Topics in Current Chemistry (2019) 377:11
https://doi.org/10.1007/s41061-019-0236-5
1 3
REVIEW
Pt‑Based Catalysts for Electrochemical Oxidation of Ethanol
Nebojsa S. Marinkovic
1
· Meng Li
2
· Radoslav R. Adzic
2
Received: 16 October 2018 / Accepted: 18 March 2019 / Published online: 4 April 2019
© Springer Nature Switzerland AG 2019
Abstract
Despite its attractive features as a power source for direct alcohol fuel cells, utilization of ethanol is still hampered by both fundamental and technical challenges. The
rationale behind the slow and incomplete ethanol oxidation reaction (EOR) with low
selectivity towards CO 2 on most Pt-based catalysts is still far from being understood,
and a number of practical problems need to be addressed before an efficient and
low-cost catalyst is designed. Some recent achievements towards solving these problems are presented. Pt film electrodes and Pt monolayer (Pt ML ) electrodes on various single crystal substrates showed that EOR follows the partial oxidation pathway
without C–C bond cleavage, with acetic acid and acetaldehyde as the final products.
The role of the substrate lattice on the catalytic properties of Pt ML was proven by
the choice of appropriate M(111) structure (M = Pd, Ir, Rh, Ru and Au) showing
enhanced kinetics when Pt ML is under tensile strain on Au(111) electrode. Nanostructured electrocatalysts containing Pt–Rh solid solution on SnO 2 and Pt monolayer on non-noble metals are shown, optimized, and characterized by in situ methods. Electrochemical, in situ Fourier transform infrared (FTIR) and X-ray absorption
spectroscopy (XAS) techniques highlighted the effect of Rh in facilitating C–C bond
splitting in the ternary PtRh/SnO 2 catalyst. In situ FTIR proved quantitatively the
enhancement in the total oxidation pathway to CO 2 , and in situ XAS confirmed that
Pt and Rh form a solid solution that remains in metallic form through a wide range
of potentials due to the presence of SnO 2 . Combination of these findings with density functional theory calculations revealed the EOR reaction pathway and the role
of each constituent of the ternary PtRh/SnO 2 catalyst. The optimal Pt:Rh:Sn atomic
ratio was found by the two in situ techniques. Attempts to replace Rh with costeffective alternatives for commercially viable catalysts has shown that Ir can also
split the C–C bond in ethanol, but the performance of optimized Pt–Rh–SnO 2 is still
higher than that of the Pt–Ir–SnO 2 catalyst.
Keywords Platinum-based catalysts · Ethanol oxidation · In situ FTIR · In situ
EXAFS
Extended author information available on the last page of the article
1
Reprinted from the journal
Chapter 1 was originally published as Marinkovic, N. S., Li, M. & Adzic, R. R. Topics in Current Chemistry
(2019) 377: 11. https://doi.org/10.1007/s41061-019-0236-5.
https://doi.org/10.1007/s41061-019-0236-5
1 3
REVIEW
Pt‑Based Catalysts for Electrochemical Oxidation of Ethanol
Nebojsa S. Marinkovic
1
· Meng Li
2
· Radoslav R. Adzic
2
Received: 16 October 2018 / Accepted: 18 March 2019 / Published online: 4 April 2019
© Springer Nature Switzerland AG 2019
Abstract
Despite its attractive features as a power source for direct alcohol fuel cells, utilization of ethanol is still hampered by both fundamental and technical challenges. The
rationale behind the slow and incomplete ethanol oxidation reaction (EOR) with low
selectivity towards CO 2 on most Pt-based catalysts is still far from being understood,
and a number of practical problems need to be addressed before an efficient and
low-cost catalyst is designed. Some recent achievements towards solving these problems are presented. Pt film electrodes and Pt monolayer (Pt ML ) electrodes on various single crystal substrates showed that EOR follows the partial oxidation pathway
without C–C bond cleavage, with acetic acid and acetaldehyde as the final products.
The role of the substrate lattice on the catalytic properties of Pt ML was proven by
the choice of appropriate M(111) structure (M = Pd, Ir, Rh, Ru and Au) showing
enhanced kinetics when Pt ML is under tensile strain on Au(111) electrode. Nanostructured electrocatalysts containing Pt–Rh solid solution on SnO 2 and Pt monolayer on non-noble metals are shown, optimized, and characterized by in situ methods. Electrochemical, in situ Fourier transform infrared (FTIR) and X-ray absorption
spectroscopy (XAS) techniques highlighted the effect of Rh in facilitating C–C bond
splitting in the ternary PtRh/SnO 2 catalyst. In situ FTIR proved quantitatively the
enhancement in the total oxidation pathway to CO 2 , and in situ XAS confirmed that
Pt and Rh form a solid solution that remains in metallic form through a wide range
of potentials due to the presence of SnO 2 . Combination of these findings with density functional theory calculations revealed the EOR reaction pathway and the role
of each constituent of the ternary PtRh/SnO 2 catalyst. The optimal Pt:Rh:Sn atomic
ratio was found by the two in situ techniques. Attempts to replace Rh with costeffective alternatives for commercially viable catalysts has shown that Ir can also
split the C–C bond in ethanol, but the performance of optimized Pt–Rh–SnO 2 is still
higher than that of the Pt–Ir–SnO 2 catalyst.
Keywords Platinum-based catalysts · Ethanol oxidation · In situ FTIR · In situ
EXAFS
Extended author information available on the last page of the article
1
Reprinted from the journal
Chapter 1 was originally published as Marinkovic, N. S., Li, M. & Adzic, R. R. Topics in Current Chemistry
(2019) 377: 11. https://doi.org/10.1007/s41061-019-0236-5.