Nanotechnology in the High School Science Curriculum Kenneth Bowles- NBCT Apopka High School UCF- Science Instructional Analysis October 5, 2004

What Is All the Fuss About Nanotechnology? Any given search engine will produce 1.6 million hits Nanotechnology is on the way to becoming the FIRST trillion dollar market Nanotechnology influences almost every facet of every day life such as security and medicine.

Does Nanotechnology Address Teaching Standards? Physical science content standards 9-12 Structure of atoms Structure and properties of matter Chemical reactions Motion and forces Conservation of energy and increase in disorder (entropy) Interactions of energy and matter

Does Nanotechnology Address Teaching Standards? Science and technology standards Abilities of technological design Understanding about science and technology Science in personal and social perspectives Personal and community health Population growth Natural resources Environmental quality Natural and human-induced hazards Science and technology in local, national, and global challenges

Does Nanotechnology Address Teaching Standards? History and nature of science standards Science as a human endeavor Nature of scientific knowledge Historical perspective

Does Nanotechnology Address Teaching Standards? Nanotechnology IdeaStandard it can address The idea of “Nano” – being smallStructure of Atoms Nanomaterials have a high surface area (nanosensors for toxins) Structure and properties of matter, Personal and Community Health Synthesis of nanomaterials and support chemistry (space propulsion) Chemical Reactions Shape Memory AlloysMotion and Forces, Abilities of technological design, Understanding about science and technology Nanocrystalline Solar CellsConservation of Energy and increase in disorder (entropy), Interactions of energy and matter, Natural Resources Nanocoatings resistive to bacteria and pollution Personal and Community Health, Population Growth, Environmental Quality, Natural and human-induced hazards i

Does Nanotechnology Address Teaching Standards? Nanotechnology IdeaStandard it can address Nanomaterials, such as MR (magneto-rheological) fluids in security Science and technology in local, national, and global challenges Richard P. Feynman’s talk, “There is plenty of room at the bottom”. Feynman had a vision. Science as a human endeavor, Nature of scientific knowledge, Historical perspective Nanocosmetics and nanoclothingScience as a human endeavor, Science and technology in local, national, and global challenges Nanotechnology and Science EthicsScience and technology in local, national, and global challenges, Science as a human endeavor, Historical perspective, Natural and human-induced hazards, Population Growth, Personal and Community Health

Energy Capture and Storage Ever consider how much sunlight actually strikes the earth? On average every square yard of land exposed to the sun will receive 5 kW-hours of solar energy per day. So if you had an area covering 100 square yards you would generate 500 kW-hours per day. Upon careful inspection of our energy bill we discover that the average U.S. household generates kW-hours of electrical energy in ONE MONTH. So if we could efficiently harness the sun’s energy there could be limitless energy for us to use.

Ubiquitous? Alan Heeger, 2000 Nobel Prize winner in chemistry for the materials used in PDA screens. These materials conduct electricity and emit light. It was discovered that these SAME materials could absorb light and emit electricity Goal: inexpensive solar cells EVERYWHERE!

It Is All About the Benjamins! Silicon is a costly semi-conductor Silicon is bulky Silicon is inflexible THREE time more expensive than fuel currently used on the power grid. Costs, due to scale, are going down by 7% per year, which is TOO slow. “More people have lost money in bets against silicon than I know,”-Arno Penzias ( Nobel Prize winner in Physics) – “But then you’re talking a HUGE possible payback: The power market is about $1 trillion.”

We Think It IS Achievable! Goal: To capture 10% of the incoming solar energy. Plan: To develop, using nanoparticles such as titanium dioxide, solar cells which are made from cheap plastics. These plastics are very flexible. The solar cell can even be printed out using an ink jet printer onto the plastic and rolled up during manufacturing.

Applications of Thin Film Solar Cells The idea is that these solar cells can be taken EVERYWHERE to supply a steady amount of electricity, reducing the need to PLUG IN for power. Eventually, we believe these materials might be able to be sprayed onto business tiles, vehicles, and billboards, and then wired up to electrodes. It might even be possible to eventually feed into the electric power grid. Manufacturing will come first, but then:???

An Example of a Nanotechnology Experiment, Which Addresses the Standards: Constructing Nanocrystalline Solar Cells Using the Dye Extracted From Citrus Four main parts: 1.Nanolayer 2.Dye 3.Electrolyte 4.2 electrodes

Nanocrystalline Solar Cells Main component: Fluorine doped tin oxide conductive glass slides Test the slide with a multimeter to determine which side is conductive

Synthesis of the Nanotitanium Suspension Procedure: Add 9 ml (in 1 ml increments) of nitric or acetic acid (ph3-4) to six grams of titanium dioxide in a mortar and pestle. Grinding for 30 minutes will produce a lump free paste. 1 drop of a surfactant is then added ( triton X 100 or dish washing detergent). Suspension is then stored and allow to equilibrate for 15 minutes.

Coating the Cell After testing to determine which side is conductive, one of the glass slides is then masked off 1-2 mm on THREE sides with masking tape. This is to form a mold. A couple of drops if the titanium dioxide suspension is then added and distributed across the area of the mold with a glass rod. The slide is then set aside to dry for one minute.

Calcination of the Solar Cells After the first slide has dried the tape can be removed. The titanium dioxide layer needs to be heat sintered and this can be done by using a hot air gun that can reach a temperature of at least 450 degrees Celsius. This heating process should last 30 minutes.

Dye Preparation Crush 5-6 fresh berries in a mortar and pestle with 2-ml of de-ionized water. The dye is then filter through tissue or a coffee filter and collected. As an optional method, the dye can be purified by crushing only 2-3 berries and adding 10-ml of methanol/acetic acid/water (25:4:21 by volume)

Dye Absorption and Coating the Counter Electrode Allow the heat sintered slide to cool to room temperature. Once the slide has cooled, place the slide face down in the filtered dye and allow the dye to be absorbed for 5 or more minutes. While the first slide is soaking, determine which side of the second slide is conducting. Place the second slide over an open flame and move back and forth. This will coat the second slide with a carbon catalyst layer

Assembling the Solar Cell After the first slide had absorbed the dye, it is quickly rinsed with ethanol to remove any water. It is then blotted dry with tissue paper. Quickly, the two slides are placed in an offset manner together so that the layers are touching. Binder clips can be used to keep the two slides together. One drop of a liquid iodide/iodine solution is then added between the slides. Capillary action will stain the entire inside of the slides

How Does All This Work? 1.The dye absorbs light and transfers excited electrons to the TiO 2. 2.The electron is quickly replaced by the electrolyte added. 3.The electrolyte in turns obtains an electron from the catalyst coated counter electrode. TiO 2 =electron acceptor; Iodide = electron donor; Dye = photochemical pump

Classroom Ideas For Biology Re-creating photosynthesis Studying nature can gives us clues as to the nature of self-assembly Analyzing the potential using different types of citrus

Classroom Ideas for Chemistry Solution chemistry making the electrolyte(concentration is important) Chemical reaction involving titanium dioxide Oxidation/Reduction Reactions Voltaic Cells

Classroom Ideas for Physics Ohm’s Law Internal Resistance Cells in Series or parallel Measuring current/power density Storing solar energy using a capacitor Conservation of Energy

Inquiry Based Learning Model “Let the Kids Play…” Inquiry LevelMain Theme 0 Purpose, Procedure, and outcome is given 1 Outcome is taken away 2 Outcome and Procedure is taken away 3 Students completely design their own experiment

Inquiry Examples Does the potential change when sunlight is filtered using color films? Will mixing citrus dyes change the electric potential? Will aligning the grains of the titanium dioxide during drying improve the gain in potential? Will cells in series produce a larger voltage?

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