Performance In Sunlight Research Articles

Low bandgap carbon nitride nanoparticles incorporated in titania nanotube arrays by in situ electrophoretic anodization for photocatalytic CO2 reduction

We report an in situ electrophoretic anodization process to realize a binary semiconductor heterojunction photocatalyst comprising green-emitting, water-soluble carbon nitride (CN) nanoparticles (NPs) embedded in TiO2 nanotube (TNT) arrays. Embedding CN inside a TiO2 matrix eliminates the possibility of the CNNPs leaching away during photocatalysis or photoelectrochemistry. The synthesized CN exhibits visible light absorption down to 600 nm and an unusually redshifted green emission peak at 527 nm, which are attributed to a carbon rich g-C3N4 composition with a C:N ratio of ∼ 1.9 at the surface. Spectroscopy revealed the excess carbon to be both amorphous and graphitic while the structural features characteristic of g-C3N4 were preserved. Raman spectroscopy, transmission electron microscopy (TEM), electron energy-loss spectroscopy (EELS) and X-ray photoelectron spectroscopy (XPS) analysis verified the formation of the heterostructure as well as indicated strong interaction between the CN and TiO2 in the hybrid. The CNNP@TNT hybrid demonstrated superior performance in sunlight driven photocatalytic CO2 reduction without the need for a sacrificial agent. The CO yield of photoreduction showed a more than threefold improvement for the CNNP@TNT hybrid compared to the stand-alone TNT photocatalyst. The synergistic enhancement of photocatalytic performance emerged due to the formation of a high-quality interface between the constituent semiconductors (TiO2 and CN) that facilitated efficient charge carrier separation. Density functional theory (DFT) calculations showed the feasibility of efficient photogenerated electron-hole pair separation at the heterointerface. Molecular dynamics (MD) simulations validated the facile dispersibility of CNNPs in water and polar solvents.

Building integrated photovoltaic design of nonlinear airport roof based on ruled surface fitting

Solar energy is a new renewable energy. Using solar energy to generate electricity is an effective means to achieve sustainable development. The huge roof at the top of the airport is a natural interface to receive solar energy, which can be used to supply the energy needed by the airport through building integrated photovoltaic design. However, due to the curved shape of the airport roof, there are limitations in solar energy acquisition and construction of the airport roof. In this paper, the method of “ruled surface fitting-solar radiation analysis-modular unit arrangement” is used to optimize the shape of the non-linear airport roof, and convert the complex roof surface shape into a straight line with good sunlight performance and easy construction. The ruled surface can better integrate BIPV and nonlinear airport, and improve the solar power generation efficiency of the building, thus improving the sustainable performance of the building.

Fabrication of superhydrophobic fabrics with outstanding self-healing performance in sunlight

Superhydrophobic fabrics with an outstanding self-healing performance in sunlight have been prepared by loading all-water-based octadecylamine@polydopamine core–shell nanospheres.

ZnO nanopinecone arrays with enhanced photocatalytic performance in sunlight

ZnO nanopinecone arrays exhibit much better photocatalytic properties for the photodegradation of phenol in sunlight.

Effect of shading and air temperature on leaf photosynthesis, fluorescence and growth in lily plants

Research was conducted in southern Italy to evaluate the physiological and productive responses of field-grown plants ( Lilium) in full light in comparison with the local practice of covering the crop with a shading net. Air and leaf temperature, leaf photosynthesis, leaf fluorescence, chlorophyll content, leaf area and plant dry matter were monitored during the crop cycle at different plant heights (apical, medial and basal parts). At harvest, flower quality production was slightly higher in sunlit plants, whereas dry matter accumulation did not differ between shaded and sunlit plants. During the growing season, leaves exposed to full sunlight showed slight reductions in fluorescence parameters without a parallel reduction in CER. Despite air temperature considered detrimental (over 30°C) and photon flux density (PFD) levels well above the light saturation point for this crop, lily plants showed good photosynthetic performance, supported both by high intrinsic efficiency of PSII photochemistry in darkness (ratio of variable to maximal fluorescence; F v/ F m) and good value of total chlorophyll without evident photoinhibition. No difference was detected among leaves at apical and medial positions, whereas basal leaves showed a progressive reduction of photosynthetic performance in sunlight, probably linked to high air temperatures near the ground. In sunlit conditions, although the temperature did not appreciably reduce the F v/ F m ratio, it was the main limiting factor of Lilium photosynthesis: while photosynthesis was almost zero at 37°C, the highest values were obtained at temperatures of 31–32°C with PFDs of 800 and 2000 μmol m −2 s −1. High light intensities are thus well tolerated by this crop. This is confirmed by the fact that apical leaves made a large contribution to total photosynthesis, even though they were exposed to higher PFDs. Our data confirm that Lilium shows good acclimation to high light conditions, although it is sensitive to high temperatures. As critical conditions occur infrequently during the plant crop cycle, shading may be restricted to the early vegetative growth phases after transplanting, when the plants are more sensitive to high temperatures. As shading reduces transpiration and soil evaporation, it may be used to reduce irrigation requirements of the crop.

Diurnal photosynthetic performance of seaweeds measured under natural conditions

Statements comparing photosynthetic performance characteristics of species rely upon empirical data, usually light-saturation curves (photosynthesis, P, versus incidentlight flux-density, I o, relationships) derived from instantaneous measurements. The specific comparative parameters are initial slope and maximum photosynthesis, P max. For phytoplankton, diurnal variation in specific productivity at maximum incident light, I max is typically asymmetrical, i.e., there is a morning maximum followed by an afternoon depression. Five seaweed species, numerical dominants from the Outer Banks of North Carolina, were examined for patterns of diurnal photosynthetic performance in sunlight of habitat equivalence. These were Codium decorticatum (Woodw.) Howe and Ulva curvata (Kutz.) De Toni in the Chlorophyceae, Dictyota dichotoma (Huds.) Lamour. and Petalonia fascia (O.F. Mull.) Kuntze in the Phaeophyceae, and Gracilaria foliifera (Forssk.) Borg. in the Rhodophyceae. Diurnal patterns of oxygen exchange were varied, some symmetrical about the midday axis, others asymmetrical, and were specific for (1) species, (2) derived habitat, (3) thallus absorptance (1-I/I o, where I is the transmitted light), (4) developmental stage, and (5) diurnal photosynthetically active radiation (PAR) history. All species show a depression in oxygen exchange rates at less than 0.1 I max, and show varying degrees of recovery when I o decreases from that value. Diurnal photosynthetic performance of some species at 0.03 I o (total diurnal maximum) exceeds several times that at 0.70 I o (total diurnal maximum), an observation not predicted by instantaneous measurements. Specific day-rate integrals of I o vary, producing transient initial slope and P max values. Thus, initial slope and P max values derived from instantaneous measurements in the laboratory bear little relationship to actual diurnal production. At this time there appears to be no substitute for direct measurement of diurnal photosynthesis.

Letter: Limited usefulness of artificial light sources.

To the Editor.— A recent report 1 on ultraviolet light sources showed that the ultraviolet output of a solar simulator was similar to the natural spectrum of sunlight. For this reason, investigators are using this artificial light source to evaluate the effectiveness of sun-protective agents prior to sunlight performance tests. Implicit in this method is the assumption that the data obtained with such artificial light sources can be used to predict the results in sunlight tests. A recent study 2 with patients having erythropoietic protoporphyria (EPP) compared the ultraviolet protective qualities of orally administered β-carotene in tests using sunlightand a solar simulator. The authors reported that the results showed the qualitative protective effect of β-carotene with either light conditions, but they were concerned about "a lack of more quantitative correlation." We compared their data 2 obtained with sunlight and xenon-arc light in the 21 patients who had both tests by comparing the protective factors obtained with each light source (Table). The correlation coefficient for this comparison was