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This work applies a cultural historical activity theory (CHAT) framework to understand how the outcome of a high school laboratory task may be positively influenced without making changes to the hands-on practical task itself. Informed by cognitivism, novel practical instruction videos that were based on the same video but had different audio content (“one video two voice overs”) have been developed to provide opportunities to prepare for the practical task procedure and then to reflect upon the task's underlying concepts. We use the CHAT framework as a guide to change pupils’ lab roles and rules of engagement were made to structure student interaction and facilitate an equitable and cooperative learning environment. We demonstrate that students benefit from these interventions and achieve significantly higher attainment scores in GCSE chemistry examination practical-themed questions than those students who prepared for the practical task by watching either the novel videos or standard instructional videos during the lesson. In, addition the students working in the scaffolded cooperative learning environment also perceived their confidence in relation to practical-related tasks at higher levels than those in other groups. This work contributes a novel approach to laboratory teaching by placing greater emphasis on dialogic processes as a tool accomplish a practical-based activity.

Textbooks are an important aspect of students’ school lives and the representation of scientists in textbooks is a proxy for the representation of who can do science. This study investigated the names of scientists and other people mentioned in four commonly used textbooks in the three education systems in the UK and Republic of Ireland (England, Wales, and Northern Ireland using the A Level system; Scotland using the Curriculum for Excellence Highers system; Republic of Ireland using the Leaving Certificate system) and characterised them by gender. We found an overwhelming bias towards naming of famous men in three of the four textbooks (1 man and 0 women in the A Level textbook; 8 men and 0 women in the first, and 48 men and 2 women in the second Curriculum for Excellence textbooks, and 45 men and 1 woman in the Leaving Certificate). We subsequently analysed images and again found a dominance of images representing men in three of the four textbooks including only 4 women in a total of 68 images in the Leaving Certificate textbook. These images were analysed by role (scientist or not), and by activity according to UNESCO criteria. There was a tendency to show men in scientific and other occupational roles while women were less well represented in scientific roles and were pictured in domestic and buying activities. This work aims to raise awareness of these representations and prompt action for reform in line with UN Strategic Development goals.

Pedagogical practices can influence students’ confidence and ability beliefs and affect their ambition to persevere in science. Given the continuing need to diversify science and retain students in scientific programmes, science education must be tailored to cater to the needs of varied student groups. Since early experience in university programmes can be decisive in determining students’ further academic and professional choices, pedagogies employed in undergraduate science courses can be particularly influential in supporting science careers. Undergraduate science instructors are therefore encouraged to consider their approaches to teaching and learning from a variety of perspectives that could help empower students from under-represented groups.

The laboratory occupies a central place in chemistry curricula, but the reported goals of laboratory work are very broad. This commentary considers the variety of reported goals of laboratory work and seeks to address the question of what the pedagogic goals for laboratory work are in our curriculum. Drawing on literature from chemistry education research, history of science, and epistemology of laboratory work, it advocates seeking a single, well-defined goal of laboratory work as the place to learn how to do chemistry.

Student-generated videos are growing in popularity in education generally, and in chemistry education there are several reports emerging on their use in practice. Interest in their use in chemistry is grounded in the visual nature of chemistry, the role of laboratory work in chemistry, and a desire to enhance digital literacy skills. In this perspective, we consider the place of student-generated videos in chemistry education, by first considering an appropriate pedagogical rationale for their usage. We then survey the reports of student-generated video with this framework in mind, exploring the role of generation in the reports surveyed. From this, we summarise the current status of student-generated videos in chemistry education and highlight from our readings some considerations for future research in this area, as well as guidelines for practitioners wishing to integrate student-generated video into their practice.

Visuospatial thinking is considered crucial for understanding of three-dimensional spatial concepts in STEM disciplines. Despite their importance, little is known about the underlying cognitive processing required to spatially reason and the varied strategies students may employ to solve visuospatial problems. This study seeks to identify and describe how and when students use imagistic or analytical reasoning when making pen-on-paper predictions about molecular geometry and if particular reasoning strategies are linked to greater accuracy of responses. Student reasoning was evidenced through pen-on-paper responses generated by high attaining, high school students (N = 10) studying Valence Shell Electron Pair Repulsion (VSEPR) Theory in their final year of chemistry. Through analysis and coding of students’ open-ended paper-based responses to an introductory task, results revealed that students employed multiple reasoning strategies, including analytical heuristics and the spontaneous construction of external diagrammatic representations to predict molecular geometry. Importantly, it was observed that despite being instructed on the use of VSEPR theory to find analytical solutions, some students exhibited preference for alternative reasoning strategies drawing on prior knowledge and imagistic reasoning; showing greater accuracy with 3D diagrammatic representations than students who used the algorithmic method of instruction. This has implications for both research and practice as use of specific reasoning strategies are not readily promoted as a pedagogical approach nor are they given credit for in national examinations at school level.

Online conferences are a means of replacing the absence of physical meetings canceled due to COVID-19. In this communication we outline ten tips for those looking to host online meetings, based on our recent experience of running the conference “Methods in Chemistry Education Research (MICER)” online to 320 participants over 3 days in May and June 2020, so that other chemistry educators looking to host online conferences have some of the insight we learned in our experience.

Experimental design is a desirable outcome of laboratory education. Incorporating inquiry into the laboratory curriculum is attractive, but there are acknowledged concerns from practical, theoretical, and epistemological perspectives, and these are accentuated in upper-division courses. In this work, we draw on the extensive literature relating to experimental design and inquiry learning to conceive a pragmatic laboratory curriculum that invokes the development of experimental design skills in a structured way. The model also incorporates the core principles of formative assessment, so that students get a chance to improve their work on the basis of feedback as they are doing it. We illustrate this model with two examples from our own practice of upper-division physical chemistry, but the basis of the design is elaborated so that interested readers can adopt it for any aspect of practical chemistry where there is a desire to incorporate experimental design skills.

Digital badges are emerging as an approach to offer microaccreditation for student achievements obtained in ongoing course work. They act to offer a formal recognition and framework for multiple small components which together make a significant contribution to student learning. Badges are promoted as a way of highlighting these particular components. The process of awarding a badge relies on evidence, typically in digital form, such as video. In this article, we report on the implementation of digital badges in high school chemistry for the teaching and accrediting of achievement in laboratory skills. Pupils watched videos prior to the classroom to assist them in preparation for a demonstration activity. In the classroom, students demonstrated the laboratory technique to a peer while the peer videoed the demonstration on a mobile phone. This video was then used to review the demonstration by both peers and teacher, and once the technique was considered satisfactorily demonstrated, a badge was awarded. As...

Laboratory work is at the core of any chemistry curriculum but literature on the assessment of laboratory skills is scant. In this study we report the use of a peer-observation protocol underpinned by exemplar videos. Students are required to watch exemplar videos for three techniques (titrations, distillations, preparation of standard solutions) in advance of their practical session, and demonstrate the technique to their peer, while being reviewed. For two of the techniques (titrations and distillations), the demonstration was videoed on a mobile phone, which provide evidence that the student has successfully completed the technique. In order to develop digital literacy skills, students are required to upload their videos to a video sharing site for instructor review. The activity facilitated the issuing of digital badges to students who had successfully demonstrated competency. Students' rating of their knowledge, experience, and confidence of a range of aspects associated with each technique significantly increased as a result of the activity. This work, along with student responses to questions, video access, and observations from implementation are reported in order to demonstrate a novel and useful way to incorporate peer-assessment of laboratory skills into a laboratory programme, as well as the use of digital badges as a means of incorporating and documenting transferable skills on the basis of student generated evidence.

Designing laboratory activities is a real challenge for those working in higher education. There is often an acknowledged frustration with the status quo, but a lack of clear guidance on what strategies might be useful in considering a redesign. This article aims to address the question: what considerations should be taken into account when designing a laboratory activity? To address it, we first describe an overarching framework for laboratory learning, describing it as a complex learning environment. The reason for this is that two clear overarching guidelines emerge – the first is that the laboratory curriculum should be structured so that each new challenge for student is adequately supported by their prior learning so that they can draw on their knowledge to address the new learning situation, and the second is that guidelines for the kinds of preparation for laboratory learning emerge. Based on this framework, we advocate four core principles for laboratory learning that should be considered when designing a laboratory activity regarding the overall purpose, the role of preparation, the teaching of technique, and the consideration of affective dimensions of learning. We illustrate this framework in practice with examples from our own practice, with suggestions on using the literature on laboratory education as a source for curriculum reform within an institution.

In this article we summarise over 60 reports and research articles on pre-laboratory activities in higher education chemistry. In the first section of the review, we categorise these activities as follows. First are those intending to introduce chemical concepts, that typically take the form of a pre-laboratory lecture, pre-laboratory quizzes, and pre-laboratory discussion. Second are those intending to introduce laboratory techniques, that typically take the form of interactive simulations, technique videos, mental preparation, and safety information. Finally, a small number of activities intended to prepare students for affective aspects of laboratory work, in the form of enabling confidence and generating motivation are described. In the second section of the review, we consider a framework for design of pre-laboratory activities that aligns with the principles of cognitive load theory. We propose how the two tenets of such a framework – supporting learners in complex scenarios and provision of information necessary to complete tasks – can be considered for the case of preparing for laboratory learning. Of particular relevance is the nature of information provided in advance and that provided just in time, characterised as supportive and procedural information respectively. Finally, in the concluding section, we draw together the principles outlined in the framework and findings from reports of pre-laboratory work in chemistry to propose five guidelines for those wishing to incorporate pre-laboratory activities into their laboratory curriculum; an activity we argue has a significant literature basis for us to encourage.

Using technology when teaching or to support learning is becoming more common place. This perspective discusses the use of technology in our teaching by considering it from the viewpoint of what we need to support our curricula, investigating how technology can help. Nine approaches that have become popular in recent years are outlined with particular emphasis on curriculum delivery problems that they could address, and some recent literature examples of where they have been used. The integration of technology argued for is considered under the umbrella of cognitive load theory, and arising out of this, an approach of how we might progress the use of technology in our teaching is suggested.

Nanocrystalline photocatalysts, prepared under ambient conditions using a microwave assisted synthesis, show indoor light photocatalytic activity for the degradation of Staphylococcus aureus and Escherichia coli . The zinc sulphide (ZnS) nanomaterials, prepared by a microwave assisted synthesis, are shown to be cubic blende structure with an average crystallite size of 4–6 nm. The anti-bacterial activity of these nanomaterials is investigated under irradiation from a 60 W light bulb and photocatalytic activity is revealed to be due to the defects present in the crystal structure. The ZnS shows anti-bacterial action as both a bacteriostatic and bacteriocidal (88% reduction in the amount of bacteria in 5 h) material and the methods of bacterial degradation on the ZnS is discussed. The anti-bacterial actions of these materials were also compared with commercial ZnS and Evonik-Degussa P-25. A detailed mechanism for the light absorption in the visible light region of the microwave prepared ZnS is proposed based on the luminescence spectroscopy.

Development of visible light active (VLA) titania photocatalysts Fujishima and Honda (1972) demonstrated the potential of titanium dioxide (TiO 2) semiconductor mate-rials to split water into hydrogen and oxygen in a photo-electrochemical cell. Their work triggered the development of semiconductor photocatalysis for a wide range of environmental and energy applica-tions. One of the most significant scientific and commercial advances to date has been the development of visible light active (VLA) TiO2 photocatalytic materials. In this review, a background on TiO2 struc-ture, properties and electronic properties in photocatalysis is presented. The development of different strategies to modify TiO2 for the utilization of visible light, including non metal and/or metal doping, dye sensitization and coupling semiconductors are discussed. Emphasis is given to the origin of visible light absorption and the reactive oxygen species generated, deduced by physicochemical and photo-electrochemical methods. Various applications of VLA TiO2, in terms of environmental remediation and in particular water treatment, disinfection and air purification, are illustrated. Comprehensive studies on the photocatalytic degradation of contaminants of emerging concern, including endocrine disrupting compounds, pharmaceuticals, pesticides, cyanotoxins and volatile organic compounds, with VLA TiO2 are discussed and compared to conventional UV-activated TiO2 nanomaterials. Recent advances in bac-terial disinfection using VLA TiO2 are also reviewed. Issues concerning test protocols for real visible light activity and photocatalytic efficiencies with different light sources have been highlighted.

This article summarises the author's 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 Salmon's 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.

The simultaneous existence of visible light photocatalytic activity and high temperature anatase phase stability up to 900 °C in undoped TiO2 is reported for the first time. These properties are achieved by the in-situ generation of oxygen through the thermal decomposition of peroxo-titania complex (formed by the precursor modification with H2O2). Titania containing the highest amount of oxygen (16 H2O2-TiO2) retains 100% anatase phase even at 900 °C, where as the control sample exists as 100% rutile at this temperature. The same composition exhibits a six-fold and two-fold increase in visible light photocatalytic activities in comparison to the control sample and the standard photocatalyst Degussa P-25 respectively. Among the various para­meters affecting the photocatalytic action, such as band gap narrowing, textural properties, crystallite size, and anatase phase stability, band gap narrowing was identified as the major factor responsible for the visible light photocatalytic activity. Increased Ti–O–Ti bond strength and upward shifting of the valence band (VB) maximum, which is responsible for the high temperature stability and visible light activity respectively, are identified from FT–IR, XPS, and photoluminescence (PL) spectroscopic studies. It is therefore proposed that the oxygen excess defects present in these titania samples are responsible for the high temperature stability and enhanced visible light photocatalytic activities.

The synthesis of a ZnO−TiO2 nanocomposite usually results in the formation of one or more of three compounds—Zn2TiO4, Zn2Ti3O8, and ZnTiO3—along with other secondary impurity phases, such as rutile-TiO2 or ZnO. Obtaining a phase-pure composite of either of these materials is one of the challenges in materials chemistry. For example, pure ZnTiO3 cannot be synthesized under normal conditions, because the ZnTiO3 phase readily transforms to Zn2TiO4 and rutile. Zn2Ti3O8 is reported as a metastable form of ZnTiO3. The Zn2TiO4 form is usually synthesized via solid-state reaction at high temperatures (typically above 1000 °C). In the current study, the crystalline and phase-transformation behaviors of sol−gel-synthesized zinc titanates has been investigated systematically, with regard to various Zn:Ti precursor molar ratios. X-ray diffraction (XRD) has shown that, with excess titanium precursor, zinc metatitanate (ZnTiO3) is the preferred zinc titanate phase formed at temperatures of 600−900 °C, with a direct tra...

Nitrogen doped anatase-rutile heterojunctions are successfully synthesized through an ethylene-diaminetetraacetic acid (EDTA) modified sol-gel process.An FT-IR study of EDTA modified TiO2 gel confirms the existence of an ionic intermediate (as indicated by a Δν value of 233 cm-1).Differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Raman spectroscopy are employed to study the phase evolution, phase purity, and crystallite size of samples. Formations of O-Ti-N and N-Ti-N bonds in calcined samples are confirmed using XPS and FT-IR spectro- scopy. AllEDTAmodified samples show significantly higher visible light photocatalytic activity than the unmodified sample. The most active nitrogen doped heterojunction obtained at 400C exhibits 9-fold visible light activity in comparison to the standard photocatalyst Degussa P-25. It is proposed that the photo excited electrons (from the visible midgap level) are effectively transferred from the conduction band of anatase to that of rutile causing effective electron-hole separation, which is responsible for the higher visible light activity and lower photoluminescence (PL) intensity

Highly photocatalytically active silver-modified ZnO has been prepared and the effect of silver modification was studied. The structural and optical properties were characterized by X-ray diffraction, Fourier transform IR, differential scanning calorimetry, BET surface area, Raman, UV-vis, and photoluminescence spectroscopy. The photocatalytic activity of these materials was studied by analyzing the degradation of an organic dye, rhodamine 6G (R6G), and it is found that 3 mol % silver-modified ZnO at 400°C shows approximately four times higher rate of degradation than that of unmodified ZnO and a three times higher rate than that of commercial TiO 2 photocatalyst Degussa P-25. It was also noted that the photocatalytic activity for the modified ZnO sample was five times higher than the unmodified sample using sunlight. The effect of silver in enhancing the photocatalytic activity has been studied by analyzing the emission properties of both ZnO and silvermodified ZnO in the presence (emission increases) and absence (emission decreases) of R6G. We attribute these observations to the extent of valence band hole production and the role of silver in trapping the conduction band (CB) electrons in the absence of R6G. In the presence of R6G, the dye preserves the CB electron population in the metal oxide, thus preserving and enhancing emission intensity. The sensitizing property of the dye and electron scavenging ability of silver together constitute to the interfacial charge transfer process in such a way to utilize the photoexcited electrons.

This paper presents a systematic study on two different preparation methods for titanium dioxide with silver. The silver can be incorporated by irradiating the reaction mixture during preparation to reduce silver ion to silver metal or by direct calcination of the sol–gel material to decompose silver nitrate to silver. Of the two methods, we found the latter produces a more effective photocatalytic material (6–50% improvement in catalytic efficiency), which is attributed to the fact that the silver is homogeneously dispersed throughout the material. The efficiency of the materials were examined using a Q-Sun solar simulator (visible light) and in Dublin summer sunlight (latitude 54°N). In both cases, the addition of increasing amounts of silver, for both batches of samples, significantly increases the rate of degradation of a model dye, rhodamine 6G (R6G), increasing the rate of degradation from 0.06 min−1 for TiO2 to 0.34 min−1 for 5 mol% Ag–TiO2. This is attributed to the increasing visible absorption capacity due to the presence of silver nanoparticles.

In the absence of a dopant or precursor odification, anatase to rutile transformation in synthetic TiO2 sually ccurs at a temperature of 600 700 °C. Conventionally, metal oxide dopants (e.g., Al2O3 nd SiO2 are used o tune the anatase to rutile transformation. A simple methodology is reported here to extend the anatase utile transformation by employing various concentrations of urea. XRD and Raman spectroscopy were used uring thermal treatment. A significantly higher anatase phase (97%) as been obtained at 800 C with use of a 1:1 Ti(OPr)4 urea composition and 11% anatase composition is etained even after calcining the powder at 900 . On comparison a sample that has been prepared without rea showed that rutile phases started to form at a temperature as low as 600C. The effect of smaller mounts of urea such as 1:0.25 and 1:0.5 Ti(OPr) urea has also been studied and compared. The investigation oncluded that the stoichiometric modification by urea 1:1 Ti(OPr) urea composition is most effective in extending the anatase to rutile phase transformation by 200°C compared to the unmodified sample. In addition, ET analysis carried out on samples calcined at 500°C showed that the addition of urea up to 1:1 Ti(OPr4:urea increased the total pore volume (from 0.108 to 0.224 cm3/g) and average pore diameter (11 to 30 nm)compared to the standard sample. Samples prepared with 1:1 Ti(OPr)4:urea composition calcined at 900 °C how significantly higher photocatalytic activity compared to the standard sample prepared under similarconditions. Kinetic analysis shows a marked increase in the photocatalytic degradation of rhodamine 6G on oing from the standard sample (0.27 min, decoloration in 120 min) to the urea-modified sample (0.73min-1, decoloration in 50 min).

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 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.

This paper presents topological constraints of gate-level circuits obtained through standard cell recognition applied to gate-level commercial microelectronics verification. A suite of topological constraints, including the gate vertex count, net vertex count, terminal count, blocks, circuit genus, Euler characteristic, and number of faces are extracted from gate-level circuits obtained through standard cell recognition. Topological constraints are computed for two full adder cells at fourth level of abstraction and for two full adder cells at the third level of abstraction. Two mathematical frameworks are also introduced to describe physically distinct situations in hardware that are represented in a schematic as functionally equivalent. The first method uses the concept of a braid word, and the second method uses the concept of a crossing vertex. Schematic braid words corresponding to each of two full adder cell schematics at fourth level of abstraction and for two full adder cell schematics at the third level of abstraction are derived. Chip braid words corresponding to the set of unique physical designs that could potentially be realized in chip hardware from a schematic are obtained and discussed. Potential capabilities of these approaches for gate-level circuits are discussed.

The interactions between [Ru(bpy)3]2+ and the polyoxotungstate anion [S2W18O62]4- in acetonitrile solution were investigated using a combination of photophysics and optical and Raman spectroscopies. The presence of ion clusters of {[Ru(bpy)3][S2W18O62]}2- (K2 = 7.7 × 105) and [Ru(bpy)3]2[S2W18O62] (K1 = 1.0 × 106 mol-2 dm-6) are inferred. The 2:1 complex is weakly luminescent, with a lifetime at room temperature of 20 ns under aerobic conditions. Difference electronic absorption, excitation, and resonance Raman spectroscopies indicate that the tungstate anion participates in this transition. Under conditions where [Ru(bpy)3]2+ alone is photolabile, the ion clusters are photostable, with no photodecomposition or photoinduced ligand exchange reactions evident in acetonitrile. This characteristic is examined employing temperature-dependent luminescent studies which demonstrate that the observed activation energy and preexponential factor are considerably different from those of free [Ru(bpy)3]2+and are chara...

If the last decade was of the rise of online content, the coming one is likely going to focus on how best to use this content in the teaching and learning of the chemistry curriculum. The boundary between online material and the content as delivered in the lecture hall is becoming increasingly blurred, as educators seek to use the online space to support and supplement their in-class teaching. Online materials can be used to prepare for lectures or laboratories and supplement lecture content with additional explanatory material. Classroom conversation can move online to discussion boards, and there is a diversity in assessment methods available, often automated, which allows students to get immediate feedback on their understanding of a topic. The lecturer's toolkit has expanded enormously, and the difficulty is likely to center on how best to design the curriculum delivery to meaningfully incorporate learning technologies so that they enhance learning in and out of the classroom. In this chapter, we present a series of learning technologies, some better known than others, with an emphasis on how they may be usefully incorporated into the twenty-first century classroom. We advocate these technologies by basing them on what is known about how people learn. In order to be useful to practitioners in higher education, we supplement them with examples from the chemistry practice literature.

The DARPA TRUST program was established to address the need to verify integrated circuits (ICs). This paper explores methodologies to resolve conflicts among IC designs in prior applications of commercial software to verify designs ranging in size from 1 to 283,359 cells. Preliminary results show the capability of commercial software tools to generate test cases for evaluation.

This project introduces the idea of “flipped lecturing” to a group of second-year undergraduate students. The aim of flipped lecturing is to provide much of the “content delivery” of the lecture in advance, so that the lecture hour can be devoted to more in-depth discussion, problem solving, and so on. As well as development of the material, a formal evaluation was conducted. Fifty-one students from a year 2 chemical thermodynamics module took part in this study. Students were provided with online lectures in advance of their lectures. Along with each online lecture, students were given a handout to work through as they watch the video. Each week, a quiz was completed before each lecture, which allowed students to check their understanding and provided a grade for their continuous assessment mark. The evaluation examines both the students’ usage of materials and their engagement in lectures. This involves analysis of access statistics, along with an in-class cognitive engagement instrument. The latter is ...

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) non-hydrothermal 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 minutes 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 photo-excited 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. KEYWORDS: Titanium dioxide; Microwave synthesis; Carbon-doping; Visible-light induced photocatalysis; Antibacterial activity; Heterojunctions

A novel ambient pressure microwave-assisted technique is developed in which silver and indium modified ZnS is synthesised. The as prepared ZnS is characterised 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 watt light bulb. These ZnS samples also show significantly higher photocatalytic activity compared to the commercially available TiO2 (Evonik-Degussa P-25).

Highly visible light active S, N co-doped anatase-rutile heterojunctions is 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 Ti4+-thiourea complex upon reaction between peroxo-titania complex and thiourea. Decomposition of the Ti4+-thiourea complex and formation of visible light active S, N co-doped TiO2 heterojunctions are confirmed using X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM) and UV/Vis spectroscopic studies. Existence of sulfur as sulfate ions (S6+) 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 co-doped heterojunctions proved the fact that the formation of isolated S 3p, N 2p and П* N-O states between the valence and conduction bands are responsible for the visible light absorption. Titanium dioxide obtained from the un-doped 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 co-doped anatase-rutile heterojunctions at a temperature as low as 500 °C. The most active S, N co-doped heterojunction (0.2 SN-TiO2) obtained at 600 °C exhibits a two-fold and eight-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 exceptionally high visible light photocatalytic activities of S, N co-doped heterojunctions.

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 60W 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. © 2011.

Anatase to rutile transition in an unmodified synthetic titania usually occurs at a temperature range of 600 – 700 °C. Various methods such as addition of metallic and non-metallic dopants and modifying the precursor have previously been reported to influence the anatase to rutile transition temperature. In the current study, the effect of addition of increasing amounts of silver to the extent of chelation of a formate group to a titanium precursor and the resulting effects on the transformation of anatase to rutile has been studied. The addition of silver (0, 1, 3 and 5 mol %) on the anatase to rutile transformation temperature has been systematically followed by FTIR, Raman, XRD, DSC and XPS. From the FTIR and Raman spectroscopy studies it was observed that the incorporation of silver caused a reduction in the intensity of the COO- stretches indicating that the titania – formate bridging complex is becoming weaker in the presence of silver. XRD studies indicated an early rutile formation for the silver doped samples. XRD of the samples calcined at 700 °C showed that 5 mol % Ag TiO2 contained both anatase (46 %) and rutile (54 %), whereas the undoped sample primarily consists of anatase (95 %). At 800 °C all silver doped samples converted to 100% rutile and the the un-doped TiO2 consisted of both anatase (55 %) and rutile (45 %). XPS analysis showed that Ag0 and Ag2O has been formed on the surface of the titania – formate complex, without calcination (> 100 °C) indicating that photo oxidation has occurred. FTIR, Raman and XPS studies confirmed that the presence of silver in the xerogel before calcination may be responsible for the reduction of the titanium – formate bridge. It was concluded that the presence of silver (Ag2O and Ag0) hindered bridging ligands, which resulted in a weakened titanium gel network. This structurally weakened gel network could easily be collapsed during calcination and it favors an early rutile formation.

Among the three major phases in titania, anatase is reported to be a better photocatalytically active phase. Anatase to rutile transformations, under normal conditions, usually occurs at a temperatue range of 600- 700 °C. Various chemical additives have previously been employed to extend the anatase transition to higher temperatures. Effect of employing various concentrations of formic acid and water on phase transition has systematically been studied by XRD, FTIR and Raman spectroscopy. A considerably higher anatase phase (41%) has been obtained at 800 ºC and 10% anatase composition is retained after annealing the materials at 900 ºC for the optimised composition. On comparison a control sample which has been prepared without formic acid showed that rutile phases started to form at a temperature of 600 C, FTIR and Raman studies indicated that the formate group favoured a bridging (syn-anti or syn-syn) mode of chelation depending on the reaction conditions. It has been concluded that the resulting syn-anti binding hinders crosslinking of the gel network, resulting in a weakened structure and thus causing the anatase to rutile transformation temperature to occur at a lower temperature than with the syn-syn¬ mode of binding where more ordered gel networks are formed.

Practical work has an unassailable position in the study of chemistry and, as a consequence, its role, its relevance and most importantly, its nature have rarely been seriously questioned. This chapter seeks to examine what the traditional approach to practical work actually achieves and to expose some of its limitations. A distinction between exercise and experiment is made in the context of an analysis of possible approaches to practical work and ways for optimising the use of costly laboratory resources are suggested. A tighter correspondence between learning outcomes and practical activity can lead to improved and deeper learning as well as to better mapping to assessment.

Context and problem-based learning are approaches to teaching that have been found to engage and motivate students and to develop a range of intellectual and transferable skills. This chapter discusses the literature related to these approaches and describes strategies to implement them in the teaching of chemistry within higher education.

The interactions between luminophore [Ru(bpy)3]2+, and the lacunary Dawson heteropolyanions, [P2W17O61(FeOH2)]7-, [P2W17O61(FeBr)]6- and [P2W17O61]10- were investigated using a combination of photophysics, optical and Raman spectroscopy. Extensive quenching of the excited state of [Ru(bpy)3]2+ was observed in each case. Quenching is attributed to the formation of association complexes between [Ru(bpy)(3)]2+ and the heteropolyanions in which the charge on the heteropolyanions is fully compensated for by the ruthenium polypyridyl species. The interaction appears to be principally electrostatic in nature producing [Ru(bpy)3]3.5[P2W17O61(FeOH2)], [Ru(bpy)3]3[P2W17O61(FeBr)] and [Ru(bpy)3]5[P2W17O61]10-. The association constants for formation of the clusters were obtained from photophysical studies and surprisingly, despite the electrostatic nature of the interaction, there was no correlation between the charge on the polyoxometallate and the association constant. In particular, the unsubstituted lacunary, [P2W17O61]10-, showed considerably weaker association compared to the transition metal substituted lacunaries, in spite of its 10- charge. Difference absorption spectroscopy revealed a new transition at ca. 480 nm for each of the cluster complexes. From resonance Raman spectroscopy the origin of this transition was found to involve the polyoxometallate. Unlike previously reported adducts, the cluster complexes formed were not luminescent. In all cases the cluster complexes exhibit remarkable photostability, with no photodecomposition or photo-induced ligand exchange reactions evident in acetonitrile, under conditions where [Ru(bpy)3]2+ alone exhibits considerable photolability.