bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Electrosynthesis in Proton Conducting Solid Electrolytes a) CO2/H2o Co-Electrolysis and b) NH3 Synthesis
Authors: Garagounis Ioannis , Kyriakou Vasileios , Vourros Anastasios , Stoukides Michael 
Published: May 2020

In addition to their applications in the construction of fuel cells, hydrogen separators and sensors, solid state proton (H+) conductors can be used as the main component of catalytic and electrocatalytic reactors. Their advantage, compared to low-temperature proton conductors, is that they can operate in a temperature range within which the kinetics of several industrially important catalytic hydro- and dehydrogenation are acceptably fast. In most of the applications of H+ cell reactors in catalytic research, the reaction of interest takes place on the working electrode while the counter electrode serves for the formation of protons from a hydrogen containing compound. These reactors, however, would become more competitive if useful chemicals were produced on both, working and counter electrode [1, 2].
Results on two reaction systems in which both, cathode and anode were properly utilized are presented here. The aim of this study is the electrochemical production of methanol from carbon dioxide and steam, in a co-ionic conducting solid electrolyte cell at atmospheric pressure. Steam and CO2 are introduced at the anode and cathode side, respectively, of a co-ionic (H+ and O2-) conductor. Steam is electrolyzed to form O2 and protons (H+). The latter are transferred to the cathode and react with CO2 to form CH3OH. The second system is an electrochemical Haber-Bosch (H-B) Process [3, 4]. A mixture of steam and methane is fed over the anode (a Ni-composite electrode) and gaseous N2 is fed over the cathode (VN-Fe). Hydrogen extraction from the steam reforming compartment, enhances the thermodynamically limited methane conversions, whereas 5-14% of the protons pumped are converted to ammonia. A protonic ceramic fuel cell is used to recover electricity and separate nitrogen from ambient air by exploiting by-product hydrogen. This process could potentially require less energy and release fewer CO2 emissions than its conventional counterpart.
References:
[1] A.Vourros, V. Kyriakou, I. Garagounis, E. Vasileiou,M. Stoukides, Solid State Ionics, 306 (2017) 76-81.
[2] S.H. Morejudo, R. Zanon, S. Escolastico, I. Yuste, H. Malerød-Fjeld, P.K. Vestre, W.G. Coors, A. Martínez, T. Norby, J.M. Serra, C. Kjølseth, Science, 353 (2016) 563-566.
[3] I. Garagounis, A.Vourros, D. Stoukides, D. Dasopoulos, M. Stoukides, Membranes 9 (2019) 2-17.
[4] V. Kyriakou, I. Garagounis, A. Vourros, E. Vasileiou, M. Stoukides, JOULE, in press, (2019);
(Invited) Electrochemistry Meets Heterogeneous Catalysis for the Conversion of CO2 and N2 to Fuels and Chemicals
Authors: Holtappels Peter , Lapina Alberto , Hallinder Jonathan , Mogensen Mogens Bjerg , Chatzichristodoulou Christodoulos 
Published: May 2020

Electrochemical reactors operating at intermediate temperatures (200 – 400 °C) can potentially have several advantages over their high temperature (600- 1000 °C) and low temperature (< 100 °C) counterparts. For example their potential of an increased catalytic activity enabling a decrease in material cost compared to low temperature cells, and can be thermally integrated into other chemical processes like synthesis of synthetic fuels and chemicals, such as methanol and ammonia.
Electrochemical reduction of CO2 to chemical building blocks such as CO, CH3OH, and CH4 is a dream for electrochemists, and high faradaic efficiencies have been reported for liquid electrochemical cells operated at ambient temperature, using e.g. Cu electrodes [1]. However, selectivity and electrochemical activity are far from being technically relevant, so that heterogeneous catalysis processes still are the matter of choice. Even more difficult is the electrochemical reduction of nitrogen f.i. to ammonia.
In this contribution, activities at DTU Energy are summarized using solid state electrochemical cells under operating conditions close to the well-known catalytic synthesis of methanol and ammonia. For CO2 reduction, cells based on CsH2PO4 as electrolyte and Cu based cathodes have been investigated towards their electrochemical activity in both H2/H2O and H2/H2O/CO2 containing atmospheres at elevated temperatures of 240 °C. Proton conducting ceramics cells based on barium cerate with Mo and Fe electrodes have been characterized in H2/N2 atmospheres between 300 and 500 °C. Electrochemical impedance analysis point towards a predominant hydrogen evolution and the role of adsorption and desorption processes as well as overpotential will be discussed.
[1] Y. Hori, Modern Aspects of Electrochemistry: Electrochemical CO2 Reduction on Metal Electrodes, Springer New York, USA 42 (2008), 89-189.
(Invited) Electrifying Our Fuel and Chemical Production
Authors: Chorkendorff Ib 
Published: May 2020

Initially we shall discuss the need for electrifying fuels and chemical reducing the CO2 emmission of our society and give an example on how this can be done by supplying electrical heat instead of thermal heat for strongly endothermic reactions [1,2]. The same principles can also be used to convert sustainable energy into chemical energy by instead of making hydrogen sequentially adding protons from water splitting to CO or CO2 converting them into valuable fuels and chemical [4]. Fundamental aspect of electrochemistry on Copper shall be discussed [5-8] and it shall be shown that the CO2 balance is very important for scaling up the reaction in a fuel cell set-up [9]. I shall also touch upon electrochemical ammonia productions – facts or dreams [10].

References

[1] S.T. Wismann, ..... I. Chorkendorff, P.M. Mortensen, SCIENCE 364 (2019) 756
[2] S.T. Wismann, ..... I. Chorkendorff, Submitted (2019).
[3] Z. W Seh,.... I. Chorkendorff, J. K. Nørskov, T. F. Jaramillo, Science (2017) 355.
[4] S. A. Nitopi,..... I. Chorkendorff, Chem. Rev. 119 (2019) 7610.
[5] E. Bertheussen, ...I. Chorkendorff, Angewandte Chemie 55 (2016) 1450.
[6] S. B. Scott,.... I. Chorkendorff ACS Energy Lett. 4 (2019) 803.
[7] A. Tiwari,... I. Chorkendorff, and S. Horch, ACS Energy Letters (2019),
DOI:10.1021/acsenergylett.9b01064.
[8] S. Scott, .... I. Chorkendorff. Submitted (2019).
[9] M. Ming, .....I. Chorkendorff, and B. Seger, Submitted (2019).
[10] S. Z. Andersen, .... and I. Chorkendorff, Nature 570 (2019) 504.
Heterointerface Engineered Oxygen Electrode for High Performance Reversible Solid Oxide Fuel Cells (R-SOFCs)
Authors: Kim Jinhyeon , Lee Channyung , Choi Mansoo , Shin Hyunho 
Published: May 2020

Solid oxide fuel cells (SOFCs) are promising alternatives to combustion technology for electric energy production due to no emission and high efficiency in chemical to electric energy conversion. Despite such advantages, the commercialization of SOFCs is hindered by the high operating temperature, resulting in a few problems, such as expensive system cost and short lifetime. Thus, while reduced-temperature SOFCs have been a long-lasting interest in the SOFC community, the sluggish oxygen reduction reaction (ORR) occurring at the oxygen electrode at intermediate temperature is the most critical challenge for the enhanced overall performance of SOFCs. As a promising strategy to achieve higher catalytic activity of oxygen electrode, the infiltration method has been employed due to not only extended active site for ORR by electrode surface decoration with active nanoparticle catalysts, but enriched oxygen vacancies additionally formed on the surface of infiltrates. Furthermore, heterointerface engineering in the infiltrated oxygen electrode has, more recently, emerged as a promising approach to optimize oxygen electrode performance. The lattice strain, induced by lattice parameter mismatch in heterostructured materials, can significantly influence the ORR/OER (oxygen evolution reaction) kinetics by changing oxygen defect formation energy and migration barrier.
We report the enhancement in the electrochemical performance of the La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) based heterostructured oxygen electrode, when infiltrated with aliovalent cation doped La2-xAxNi1-yByO4 (Ruddlesden-Popper, RP), leading to different intrinsic catalytic ability according to dopant; Sr and Co for A and B site, respectively, to generate oxygen defect (e.g., oxygen vacancy or interstitial O2-). This study demonstrates the impact of the oxygen defect in the infiltrates on the heterointerface, dominating ORR & OER kinetics in the heterostructured oxygen electrode, and investigate the primary oxygen defect for RP structured infiltrate to realize high ORR & OER activity.
To characterize the morphology of infiltrates anchored on the oxygen electrode surface and the heterointerface synthesized between infiltrated layers and backbones, scanning electron microscope (SEM) and transmission electron microscopy (TEM) are performed. The electrochemical performances of the infiltrated SOFCs were examined by electrochemical impedance spectroscopy and analyzed in terms of the distribution of relaxation time (DRT) from impedance data. Thermogravimetric analysis (TGA) and iodometric titration are conducted to understand the correlation between oxygen defect produced by aliovalent doping and electrochemical ORR activity.
(Invited) HT-PEM Fuel Cell Development for Product Definition and Scaleup
Authors: Primdahl Søren , Alfaro Silvia M. , García Héctor R. , Terkelsen Carina , Steenberg Thomas , Hjuler Hans Aage 
Published: May 2020

“High Temperature” proton conducting electrolyte membrane (HT-PEM) fuel cells offer an attractive method of converting renewable energy carriers (e.g. methanol) to electricity, especially remotely and in transportation. A particular advantage is their ability to digest reformates containing a few % CO, thus not requiring high purity hydrogen.
Membranes of polybenzimidazole (PBI) allow for operation in the 150-200 °C range, as they do not require liquid-water for continuous moisturizing as do classical fluorinated polymer membranes. This temperature range is advantageous for the typically used Pt catalyst, as passivation by CO is limited.
A central challenge is cost reduction, with particular focus on Pt loading of electrodes. The critical trade-off is against lifetime and electrode performance while maintaining adequate tolerance to CO and fuel trace impurities. These limitations are sensitive to system and customer parameters via selection of fuel, reformer characteristics and operation mode.
Results will be presented and discussed on single cell lifetime in the 10.000 h range; objectives and results in electrode development and Pt loading, as well as results on methanol slip testing, start-stop testing and testing at elevated pressure. Lessons from early upscaling will be shared.
The Sabatier Electrolyzer: Harnessing Proton-Conducting Ceramics to Upgrade Carbon Dioxide into Methane
Authors: Pan Zehua , Sullivan Neal P 
Published: May 2020

We present our development of the Sabatier Electrolyzer incorporating Sabatier catalysts into proton conducting ceramic membranes to synthesize CH4 and O2 from CO2 and H2O feed streams. Our work seeks to combine steam electrolysis and hydrogen production with carbon dioxide hydrogenation into a single Sabatier Electrolyzer reactor based on proton conducting ceramic membranes and Sabatier catalysts. Proton-conducting ceramic membranes transport reasonable rates of H+ ions at lower overall cell voltages at 400 - 500 ºC with low overpotentials for H2O splitting. The decreased electric power requirements for the Sabatier Electrolyzer are further enabled by autothermal operation; ohmic heating maintains the electrolysis cell at the necessary temperatures for high H+ conduction and effective Sabatier chemistry. Integration of the catalyst with the electrolyzer simplifies the system, improves reliability, and provides increased performance within a smaller package.
Figure 1 illustrates the Sabatier Electrolyzer concept. H2O and CO2 are fed to opposing electrodes of a protonic-ceramic electrolysis cell. Steam is electrolyzed with the product O2 exhausting from the cell. The product protons are driven across the protonic-ceramic membrane to the fuel electrode, where they react with CO2 to form CH4 and H2O. The combination of processes can match the exothermicity of CO2 hydrogenation with the endothermicity of H2O electrolysis, promoting thermal balance and high efficiency.
The Sabatier Electrolyzer cell features a BaCe0.4Zr0.4Y0.1Yb0.1O3-δ (BCZYYb4411) electrolyte, a Ni-BCZYYb4411 fuel electrode support, and a BaCo0.4Fe0.4Zr0.1Y0.1O3-δ (BCFZY) steam electrode. The Ni-cermet fuel electrode serves as the CO2-upgrading catalyst. To date, we have CO2 conversion and CH4 selectivity were demonstrated to be 28% and 43%, respectively, at 450 °C. This result is encouraging but still much lower than the thermodynamic predictions (~70% for CO2 conversion and ~95% for CH4 selectivity). In this presentation, we will review our efforts to achieve the thermodynamically predicted CO2 conversion and CH4 selectivity of 70% and 95%, respectively.

Figure 1
Exploring High-Activity Copper Doping Zirconia Bi-Metal Oxides Catalysts for Methane Conversion at Room Temperature
Authors: Coco Cameron , Xu Nengneng , Zhang Yanxing , Clause Thomas , Schilling Austin , Wang Yu , Zhou Xiao-Dong , Qiao Jinli 
Published: May 2020

Recently, a large quantity of research has been done on the conversion of CH4.(1) Compared to photo-catalysis and thermo-catalysis with precious metal catalysts and high reaction temperatures, the electro-catalysis path, which are always performed at room temperature, demonstrates more potential. In this regard, the electrochemical oxidation and conversion of CH4 to commodity chemicals, such as wide-application liquid alcohols, shows obvious economic benefit and high energy/ conversion-efficient. Zirconia (ZrO2) has rich Lewis acid active sites and huge electron acceptability, showing a remarkable adsorption capacity of CO32-.(2) Based on the above characters, zirconia-based hybrid has attracted a lot of attention and made some breakthroughs. In particular, transition metal oxide (TMO, such as NiO and Co3O4) doping ZrO2 forming TMO/ZrO2 compound demonstrates the potential of methane oxidation with CO32- at room temperature. Compared to NiO and Co3O4, copper-based (Cu) catalysts have a high activity and a long-term durability on forming liquid and gas organics of C1 catalysis reaction system (CO2 reduction reaction) at room temperature.(3-5) Hence, we present a facile strategy of using Cu ions doping ZrO2 to activate the hybrid activity by manipulating its crystal and electronic structure. As expected, the unique cylindrical ZrO2:CuOx catalyst shows remarkable CH4 oxidation performance with large current density differences (13.35 mA cm-2) and long-term electrochemical stability (negligible attenuation (10 %) after 48 hours). According to theoretical and experimental observations of the CH4 oxidation on ZrO2: CuOx hybrid, the high activity and durability of the hybrid should be attributed to 1) strong synergistic-coupling effect; 2) the unique doping structure forming favorable electronic and crystal structure; 3) fast oxidation reaction mechanism by shortening the reaction path. The mechanism could be described as that ZrO2 facilitating CO32- adsorption, then CO32- as the oxidizing agent source rapidly oxidizes CH4 adsorbed on the surface of Cu in zirconia.
Keywords: ZrO2:CuOx, Methane conversion, high activity, Unique doping structure

Uncategorized References

1. B. Wang, S. Albarracín-Suazo, Y. Pagán-Torres and E. Nikolla, Catal. Today, 285, 147 (2017).
2. M. Ma, B. J. Jin, P. Li, M. S. Jung, J. I. Kim, Y. Cho, S. Kim, J. H. Moon and J. H. Park, Advanced science, 4, 1700379 (2017).
3. H. Oguchi, H. Kanai, K. Utani, Y. Matsumura and S. Imamura, Applied Catalysis A: General, 293, 64 (2005).
4. Z. Riguang, L. Hongyan, L. Lixia, L. Zhong and W. Baojun, Applied Surface Science, 257, 4232 (2011).
5. S. Tada, K. Larmier, R. Büchel and C. Copéret, Catalysis Science & Technology, 8, 2056 (2018).
Observations of Mass Transport Losses in Two-Phase CO2 electroreduction
Authors: Krause Kevin , Lee ChungHyuk , Fahy Kieran F. , Lee Jason Keonhag , Shafaque Hisan Waleed , Bazylak Aimy 
Published: May 2020

The need for capturing CO2 has become urgent with a record-breaking concentration of CO2 in our atmosphere (average of 407.4 ppm in 2018 [1]). CO2 electrolyzers are a promising technology capable of achieving a net-negative CO2 cycle when coupled with renewable energy sources. Aqueous electrolyte-based alkaline CO2 electrolyzers have recently been demonstrated to exhibit high selectivity for CO2 reduction to CO [2]. While the selectivity and enhanced performance of the aqueous alkaline environment are desired, the mass transport limitations introduced with this design have largely been overlooked.
In this study, we investigated the transport mechanisms near the electrolyte-catalyst interface over a range of current densities via sub-second in-operando X-ray synchrotron radiography. For the first time, we report fluctuations in cell overpotential driven by the dynamic accumulation and removal of gas at the electrolyte-catalyst interface region. Moreover, this fluctuation in potential due to the gas accumulation and removal in the liquid electrolyte layer was also observed to occur at a periodic rate that became increasingly frequent with increasing current density. The transient gas behavior observed from this study must be accounted for to further enhance the performance of alkaline CO2 electrolyzers with a liquid electrolyte.
References:
[1] Lindsey, R. “Climate Change: Atmospheric Carbon Dioxide”, NOAA Climate.gov, 2019.
[2] A. Martín, G. Larrazábal and J. Pérez-Ramírez, "Towards sustainable fuels and chemicals through the electrochemical reduction of CO2: lessons from water electrolysis", Green Chemistry, vol. 17, no. 12, pp. 5114-5130, 2015.
Manganese-Carbonyl Complexes As Catalysts for CO2 Electrochemical Reduction
Authors: Chardon Sylvie 
Published: May 2020

Carbon dioxide conversion is increasingly gaining attention as CO2 is increasingly being regarded as a feedstock for the preparation of a wide range of value added commodities such as useful chemical raw materials or energy rich products. However, an efficient CO2 transformation process is challenging, but it has great potential for the demand of future resources that do not rely on petrochemical sources.
The CO2 reduction reaction requires high-yield, an input of energy and a catalyst. It can be performed on molecular catalysts. Among various experimental techniques that can be implemented, catalytic CO2 Electrochemical Reduction Reactions (CO2ERR) have promise as they convert electrical energy into chemicals (energy storage). In the past thirty years, several transition metal complexes, able to convert CO2 by CO2ERR, have been studied. This includes systems based on Re, Ru and Os bipyridyl carbonyl systems, however, very few earth abundant efficient metal based molecular catalysts have been reported so far.
Much of our present work[[1]] is focussed on developing and studying new Mn-based catalysts and understanding their catalytic properties towards CO2ERR pathway (Scheme), in order to gain a better understanding with the aim to improving and advancing this field of CO2 transformation.
Therefore here we will present our on-going research on Mn-carbonyl based molecular complexes, which is helping to better understand bipyridyl ligand effects on the CO2 catalytic electro(photo)reduction processes and especially the important role that ligands can have on catalytic activity and therefore efficiency and product selectivity, yield and overall catalyst stability under catalytic conditions.

References

[1] (a) M. Bourrez, F. Molton, S. Chardon-Noblat, A. Deronzier, Angew. Chem. Int. Ed. 50 (2011) 9903; (b) E. Torralba-Penalver, Y. Luo, J.-D. Compain, S. Chardon-Noblat, B. Fabre, ACS Catal. 5 (2015) 6138; (c) J.-D. Compain, M. Stanbury, M. Trejo and S. Chardon-Noblat, Eur. J. Inorg. Chem. (2015) 5757; (d) M. Stanbury, J.-D. Compain, M. Trejo, P. Smith, E. Gouré, S. Chardon-Noblat, Electrochim. Acta 240 (2017) 288; (e) M. Stanbury, J.-D. Compain, S. Chardon-Noblat, Coord. Chem. Rev. 361 (2018) 210. L. Le-Quang, M. Stanbury, S. Chardon-Noblat, J.-M. Mouesca, V. Maurel, J. Chauvin, Chem. Commun. 55 (2019) 13598.

Figure 1
Gold and Platinum Decorated Iron Oxides As Efficient Overall Water Splitting Catalysts
Authors: Sayeed Md Abu , O'Mullane Anthony 
Published: May 2020

Transition metal oxides (TMOs) have gained much interest due their water splitting properties, producing oxygen and hydrogen as a clean source of energy, with the possibility of replacing fossil fuels for the future energy demands. Iron, Cobalt, Nickel and their oxides/oxyhydroxides have been investigated extensively due to their cost effectiveness and applicability in catalysing the water-splitting reaction, although there are some issues with performance degradation. In particular, recent studies on mixed metal oxides of Ni, Fe and Co show enhanced performance for oxygen and hydrogen production compared to the single metallic component.[1]

Iron oxides do not show good activity for the OER or the HER but are attractive for such an application if their activity can be enhanced given the low cost of such materials. Interestingly, it has been shown that fast active sites at FeOOH are responsible for enhanced OER activity within the mixed oxide system of Ni and Co.[2] A more recent development is the pursuit of bifunctional materials that can catalyse both the OER and HER which is attractive from a commercial viewpoint and electrolyser manufacturing. Again if Fe based materials can be used for this reaction, it would be highly beneficial.
In this work we galvanically replace iron and iron hydroxide nanostructures with Pt and Au and investigate the catalyst for both the OER and HER in an alkaline environment. The decoration of the iron surface with a low concentration of Pt or Au results in significantly increased activity for both the HER and more surprisingly the OER. The increased HER activity is expected as Pt is an excellent HER catalyst, however the presence of Au was also found to provide excellent performance. Although both Pt and Au are poor materials for the OER, they promote the reaction at iron oxide. To date, there have been no reports showing Au or Pt decorated Iron oxides that can split water effectively. The material was characterised using Scanning Electron Microscopy coupled with field emission spectra (SEM), Grazing Incidence X-ray Diffraction (GIXRD), X-ray Photoelectron Spectroscopy (XPS), and Transmission Electron Microscopy (TEM). The SAED and Dark Field Scanning Transmission Electron microscopy (DF-STEM) indicating that Au or Pt decorates the surface of the core polycrystalline nanocubes of iron. After the OER, a core-shell structure of Au-FeOOH or Pt-FeOOH is realised which is an effective bifunctional electrocatalyst that can catalyse both the OER and HER.
[1] aM. S. Burke, L. J. Enman, A. S. Batchellor, S. Zou, S. W. J. C. o. M. Boettcher, 2015, 27, 7549-7558; bM. Görlin, P. Chernev, J. Ferreira de Araújo, T. Reier, S. r. Dresp, B. Paul, R. Krähnert, H. Dau, P. Strasser, Journal of the American Chemical Society
2016, 138, 5603-5614.
[2] Z. Liang, H. S. Ahn, A. J. Bard, Journal of the American Chemical Society
2017, 139, 4854-4858.

Figure 1