Digitala Vetenskapliga Arkivet

Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Electrochemical water splitting based on metal oxide composite nanostructures
Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
2020 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The occurrence of available energy reservoirs is decreasing steeply, therefore we are looking for an alternative and sustainable renewable energy resources. Among them, hydrogen is considered as green fuel with a high density of energy. In nature, hydrogen is not found in a free state and it is most likely present in the compound form for example H2O. Water covers almost 75% of the earth planet. To produce hydrogen from water, it requires an efficient catalyst. For this purpose, noble materials such as Pt, Ir, and Ru are efficient materials for water splitting. These precious catalysts are rare in nature, very costly, and are restricted from largescale applications. Therefore, search for a new earth-abundant and nonprecious materials is a hot spot area in the research today. Among the materials, nanomaterials are excellent candidates because of their potential properties for extended applications, particularly in energy systems. The fabrication of nanostructured materials with high specific surface area, fast charge transport, rich catalytic sites, and huge ion transport is the key challenge for turning nonprecious materials into precious catalytic materials. In this thesis, we have investigated nonprecious nanostructured materials and they are found to be efficient for electrochemical water splitting. These nanostructured materials include MoS2-TiO2, MoS2, TiO2, MoSx@NiO, NiO, nickeliron layered double hydroxide (NiFeLDH)/Co3O4, NiFeLDH, Co3O4, Cu-doped MoS2, Co3O4- CuO, CuO, etc. The composition, morphology, crystalline structure, and phase purities are investigated by a wide range of analytical instruments such as XPS, SEM, HRTEM, and XRD. The production of hydrogen/oxygen from water is obtained either in the acidic or alkaline media. Based on the functional characterization we believe that these newly produced nanostructured materials can be capitalized for the development of water splitting, batteries, and other energy-related devices.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2020. , p. 64
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 2066
Keywords [en]
Composite metal oxides, hydrothermal method, water splitting, Tafel slope, stability, durability, alkaline media, acidic media
National Category
Materials Chemistry
Identifiers
URN: urn:nbn:se:liu:diva-165726DOI: 10.3384/diss.diva-165726ISBN: 9789179298661 (print)OAI: oai:DiVA.org:liu-165726DiVA, id: diva2:1430323
Public defence
2020-06-12, TPM55, Täppan, Campus Norrköping, Norrköping, 10:15 (English)
Opponent
Supervisors
Available from: 2020-05-14 Created: 2020-05-14 Last updated: 2020-05-18Bibliographically approved
List of papers
1. Advanced Electrocatalysts for Hydrogen Evolution Reaction Based on Core-Shell MoS2/TiO2 Nanostructures in Acidic and Alkaline Media
Open this publication in new window or tab >>Advanced Electrocatalysts for Hydrogen Evolution Reaction Based on Core-Shell MoS2/TiO2 Nanostructures in Acidic and Alkaline Media
Show others...
2019 (English)In: ACS APPLIED ENERGY MATERIALS, ISSN 2574-0962, Vol. 2, no 3, p. 2053-2062Article in journal (Refereed) Published
Abstract [en]

Hydrogen production as alternative energy source is still a challenge due to the lack of efficient and inexpensive catalysts, alternative to platinum. Thus, stable, earth abundant, and inexpensive catalysts are of prime need for hydrogen production via hydrogen evolution reaction (HER). Herein, we present an efficient and stable electrocatalyst composed of earth abundant TiO2 nanorods decorated with molybdenum disulfide thin nanosheets, a few nanometers thick. We grew rutile TiO2 nanorods via the hydrothermal method on conducting glass substrate, and then we nucleated the molybdenum disulfide nanosheets as the top layer. This composite possesses excellent hydrogen evolution activity in both acidic and alkaline media at considerably low overpotentials (350 mV and 700 mV in acidic and alkaline media, respectively) and small Tafel slopes (48 and 60 mV/dec in acidic and alkaline conditions, respectively), which are better than several transition metal dichalcogenides, such as pure molybdenum disulfide and cobalt diselenide. A good stability in acidic and alkaline media is reported here for the new MoS2/TiO2 electrocatalyst. These results demonstrate the potential of composite electrocatalysts for HER based on earth abundant, cost-effective, and environmentally friendly materials, which can also be of interest for a broader range of scalable applications in renewable energies, such as lithium sulfur batteries, solar cells, and fuel cells.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
Keywords
hydrogen evolution reaction; MoS2; TiO2; catalyst; acidic; alkaline
National Category
Other Chemical Engineering
Identifiers
urn:nbn:se:liu:diva-163971 (URN)10.1021/acsaem.8b02119 (DOI)000462944700053 ()
Note

Funding Agencies|Knut & Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation [2016.0346]; Kempe Foundation [JCK-1606]; European Unions Horizon 2020 research and innovation programme [654002]

Available from: 2020-03-05 Created: 2020-03-05 Last updated: 2020-05-14
2. MoSx@NiO Composite Nanostructures: An Advanced Nonprecious Catalyst for Hydrogen Evolution Reaction in Alkaline Media
Open this publication in new window or tab >>MoSx@NiO Composite Nanostructures: An Advanced Nonprecious Catalyst for Hydrogen Evolution Reaction in Alkaline Media
Show others...
2019 (English)In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 29, no 7, article id 1807562Article in journal (Refereed) Published
Abstract [en]

The design of the earth-abundant, nonprecious, efficient, and stable electrocatalysts for efficient hydrogen evolution reaction (HER) in alkaline media is a hot research topic in the field of renewable energies. A heterostructured system composed of MoSx deposited on NiO nanostructures (MoSx@NiO) as a robust catalyst for water splitting is proposed here. NiO nanosponges are applied as cocatalyst for MoS2 in alkaline media. Both NiO and MoS2@NiO composites are prepared by a hydrothermal method. The NiO nanostructures exhibit sponge-like morphology and are completely covered by the sheet-like MoS2. The NiO and MoS2 exhibit cubic and hexagonal phases, respectively. In the MoSx@NiO composite, the HER experiment in 1 m KOH electrolyte results in a low overpotential (406 mV) to produce 10 mA cm(-2) current density. The Tafel slope for that case is 43 mV per decade, which is the lowest ever achieved for MoS2-based electrocatalyst in alkaline media. The catalyst is highly stable for at least 13 h, with no decrease in the current density. This simple, cost-effective, and environmentally friendly methodology can pave the way for exploitation of MoSx@NiO composite catalysts not only for water splitting, but also for other applications such as lithium ion batteries, and fuel cells.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2019
Keywords
alkaline media; electrolysis; MoSx@NiO composites
National Category
Materials Chemistry
Identifiers
urn:nbn:se:liu:diva-155574 (URN)10.1002/adfm.201807562 (DOI)000459719800018 ()2-s2.0-85059344786 (Scopus ID)
Note

Funding Agencies|Knut and Alice Wallenberg Foundation; Kempe Foundation; LTU Lab fund program; Generalitat de Catalunya [2017 SGR 327, JRM 2017 SGR 1246]; Spanish MINECO project [ENE2017-85087-C3]; Severo Ochoa Programme (MINECO) [SEV-2013-0295-17-1]; CERCA Programme/Generalitat de Catalunya

Available from: 2019-03-20 Created: 2019-03-20 Last updated: 2020-05-14Bibliographically approved
3. An efficient bifunctional electrocatalyst based on a nickel iron layered double hydroxide functionalized Co3O4 core shell structure in alkaline media
Open this publication in new window or tab >>An efficient bifunctional electrocatalyst based on a nickel iron layered double hydroxide functionalized Co3O4 core shell structure in alkaline media
Show others...
2019 (English)In: Catalysis Science & Technology, ISSN 2044-4753, E-ISSN 2044-4761, Vol. 9, no 11, p. 2879-2887Article in journal (Refereed) Published
Abstract [en]

Developing highly active nonprecious metal and binder free bifunctional electrocatalysts for water splitting is a challenging task. In this study, we used a simple strategy to deposit a nickel iron layered double hydroxide (NiFeLDH) onto cobalt oxide (Co3O4) nanowires. The cobalt oxide nanowires are covered with thin nanosheets of NiFeLDH forming a core shell structure. The Co3O4 nanowires contain the mixed oxidation states of Co2+ and Co3+, and the surface modification of Co3O4 nanowires has shown synergetic effects due to there being more oxygen defects, catalytic sites, and enhanced electronic conductivity. Further, the core shell structure of Co3O4 nanowires demonstrated a bifunctional activity for water splitting in 1 M KOH aqueous solution. From the hydrogen evolution reaction (HER), a current density of 10 mA cm - 2 is achieved at a potential of - 0.303 V vs. reversible hydrogen electrode (RHE). Meanwhile for the case of the oxygen evolution reaction (OER), a current density of 40 mA cm - 2 is measured at a potential of 1.49 V vs. RHE. Also, this electrocatalyst has shown a considerable long- term stability of 15 h for both the HER and the OER. Importantly, electrochemical impedance spectroscopy has shown that the NiFeLDH integration onto cobalt oxide exhibited around 3 fold decrease of charge transfer resistance for both the HER and the OER in comparison with pristine cobalt oxide films, which reveals an excellent electrocatalytic activity for both faradaic processes. All these results confirm that the proposed electrocatalyst can be integrated into an efficient water splitting system.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
National Category
Materials Chemistry
Identifiers
urn:nbn:se:liu:diva-158546 (URN)10.1039/c9cy00351g (DOI)000470710300013 ()2-s2.0-85066976848 (Scopus ID)
Available from: 2019-07-03 Created: 2019-07-03 Last updated: 2020-05-14Bibliographically approved
4. Advanced Co3O4-CuO nano-composite based electrocatalyst for efficient hydrogen evolution reaction in alkaline media
Open this publication in new window or tab >>Advanced Co3O4-CuO nano-composite based electrocatalyst for efficient hydrogen evolution reaction in alkaline media
2019 (English)In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 44, no 48, p. 26148-26157Article in journal (Refereed) Published
Abstract [en]

In this study, we incorporate a copper impurity into (Co3O4) nanowires precursor that turn them into an active catalyst for the hydrogen evolution reaction in 1M KOH. The XRD and XPS results are in good agreement and confirmed the formation of Co3O4-CuO nano composite by wet chemical method. To date, the performance of hydrogen evolution reaction in alkaline for the composite catalyst is comparable or superior to cobalt oxide based HER electro-catalysts. The HER catalyst exhibits the lowest Tafel slope of 65 mVdec(-1) for the cobalt-based catalysts in alkaline media. A current density of 10 mA/cm(2) is achieved at a potential of 0.288 V vs reversible hydrogen electrode (RHE). The mixed transition metal oxide Co3O4-CuO based HER electro-catalyst is highly stable and durable. The EIS results demonstrates that HER is highly favorable on the Co3O4-CuO due to the relatively small charge transfer resistance (173.20 Ohm) and higher capacitance values (1.97 mF). (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2019
Keywords
Composite metal oxide; Electro-catalyst; Hydrogen evolution reaction
National Category
Other Chemical Engineering
Identifiers
urn:nbn:se:liu:diva-162348 (URN)10.1016/j.ijhydene.2019.08.120 (DOI)000494890900004 ()
Available from: 2019-11-28 Created: 2019-11-28 Last updated: 2020-05-14
5. The chemically reduced CuO-Co3O4 composite as a highly efficient electrocatalyst for oxygen evolution reaction in alkaline media
Open this publication in new window or tab >>The chemically reduced CuO-Co3O4 composite as a highly efficient electrocatalyst for oxygen evolution reaction in alkaline media
Show others...
2019 (English)In: Catalysis Science & Technology, ISSN 2044-4753, E-ISSN 2044-4761, Vol. 9, no 22, p. 6274-6284Article in journal (Refereed) Published
Abstract [en]

The fabrication of efficient, alkaline-stable and nonprecious electrocatalysts for the oxygen evolution reaction is highly needed; however, it is a challenging task. Herein, we report a noble metal-free advanced catalyst, i.e. the chemically reduced mixed transition metal oxide CuO-Co3O4 composite, with outstanding oxygen evolution reaction activity in alkaline media. Sodium borohydride (NaBH4) was used as a reducing agent for the mixed transition metal oxide CuO-Co3O4. The chemically reduced composite carried mixed valence states of Cu and Co, which played a dynamic role in driving an excellent oxygen evolution reaction process. The X-ray photo-electron spectroscopy (XPS) study confirmed high density of active sites in the treated sample with a large number of oxygen vacancies. The developed electrocatalyst showed the lowest overpotential of 144.5 mV vs. the reversible hydrogen electrode (RHE) to achieve the current density of 40 mA cm(-2) and remained stable for 40 hours throughout the chronoamperometry test at the constant potential of 1.39 V vs. RHE. Moreover, the chemically reduced composite was highly durable. Electrochemical impedance spectroscopy (EIS) confirmed the low charge transfer resistance of 13.53 ohms for the chemically reduced composite, which was 50 and 26 times smaller than that of Co3O4 and untreated CuO-Co3O4, respectively. The electrochemically active surface area for the chemically reduced composite was found to be greater than that for pristine CuO, Co3O4 and untreated pristine CuO-Co3O4. These findings reveal the possibility of a new gateway for the capitalization of a chemically reduced sample into diverse energy storage and conversion systems such as lithium-ion batteries and supercapacitors.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2019
National Category
Materials Chemistry
Identifiers
urn:nbn:se:liu:diva-162507 (URN)10.1039/c9cy01754b (DOI)000496465000004 ()
Available from: 2019-12-13 Created: 2019-12-13 Last updated: 2020-05-14

Open Access in DiVA

fulltext(7388 kB)20 downloads
File information
File name FULLTEXT02.pdfFile size 7388 kBChecksum SHA-512
a72975b4811ff652f0db7b383ee5170a45fe3003196bfee082915bb7337cf2fc6361980bea64bb1907bd40baeafa47c253cf56ffd9deca58d2eddc67bb8b472b
Type fulltextMimetype application/pdf
Order online >>

Other links

Publisher's full text

Search in DiVA

By author/editor
Tahira, Aneela
By organisation
Physics, Electronics and MathematicsFaculty of Science & Engineering
Materials Chemistry

Search outside of DiVA

GoogleGoogle Scholar
Total: 20 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

doi
isbn
urn-nbn

Altmetric score

doi
isbn
urn-nbn
Total: 153 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf