Robert Kutz | University of Illinois at Urbana-Champaign (original) (raw)
Papers by Robert Kutz
Meeting Abstracts, Mar 8, 2013
Ethanol is one of the most promising fuels for alcoholbased fuel cells since it can be easily pro... more Ethanol is one of the most promising fuels for alcoholbased fuel cells since it can be easily produced in large quantities from plant matter, is renewable, and its ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 54.224.53.85 Downloaded on 2017-04-03 to IP
Vibrational Spectroscopy at Electrified Interfaces, 2013
ABSTRACT This chapter focuses on the application of vibrational sum frequency generation (SFG) sp... more ABSTRACT This chapter focuses on the application of vibrational sum frequency generation (SFG) spectroscopy to study the molecular structure of electrode‐electrolyte and electrified liquid‐gas interfaces. Vibrational SFG is inherently interface specific because a second‐order process such as SFG is not allowed in the bulk of materials with inversion symmetry. The development of direct ethanol fuel cells demands an in‐depth understanding of ethanol's electrooxidation reactions. With recent advances in the practical design of alkaline fuel cells, a thorough understanding of the ethanol electrooxidation mechanism in alkaline media is now more important than ever. The chapter provides novel insights into this mechanism by examining new data on surface‐adsorbed reaction intermediates at fuel cell relevant conditions. Foams are materials of particular importance since they have a broad range of applications such as metal foams for light‐weight structures, polymer foams for thermal insulation, as well as in textured food products.
Energy Procedia, 2014
ABSTRACT CO2 conversion to fuels and chemicals has the potential to treat hundreds of millions of... more ABSTRACT CO2 conversion to fuels and chemicals has the potential to treat hundreds of millions of tons of CO2 annually, but so far, the process has never been economic. This paper will consider a new process for carbon capture and recycling in which CO2 is captured, and is subsequently converted to fuels and chemicals using a low temperature, low pressure, electrochemical process running on renewable energy. The key advantage of the process is that it offers a potential economic route for CO2 conversion to high value chemicals. Preliminary cost modelling indicates that the process is likely to be economic at current CO2 separation costs ($60/MT) even in the absence of carbon credits.
The Journal of Physical Chemistry Letters, 2011
The ethanol electrooxidation reaction (EOR) on polycrystalline Pt catalysts in alkaline solution ... more The ethanol electrooxidation reaction (EOR) on polycrystalline Pt catalysts in alkaline solution was studied for the first time with broadband sum-frequency generation (BB-SFG) spectroscopy. We find that CÀC bond cleavage and CO formation occur as early as 0.05 V versus reversible hydrogen electrode (RHE), and that CO is oxidized at ∼0.45 V, which is 0.2 V lower than in acidic media. In order to track the oxidation of singlecarbon intermediates, we have monitored the oxidation of isotopically labeled ethanol ( 12 CH 3 13 CH 2 OH). Surface-adsorbed 12 CO and 13 CO are observed and show very different potential-dependent behaviors. 13 CO molecules formed from preoxidized carbon species such as ÀCH x O, show the behavior expected from studies of CO-saturated alkaline media. 12 CO, however, which is indicative of the oxidation of methyl-like species (ÀCH x ) on the catalyst surface, is observed at unusually high potentials. The strongly adsorbed ÀCH x is not oxidatively removed from the surface until the electrode potential is swept past 0.65 V.
Journal of Electroanalytical Chemistry, 2013
We co-deposited cobalt porphyrins (CoP) and transition metal oxides on gold and carbon/graphene e... more We co-deposited cobalt porphyrins (CoP) and transition metal oxides on gold and carbon/graphene electrodes as catalysts for the oxygen reduction reaction (ORR). Porphyrins were adsorbed spontaneously, and the transition metal oxides (CoO x and NiO x ) were deposited using spontaneous deposition tactics or an electrochemical deposition method. The electrodes were characterized in acidic media by cyclic voltammetry (CV), by broad-band sum frequency generation (BB-SFG) and -in vacuum -by the Auger electron spectroscopy (AES). The ORR activity data indicate that the activity of cobalt porphyrin towards ORR is enhanced by co-deposited transition metal oxides. The detailed reasons for this behavior are being interrogated.
The Journal of Chemical Physics, 2010
The reversible adsorption of acetate on polycrystalline Au and Pt surfaces was investigated with ... more The reversible adsorption of acetate on polycrystalline Au and Pt surfaces was investigated with broadband sum-frequency generation (SFG) and cyclic voltammetry. Specifically adsorbed acetate as well as coadsorbed sulfuric acid anions are observed for the first time with SFG and give rise to dramatically different SFG intensities on Au and Pt surfaces. While similar coverages of acetate adlayers on Au and Pt surfaces are well established by previous studies, an identification of the interfacial molecular structure has been elusive. However, we have applied the high sensitivity of SFG for interfacial polar ordering to identify different acetate structures at Au and Pt surfaces in contact with HClO 4 and H 2 SO 4 electrolytes. Acetate competes with the formation of surface oxides and shifts the oxidation threshold of both Au and Pt electrodes anodically. Effects of the supporting electrolyte on the formation of acetate adlayers are revealed by comparing SFG spectra in HClO 4 and H 2 SO 4 solutions: Sulfuric acid anions modify the potential-dependent acetate adsorption, compete with adsorbed acetate on Au and coadsorb with acetate on Pt surfaces. to 192.17.144.60. Redistribution subject to AIP license or copyright; see http://jcp.aip.org/about/rights_and_permissions Braunschweig et al.
Journal of Catalysis, 2011
Ethanol electrooxidation reaction (EOR) pathways on polycrystalline platinum were studied with br... more Ethanol electrooxidation reaction (EOR) pathways on polycrystalline platinum were studied with broadband sum-frequency generation (BB-SFG) spectroscopy and electrochemistry in unprecedented detail and under working fuel cell conditions. We present the first observation of adsorbed acetate and coadsorbed sulfuric acid anions with SFG and a discussion of their relation to the EOR. Surface-adsorbed intermediates such as CO on Pt atop sites and acetate are observed in both H 2 SO 4 and HClO 4 solutions. However, CO molecules on bridge sites and sulfuric acid anions are found in H 2 SO 4 only. At E < 0.5 V vs. Ag/AgCl, CO is the predominantly adsorbed species. Increasing the potential to E > 0.5 V results in the oxidative removal of CO and the adsorption of acetate anions. Experiments with isotopically labeled ethanol ( 12 CH 3 13 CH 2 OH) reveal information on the carbon-carbon bond cleavage and the subsequent CO formation. In particular, the methyl fragment (-12 CH x ) produces far less 12 CO and suggests methyl electroreduction to methane and/or the persistence of -CH x on the Pt surface.
Meeting Abstracts, Mar 8, 2013
Ethanol is one of the most promising fuels for alcoholbased fuel cells since it can be easily pro... more Ethanol is one of the most promising fuels for alcoholbased fuel cells since it can be easily produced in large quantities from plant matter, is renewable, and its ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 54.224.53.85 Downloaded on 2017-04-03 to IP
Vibrational Spectroscopy at Electrified Interfaces, 2013
ABSTRACT This chapter focuses on the application of vibrational sum frequency generation (SFG) sp... more ABSTRACT This chapter focuses on the application of vibrational sum frequency generation (SFG) spectroscopy to study the molecular structure of electrode&hyphen;electrolyte and electrified liquid&hyphen;gas interfaces. Vibrational SFG is inherently interface specific because a second&hyphen;order process such as SFG is not allowed in the bulk of materials with inversion symmetry. The development of direct ethanol fuel cells demands an in&hyphen;depth understanding of ethanol's electrooxidation reactions. With recent advances in the practical design of alkaline fuel cells, a thorough understanding of the ethanol electrooxidation mechanism in alkaline media is now more important than ever. The chapter provides novel insights into this mechanism by examining new data on surface&hyphen;adsorbed reaction intermediates at fuel cell relevant conditions. Foams are materials of particular importance since they have a broad range of applications such as metal foams for light&hyphen;weight structures, polymer foams for thermal insulation, as well as in textured food products.
Energy Procedia, 2014
ABSTRACT CO2 conversion to fuels and chemicals has the potential to treat hundreds of millions of... more ABSTRACT CO2 conversion to fuels and chemicals has the potential to treat hundreds of millions of tons of CO2 annually, but so far, the process has never been economic. This paper will consider a new process for carbon capture and recycling in which CO2 is captured, and is subsequently converted to fuels and chemicals using a low temperature, low pressure, electrochemical process running on renewable energy. The key advantage of the process is that it offers a potential economic route for CO2 conversion to high value chemicals. Preliminary cost modelling indicates that the process is likely to be economic at current CO2 separation costs ($60/MT) even in the absence of carbon credits.
The Journal of Physical Chemistry Letters, 2011
The ethanol electrooxidation reaction (EOR) on polycrystalline Pt catalysts in alkaline solution ... more The ethanol electrooxidation reaction (EOR) on polycrystalline Pt catalysts in alkaline solution was studied for the first time with broadband sum-frequency generation (BB-SFG) spectroscopy. We find that CÀC bond cleavage and CO formation occur as early as 0.05 V versus reversible hydrogen electrode (RHE), and that CO is oxidized at ∼0.45 V, which is 0.2 V lower than in acidic media. In order to track the oxidation of singlecarbon intermediates, we have monitored the oxidation of isotopically labeled ethanol ( 12 CH 3 13 CH 2 OH). Surface-adsorbed 12 CO and 13 CO are observed and show very different potential-dependent behaviors. 13 CO molecules formed from preoxidized carbon species such as ÀCH x O, show the behavior expected from studies of CO-saturated alkaline media. 12 CO, however, which is indicative of the oxidation of methyl-like species (ÀCH x ) on the catalyst surface, is observed at unusually high potentials. The strongly adsorbed ÀCH x is not oxidatively removed from the surface until the electrode potential is swept past 0.65 V.
Journal of Electroanalytical Chemistry, 2013
We co-deposited cobalt porphyrins (CoP) and transition metal oxides on gold and carbon/graphene e... more We co-deposited cobalt porphyrins (CoP) and transition metal oxides on gold and carbon/graphene electrodes as catalysts for the oxygen reduction reaction (ORR). Porphyrins were adsorbed spontaneously, and the transition metal oxides (CoO x and NiO x ) were deposited using spontaneous deposition tactics or an electrochemical deposition method. The electrodes were characterized in acidic media by cyclic voltammetry (CV), by broad-band sum frequency generation (BB-SFG) and -in vacuum -by the Auger electron spectroscopy (AES). The ORR activity data indicate that the activity of cobalt porphyrin towards ORR is enhanced by co-deposited transition metal oxides. The detailed reasons for this behavior are being interrogated.
The Journal of Chemical Physics, 2010
The reversible adsorption of acetate on polycrystalline Au and Pt surfaces was investigated with ... more The reversible adsorption of acetate on polycrystalline Au and Pt surfaces was investigated with broadband sum-frequency generation (SFG) and cyclic voltammetry. Specifically adsorbed acetate as well as coadsorbed sulfuric acid anions are observed for the first time with SFG and give rise to dramatically different SFG intensities on Au and Pt surfaces. While similar coverages of acetate adlayers on Au and Pt surfaces are well established by previous studies, an identification of the interfacial molecular structure has been elusive. However, we have applied the high sensitivity of SFG for interfacial polar ordering to identify different acetate structures at Au and Pt surfaces in contact with HClO 4 and H 2 SO 4 electrolytes. Acetate competes with the formation of surface oxides and shifts the oxidation threshold of both Au and Pt electrodes anodically. Effects of the supporting electrolyte on the formation of acetate adlayers are revealed by comparing SFG spectra in HClO 4 and H 2 SO 4 solutions: Sulfuric acid anions modify the potential-dependent acetate adsorption, compete with adsorbed acetate on Au and coadsorb with acetate on Pt surfaces. to 192.17.144.60. Redistribution subject to AIP license or copyright; see http://jcp.aip.org/about/rights_and_permissions Braunschweig et al.
Journal of Catalysis, 2011
Ethanol electrooxidation reaction (EOR) pathways on polycrystalline platinum were studied with br... more Ethanol electrooxidation reaction (EOR) pathways on polycrystalline platinum were studied with broadband sum-frequency generation (BB-SFG) spectroscopy and electrochemistry in unprecedented detail and under working fuel cell conditions. We present the first observation of adsorbed acetate and coadsorbed sulfuric acid anions with SFG and a discussion of their relation to the EOR. Surface-adsorbed intermediates such as CO on Pt atop sites and acetate are observed in both H 2 SO 4 and HClO 4 solutions. However, CO molecules on bridge sites and sulfuric acid anions are found in H 2 SO 4 only. At E < 0.5 V vs. Ag/AgCl, CO is the predominantly adsorbed species. Increasing the potential to E > 0.5 V results in the oxidative removal of CO and the adsorption of acetate anions. Experiments with isotopically labeled ethanol ( 12 CH 3 13 CH 2 OH) reveal information on the carbon-carbon bond cleavage and the subsequent CO formation. In particular, the methyl fragment (-12 CH x ) produces far less 12 CO and suggests methyl electroreduction to methane and/or the persistence of -CH x on the Pt surface.