Michael K. Seery

A Highly Efficient TiO2–xCx Nano-heterojunction Photocatalyst for Visible Light Induced Antibacterial Applications

Visible-light-induced antibacterial activity of carbon-doped anatase-brookite titania nano-heterojunction photocatalysts are reported for the first time. These heterostructures were prepared using a novel low temperature (100 °C) nonhydrothermal low power microwave (300 W) assisted method. Formation of interband C 2p states was found to be responsible for the band gap narrowing of the carbon doped heterojunctions. The most active photocatalyst obtained after 60 min of microwave irradiation exhibits a 2-fold higher visible-light induced photocatalytic activity in contrast to the standard commercial photocatalyst Evonik-Degussa P-25. Staphylococcus aureus inactivation rate constant for carbon-doped nano-heterojunctions and the standard photocatalyst was 0.0023 and -0.0081 min(-1), respectively. It is proposed that the photoexcited electrons (from the C 2p level) are effectively transferred from the conduction band of brookite to that of anatase causing efficient electron-hole separation, which is found to be responsible for the superior visible-light induced photocatalytic and antibacterial activities of carbon-doped anatase-brookite nano-heterojunctions.

Effect of N-doping on the photocatalytic activity of sol-gel TiO2

In order to study the visible light photocatalytic activity of nitrogen doped titanium dioxide, the interaction between nitrogen dopant sources and titania precursors during sol-gel synthesis is investigated. N-TiO(2) was synthesised using the sol-gel method using 1,3-diaminopropane as a nitrogen source. Samples were annealed several temperatures and the percentage of rutile present determined by X-ray diffraction to be 0% (500°C), 46% (600°C), and 94% (700°C). The reducing amounts of anatase at higher temperatures are studied using FTIR, which suggests the absence of any polymeric chains formed by the chelating agents, which would normally extend anatase-to-rutile transformation temperatures. Differential scanning calorimetry shows that crystalliation occurs before 500°C, providing the crystalline form determined by XRD at 500°C. Increased temperature also resulted in diminished visible light absorption capability, with only the 500°C sample showing significant absorption in the visible region. XPS studies revealed that nitrogen remained within the TiO(2) lattice at higher temperatures. Consequent with the reduced visible light absorption capacity, photocatalytic activity also reduced with increased annealing temperature. Degradation kinetics of methylene blue, irradiated with a 60 W house-bulb, resulted in first order degradation rates constants of 0.40 × 10(-2), 0.19 × 10(-2), and 0.22 × 10(-2)min(-1) for 500, 600, and 700°C respectively. Degradation of Degussa P25 was minimal under the same conditions, and that of undoped TiO(2) was 0.02 × 10(-2)min(-1). Similarly, using 4-chlorophenol under solar irradiation conditions, the N-doped sample at 500°C substantially out-performed the undoped sample. These results are discussed in the context of the effect of increasing temperature on the nature of the band gap.

Developing practical chemistry skills by means of student-driven problem based learning mini-projects

Problem-based learning mini-projects (‘PBL mini-projects’) are used as an alternative to the traditional ‘recipe-style’ laboratory teaching method with the aim of enhancing students’ experience of chemistry laboratory practicals. Small groups of students (3–4) in the second year of their degree are assigned a project title and they must devise the experimental protocol to carry it out. This teaching method better reflects real-life problem solving situations. The students responded favourably in their feedback on these laboratory classes. Class attendance and general class morale were found to be noticeably higher than in previous years. This paper describes the implementation of the PBL mini-projects in our teaching laboratories and examines some feedback obtained from the students (42 in total) and teaching staff involved over a two year period (2004/5 and 2005/6). [Chem. Educ. Res. Pract., 2007, 8 (2), 130-139]

Flipped learning in higher education chemistry: emerging trends and potential directions

Flipped learning has grown in popularity in recent years as a mechanism of incorporating an active learning environment in classrooms and lecture halls. There has been an increasing number of reports for flipped learning in chemistry at higher education institutions. The purpose of this review is to survey these reports with a view to examining the rationale for adopting the flipped learning approach, how educators have implemented the flipped learning approach into their own practice and how these implementations have been evaluated. The reports are analysed for emerging themes on the benefits and challenges of integrating this approach in chemistry education at university level, with a view to understanding how we can continue to develop the approaches taken for implementation of flipped learning methods in higher education chemistry. Analysis of the articles surveyed indicate that the approach is highly popular with students, with educators adopting it as a means of developing an active learning environment, to increase engagement, and to allow time for developing a deeper understanding of the discipline. Despite the approach being open-ended in terms of how it can be implemented, there is some uniformity in how it has been adopted. These approaches are discussed, along with lessons learned from evaluations, with some suggestions for future iterations so that the implementation relies on evidence-based methods.

The implementation of pre‐lecture resources to reduce in‐class cognitive load: A case study for higher education chemistry

This case study describes an effective method to ameliorate the cognitive load caused by new terminology and concepts in lectures. Ten online pre-lecture resources whose design was underpinned by the principles of cognitive load theory were provided to a class of 49 first year university level chemistry students. Each resource introduced a number of key concepts to the forthcoming lecture and included a quiz for students to test understandings and identify misconceptions. The evaluation of the implementation of resources was measured by considering the difference in exam marks for in-semester test and end of module exam. These showed that the marks for students who had no prior knowledge of chemistry before coming to college significantly improved to the point that there was no difference between students with and without prior knowledge. A key outcome of this work is that providing students with resources to prepare for lectures can help in reducing their cognitive load. What is already known about this topic • Prior knowledge (e.g. from school level) is a strong predictor factor for future performance (e.g. at college level). • Cognitive load theory describes how the working memory has a limited capacity to process new information. • E-resources can be designed so as to minimise the difficulty of extracting new information from the resources. What this paper adds • Designing e-resources to introduce some core concepts for a lecture can help students identify these in a lecture with a lot of new terminology. • These e-resources can be easily embedded into the virtual learning environment so that students can access resources, complete quiz and receive feedback and a grade with little extra work for the lecturer. • These e-resources can provide a basis for in-lecture discussion between students and between lecturer and students to further discuss content using core terminology. Implications for practice/policy • Embedding of the resources into the module design is important to attribute them value. The lecture should build on the material introduced in the e-resource. • Feedback should be as rich as possible, correcting wrong ideas for novices to the discipline and misconceptions for those with prior knowledge. • Identifying core concepts in a structured way before each lecture, and providing feedback on students’ understanding of these, give students an opportunity to take control of their own learning both before and after a lecture.

Nanostructured Ti 1‑x S x O 2‑y N y Heterojunctions for Efficient Visible- Light-Induced Photocatalysis

Highly visible-light-active S,N-codoped anatase-rutile heterojunctions are reported for the first time. The formation of heterojunctions at a relatively low temperature and visible-light activity are achieved through thiourea modification of the peroxo-titania complex. FT-IR spectroscopic studies indicated the formation of a Ti(4+)-thiourea complex upon reaction between peroxo-titania complex and thiourea. Decomposition of the Ti(4+)-thiourea complex and formation of visible-light-active S,N-codoped TiO(2) heterojunctions are confirmed using X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and UV/vis spectroscopic studies. Existence of sulfur as sulfate ions (S(6+)) and nitrogen as lattice (N-Ti-N) and interstitial (Ti-N-O) species in heterojunctions are identified using X-ray photoelectron spectroscopy (XPS) and FT-IR spectroscopic techniques. UV-vis and valence band XPS studies of these S,N-codoped heterojunctions proved the fact that the formation of isolated S 3p, N 2p, and Π* N-O states between the valence and conduction bands are responsible for the visible-light absorption. Titanium dioxide obtained from the peroxo-titania complex exists as pure anatase up to a calcination temperature as high as 900 °C. Whereas, thiourea-modified samples are converted to S,N-codoped anatase-rutile heterojunctions at a temperature as low as 500 °C. The most active S,N-codoped heterojunction 0.2 TU-TiO(2) calcined at 600 °C exhibits a 2-fold and 8-fold increase in visible-light photocatalytic activities in contrast to the control sample and the commercial photocatalyst Degussa P-25, respectively. It is proposed that the efficient electron-hole separation due to anatase to rutile electron transfer is responsible for the superior visible-light-induced photocatalytic activities of S,N-codoped heterojunctions.

The role of prior knowledge and student aptitude in undergraduate performance in chemistry: a correlation-prediction study

This paper examines the role of prior knowledge in first year performance of undergraduate chemistry, considering specifically the context of general student aptitude. Statistical testing shows that there were significant differences between the mean scores of students who have and those who have not prior knowledge of chemistry in semester tests and end of year 1 exams, with the former group obtaining higher scores. Correlational analysis shows a strong correlation between prior knowledge and exam performance, and allows for probing of the role of student aptitude. Finally, regression analysis confirms that prior knowledge has a demonstrable influence on future exam performance over and above student aptitude. Two prediction models based on the regression analysis study are proposed.

Novel Microwave Assisted Synthesis of ZnS Nanomaterials

A novel ambient pressure microwave assisted technique is developed in which silver and indium-modified ZnS is synthesized. The as-prepared ZnS is characterized by x-ray diffraction, UV-vis spectroscopy, x-ray photoelectron spectroscopy and luminescence spectroscopy. This procedure produced crystalline materials with particle sizes below 10 nm. The synthesis technique leads to defects in the crystal which induce mid-energy levels in the band gap and lead to indoor light photocatalytic activity. Increasing the amount of silver causes a phase transition from cubic blende to hexagonal phase ZnS. In a comparative study, when the ZnS cubic blende is heated in a conventional chamber furnace, it is completely converted to ZnO at 600 °C. Both cubic blende and hexagonal ZnS show excellent photocatalytic activity under irradiation from a 60 W light bulb. These ZnS samples also show significantly higher photocatalytic activity than the commercially available TiO(2) (Evonik-Degussa P-25).

The application of technology to enhance chemistry education

Technology is accepted to be an integral part of chemistry education, with the use of videos, simulations, and student response systems well reported. The first issue of University Chemistry Education—one of this journal’s two predecessors—was published in 1997, and it contained several articles on topics that still provoke thought and research today, and many of the topics in this themed issue are directly related to issues raised in those articles. Alex Johnstone’s article in that issue ‘. . . And some fell on good ground’ discusses the role of prior knowledge and cognitive load in chemistry education (Johnstone, 1997). Cognitive load theory (CLT) is now of central importance in considering technology in education, with the work of Sweller (2008) and Mayer (2005) providing a basis for considering how technology can help alleviate the load for novice learners as they engage with new material. Several contributions to this special issue resonate with the theme of cognitive load. Behmke and Atwood consider the design of online homework from a CLT perspective, by facilitating students’ mastery of the stages of answering online questions in a step-wise manner. Rosenthal and Sanger contribute further to their work on online simulations. Drawing on Mayer’s work on the design of e-resources, they study the sequencing of the complexity of animations and find that viewing simpler simulations before more complex ones leads to students being better able to explain what they are observing. This may be attributed to the reduction in the extraneous load of viewing the more complex animation that the simple animation provides. John Garratt’s article in the first issue of University Chemistry Education was also about simulations. In ‘‘Virtual Investigations’’, he argues that ‘‘fact-making’’ by students can be enabled by simulations where students learn by experience rather than by being taught (Garratt, 1997). In this themed issue, Akaygun and Jones present a detailed study on the process of simulation design in the context of cognitive science, using liquid–vapour equilibrium as an example. In research that is again grounded in the concept of working memory, Avramiotis and Tsaparlis examine whether computer simulations assist students’ problem solving ability in the laboratory, and find that students who use simulations record a higher achievement. Similarly, Moore, Herzog and Perkins demonstrate in their study that the use of interactive simulations provides implicit scaffolding to students in guided inquiry activities. Sesen uses videos to allow students to compare their predictions with observations of events relating to surface tension, cohesion, and adhesion forces and to subsequently develop explanations for what they observe. Krause, Kienast, Witteck, and Eilks describe an online environment for students to develop their own understanding of topics at lower secondary level before progressing to upper secondary level. Several papers in that first issue of University Chemistry Education address transferable skills. For example Tina Overton’s article, ‘‘Creating Critical Chemists’’, argues for the need to move beyond the teaching of a series of facts towards allowing students freedom to discuss and develop their own opinions, and with this the critical thinking skills needed for genuine problem solving, especially important in a professional context (Overton, 1997). Ryan’s work, reported in this issue, on facilitating peer learning demonstrates the ability of this technology to enable student debate and student-centred discussion when addressing chemistry problems. Blonder et al. write about the development of content knowledge, technological knowledge and pedagogical knowledge as well as technological pedagogical content knowledge (TPACK) among a cohort of teachers. They achieve this by using a professional development programme to develop video editing skills in the context of chemistry topics the teachers wanted to teach for a given pedagogic purpose. Development of TPACK also features in the work of Shwartz and Katchevitch who describe the use of a wiki learning environment in a professional development School of Chemical and Pharmaceutical Sciences, Dublin Institute of Technology, Kevin Street, Dublin 8, Ireland. E-mail: michael.seery@dit.ie, claire.mcdonnell@dit.ie DOI: 10.1039/c3rp90006a

Moving an in-class module online: a case study for chemistry

This article summarises the authors experiences in running a module “Computers for Chemistry” entirely online for the past four years. The module, previously taught in a face-to-face environment, was reconfigured for teaching in an online environment. The rationale for moving online along with the design, implementation and evaluation of the online module are presented. The design and implementation were structured to align with Salmons five stage model for e-moderating. The issues that arose on implementation are discussed along with an outline of supporting learners in an online environment. Lessons learned from running the module online are presented to provide interested practitioners some guidelines for adopting a similar approach.