In the Classroom
Development of a Nanomaterials One-Week Intersession Course Keith A. Walters* and Heather A. Bullen** Department of Chemistry, Northern Kentucky University, Highland Heights, KY 41099; *
[email protected] **
[email protected] The field of nanomaterials is arguably one of the most rapidly growing fields of science today, as well as one of the most controversial. Nanomaterials currently are being used in the electronic, magnetic, optoelectronic, biomedical, pharmaceutical, cosmetic, energy, and catalytic fields, and some industry experts predict that nanomaterials will be used in half of all newly introduced products over the next ten years (1). However, with all of these advances there are significant concerns expressed by the general public as to the safety and potential societal implications resulting from the use of nanomaterials (2, 3). Indeed, a recent survey indicated that at least 80% of Americans feel uninformed about nanotechnology (4). Clearly one of the most effective ways to educate the public about nanomaterials is to start in the classroom, particularly those of undergraduate science students. Students currently enrolled in undergraduate institutions represent the “future ambassadors” of science that will be largely responsible for the effective use and practice of science, including nanomaterials. However, our current science curriculum gives only tangential opportunities to present on such topics. Taking both the immense promise and challenges presented by nanomaterials, we endeavored to create a unique course for science majors on the chemistry of these nanomaterials. A challenge faced by many colleges today is to find a way to offer courses on significant topics like nanomaterials without increasing the number of required hours in the curriculum. In addition, instructors are routinely overburdened by teaching loads and do not have time to offer these topical courses. Many schools have strived to expand their course offerings by creating two- or three-week “intersession” periods in the breaks between
the traditional academic semesters (5). The short time format, coupled with the opportunity to interact with students over multi-hour blocks, is an excellent opportunity to offer a lecture– lab hybrid course on specialized topics. These courses carry one semester credit hour and can be added to a departmental major requirement without significant increase to the student’s workload.1 This chemistry department was a pioneer in offering these courses with the initiation of a one-week organometallic chemistry course in 1999. This course was popular both for chemistry majors and other students completing their chemistry minors (mainly biology majors) and has been offered several times since its inception. Using this course as a model, we set about to offer an intensive one-week course on the chemistry of materials, with a heavy emphasis on nanomaterials. Course Structure The chemistry of materials course was open to all science majors; the prerequisite was completion of two semesters of general chemistry. Hence, the composition of our class included both introductory and upper-class chemistry and biology majors. Fourteen students received grades during this initial offering. The objectives of the course were to (i) introduce students to nanomaterials through the synthesis and characterization of nanomaterials; (ii) evaluate nanomaterial applications; and (iii) understand the potential implications of nanomaterials on society. Emphasis was placed on the connection between theory and “real-world” application (e.g., band theory was tied to the design of solar cells). The lecture–lab hybrid design of the course interspersed laboratory experiments
Table 1. Chemistry of Materials Lab–Lecture Hybrid Course Structure Morning
Day
Afternoon
Time
Topic
Time
Topic
Monday
8 am – 10 am 10 am –12 pm
Lecture 1 Lab: Quantum Dots
1 pm – 2 pm 2 pm – 3 pm 3 pm – 5 pm — (night)
Lab: Quantum Dots Lecture 2 Lab: Sol-gel Part I HW #1 Finish HW/Q Dot Lab Report
Tuesday
— 8 am – 9:30 am 9:30 am –-12 pm
HW #1 Due Lecture 3 Lab: Nanowires
1 pm – 2:30 pm 2:30 pm – 5 pm (night)
Lecture 4 Lab: Solar Cells HW #2/Nanowire Report
Wednesday
— 8 am – 10:30 am 10:30 am – 12 pm
HW #2/Q Dot Report Due Lab: Solar Cells Lecture 5
1 pm – 5 pm — (night)
Lab: Sol-gel Part 2 Solar Cell Report Sol-gel Presentation Prep
Thursday
— 8 am – 10:30 am 10:30 am – 12 pm
Nanowire Report Due Lab: Sol Gel/Presentations Lecture 6
1 pm – 3 pm 3 pm – 5 pm
Lab: SEM Analysis Nanowires Lab: Phosphor complex
Friday
8 am – 3 pm
Solar Cell Report Due/Phosphor Lab Discussion Characterization: XRD, SEM, AFM
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In the Classroom
with lectures (70% lab, 30% lecture) over a one-week period meeting 8 hours each day, as shown in Table 1. Students were also expected to complete lab reports and homework assignments outside of class. Grading was based on lab performance (15%), lab reports (50%), lab notebook (15%), and homework assignments (20%). The authors team-taught the course, each contributing 50% to the lecture content and supervising two of the labs. Lectures No textbook was required for the course; however, several different texts were used as reference materials (6–9). In addition, articles on nanotechnology were utilized as supplemental materials for lecture discussion focusing on the potential use and impact on society of nanomaterials (10–13). All source materials were provided to students through a course Web site. During the first day, an introduction to materials science and the interesting aspects of nanotechnology were presented. Subsequent lectures focused on structure–property relationships; electrical, magnetic, and optical properties of nanomaterials; self-organization; materials characterization techniques; and potential applications of nanomaterials. The organization of the lectures was designed to facilitate introductions or summaries on the planned laboratory experiments at the appropriate points of the lecture material. Lectures also provided an open forum for discussion of topics related to nanomaterials, and many lively discussions were held during the course. For example, when research on nanomachines was presented to the class, a discussion ensued on the positive and negative impacts of such devices. Some students saw the immense benefit to medicine with the advent of these devices, while others were wary that these same machines could be used to harm rather than help. Indeed, parallels were made between the positive and negative impacts of nanotechnology and those of previous major technical advances (e.g., nuclear technology). The opportunities for spontaneous discussion during these lecture periods were in many ways some of the most rewarding and enlightening moments of the course. Homework Homework assignments were given the first two days of class to ensure students’ understanding of lecture topics. An example from the homework sets can be found in the online materials. The assignments were often designed to get students to apply their understanding of material properties to the “bigger picture”. In addition, an interactive module was incorporated that utilized a freeware powder X-ray diffraction software program (PowderCell 2.3) (14). This module was designed to aid in students’ understanding of crystal structures and X-ray diffraction as a method of materials characterization (see online materials for more details). Students evaluated how changing crystal structure, lattice parameter sizes, and atomic number influence the observed diffraction patterns. The use of the XRD freeware proved beneficial in explaining X-ray diffraction concepts and may prove useful for educators with or without access to an XRD.
Labs The labs presented during the intersession course were designed to provide hands-on experiences in the synthesis and characterization of nanomaterials. Many of the experiments performed during the course were either previously reported in this Journal or through the “Exploring the Nanoworld” Web site (15). Each lab focused on a unique property of nanomaterials. Students were divided into groups of 2–3 for all experiments. First on the list was a CdSe quantum dot lab that examined the effects of size on spectral properties (16). Students in this lab synthesized quantum dots of various sizes and then measured their absorption and emission spectra. While the experiment was short in duration, the students were able to easily obtain quantum dots of various colors. After a brief lecture on the “particle in a box” concept geared toward students without a significant physical chemistry background, they were able to determine the various sizes of their prepared quantum dots based on their color. Several of the students were also able to image their quantum dots on a mica surface using our department’s atomic force microscope. The second lab provided students an opportunity to synthesize sol-gel materials and evaluate their potential for chemical sensing applications (17). A collaborative plan was developed where each group evaluated a specific set of experimental conditions on the formation of the sol-gel and their subsequent sensor properties. Students adjusted a variety of synthetic conditions, including pH and curing temperature, to observe their effects on gel formation. The capability of the prepared sol-gels was then assessed as both colorimetric and biosensors. The synthesis of the sol-gels was defined, but their evaluation as sensors was set up as a “discovery-based” lab, where students were encouraged to design their own approach to assess the ability of the sol-gels to act as sensors. In addition to qualitative data, students were able to collect information on pore size by evaluating analyte leaching using atomic absorbance spectroscopy and trapped water within the sol-gels using thermogravimetry. Each group conveyed their results to the class with an oral presentation; the class then drew conclusions as to the best method to create a sol-gel colorimetric sensor for Fe3+. During a class discussion on the potential role of carbon nanotubes or molecular wires in microelectronics, a question was posed: “How would you handle something in the nanoscale to form an electrical circuit?” The template synthesis of magnetic nickel nanowires provided an exciting opportunity for students to see how this potentially might be done (18). The approach is based on nickel electrochemical deposition through a porous alumina membrane. Over half the class was successful in creating individual Ni nanowires. The wires were subsequently characterized by monitoring their movement under a microscope during magnetic manipulation. Students also characterized their synthesized nanowires in the scanning electron microscopy lab, verifying differences in both length and chemical composition. Problems with the nanowire synthesis were associated with the contact between the conductive coating and alumina membrane not remaining stable and the subsequent incomplete removal of the membrane. These issues will be addressed the next time the course is offered.
© Division of Chemical Education • www.JCE.DivCHED.org • Vol. 85 No. 10 October 2008 • Journal of Chemical Education
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In the Classroom
The use of semiconductors in solar cell design was also examined via a modification of a nanocrystalline solar cell lab (19, 20). Students prepared a nanocrystalline TiO2 coated ITO electrode and created an anthocyanin dye layer from a raspberry suspension. Following the preparation of a graphite-catalyzed counterelectrode and triiodide redox shuttle, students were able to measure voltage–current curves for their devices. Unfortunately, it was a cloudy day (the only one during the week), so students used high-intensity lamps to “simulate” daylight. Some of the students also overheated their ITO/TiO2 electrodes, fouling the surface. Although only two groups were able to obtain usable data, all class members determined the current and power densities from these data and obtained a 9.24% device efficiency (which is quite good for these materials). Along with this lab was a detailed lecture on nanocrystalline semiconductors, band theory, and solar cell design. When the class is repeated, document camera lamps will be used to simulate daylight for this lab and hopefully better results will be obtained. A final experiment conducted during the course was a group project, owing to its explosive nature and the high temperatures required. A nanocrystalline Y2O3:Eu3+ phosphor was prepared (21) as an example of the synthesis of ceramics. Students mixed the reactant materials and allowed them to combust in a muffle furnace. The resulting phosphor product is similar to components found in modern fluorescent tubes, so there were opportunities to discuss both synthesis and application of these materials in lecture. The resulting material was also studied using our new powder X-ray diffractometer. The usage of this instrument will be expanded in future offerings of the course. Student Response and Assessment Following completion of the course, students were encouraged to provide their thoughts and suggestions for improvement in a survey. The response was largely positive. Students liked the hybrid lecture–lab approach, as “switching from lecture to lab throughout the day helped to connect concepts learned with their applications.” Perhaps more importantly, the approach was “a great idea so that students weren’t getting bored quickly.” Although many of the labs were long and somewhat time-consuming, all of the students felt that they had adequate time to complete the labs during the week. Students liked the lectures that tied the nanomaterial topics to potential “realworld” applications and did not express any significant dislike in the covered topics. All the experiments were universally liked, again due to their potential applications in society. Students also liked the mix of lab reports and group presentations, as “giving a presentation allows you to give your results in a different manner than just writing.” The presentation component will likely be increased in subsequent course offerings. Students suggested that polymers and other industrial applications of nanomaterials be presented, along with the offering of a “course packet” of the primary source literature used in the labs (although all needed materials were available online). Perhaps the most interesting comments from the students centered on their views regarding the societal implications of nanotechnology. At the start of the course it was clear from discussions that many students did not have any definite views other than some vague “nanotechnology could impact society
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for the good” thoughts. However, following the course the students were much more opinionated on the subject. One believed that “nanotechnology is a crucial technology for the future of drug delivery and [the] various other industries that it impacts.” Others stated that their interest for the field greatly increased. Another stated that they now “believe nanoscale research is very important. I never thought in depth how such advances in nanotechnology will set implications for health, wealth, and peace…I know I was lacking knowledge in the nanoscience field before I took this class.” Clearly the societal implication of nanotechnology will continue to be an important component in future offerings of the course. Full details of this survey can be found in the supplementary material. Conclusion A new one-week intersession lecture–lab hybrid course on nanomaterials has been successfully offered. Of course, it is impossible to cover everything related to nanomaterials regardless of the time frame of the course. Furthermore, the wide range of student backgrounds (second- through fourthyear chemistry and biology majors) was an additional challenge when designing the level and content of the course. Therefore, topics had to be chosen that are interesting to students. Additionally, the instructors had to make a constant effort to relate these topics back to students’ everyday lives. It can be argued that retooling this course as a strictly upper-level chemistry major offering would allow for the inclusion of more advanced material, but the mix of students added to the vibrancy of the lecture and lab experiences (especially when societal implications were discussed). Although time-intensive experiments were not feasible, teamwork activities created a great learning environment for students. This hybrid course provides a mix of background theory and hands-on experience to educate students about nanomaterials and nanotechnology. Eventually, some of these experiments may be incorporated into the general chemistry curriculum. Acknowledgments This work was supported in part by a National Science Foundation Instrument for Materials Research award (DMR-0526686) and the National Science Foundation Major Research Instrumentation award (MRI-0520921). Note 1. In our department, the intersession courses count towards the number of required upper-level credit hours needed to graduate with a major or minor in chemistry.
Literature Cited 1. Roco, M. I.; Bainbridge, W. S. Nanotechnology: Societal Implications—Maximizing Benefit for Humanity, Report of the National Nanotechnology Initiative Workshop, Dec 2–3, 2003; National Science Foundation: Arlington, VA, 2005. http://www.nsf.gov/ crssprgm/nano/reports/nni05_si_societal_implications_2005.pdf (accessed Jun 2008).
Journal of Chemical Education • Vol. 85 No. 10 October 2008 • www.JCE.DivCHED.org • © Division of Chemical Education
In the Classroom 2. Einsiedel, E. In the Public Eye: The Early Landscape of Nanotechnology among Canadian and U.S. Publics. J. Nanotechnology Online [Online] 2005, Article 1. http://www.azonano.com/ Details.asp?ArticleID=1468 (accessed Jun 2008). 3. Macoubrie, J. Informed Public Perceptions of Nanotechnology and Trust in Government. http://www.wilsoncenter.org/events/ docs/macoubriereport.pdf (accessed Jun 2008). 4. Rejeski, D. Capitol Hill Hearing Testimony: Environmental and Safety Impacts of Nanotechnology, Nov 17, 2005. http://commdocs.house.gov/committees/science/hsy24464.000/hsy24464_0. HTM (accessed Jun 2008). 5. Wilson, G. IEEE Computational Science & Engineering 1996, 3, 46–55. 6. Askeland, D. R.; Phule, P. The Science and Engineering of Materials, 5th ed.; Thomson Learning: Boston, 2005. 7. Smith, W. F. Foundations of Materials Science and Engineering, 3rd ed.; McGraw-Hill: New York, 2004. 8. Solymar, L.; Walsh, D. Electric properties of Materials, 7th ed.; Oxford University Press: Oxford, 2004. 9. Ratner, M.; Ratner, D. Nanotechnolgy: A Gentle Introduction to the Next Big Idea; Prentice Hall: Upper Saddle River, NJ, 2003. 10. Freemantle, M. Chem. Eng. News 2006, 84 (8), 8. 11. McGuire, N. K. In Today’s Chemist at Work 2003, Nov, 30–34. 12. Thayer, A. M. Chem. Eng. News 2006, 84 (18), 10–18. 13. Felton, M. J. Today’s Chemist at Work 2004, Mar, 19–21.
14. BAM Berlin PowderCell. http://www.ccp14.ac.uk/ccp/web-mirrors/powdcell/a_v/v_1/powder/e_cell.html (accessed Jun 2008). 15. MRSEC Nanostructured Interfaces Homepage. http://mrsec.wisc. edu/Edetc/nanolab/index.html (accessed Jun 2008). 16. Boatman, E. M.; Lisensky, G. C.; Nordell, K. J. J. Chem. Educ. 2005, 82, 1697–1699. 17. Laughlin, J. B.; Sarquis, J. L.; Jones, V. M.; Cox, J. A. J. Chem. Educ. 2000, 77, 77. 18. Bentley, A. K.; Farhoud, M.; Ellis, A. B.; Lisensky, G. C.; Nickel, A.-M. L.; Crone, W. C. J. Chem. Educ. 2005, 85, 765. 19. Smestad, G. P. Nanocrystalline Solar Cell Kit: Recreating Photosynthesis. Institute for Chemical Education, Madison, WI, 1998. http://www.solideas.com/solrcell/cellkit.html (accessed Jun 2008). 20. Meyers, G. J. Chem. Educ. 1997, 74, 652. 21. Bolstad, D. B.; Diaz, A. L. J. Chem. Educ. 2002, 79, 1101–1104
Supporting JCE Online Material
http://www.jce.divched.org/Journal/Issues/2008/Oct/abs1406.html Abstract and keywords Full text (PDF) Links to cited URLs and JCE articles Supplement
Example homework sets including the X-ray diffraction module
Notes regarding the sol-gel laboratory experiment
Results of the final survey
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