1
|
Xia X, Vogt BD. Microwave Processing Controls the Morphology of Block Copolymer-Templated Mesoporous Cobalt Oxide Films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:1288-1297. [PMID: 31958015 DOI: 10.1021/acs.langmuir.9b03138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Microwave heating provides an efficient method to rapidly heat materials through interaction of microwaves with the media. Here, we demonstrate the rapid synthesis of mesoporous cobalt oxide films through the heating of the silicon substrate by microwaves. A non-sol-gel approach based on cobalt nitrate-citric acid complex cooperative assembly with a poly[methoxy poly(ethylene glycol)methacrylate]-block-poly(butyl acrylate) (PMPEGMA-b-PBA) block copolymer was used to fabricate the cobalt oxide through a cobalt carbonate intermediate. The time required to convert cobalt carbonate to cobalt oxide with the full removal of the PMPEGMA-b-PBA template can be decreased by two orders of magnitude with microwaves in comparison to standard heating in a furnace at 350 °C. At the highest microwave power examined (1500 W), this can be accomplished within 2 s, while >5 min is required at 350 °C in a furnace. At a microwave power of <400 W, there is insufficient energy to induce the transition from carbonate to oxide, but even at only 420 W, the oxide can be formed within 26 s. The rapid heating by the microwaves tends to increase the crystallinity and mean crystal size of the cobalt oxide within the mesoporous films. Despite the growth of larger average crystals, the pore size and porosity tend to be larger when the film is processed using microwaves. Higher microwave power leads to larger average crystals and average pore size. These results suggest that rapid processing to crystallize frameworks in mesoporous materials may allow for highly crystalline frameworks without loss of the templated mesostructure.
Collapse
Affiliation(s)
- Xuhui Xia
- Department of Polymer Engineering , University of Akron , Akron , Ohio 44325 , United States
| | - Bryan D Vogt
- Department of Chemical Engineering , The Pennsylvania State University , University Park , Pennsylvania 16803 , United States
| |
Collapse
|
2
|
Lee DK, Lee D, Lumley MA, Choi KS. Progress on ternary oxide-based photoanodes for use in photoelectrochemical cells for solar water splitting. Chem Soc Rev 2019; 48:2126-2157. [PMID: 30499570 DOI: 10.1039/c8cs00761f] [Citation(s) in RCA: 115] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Solar water splitting using photoelectrochemical cells (PECs) has emerged as one of the most promising routes to produce hydrogen as a clean and renewable fuel source. Among various semiconductors that have been considered as photoelectrodes for use in PECs, oxide-based photoanodes are particularly attractive because of their stability in aqueous media in addition to inexpensive and facile processing compared to other types of semiconductors. However, they typically suffer from poor charge carrier separation and transport. In the past few years, there has been tremendous progress in developing ternary oxide-based photoelectrodes, specifically, photoanodes. The use of ternary oxides provides more opportunities to tune the composition and electronic structure of the photoelectrode compared to binary oxides, thus providing more freedom to tune the photoelectrochemical properties. In this article, we outline the important characteristics to analyze when evaluating photoanodes and review the major recent progress made on the development of ternary oxide-based photoanodes. For each system, we highlight the favorable and unfavorable features and summarize the strategies utilized to address the challenges associated with each material. Finally, by combining our analyses of all the photoanodes surveyed in this review, we provide possible future research directions for each compound and an outlook for constructing more efficient oxide-based PECs. Overall, this review will provide a critical overview of current ternary oxide-based photoanodes and will serve as a platform for the design of future oxide-based PECs.
Collapse
Affiliation(s)
- Dong Ki Lee
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA.
| | | | | | | |
Collapse
|
3
|
Bernsmeier D, Sachse R, Bernicke M, Schmack R, Kettemann F, Polte J, Kraehnert R. Outstanding hydrogen evolution performance of supported Pt nanoparticles: Incorporation of preformed colloids into mesoporous carbon films. J Catal 2019. [DOI: 10.1016/j.jcat.2018.11.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
4
|
Xia Y, Qiang Z, Lee B, Becker ML, Vogt BD. Solid state microwave synthesis of highly crystalline ordered mesoporous hausmannite Mn3O4films. CrystEngComm 2017. [DOI: 10.1039/c7ce00900c] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Microwave calcination of ordered micelle templated manganese carbonate films leads to highly crystalline, ordered mesoporous manganese oxide, while similar temperatures in a furnace lead to disordered, amorphous manganese oxide.
Collapse
Affiliation(s)
- Yanfeng Xia
- Department of Polymer Science
- University of Akron
- Akron
- USA
| | - Zhe Qiang
- Department of Polymer Engineering
- University of Akron
- Akron
- USA
| | - Byeongdu Lee
- X-ray Science Division
- Advanced Photon Source
- Argonne National Laboratory
- Argonne
- USA
| | | | - Bryan D. Vogt
- Department of Polymer Engineering
- University of Akron
- Akron
- USA
| |
Collapse
|
5
|
Majewski PW, Yager KG. Rapid ordering of block copolymer thin films. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:403002. [PMID: 27537062 DOI: 10.1088/0953-8984/28/40/403002] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Block-copolymers self-assemble into diverse morphologies, where nanoscale order can be finely tuned via block architecture and processing conditions. However, the ultimate usage of these materials in real-world applications may be hampered by the extremely long thermal annealing times-hours or days-required to achieve good order. Here, we provide an overview of the fundamentals of block-copolymer self-assembly kinetics, and review the techniques that have been demonstrated to influence, and enhance, these ordering kinetics. We discuss the inherent tradeoffs between oven annealing, solvent annealing, microwave annealing, zone annealing, and other directed self-assembly methods; including an assessment of spatial and temporal characteristics. We also review both real-space and reciprocal-space analysis techniques for quantifying order in these systems.
Collapse
Affiliation(s)
- Pawel W Majewski
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY, USA. Department of Chemistry, University of Warsaw, Warsaw, Poland
| | | |
Collapse
|
6
|
Bhaway SM, Chen YM, Guo Y, Tangvijitsakul P, Soucek MD, Cakmak M, Zhu Y, Vogt BD. Hierarchical Electrospun and Cooperatively Assembled Nanoporous Ni/NiO/MnOx/Carbon Nanofiber Composites for Lithium Ion Battery Anodes. ACS APPLIED MATERIALS & INTERFACES 2016; 8:19484-93. [PMID: 27399605 DOI: 10.1021/acsami.6b05592] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A facile method to fabricate hierarchically structured fiber composites is described based on the electrospinning of a dope containing nickel and manganese nitrate salts, citric acid, phenolic resin, and an amphiphilic block copolymer. Carbonization of these fiber mats at 800 °C generates metallic Ni-encapsulated NiO/MnOx/carbon composite fibers with average BET surface area (150 m(2)/g) almost 3 times higher than those reported for nonporous metal oxide nanofibers. The average diameter (∼900 nm) of these fiber composites is nearly invariant of chemical composition and can be easily tuned by the dope concentration and electrospinning conditions. The metallic Ni nanoparticle encapsulation of NiO/MnOx/C fibers leads to enhanced electrical conductivity of the fibers, while the block copolymers template an internal nanoporous morphology and the carbon in these composite fibers helps to accommodate volumetric changes during charging. These attributes can lead to lithium ion battery anodes with decent rate performance and long-term cycle stability, but performance strongly depends on the composition of the composite fibers. The composite fibers produced from a dope where the metal nitrate is 66% Ni generates the anode that exhibits the highest reversible specific capacity at high rate for any composition, even when including the mass of the nonactive carbon and Ni(0) in the calculation of the capacity. On the basis of the active oxides alone, near-theoretical capacity and excellent cycling stability are achieved for this composition. These cooperatively assembled hierarchical composites provide a platform for fundamentally assessing compositional dependencies for electrochemical performance. Moreover, this electrospinning strategy is readily scalable for the fabrication of a wide variety of nanoporous transition metal oxide fibers.
Collapse
Affiliation(s)
- Sarang M Bhaway
- Department of Polymer Engineering and ‡Department of Polymer Science, University of Akron , Akron, Ohio 44325, United States
| | - Yu-Ming Chen
- Department of Polymer Engineering and ‡Department of Polymer Science, University of Akron , Akron, Ohio 44325, United States
| | - Yuanhao Guo
- Department of Polymer Engineering and ‡Department of Polymer Science, University of Akron , Akron, Ohio 44325, United States
| | - Pattarasai Tangvijitsakul
- Department of Polymer Engineering and ‡Department of Polymer Science, University of Akron , Akron, Ohio 44325, United States
| | - Mark D Soucek
- Department of Polymer Engineering and ‡Department of Polymer Science, University of Akron , Akron, Ohio 44325, United States
| | - Miko Cakmak
- Department of Polymer Engineering and ‡Department of Polymer Science, University of Akron , Akron, Ohio 44325, United States
| | - Yu Zhu
- Department of Polymer Engineering and ‡Department of Polymer Science, University of Akron , Akron, Ohio 44325, United States
| | - Bryan D Vogt
- Department of Polymer Engineering and ‡Department of Polymer Science, University of Akron , Akron, Ohio 44325, United States
| |
Collapse
|
7
|
Wu Y, Tao Y, Cai K, Liu S, Zhang Y, Chi Z, Xu J, Wei Y. Temperature-Induced Transformation from Large Compound Vesicles to Worm-like Aggregates by ABC Triblock Copolymer. CHINESE J CHEM 2015. [DOI: 10.1002/cjoc.201500728] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
8
|
Kim TW, Ping Y, Galli GA, Choi KS. Simultaneous enhancements in photon absorption and charge transport of bismuth vanadate photoanodes for solar water splitting. Nat Commun 2015; 6:8769. [PMID: 26498984 PMCID: PMC4640143 DOI: 10.1038/ncomms9769] [Citation(s) in RCA: 205] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 09/29/2015] [Indexed: 12/23/2022] Open
Abstract
n-Type bismuth vanadate has been identified as one of the most promising photoanodes for use in a water-splitting photoelectrochemical cell. The major limitation of BiVO4 is its relatively wide bandgap (∼2.5 eV), which fundamentally limits its solar-to-hydrogen conversion efficiency. Here we show that annealing nanoporous bismuth vanadate electrodes at 350 °C under nitrogen flow can result in nitrogen doping and generation of oxygen vacancies. This gentle nitrogen treatment not only effectively reduces the bandgap by ∼0.2 eV but also increases the majority carrier density and mobility, enhancing electron-hole separation. The effect of nitrogen incorporation and oxygen vacancies on the electronic band structure and charge transport of bismuth vanadate are systematically elucidated by ab initio calculations. Owing to simultaneous enhancements in photon absorption and charge transport, the applied bias photon-to-current efficiency of nitrogen-treated BiVO4 for solar water splitting exceeds 2%, a record for a single oxide photon absorber, to the best of our knowledge.
Collapse
Affiliation(s)
- Tae Woo Kim
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Yuan Ping
- Department of Chemistry, University of California, Davis, California 95616, USA
| | - Giulia A. Galli
- Institute for Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
| | - Kyoung-Shin Choi
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| |
Collapse
|