The most widely used oxide for photocatalytic applications owing to its low cost and high activity is TiO₂. The discovery of the photolysis of water on the surface of TiO₂ in 1972 launched four decades of intensive research into the underlying chemical and physical processes involved. Despite much collected evidence, a thoroughly convincing explanation of why mixed-phase samples of anatase and rutile outperform the individual polymorphs has remained elusive. One long-standing controversy is the energetic alignment of the band edges of the rutile and anatase polymorphs of TiO₂ (ref. ). We demonstrate, through a combination of state-of-the-art materials simulation techniques and X-ray photoemission experiments, that a type-II, staggered, band alignment of ~ 0.4 eV exists between anatase and rutile with anatase possessing the higher electron affinity, or work function. Our results help to explain the robust separation of photoexcited charge carriers between the two phases and highlight a route to improved photocatalysts.

Monoclinic vanadium (IV) oxide (VO2) has received much attention for applications as intelligent solar control coatings, with the potential to reduce the need for both heating and air conditioning loads within building infrastructure. Chemical vapour deposition-a high-throughput industrially scalable method-is an ideal technology for the deposition of VO2 thin films on window panels. However, these films suffer from poor adhesion and are chemically susceptible to attack. In addition, the VO2 films with optimum solar modulation are unfortunately translucent, restraining their commercial use in energy-efficient fenestration. In this work, multi-functional, robust, layered VO2/SiO2/TiO2 films were quickly deposited on glass substrates using atmospheric-pressure chemical vapour deposition and fully characterised using structural, vibrational spectroscopy and electron microscopy techniques. The VO2/SiO2/TiO2 thin films were designed to exhibit excellent solar modulation properties as well as high transparency and resistance to abrasion, compared to single VO2 films of the same thickness. The films also showed self-cleaning properties comparable to those of commercial Pilkington Activ TM glass, as demonstrated here during the photodegradation of a model organic pollutant (stearic acid). The SiO2 acted as a barrier layer, preventing the diffusion of Ti 4+ ions into the VO2 layer but it also promoted the optical properties and allowed for superior thermochromic behaviour when compared to single VO2 films. The system was modelled to determine the effect of the individual components on the properties of the overall material. It was found that the deposition of the SiO2/TiO2 overlayer resulted in a dramatic improvement of visible light transmission (~30 % increase when compared to single layer analogues) whilst also doubling the solar modulation of the material.

Al‐, Ga‐, and In‐doped ZnO thin films were deposited on glass substrates by aerosol assisted chemical vapour deposition (AACVD) at a deposition temperature of 450 °C. The air‐stable compound zinc acetylacetonate [Zn(acac)2] was used as a Zn source, whilst for the dopants of Al, Ga and In, the corresponding trichloride was used. Methanol solutions of the metal salts were used as precursor solutions and N2 carrier gas was used for the aerosol. Films were grown in approximately 30 min and were synthesised using dopant values of 5, 10, 15 and 20 mol.% (with respect to the Zn) in the precursor solution. XRD analysis showed that the films were wurtzite ZnO. XPS analysis confirmed the presence of the dopants in the films. Several of the films showed high transparency (>80%) in the visible range, and low resistivity (∼10−3 Ω cm).

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PurposeThis paper seeks to explore and explain the dramatic organizational changes that took place over a relatively short time period in the five largest global professional networks, or GPNs – a group of organizations that were originally global accounting firms and traditionally accustomed to relatively gradual change.Design/methodology/approachBegins by describing the background of divestiture and diversification in GPNs. The data were collected from the firms' web sites, interviews with GPN managers, e‐mail requests for information via Big Five web sites, and from reports in the newspapers and business press over the two‐year period to June 2001. Uses neo‐institutional theory to study the context, precipitating dynamics, and enabling dynamics of large‐scale organizational change, including the part played by governmental and regulatory forces.FindingsExplains the extent to which changes have occurred in a sample of countries in which these organizations operate, noting that the firm effects seem to be stronger than the country effects in the consulting area, while country effects are more pronounced in the law area.Originality/valueThis paper is an original study of mainly secondary data – including those collected from firms' internet sites – analyzing change in an institutionalized environment. It is one of the first studies to make use of the GPN concept. Researchers and practitioners interested in professional service firms in general will find a unique combination of data, analyses, and conclusions.