In this experiment students prepare nickel nanowires using a template synthesis technique and characterize their properties. Electrodeposition of nickel to fill the 200-nm diameter pores of a commercially-available alumina filtration membrane is accomplished using a nickel salt solution and a AA battery. The nanowires, which are ~200 nm in diameter and up to ~50 μm in length, can be liberated from the membrane by dissolving the alumina template with sodium hydroxide. Suspensions of nanowires on a microscope slide can be observed using a common optical microscope. The alignment and movement of the magnetic nanowires can be controlled using magnets. This experiment is appropriate in introductory college chemistry courses and in upper-level physical and inorganic chemistry courses. The experiment provides students with a hands-on laboratory experience in nanotechnology, while illustrating fundamental ideas from a variety of areas, including electrochemistry, magnetism, and materials science.

Electrochemical water oxidation is a major focus of solar energy conversion efforts. A new laboratory experiment has been developed that utilizes real-time, hands-on research to discover catalysts for solar energy conversion. The HARPOON, or Heterogeneous Anodes Rapidly Perused for Oxygen Overpotential Neutralization, experiment allows an array of mixed-metal oxide compositions to be analyzed in parallel to test their activity as water oxidation catalysts. Students create unique combinations of mixed-metal oxide materials, which are then analyzed utilizing a simple, inexpensive system that detects the amount of oxygen evolved during electrolysis. This experiment has the flexibility to be implemented at a variety of educational levels with the depth and breadth of the material covered accordingly. Concepts such as stoichiometry, materials, solutions, and fluorescence can be emphasized, while the research-like experience strengthens students’ independence, critical-thinking skills, and excitement for science. An online questionnaire was developed to measure various effects of the experiment on students, including learning gains, attitudes toward chemistry, and motivation to pursue a career in scientific research. The assessment results indicate positive gains for students in their understanding of the social nature of scientific work, scientific literacy, and interest in pursuing additional research opportunities.

Molecularly imprinted films of poly(acrylic acid) (PAA) have been coated onto n-CdSe in order to make the band-edge photoluminescence (PL) of the semiconductor respond selectively to the imprinting analyte. This strategy has been implemented using PAA films deposited in the presence of ammonia and trimethylamine analytes. PAA films have been characterized by IR spectroscopy, which indicates that binding of either analyte nearly reversibly deprotonates the polymer carboxylic acid groups. PL measurements suggest that the imprinted PAA coatings serve as sieves for selective surface binding: In contrast to the bare CdSe surface, which responds both to ammonia and trimethylamine with reversible enhancements in PL intensity, CdSe coated with ammonia-imprinted PAA (AI-PAA) films exhibits reversible PL changes toward ammonia but no response to trimethylamine. The PL changes for the AI-PAA films can be fit to a dead-layer model that indicates that ammonia binding reduces the CdSe depletion width by ∼100 Å, an effect comparable to that seen for the bare surface. Binding constants of ∼10 3 M-1 , estimated using the Langmuir adsorption isotherm model, are similar for adsorption of ammonia onto bare and AI-PAAcoated CdSe surfaces. Coating the CdSe substrate with trimethylamine-imprinted PAA (TI-PAA) films leads to PL responses to both ammonia and trimethylamine, presumably reflecting larger imprint pores that are less sterically demanding. Implications for chemical sensing using these composite structures are discussed.

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Given the importance of questions in science, it is critical that students learn to ask questions as well as learning to answer them. This paper describes a classroom exercise to help students better ask their own questions. It has been classroom-tested in multiple formats and has also been used for curriculum development workshops for faculty. This exercise in creating questions can be easily customized to suit different instructional contexts; some variations are outlined. More broadly, this paper also discusses the pedagogical significance of questioning, raising four salient points: (1) learners are more likely to have a personal interest in the questions they raise; (2) questions can serve as entry points for issues relating to ethnicity and gender; (3) questions give control to the person who asks them; and (4) questions can challenge existing structures, categories, and norms.