al 2 O 3, and (c) Pd 0.38 Ag Mn 0.32 /TiO 2 catalysts after synthesis; demonstrating the formation of agglomerates and sintering (scale bars in TEM images correspond to 50 nm).

17 Figure S15. CO-stripping voltammogram for PdAg/N-SiO 2 catalyst in H 2 SO 4 solution with a 10 mvs 1 scan rate.

18 Figure S16. CO-stripping voltammogram for PdAg-MnO x /N-SiO 2 catalyst in H 2 SO 4 solution with a 10 mvs 1 scan rate.

19 Figure S17. Plot for the volume of the generated gas (i.e. CO 2 +H 2 ) versus time corresponding to the additive-free dehydrogenation of FA ([FA(aq)] = 0.25 M, [catalyst] = 3.2 mm, V FA(aq) = 10 ml) at 298 K in the presence of fresh (square) and annealed (sphere) Pd 0.44 Ag Mn 0.37 /N-SiO 2 catalysts. Table S-1. Specific surface areas of PdAg/N-SiO 2, PdAg-MnO x /N-SiO 2 and MnO x /N-SiO 2.

20 Material S BET (m 2 /g) PdAg/N-SiO PdAg-MnO x /N-SiO MnO x /N-SiO Calculation of TOF values; TOF values were calculated by considering the region where 20 % conversion is achieved (Angew. Chem. Int. Ed. 2013, 52, 4406). For example TOF value at 313 K was calculated as given below. (1 st step) 0.25 M FA in 10.0 ml solution corresponds to 2.5 mmol FA; (2 nd step) According to stoichiometry (HCOOH H 2 + CO 2 ) mole FA generates mole gas at complete conversion; (3 rd step) At complete conversion mole (CO 2 +H 2 ) gas generation equals to ml gas production; (4 th step) We considered the region where 20 % of conversion is reached, so ~ 24.0 ml gas should be produced at 20 % conversion; (5 th step) From Fig. 4(a) in the presence of mol catalyst at 313 K, 24.0 ml gas generated at 46 sec ( h). (6 th step) initial TOF = [1/2 [(24 ml/23527 ml.mol -1 )]/[( mol) ( h)] initial TOF ~ 1430 h -1 As given in the equation, this value was found by considering only the amount of H 2 not CO 2 +H 2 (this is the reason why the equation given above is multiplied with ½ in).