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Kawde, A., Annamalai, A., Sellstedt, A., Glatzel, P., Wågberg, T. & Messinger, J. (2019). A microstructured p-Si photocathode outcompetes Pt as a counter electrode to hematite in photoelectrochemical water-splitting. Dalton Transactions, 48(4), 1166-1170
Open this publication in new window or tab >>A microstructured p-Si photocathode outcompetes Pt as a counter electrode to hematite in photoelectrochemical water-splitting
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2019 (English)In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 48, no 4, p. 1166-1170Article in journal (Refereed) Published
Abstract [en]

Herein, we communicate about an Earth-abundant semiconductor photocathode (p-Si/TiO2/NiOx) as an alternative for the rare and expensive Pt as a counter electrode for overall photoelectrochemical water splitting. The proposed photoelectrochemical (PEC) water-splitting device mimics the "Z"-scheme observed in natural photosynthesis by combining two photoelectrodes in a parallelillumination mode. A nearly 60% increase in the photocurrent density (Jph) for pristine α-Fe2Oand a 77% increase in the applied bias photocurrent efficiency (ABPE) were achieved by replacing the conventionally used Pt cathode with an efficient, cost effective p-Si/TiO2/NiOx photocathode under parallel illumination. The resulting photocurrent density of 1.26 mA cm−2 at 1.23VRHE represents a new record performance for hydrothermally grown pristine α-Fe2O3 nanorod photoanodes in combination with a photocathode, which opens the prospect for further improvement by doping α-Fe2O3 or by its decoration with co-catalysts. Electrochemical impedance spectroscopy measurements suggest that this significant performance increase is due to the enhancement of the space-charge field in α-Fe2O3. 

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
National Category
Materials Chemistry
Identifiers
urn:nbn:se:umu:diva-153415 (URN)10.1039/c8dt03653e (DOI)000459625900002 ()30534760 (PubMedID)
Available from: 2018-11-20 Created: 2018-11-20 Last updated: 2019-03-27Bibliographically approved
Sandström, R., Annamalai, A., Boulanger, N., Ekspong, J., Talyzin, A., Mühlbacher, I. & Wågberg, T. (2019). Evaluation of Fluorine and Sulfonic Acid Co-functionalized Graphene Oxide Membranes in Hydrogen Proton Exchange Membrane Fuel Cell Conditions. Sustainable Energy & Fuels, 3(7), 1790-1798
Open this publication in new window or tab >>Evaluation of Fluorine and Sulfonic Acid Co-functionalized Graphene Oxide Membranes in Hydrogen Proton Exchange Membrane Fuel Cell Conditions
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2019 (English)In: Sustainable Energy & Fuels, ISSN 2398-4902, Vol. 3, no 7, p. 1790-1798Article in journal (Refereed) Published
Abstract [en]

The use of graphene oxide (GO) based membranes consisting of self-assembled flakes with a lamellar structure represents an intriguing strategy to spatially separate reactants while facilitating proton transport in proton exchange membranes (PEM). Here we chemically modify GO to evaluate the role of fluorine and sulfonic acid groups on the performance of H2/O2 based PEM fuel cells. Mild fluorination is achieved by the presence of hydrogen fluoride during oxidation and subsequent sulfonation resulted in fluorine and SO3- co-functionalized GO. Membrane electrode assembly performance in low temperature and moderate humidity conditions suggested that both functional groups contribute to reduced H2 crossover compared to appropriate reference membranes. Moreover, fluorine groups promoted an enhanced hydrolytic stability while contributing to prevent structural degradation after constant potential experiments whereas sulfonic acid demonstrated a stabilizing effect by preserving proton conductivity.

Place, publisher, year, edition, pages
Royal Society of Medicine Press, 2019
Keywords
Proton exchange membrane, Fuel Cell, Graphene oxide, Hydrogen, Fluorine, Sulfonic acid
National Category
Nano Technology Other Chemical Engineering Other Materials Engineering Energy Systems
Research subject
nanomaterials
Identifiers
urn:nbn:se:umu:diva-158496 (URN)10.1039/C9SE00126C (DOI)000472980200014 ()
Funder
Swedish Research Council, 2017-04862Swedish Energy Agency, 45419-1ÅForsk (Ångpanneföreningen's Foundation for Research and Development), 15-483Interreg Nord
Note

Originally included in thesis in manuscript form

Available from: 2019-04-29 Created: 2019-04-29 Last updated: 2019-08-05Bibliographically approved
Sandström, R., Ekspong, J., Gracia-Espino, E. & Wågberg, T. (2019). Oxidatively Induced Exposure of Active Surface Area during Microwave Assisted Formation of Pt3Co Nanoparticles for Oxygen Reduction Reaction. RSC Advances, 9(31), 17979-17987
Open this publication in new window or tab >>Oxidatively Induced Exposure of Active Surface Area during Microwave Assisted Formation of Pt3Co Nanoparticles for Oxygen Reduction Reaction
2019 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, no 31, p. 17979-17987Article in journal (Refereed) Published
Abstract [en]

The oxygen reduction reaction (ORR), the rate-limiting reaction in proton exchange membrane fuel cells, can efficiently be facilitated by properly manufactured platinum catalysts alloyed with late 3d transition metals. Herein we synthesize a platinum:cobalt nanoparticulate catalyst with a 3:1 atomic ratio by reduction of a dry organometallic precursor blend within a commercial household microwave oven. The formed nanoparticles are simultaneously anchored to a carbon black support that enables large Pt surface area. Two separate microwave treatment steps were employed, where step one constitutes a fast oxidative treatment for revealing active surface area while a reductive secondary annealing treatment promotes a Pt rich surface. The resulting Pt3Co/C catalyst (~3.4 nm) demonstrate an enhanced ORR activity directly attributed to incorporated Co with a specific and mass activity of 704 μA cm-2Pt and 352 A g-1Pt corresponding to an increase by 279 % and 66 % respectively compared to a commercial Pt/C (~1.8 nm) catalyst measured under identical conditions. The method´s simplicity, scalability and novelty is expected to further assist in Pt-Co development and bring the catalyst one step closer toward commercialization and utility in fuel cells.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
Keywords
Proton exchange membrane fuel cell, platinum cobalt, Oxygen reduction reaction, Microwave synthesis
National Category
Nano Technology Other Materials Engineering
Research subject
nanomaterials; nanoparticles; Materials Science
Identifiers
urn:nbn:se:umu:diva-158492 (URN)10.1039/c9ra02095k (DOI)000471914300054 ()
Funder
Swedish Research Council, 2017-04862ÅForsk (Ångpanneföreningen's Foundation for Research and Development), 15-483Swedish Energy Agency, 45419-1Swedish Research Council, 2018-03937Stiftelsen Olle Engkvist Byggmästare, 186-0637
Note

Originally included in thesis in manuscript form 

Available from: 2019-04-29 Created: 2019-04-29 Last updated: 2019-07-11Bibliographically approved
Sharifi, T., Gracia-Espino, E., Chen, A., Hu, G. & Wågberg, T. (2019). Oxygen Reduction Reactions on Single- or Few-Atom Discrete Active Sites for Heterogeneous Catalysis. Advanced Energy Materials, Article ID 1902084.
Open this publication in new window or tab >>Oxygen Reduction Reactions on Single- or Few-Atom Discrete Active Sites for Heterogeneous Catalysis
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2019 (English)In: Advanced Energy Materials, ISSN 1614-6832, article id 1902084Article in journal (Refereed) Epub ahead of print
Abstract [en]

The oxygen reduction reaction (ORR) is of great importance in energy-converting processes such as fuel cells and in metal-air batteries and is vital to facilitate the transition toward a nonfossil dependent society. The ORR has been associated with expensive noble metal catalysts that facilitate the O-2 adsorption, dissociation, and subsequent electron transfer. Single- or few-atom motifs based on earth-abundant transition metals, such as Fe, Co, and Mo, combined with nonmetallic elements, such as P, S, and N, embedded in a carbon-based matrix represent one of the most promising alternatives. Often these are referred to as single atom catalysts; however, the coordination number of the metal atom as well as the type and nearest neighbor configuration has a strong influence on the function of the active sites, and a more adequate term to describe them is metal-coordinated motifs. Despite intense research, their function and catalytic mechanism still puzzle researchers. They are not molecular systems with discrete energy states; neither can they fully be described by theories that are adapted for heterogeneous bulk catalysts. Here, recent results on single- and few-atom electrocatalyst motifs are reviewed with an emphasis on reports discussing the function and the mechanism of the active sites.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2019
Keywords
active sites, catalyst motifs, electrocatalysis, oxygen reduction reaction, single active atom catalysts, transition metals, X-ray adsorption spectroscopy
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:umu:diva-164137 (URN)10.1002/aenm.201902084 (DOI)000486795700001 ()
Available from: 2019-10-17 Created: 2019-10-17 Last updated: 2019-10-17
Sukhrobov, P., Numonov, S., Liu, J., Luo, J., Mamat, X., Li, Y., . . . Hu, G. (2019). Rapid Microwave-Assisted Synthesis of Copper Decorated Carbon Black Nanocomposite for Non-Enzyme Glucose Sensing in Human Blood. Journal of the Electrochemical Society, 166(13), B1238-B1244
Open this publication in new window or tab >>Rapid Microwave-Assisted Synthesis of Copper Decorated Carbon Black Nanocomposite for Non-Enzyme Glucose Sensing in Human Blood
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2019 (English)In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 166, no 13, p. B1238-B1244Article in journal (Refereed) Published
Abstract [en]

The current research performs the novelty fabricated of non-enzymatic biosensor based on copper nanoparticles decorated carbon black nanocomposite modified glassy carbon electrode (Cu/DCB/GCE) by using the microwave method. The prepared nanomaterial was applied for glucose determination in biological fluids and human serum samples. The techniques of SEM, TEM, XPS, XRD, EDS and mapping tests were selected for the morphological, compositions and crystal structure characterizations of the fabricated nanocomposite. In comparison with other electrodes based on metal decorated carbon black, the Cu/DCB/GCE demonstrated the best electrocatalytic property toward glucose oxidation in 0.1 M KOH electrolyte. Cu/DCB/GCE under the optimal potential of +0.5 V in a linear range from 0.5 up to 7000 mu M with a detection limit of 0.1 mu M (S/N=3), the coefficient of correlation R-2=0.999, performed significant high sensitivity of 1595 mu A mM(-1) cm(-2). Rapid amperometric responses of the prepared biosensor in short time with 0.8-2 s were observed by addition of different glucose concentrations in alkaline solution. Modified Cu/DCB/GCE exhibited the best anti-interference property against blood cells and some blood co-existence molecules such as dopamine, uric acid, ascorbic acid, albumin, and globulin. Most importantly, Cu/DCB/GCE biosensor was used for glucose level determination in human blood serum samples. Due to the attractable structure and properties of the fabricated biosensor, it can be suggested for the future development of glucose detection design.

Place, publisher, year, edition, pages
Electrochemical Society, 2019
National Category
Analytical Chemistry Materials Chemistry
Identifiers
urn:nbn:se:umu:diva-164407 (URN)10.1149/2.0011914jes (DOI)000485886400001 ()
Available from: 2019-11-05 Created: 2019-11-05 Last updated: 2019-11-05Bibliographically approved
Ekspong, J. & Wågberg, T. (2019). Stainless Steel as A Bi-Functional Electrocatalyst – A Top-Down Approach. Materials, 12(13), Article ID 2128.
Open this publication in new window or tab >>Stainless Steel as A Bi-Functional Electrocatalyst – A Top-Down Approach
2019 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, no 13, article id 2128Article in journal (Refereed) Published
Abstract [en]

For a hydrogen economy to be viable, clean and economical hydrogen production methods are vital. Electrolysis of water is a promising hydrogen production technique with zero emissions, but suffer from relatively high production costs. In order to make electrolysis of water sustainable, abundant, and efficient materials has to replace expensive and scarce noble metals as electrocatalysts in the reaction cells. Herein, we study activated stainless steel as a bi-functional electrocatalyst for the full water splitting reaction by taking advantage of nickel and iron suppressed within the bulk. The final electrocatalyst consists of a stainless steel mesh with a modified surface of layered NiFe nanosheets. By using a top down approach, the nanosheets stay well anchored to the surface and maintain an excellent electrical connection to the bulk structure. At ambient temperature, the activated stainless steel electrodes produce 10 mA/cm(2) at a cell voltage of 1.78 V and display an onset for water splitting at 1.68 V in 1M KOH, which is close to benchmarking nanosized catalysts. Furthermore, we use a scalable activation method using no externally added electrocatalyst, which could be a practical and cheap alternative to traditionally catalyst-coated electrodes.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
water splitting, electrolysis, bifunctional, electrocatalysts, hydrogen evolution reaction, oxygen olution reaction, sustainable, stainless steel, nano
National Category
Other Chemical Engineering
Identifiers
urn:nbn:se:umu:diva-162337 (URN)10.3390/ma12132128 (DOI)000477043900092 ()31269744 (PubMedID)2-s2.0-85068826298 (Scopus ID)
Available from: 2019-08-16 Created: 2019-08-16 Last updated: 2019-08-22Bibliographically approved
Han, X.-B., Tang, X.-Y., Lin, Y., Gracia-Espino, E., Liu, S.-G., Liang, H.-W., . . . Zheng, L.-S. (2019). Ultrasmall Abundant Metal-Based Clusters as Oxygen-Evolving Catalysts. Journal of the American Chemical Society, 141(1), 232-239
Open this publication in new window or tab >>Ultrasmall Abundant Metal-Based Clusters as Oxygen-Evolving Catalysts
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2019 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 141, no 1, p. 232-239Article in journal (Refereed) Published
Abstract [en]

The oxygen evolution reaction is a crucial step in water electrolysis to develop clean and renewable energy. Although noble metal-based catalysts have demonstrated high activity for the oxygen evolution reaction, their application is limited by their high cost and low availability. Here we report the use of a molecule-to-cluster strategy for preparing ultrasmall trimetallic clusters by using the polyoxometalate molecule as a precursor. Ultrafine (0.8 nm) transition-metal clusters with controllable chemical composition are obtained. The transition-metal clusters enable highly efficient oxygen evolution through water electrolysis in alkaline media, manifested by an overpotential of 192 mV at 10 mA cm–2, a low Tafel slope of 36 mV dec–1, and long-term stability for 30 h of electrolysis. We note, however, that besides the excellent performance as an oxygen evolution catalyst, our molecule-to-cluster strategy provides a means to achieve well-defined transition-metal clusters in the subnanometer regime, which potentially can have an impact on several other applications.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
National Category
Materials Chemistry
Identifiers
urn:nbn:se:umu:diva-155964 (URN)10.1021/jacs.8b09076 (DOI)000455561800040 ()30540181 (PubMedID)
Funder
Carl Tryggers foundation , CTS-16-161
Available from: 2019-02-07 Created: 2019-02-07 Last updated: 2019-02-07Bibliographically approved
Jiang, R., Liu, N., Gao, S., Mamat, X., Su, Y., Wågberg, T., . . . Hu, G. (2018). A Facile Electrochemical Sensor Based on PyTS-CNTs for Simultaneous Determination of Cadmium and Lead Ions. Sensors, 18(5), Article ID 1567.
Open this publication in new window or tab >>A Facile Electrochemical Sensor Based on PyTS-CNTs for Simultaneous Determination of Cadmium and Lead Ions
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2018 (English)In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 18, no 5, article id 1567Article in journal (Refereed) Published
Abstract [en]

A simple and easy method was implemented for the contemporary detection of cadmium (Cd2+) and lead (Pb2+) ions using 1,3,6,8-pyrenetetrasulfonic acid sodium salt-functionalized carbon nanotubes nanocomposites (PyTS-CNTs). The morphology and composition of the obtained PyTS-CNTs were characterized using scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and X-ray photoelectron spectroscopy (XPS). The experimental results confirmed that the fabricated PyTS-CNTs exhibited good selectivity and sensitivity for metal ion-sensing owing to the insertion of sulfonic acid groups. For Cd2+ and Pb2+, some of the electrochemical sensing parameters were evaluated by varying data such as the PyTS-CNT quantity loaded on the pyrolytic graphite electrode (PGE), pH of the acetate buffer, deposition time, and deposition potential. These parameters were optimized with differential pulse anodic sweeping voltammetry (DPASV). Under the optimal condition, the stripping peak current of the PyTS-CNTs/Nafion/PGE varies linearly with the heavy metal ion concentration, ranging from 1.0 mu g L-1 to 90 mu g L-1 for Cd2+ and from 1.0 mu g L-1 to 110 mu g L-1 for Pb2+. The limits of detection were estimated to be approximately 0.8 mu g L-1 for Cd2+ and 0.02 mu g L-1 for Pb2+. The proposed PyTS CNTs/Nafion/PGE can be used as a rapid, simple, and controllable electrochemical sensor for the determination of toxic Cd2+ and Pb2+.

Place, publisher, year, edition, pages
MDPI, 2018
Keywords
carbon nanotubes, sodium pyrene-1, 3, 6, 8-tetrasulfonate, DPASV, simultaneous determination, Cd2+, -2+
National Category
Analytical Chemistry
Identifiers
urn:nbn:se:umu:diva-151075 (URN)10.3390/s18051567 (DOI)000435580300266 ()29762494 (PubMedID)2-s2.0-85047076719 (Scopus ID)
Available from: 2018-09-03 Created: 2018-09-03 Last updated: 2018-09-03Bibliographically approved
Zhan, X., Hu, G., Wågberg, T., Zhang, D. & Zhou, P. (2018). A Label-Free Electrochemical Aptasensor for the Rapid Detection of Tetracycline Based on Ordered Mesoporous Carbon-Fe3O4. Australian journal of chemistry (Print), 71(2-3), 170-176
Open this publication in new window or tab >>A Label-Free Electrochemical Aptasensor for the Rapid Detection of Tetracycline Based on Ordered Mesoporous Carbon-Fe3O4
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2018 (English)In: Australian journal of chemistry (Print), ISSN 0004-9425, E-ISSN 1445-0038, Vol. 71, no 2-3, p. 170-176Article in journal (Refereed) Published
Abstract [en]

A novel aptasensor based on a tetracycline (TET) aptamer immobilized by physical adsorption on an ordered mesoporous carbon-Fe3O4 (OMC-Fe3O4)-modified screen-printed electrode surface was successfully fabricated. OMC-Fe3O4 was characterized by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The modification procedure of the aptasensor was characterized by cyclic voltammetry. Interaction between the TET aptamer and target was determined by differential pulse voltammetry. Under optimal conditions, the proposed aptasensor exhibited good electrochemical sensitivity to TET in a concentration range of 5 nM to 10 μM, with a detection limit of 0.8 nM (S/N =3D 3). This aptasensor exhibited satisfactory specificity, reproducibility, and stability.

Place, publisher, year, edition, pages
CSIRO Publishing, 2018
National Category
Analytical Chemistry
Identifiers
urn:nbn:se:umu:diva-146171 (URN)10.1071/CH17503 (DOI)000426369100012 ()
Available from: 2018-05-02 Created: 2018-05-02 Last updated: 2018-06-09Bibliographically approved
Sukhrobov, P., Numonov, S., Mamat, X., Li, Y., Wågberg, T. & Hu, G. (2018). A New Non-Enzymatic Amperometric Sensor Based on Nickel Decorated ZIF-8 Derived Carbon Nanoframe for the Glucose Determination in Blood Samples. International Journal of Electrochemical Science, 13(7), 6550-6564
Open this publication in new window or tab >>A New Non-Enzymatic Amperometric Sensor Based on Nickel Decorated ZIF-8 Derived Carbon Nanoframe for the Glucose Determination in Blood Samples
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2018 (English)In: International Journal of Electrochemical Science, ISSN 1452-3981, E-ISSN 1452-3981, Vol. 13, no 7, p. 6550-6564Article in journal (Refereed) Published
Abstract [en]

The present study demonstrated a highly sensitive non-enzymatic glucose biosensor in real blood samples based on simple evaluated nickel deposited on N-doped porous carbon modified glassy carbon electrode (Ni/NPC/GCE) by applying electrochemical deposition method. The prepared material initially were characterized by cyclic voltammetry, the morphology structure of the as-prepared samples was observed by SEM, and composition, crystals structure of Ni/NPC were identified by SEM mapping and EDS tests. The Ni/NPC/GCE compared with NPC/GCE and NiNPs/GCE performed the best electrocatalytic behavior towards oxidation of glucose in 0.1 M KOH medium. By applied potential of +0.6 V Ni/NPC/GCE showed very high sensitivity of 3753.78 mu AmM(-1)cm(-2) in linear range of 1-7940 mu M with the correlation coefficient of R-2=0.995. The linear ranges get views above the concentration up to 7940 mu M with the detection limit of 0.3 mu M (S/N= 3). Amperometric time responses of prepared electrode towards different glucose concentrations are 0.8-1.3s. Finally, several positive characteristics such as very high sensitivity, weak working potential, nice anti-interference properties, long stability, good selectivity, and comparison with some other non-enzymatic sensors Ni/NPC/GCE executed high sensitivity, low detection limit and wide linear range to glucose sensing, thus the selected electrode is supplying for future glucose level determination design.

Place, publisher, year, edition, pages
ESG, 2018
Keywords
Nickel deposition, N-doped porous carbon, electrodeposition, glucose biosensor
National Category
Analytical Chemistry
Identifiers
urn:nbn:se:umu:diva-151567 (URN)10.20964/2018.07.03 (DOI)000441819300030 ()
Funder
Swedish Research Council, 2013-5252
Available from: 2018-09-10 Created: 2018-09-10 Last updated: 2018-09-10Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-5080-8273

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