also be transferred from the highest occupied molecular orbital (HOMO) of the dye to the Fermi level of the dopant formate, so blocking electron±hole recombination 3 . Our results from emulsions sensitized by a carbocyanine thought to ful®ll the above criterion indicate that the sensitivity is indeed increased (Fig. 4), compared to emulsions without formate supposed to absorb the same quantity of photons. Depending on the surface coverage by dye molecules, these are in the form of either monomers or Jaggregates, which are two-dimensional arrays of edged-on adsorbed dye molecules with a large slip angle. The difference is about DlogI 3 t exp 0:9 for emulsions sensitized by dye monomers (l max 480 and 500 nm), excited at l exp > 477 nm; for emulsions sensitized by J-aggregates (additional l max at 552 nm), excited at l exp > 519 nm, we obtain DlogI 3 t exp 0:7. This enables us to assess the effect of aggregates only without coexisting monomers. The sensitivity enhancement that is systematically observed in the presence of formate ion therefore attests to ef®cient hole transfer to the dopant formate from the HOMO level of the dye, in both the monomer and the J-aggregate forms. This mechanism is comparable with the scavenging of the intrinsic hole created by direct AgBr excitation, and results in a marked inhibition of recombination. M

Chirality at the molecular level is found in diverse biological structures, such as polysaccharides, proteins and DNA, and is responsible for many of their unique properties. Introducing chirality into porous inorganic solids may produce new types of materials that could be useful for chiral separation, stereospecific catalysis, chiral recognition (sensing) and photonic materials. Template synthesis of inorganic solids using the self-assembly of lyotropic liquid crystals offers access to materials with well-defined porous structures, but only recently has chirality been introduced into hexagonal mesostructures through the use of a chiral surfactant. Efforts to impart chirality at a larger length scale using self-assembly are almost unknown. Here we describe the development of a photonic mesoporous inorganic solid that is a cast of a chiral nematic liquid crystal formed from nanocrystalline cellulose. These materials may be obtained as free-standing films with high surface area. The peak reflected wavelength of the films can be varied across the entire visible spectrum and into the near-infrared through simple changes in the synthetic conditions. To the best of our knowledge these are the first materials to combine mesoporosity with long-range chiral ordering that produces photonic properties. Our findings could lead to the development of new materials for applications in, for example, tuneable reflective filters and sensors. In addition, this type of material could be used as a hard template to generate other new materials with chiral nematic structures.

Carbon-based structures are the most versatile materials used in the modern field of renewable energy (i.e., in both generation and storage) and environmental science (e.g., purification/remediation). However, there is a need and indeed a desire to develop increasingly more sustainable variants of classical carbon materials (e.g., activated carbons, carbon nanotubes, carbon aerogels, etc.), particularly when the whole life cycle is considered (i.e., from precursor "cradle" to "green" manufacturing and the product end-of-life "grave"). In this regard, and perhaps mimicking in some respects the natural carbon cycles/production, utilization of natural, abundant and more renewable precursors, coupled with simpler, lower energy synthetic processes which can contribute in part to the reduction in greenhouse gas emissions or the use of toxic elements, can be considered as crucial parameters in the development of sustainable materials manufacturing. Therefore, the synthesis and application of sustainable carbon materials are receiving increasing levels of interest, particularly as application benefits in the context of future energy/chemical industry are becoming recognized. This review will introduce to the reader the most recent and important progress regarding the production of sustainable carbon materials, whilst also highlighting their application in important environmental and energy related fields.