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A rapid synthesis of TiO2 hybrids with significant enhancement in photocatalytic activity is reported. Using state-of-the-art techniques including sophisticated DFT calculations, we report insight into the charge transfer and modulation of the energy band edges.

Conventional metal oxide semiconductor (MOS) gas sensors have been investigated for decades to protect our life and property. However, the traditional devices can hardly fulfill the requirements of our fast developing mobile society, because the high operating temperatures greatly limit their applications in battery-loaded portable systems that can only drive devices with low power consumption. As ammonia is gaining importance in the production and storage of hydrogen, there is an increasing demand for energy-efficient ammonia detectors. Hence, in this work, a Schottky diode resulting from the contact between zinc oxide nanorods and gold is designed to detect gaseous ammonia at room temperature with a power consumption of 625 μW. The Schottky diode gas sensors benefit from the change of barrier height in different gases as well as the catalytic effect of gold nanoparticles. This diode structure, fabricated without expensive interdigitated electrodes and displaying excellent performance at room temperature, provides a novel method to equip mobile devices with MOS gas sensors.

Highly uniformed, surfactant free and vertically oriented titanium-di-oxide (TiO2) nanorods were grown on pre-treated fluorine doped tin oxide (FTO) using hydrothermal method through titanium tetra butoxide (Ti(OBu)4) as titanium source. Three different temperatures 130 °C, 150 °C and 180 °C were followed to grow the nanorods at a fixed reaction time of 4 h. The prepared TiO2 nanorods were annealed at the temperatures of 550 °C and 600 °C for 3 h. X-ray diffraction (XRD) analysis shows that obtained nanorods exhibit pure rutile phase. From scanning electron microscopy (SEM) analysis, it was found that increasing temperature led to decreasing the diameter of the nanorods. In addition to these, formation of hierarchical type TiO2 nanorods was also observed at 130 °C. UV-visible spectra analysis was carried out to find the influence of diameter of the nanorods on its optical properties. The plausible mechanism of the growth process is also discussed.

To date, a number of studies have reported the use of vibrations coupled to ferroelectric materials for water splitting. However, producing a stable particle suspension for high efficiency and long-term stability remains a challenge. Here, the first report of the production of a nanofluidic BaTiO

The development of noble-metal-free co-catalysts is seen as a viable strategy for improving the performance of semiconductor photocatalysts. Although the photocatalytic efficiency of ferroelectrics is typically low, it can be enhanced through the incorporation of a co-catalyst into nanocomposites. Here, we demonstrate the influence of ferroelectricity on the decolorization of rhodamine B under simulated solar light using RbBi2Ti2NbO10 and compared the performance with that of non-ferroelectric RbBi2Nb5O16. The decolorization rate for RbBi2Ti2NbO10 was 5 times greater than that of RbBi2Nb5O16. This behaviour can be explained in terms of ferroelectric polarization, which drives the separation of charge carriers. The photocatalytic activity of RbBi2Ti2NbO10 was further enhanced to over 30 times upon preparing a nanocomposite with tungsten carbide (WC) through high energy ball milling. This enhancement was attributed not only to the increased specific surface area, but also to the incorporated WC co-catalyst, which also serves as a source of plasmonic hot electrons and extends the photocatalytic activity into the visible light range. The WC/RbBi2Ti2NbO10 nanocomposite shows interesting water oxidation properties and evolves O-2 with a rate of 68.5 mu mol h(-1) g(-1) and a quantum yield of 3% at 420 nm. This work demonstrates a simple route for preparing WC containing nano-ferroelectric composites for solar energy conversion applications.

We report the chemical solution deposition (CSD) of a phase-pure Bi2Fe4O9 thin film for use as a photoanode in photoelectrochemical (PEC) water splitting. The energy levels of Bi2Fe4O9 films have been measured and n-type characteristics have been confirmed. With band gaps determined as 2.05 eV (indirect) and 2.80 eV (direct) and valence and conduction bands straddling the water oxidation and reduction potentials, this material is highly promising as a photocatalyst for solar water splitting. The photocurrent of a planar photoanode reached 0.1 mA cm−2 at 1.23 VNHE under AM1.5G illumination. The addition of H2O2 as a hole scavenger increased the photocurrent to 0.25 mA cm−2, indicating hole injection is one limiting factor to the performance. The performance was enhanced by nearly 5-fold when the Bi2Fe4O9 photoanode is coupled to a Co–Pi surface co-catalyst. The photoanode also shows excellent stability with no change in photocurrent over three hours of continuous illumination. These results indicate that this material represents a promising addition to the growing selection of low-cost, stable photocatalysts for use in solar water splitting.

Recently, the coupling of ferroelectrics with electrochemical reactions has attracted increasing interest for harvesting waste heat. The change of polarization of a ferroelectric with temperature can be used to influence chemical reactions, especially when the material is cycled near its Curie temperature. In this perspective, we introduce the principle of pyroelectric controlled electrochemical processes by harvesting waste heat energy and explore their potential electrochemical applications, such as water treatment, air purification, and hydrogen generation. As an emerging approach for driving electrochemical reactions, the presence of thermal fluctuations and/or transient waste heat in the environment has the potential to be the primary thermal input for driving the change in polarization of a pyroelectric to release charge for such reactions. There are a number of avenues to explore, and we summarize strategies for forming multi-functional or hybrid materials and future directions such as selecting pyroelectrics with low Curie temperature (

We have used a ferroelectric BaTiO3 substrate with a hematite (α-Fe2O3) nanostructured surface to form a heterogeneous BaTiO3/α-Fe2O3 photocatalyst. In this study we show that varying the mass ratio of α-Fe2O3 on BaTiO3 has a significant influence on photoinduced decolorization of rhodamine B under simulated sunlight. The highest photocatalytic activity was obtained for BaTiO3–Fe2O3-0.001M, with the lowest mass ratio of α-Fe2O3 in our study. This catalyst exhibited a 2-fold increase in performance compared to pure BaTiO3 and a 5-fold increase when compared to the higher-surface-area pure α-Fe2O3. The increases in performance become more marked upon scaling for the lower surface area of the heterostructured catalyst. Performance enhancement is associated with improved charge-carrier separation at the interface between the ferroelectric surface, which exhibits ferroelectric polarization, and the hematite. Increasing the mass ratio of hematite increases the thickness of this layer, lowers the number of tripl...

Pd modified TiO2 displayed an increased light harvesting potential into the visible region of the solar spectrum by 8% and an enhanced photocatalytic decolorization rate of rhodamine B by a factor of 19 compared to bare TiO2. A red-shift in the light harvesting ability of the catalyst means that there is photochemical activity present for excitations up to 600 nm. We attribute this enhanced photo-reactivity to a localized plasmon associated with nanostructured Pd that we photochemically deposited onto TiO2 prior to dye decolorization. This catalyst system has significant potential to treat environmental pollution via solar energy harvesting.

© 2019 Elsevier Ltd Water splitting by thermal cycling of a pyroelectric element that acts as an external charge source offers an alternative method to produce hydrogen from transient low-grade waste heat or natural temperature changes. In contrast to conventional energy harvesting, where the optimised load resistance is used to maximise the combination of current and voltage, for water splitting applications there is a need to optimise the system to achieve a sufficiently high potential difference for water electrolysis, whilst also maintaining a high current output. For the thermal harvesting system examined here, a high impedance 0.5 M KOH electrolyte with working electrodes connected to a rectified pyroelectric harvester produced the highest voltage of 2.34 V, which was sufficient for H2 generation. In addition to electrolyte concentration, the frequency of the temperature oscillations was examined and reducing the heating-cooling frequency led to a larger change in temperature to generate increased pyroelectric charge and a higher potential difference for pyro-water splitting. Finally, in the absence of sacrificial reagents, cyclic production of H2 (0.654 μmol/h) was demonstrated for the optimised processing parameters of electrolyte and thermal cycling frequency using the external pyroelectric element as a charge source for water splitting.

Using BaTiO

Zn1-xCuxO (0 ≤ x ≤ 0.2) nanoparticles were prepared by co-precipitation method followed by drying at 200oC. A non-ionic surfactant Tween-80 which was not reported in earlier studies, was used during preparation process. X-ray diffraction analysis showed the formation of wurtzite ZnO phase nanostructures. The Rietveld analysis showed the appearance of impurity phase (CuO), when Cu2+ was doped with ZnO (x = 0.05 to 0.2). Morphological observations using scanning electron microscopy show the formation of nanoparticles with remarkable morphologies. Photoluminescence spectra revealed emission bands in both UV and visible regions due to the defect centres acting as trap levels. Diffuse reflectance spectroscopy (DRS) showed a decreasing trend in the value of the band gap with increasing Cu2+ doping for lower concentration (x = 0 to 0.1) and then increasing trend for higher concentration of Cu2+ doping. (x = 0.1 to 0.2). The elemental composition of Zn, Cu and O was quantitatively obtained from EDAX analysis where the chemical composition was close to the starting stoichiometries. Magnetisation-Field (M-H) hysteresis curves revealed the appearance of ferromagnetic behaviour, where the magnetic characteristics such as coercivity and saturation magnetization values , were found to be sensitive to Cu2+ doping level.

In the last 10 years there has been growing interest to investigate the impact of non-centrosymmetry of piezo or ferroelectric materials for energy harvesting devices and systems. There are a large range of devices being investigated including those that convert kinetic energy into electrical energy or convert sunlight into fuels, known as solar fuels, or produce electrical energy such as in a photovoltaic device. The fundamental principle and area of interest in these materials are related to the breaking of crystal symmetry found in a piezo or ferroelectric material. This breaking of crystal symmetry intimately influences the physical properties within the material and leads to some specific behaviour. We know that the domain structure of a ferroelectric material separates photoinduced carriers that lead to regio-specific photochemistry.

Ferroelectric materials exhibit anomalous behavior due to the presence of domains and domain walls which are related to the spontaneous polarization inherent in the crystal structure. Control of fe ...

ZnO dye sensitized solar cells have been reported to be plagued with issues of dye aggregation which increased current recombination. This dye aggregation has been linked to the pH 5 ruthenium-based dye solutions, which is below ZnO's point of zero charge of pH 9, resulting in positive surface charges on ZnO which form Zn2+ - dye complexes. In this paper, a heterogeneous architecture of ZnO and bismuth ferrite (BiFeO3 or BFO) is synthesized using a technique which allows the synthesis using purely chemical solution techniques. BFO is a perovskite studied extensively for its multiferroic properties and its potential for anomalous photovoltages. The solid state solar cells are sensitized with N719, and uses copper thiocyanate (CuSCN) as a hole conductor. The ZnO-BFO-N719-CuSCN heterogeneous architecture solar cell showed efficiencies which increased ca four-fold to 0.38% and Jsc which doubled to 1.38mA/cm2 compared to ZnO-N719-CuSCN architectures. We will report that the addition of BFO improved performances due to the reduction of dye aggregation due to BFO's pzc of pH 6.5 which is close to the pH 5 of the dye solution, as well as BFO's role as an electron blocking layer which prevents the back tunneling of electrons from ZnO to CuSCN.

Zinc doped cobalt ferrite spinel nanoparticles were prepared by the microwave combustion method. All the samples were characterized by using X-ray diffraction technique (XRD), Scanning Electron Microscopy, energy dispersive X-ray analysis, UV–visible diffuse reflectance spectroscopy, Fourier transformed infrared (FT-IR) spectroscopy and vibrating sample magnetometry. The XRD patterns confirmed the formation of single phase CoFe2O4 inverse spinel structure without impurities. The lattice parameter increased from 8.380 to 8.396 A with increasing Zn2+ fraction. The average crystallite sizes obtained by a Scherrer method varied between 46.22 nm and 30.79 nm. The estimated band gap energy values increases with an increasing zinc fraction (1.88–2.10 eV). The elemental composition of Zn, Co, and Fe was qualitatively obtained from energy dispersive X-ray (EDX) analysis.

A huge number of piezoelectric materials have been demonstrated since the discovery of piezoelectricity over a century ago. The use of nanostructured piezoelectrics, however, is a relatively recent development, and the understanding of the nanoscale size effects on ferro- and piezoelectricity is still being formulated. Despite this, the application of piezoelectric nanostructures to energy harvesting has expanded rapidly in the last decade leading to a huge range of reported devices [96,97] . Most studies focus on zinc oxide, as its nanostructures are formed relatively easily using low temperature methods [98] , unlike many ferroelectrics which require high temperature processing. In addition, the nanostructures are crystallographically aligned and non-ferroelectric, and therefore do not require poling. However, more recently other well-known materials have been investigated for nanostructured energy harvesters including lead zirconate titanate (PZT) and barium titanate, with the potential for higher power outputs due to their higher piezoelectric coefficients. This review summarises the work to date on nanostructured piezoelectric energy harvesters, commonly called nanogenerators, starting with early reports of piezoelectric output from single strained ZnO nanorods, and moving through the use of nanorod arrays, flexible substrates and alternative materials and nanostructures. Applications that have been demonstrated for devices are summarised, and the future prospects for this field are considered. Before embarking on the development of any nanostructured energy harvesters a thorough understanding of piezoelectric and ferroelectric materials – and the broader energy harvesting field – is essential, for which there are a number of suitable reviews and textbooks [1–4] .

New hybrid materials consisting of ZnO nanorods sensitized with three different biomass-derived carbon quantum dots (CQDs) were synthesized, characterized, and used for the first time to build solid-state nanostructured solar cells. The performance of the devices was dependent on the functional groups found on the CQDs. The highest efficiency was obtained using a layer-by-layer coating of two different types of CQDs.

Neue Hybridmaterialien aus ZnO-Nanostabchen, die mit drei verschiedenen, aus Biomasse hergestellten Kohlenstoff-Quantenpunkten (CQDs) sensibilisiert wurden, wurden synthetisiert, charakterisiert und zum ersten Mal zur Produktion von nanostrukturierten Festkorper-Solarzellen verwendet. Die funktionellen Gruppen der CQDs beeinflussen die Leistung der Solarzellen, und der beste Wirkungsgrad konnte durch alternierende Beschichtung mit zwei verschiedenen CQD-Varianten erzielt werden.

ZnO is an interesting material for photoactive and optoelectronic devices because of the wide range of available nanostructures and advantageous semiconducting properties. However, a significant drawback of ZnO is the low stability in high or low pH solutions. This has limited the development of ZnO core-shell materials for use in Z-scheme systems or photovoltaics, where any secondary phase is produced using chemical solution processing at low or high pH. Here, we show a simple process to produce an organic capping layer of 3-aminopropyltriethoxysilane that can successfully stabilize nanostructured ZnO for processing below pH 1. We demonstrate that this process can be used to produce a ZnO-BiFeO3 (BFO) core-shell structure by a sol-gel process. Using a range of physical and analytical techniques, we show that BFO is highly crystalline and produces a conformal coating with a thickness of 2.5 nm. X-ray photoelectron spectroscopy and X-ray diffraction confirm the phase and expected chemical composition of BFO. Finally we are able to demonstrate that diodes produced using the ZnO-BFO core-shell structure have improved performance with a rectification ratio at ±3 V of 2800 because of the reduction in reverse current typically associated with surface recombination on ZnO. Our process opens a route to producing a range of hitherto prohibited ZnO core-shell structures that may have applications ranging from photovoltaic devices to core-shell photocatalysts.

Uniform CH3NH3PbI3 perovskite thin films with high phase purity and micron-sized pinhole-free grains have been successfully synthesised on fluorine-doped tin oxide (FTO) glass substrates using a novel two-step sequential aerosol-assisted chemical vapour deposition (AACVD) process.

The use of semiconductors with a ‘built in’ bias has now become of interest for a growing number of photoactive applications. Using a combination of spectroscopic techniques, gas chromatography in association with mass spectroscopy and NMR, we show that a sample of ferroelectric BaTiO3 decorated with nanostructured Ag denatures a standard dye molecule (Rhodamine B) via a photocatalytic oxidation mechanism. The photosensitized oxidation was inhibited due to band bending induced by ferroelectric polarisation. In the Ag–BaTiO3 system we find a slight hypsochromic wavelength shift during the initial stages of degradation (only 3 nm before 80% degradation percentage) and associate this shift with the cleavage of the chromophore structure which pre-empted deethylation. This shift in maximum absorption of the dye molecule did not occur until the later stages of molecule fragmentation. Our major identifiable breakdown intermediate was benzoic acid. A lack of other identifiable fragments during the breakdown of the dye is associated with retention of these fragments on the catalyst as full mineralisation of the dye liberates CO2.

We report the sol–gel synthesis of a CuWO4 (Eg ∼ 2.0–2.15 eV) thin film loaded with Ag nanowires. The incorporation of Ag nanowires into the semiconductor matrix significantly improves the performance of CuWO4 as a photoanode for use in photochemical water splitting (PEC). Here, we have developed a planar electrode to test the photoactivity of the catalyst using standard electrochemical procedures under simulated solar light. The sol–gel synthesis of CuWO4 is modified such that we add Ag nanowires during sol aging. We demonstrate that there is negligible change to the CuWO4 matrix microstructure, morphology or crystal structure. When we compare the pristine CuWO4 to the material with Ag nanowires embedded in the CuWO4 matrix there is a fourfold improvement of photocurrent at 1.23 V vs. NHE to ca. 1.5 mA cm−2 (pH 9) under simulated AM1.5G illumination. This photocurrent is very competitive against more well developed photoanode structures when consideration for surface area is allowed. The Ag nanowires increase carrier mobility film enabling a sufficiently thick sample of catalyst, measured at 750 nm, to effectively harvest incident light. The addition of the Ag nanowires removes the plateau region found for CuWO4 further indicating that there is a good flow of carriers to the surface of the catalyst, a significant improvement as carrier mobility has been shown to be low in CuWO4. The Faradaic efficiency of the catalyst was measured at 31%. Our flat band potential is found to be 0 vs. NHE. The ability to make a highly photoactive catalyst using a simple chemical process opens up opportunities in a wide range of areas that focus on PEC and other light harvesting processes.

Hydrogen fuel cells are a promising energy conversion technology due to its high energy density and zero greenhouse gas emission. As a result, the production of hydrogen from renewable and alternative resources has gained significant interest in recent decades. This paper demonstrates a new approach which uses a pyroelectric energy harvester for water splitting and represents a novel alternative hydrogen source. Pyroelectrics are attractive for harvesting waste heat due to their ability to convert temperature fluctuations into electrical energy. A range of pyroelectric materials and geometries for water electrolysis are analysed to determine, (i) the minimum material thickness to generate a critical potential to initialise water decomposition and, (ii) to maximize the charge and hydrogen mass production. We then successfully demonstrate that an appropriate pyroelectric material, when combined with rectification of the alternating current, can harvest heat fluctuations and generate a sufficient electric potential difference and current for water splitting. By harvesting the pyroelectric electrical energy, a continuous hydrogen bubble production was observed during thermal cycling. Practical routes to maximize the level of hydrogen production for this new concept are also explored.

ZnO nanostructure based energy harvesting devices (ZnO nanogenerator) were fabricated using ZnO nanorods with the surface modified using a polyelectrolyte assembly comprising bi-layers of Polydiallyldimethylammonium chloride and Polystyrene sulfonate. The peak open-circuit voltage device characteristics and power delivered across a load increased in relation to the number of bi-layers in the polyelectrolyte deposition. At the highest loading of polyelectrolyte the energy harvesters generated a peak power density of 426 µW cm−2 and 1 V peak open-circuit voltage at a peak tip acceleration of 50 g. This compares to 35 µW cm−2 without polyelectrolyte. We relate this significant enhancement in device performance to the screening of mobile carriers due to an interaction of the polar polyelectrolyte materials with the surface of the ZnO nanostructures. It is proposed that the adsorption of the polyelectrolyte on the ZnO interacts with the surface defects and reduces the rate of screening and trapping of carriers leading to increased performance.

Lithium-substituted 0.95[0.94(Bi0.5Na(0.5–x)Lix)TiO3–0.06BaTiO3]–0.05CaTiO3 materials include the polar rhombohedral R3c and the weakly polar tetragonal P4bm phases. On increasing lithium content, the (R3c/P4bm) phase ratio decreased, while the rhombohedral and tetragonal lattice distortions remained the same. The temperature corresponding to the shoulder in the dielectric permittivity shows no clear shift with respect to lithium substitution because of the rhombohedral distortion remaining constant. Electrical poling produced an increase of the rhombohedral phase fraction together with a rise of the rhombohedral and tetragonal distortion. This confirmed the occurrence of a phase transition from the weakly polar to the polar phase during electrical poling. Four peaks found in the current–electric field (I–E) loops are related to reversible electric field induced transitions. By studying the temperature dependence of the current peaks in the I–E loops, it was found that the minimum temperature where these electric field induced transitions take place decreases with increasing lithium substitution.

A number of quantum technologies require macroscopic mechanical oscillators possessing ultra-high motional Q-factors. These can be used to explore the macroscopic limits of quantum mechanics, to develop quantum sensors and to test the quantum nature of gravity. One approach is to trap nanometer to micron-sized particles in 3D; however, the use of ion or optical traps suffers from a number of difficulties including electrodynamic noise due to patch fields, damage to the particles due to unwanted laser heating, or difficulty in reaching low pressures due to particle loss. In this work, we report a completely passive, magnetic trap which confines a micro-diamond in 3D and which requires no active power—optical or electrical. We design, model, fabricate, and test the operation of our magneto-mechanical trap and experimentally demonstrate trapping down to ∼0.1 Torr. We measure the position fluctuation of the trapped micro-diamond as a function of pressure and find good agreement with Brownian theory.

This paper reports for the first time the use of perovskite bismuth ferrite (BiFeO3 or BFO) on ZnO-based solid state solar cells using only chemical solution methods for materials synthesis. As ZnO has poor chemical stability in acidic and corrosive environments, a buffer method using aminosilane ((3-aminopropyltriethoxysilane or H2N(CH2)3Si(OC2H5)3)) coating was used to provide a protective coating on the ZnO nanorods. The aminosilane layer was removed after BFO coating. The solid state solar cells, sensitized by N719, used CuSCN as the hole conductor and were tested under 100 mW cm(-2), AM 1.5G simulated sunlight. The photovoltaic performance showed current density improvement from 0.64 mA cm(-2) to 1.4 mA cm(-2) and efficiencies from 0.1% to 0.38% when comparing between ZnO and ZnO/BFO solar cells. The observed ca. 400% improved performance is shown to result from BFO's role as an electron blocking layer.

This review provides a detailed overview of the energy harvesting technologies associated with piezoelectric materials along with the closely related sub-classes of pyroelectrics and ferroelectrics. These properties are, in many cases, present in the same material, providing the intriguing prospect of a material that can harvest energy from multiple sources including vibration, thermal fluctuations and light. Piezoelectric materials are initially discussed in the context of harvesting mechanical energy from vibrations using inertial energy harvesting, which relies on the resistance of a mass to acceleration, and kinematic energy harvesting which directly couples the energy harvester to the relative movement of different parts of a source. Issues related to mode of operation, loss mechanisms and using non-linearity to enhance the operating frequency range are described along with the potential materials that could be employed for harvesting vibrations at elevated temperatures. In addition to inorganic piezoelectric materials, compliant piezoelectric materials are also discussed. Piezoelectric energy harvesting devices are complex multi-physics systems requiring advanced methodologies to maximise their performance. The research effort to develop optimisation methods for complex piezoelectric energy harvesters is then reviewed. The use of ferroelectric or multi-ferroic materials to convert light into chemical or electrical energy is then described in applications where the internal electric field can prevent electron–hole recombination or enhance chemical reactions at the ferroelectric surface. Finally, pyroelectric harvesting generates power from temperature fluctuations and this review covers the modes of pyroelectric harvesting such as simple resistive loading and Olsen cycles. Nano-scale pyroelectric systems and novel micro-electro-mechanical-systems designed to increase the operating frequency are discussed.

Acoustic vibrations are shown to enhance the photovoltaic efficiency of a P3HT/ZnO nanorod solar cell by up to 45%, correlated to a three-fold increase in charge carrier lifetime. This is assigned to the generation of piezoelectric dipoles in the ZnO nanorods, indicating that the efficiency of solar cells may be enhanced in the presence of ambient vibrations by the use of piezoelectric materials.

BaTiO3 is used as a target catalyst to probe the influence of ferroelectricity on the decolorization of a typical dye molecule—Rhodamine B—under simulated solar light. We show that there is a 3-fold increase in the decolorization rate using BaTiO3 with a high tetragonal content compared to predominantly cubic material. This is ascribed to the ferroelectricity of the tetragonal phase. The influence of ferroelectricity ensures a tightly bound layer of dye molecule and also acts to separate the photoexcited carriers due to the internal space charge layer. Both of these features act to enhance the catalytic performance. When nanostructured Ag is photochemically deposited on the surface of the BaTiO3, we find a further increase in the reaction rate that gives complete decolorization of the dye in around 45 min.

Since 1595 when Gerardus Mercator first published his collection of maps, teachers have used the paper atlas as the first means of teaching spatial literacy. The second wave took another four hundred years to evolve as the moving image developed from film, to TV, video tape and DVD bringing the real world to life into classrooms across the globe. Now we are embarking on the third wave and a new era in teaching spatial literacy in schools has now dawned. Teaching with geotechnologies [Geographic Information Systems (GIS), Global Positioning Systems, virtual globes and remote sensing)] not only engages the learner in inquiry-driven, problem-based, investigations of real-world issues, but involves essential skills for the twenty-first century workplace. This skill set and the critical thinking they stimulate enables us as educators to lay the foundations for the next generation of decision makers, a generation who will become the next custodians of the planet and who therefore need every opportunity to develop a deeper understanding and knowledge of sustainability. If we do not foster spatial thinking about issues such as water quality and availability, energy, sustainable agriculture, land use, urban sprawl, biodiversity loss, human health, natural hazards, and soil erosion, population and migration, at scales from local to global, who will?

P-type copper(I) thiocyanate (β-CuSCN) was deposited using a pneumatic micro-spray gun from a saturated solution in propyl sulphide. An as-produced 6 μm CuSCN film exhibited a hole mobility of 70 cm 2 /V·s and conductivity of 0.02 S·m −1 . A zinc oxide (ZnO) nanorod array was filled with CuSCN, demonstrating the capability of the process for filling nanostructured materials. This produced a diode with a n-type ZnO and p-type CuSCN junction. The best performing diodes exhibited rectifications of 3550 at ± 3 V. The electronic characteristics exhibited by the diode were attributed to a compact grain structure of the β-CuSCN giving increased carrier mobility and an absence of cracks preventing electrical shorts between electrode contacts that are typically associated with β-CuSCN films.

It has recently been shown that waste biomass can be converted into a wide range of functional materials, including those with desirable optical and electronic properties, offering the opportunity to find new uses for these renewable resources. Photovoltaics is one area in which finding the combination of abundant, low-cost and non-toxic materials with the necessary functionality can be challenging. In this paper the performance of carbon nanodots derived from a wide range of biomaterials obtained from different biomass sources as sensitisers for TiO

Perovskite materials are now an important class of materials in the application areas of photovoltaics and photocatalysis. Inorganic perovskites such as BiFeO3 (BFO) are promising photocatalyst materials with visible light activity and inherent stability. Here we report the large area sol-gel synthesis of BFO films for solar stimulated water photo oxidation. By modifying the sol-gel synthesis process we have produced a perovskite material that has p-type behaviour and a flat band potential of ∼1.15 V (versus NHE). The photocathode produces a density of -0.004 mA cm(-2) at 0 V versus NHE under AM1.5 G illumination. We further show that 0.6 μmol h(-1) of O2 was produced at an external bias of -0.5 V versus Ag/AgCl. The addition of a non-percolating conducting network of Ag increases the photocurrent to -0.07 mA cm(-2) at 0 V versus NHE (at 2% Ag loading) with an increase to 2.7 μmol h(-1) for O2 production. We attribute the enhancement in photoelectrochemical performance to increased light absorption due light scattering by the incorporated Ag particles, improved charge transfer kinetics at the Ag/BFO interface and reduced over potential losses. We support these claims by an observed shift in flat band and onset potentials after Ag modification through UV-vis spectroscopy, Mott-Schottky plots and j-v curve analysis.

Spontaneous polarization is shown to enhance the lifetimes of photogenerated species in BaTiO3 . This is attributed to polarization-induced surface band bending acting as a thermal barrier to electron/hole recombination. The study indicates that the efficiencies of solar cells and solar fuels devices can be enhanced by the use of ferroelectric materials.