Supplementary Information:
S1. Hydrogen-assisted Temperature Programmed Decomposition of Oxalate Precursors
The H2-TPDec of the Co1Cu1Mn1 ternary oxalate (Fig. S1) shows a major feature at
temperatures between 350 and 390 °C while smaller amounts do so between ~250 °C and the
onset of the high-temperature feature. CO and CO2 formation are correlated with H2
Carbon species outlet (a.u.)
consumption over the entire range of temperatures.
CO2
CO
H2
240
280
320
400
360
440
480
o
Temperature ( C)
Fig. S1 Formation of CO and CO2 along with H2 consumption during H2-TPDec (3°C.min-1)
of Co1Cu1Mn1 (solid line) and Co1Cu1Mo1 (dashed line).
The decomposition of the hybrid-type Co1Cu1Mo1 precursor shows peaks at 280 °C, 320
°C and 400 °C which correlate with H2 consumption. Further hydrogen consumption occurs
beyond the high-temperature decomposition peak at 420 °C, indicating that partial reduction
of MoVI takes place in the presence of CoCu. This is, at present, a tentative explanation as the
MoVI → MoIV transition (in the absence of CoCu) is known to take place at higher
temperatures [1].
1
Different from the binary CoCu-oxalate, the quantitative evaluation of the TPDec data
for the ternary system of both “CoCuMn” and “CoCuMo” demonstrates that oxygen is
retained in the catalyst when reaching the high-end of the examined temperature range. Thus,
neither Mn-oxalate nor ammonium heptamolybdate were reduced to Mn or Mo metallic
states, which is in agreement with what the literature reports [1, 2]. TPDec studies with pure
Mn-oxalate confirmed non-stoichiometric MnOx (SBET=525 m2 g-1) formation [2, 3]. Such
MnOx accompanying
“CoCuMn” did not prevent the activated catalysts from being
pyrophoric and caused a drastic increase in the specific surface area. H2-TPDec measurements
up to various temperatures between 150 °C and 500 °C, followed by BET, showed that a
maximum surface area of SBET~170 m2 g-1 occurred at 350–370 °C for Co1Cu1Mn1. An
identical set of measurements led to SBET~185 m2 g-1 for Co1Cu1Mo1 in the same range of
temperatures. Co1Cu1, however, showed a maximum of SBET~10 m2 g-1. We also note that
heating to temperatures beyond 350–370 °C resulted in a dramatic loss of the surface areas.
2
S2. Atom Probe Tomography
Fig. S2 Atom probe tomography results of a single CoCuMn catalyst nanoparticle. The image
provided is a section through a 3D tomographic reconstruction so as to reveal the
intragranular structure of the nanoparticle. The data is presented in the form of atom maps
where Co atoms are depicted as blue spheres, Cu atoms as orange spheres, Mn atoms as green
spheres, and O as white spheres.
Atom probe and TEM data (S3) reported here were obtained in the group of S. Ringer,
Australian Centre for Microscopy & Microanalysis, and School of Aerospace, Mechanical &
Mechatronic Engineering, University of Sydney, NSW, 2006, Australia
3
S3. Transmission Electron Microscopy
Fig. S3 Evaluation of catalyst grain, or particle size distribution from TEM analysis. Frames
indicate where particle sizes were analysed. Particles smaller than 7 nm were also detected
and analyzed by HRTEM. Diffraction demonstrated the existence of Mn-oxides.
References
[1] Lalik E, David WIF, Barnes P, Turner JFC (2001) J Phys Chem B 105: 9153–9156
[2] Iablokov V, Frey K, Geszti O, Kruse N (2010) Catal Lett 134: 210–216
[3] Frey K, Iablokov V, Sáfrán G, Osán J, Sajó I, Szukiewicz R, Chenakin S, Kruse N (2012)
J Catal 287: 30–36
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