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Function-integrated Ru catalyst for photochemical CO2 reduction
摘要： Visible-light driven catalytic reduction of CO2 is at the heart of artificial photosynthesis. Here, we demonstrate the first example of a Ru complex that can function both as a photosensitizer and catalyst for CO2 reduction. The catalyst exhibited excellent activity for CO evolution with a high turnover number (TON, 353 for 24 h), reaction rate (TOF, 14.7 h?1), and product selectivity (97%) under visible-light irradiation. We also succeeded in selective product formation (CO or HCOOH) by changing the basicity of the reaction media. This finding will open new avenues for visible-light driven photoredox catalysis using Ru-based function-integrated photocatalysts.
关键词： Ru complex,visible-light,artificial photosynthesis,CO2 reduction,photocatalysis
更新于2025-09-10 09:29:36
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Interface Engineering of Hematite with Nacre-like Catalytic Multilayers for Solar Water Oxidation
摘要： An efficient water oxidation photoanode based on hematite has been designed and fabricated by tailored assembly of graphene oxide (GO) nanosheets and cobalt polyoxometalates (Co-POM) water oxidation catalysts into a nacre-like multilayer architecture on a hematite photoanode. The deposition of catalytic multilayers provides a high photocatalytic efficiency and photoelectrochemical stability to underlying hematite photoanodes. Compared to the bare counterpart, the catalytic multilayer electrode exhibits a significantly higher photocurrent density and large cathodic shift in onset potential (~ 369 mV) even at neutral pH conditions due to the improved charge transport and catalytic efficiency from the rational and precise assembly of GO and Co-POM. Unexpectedly, the polymeric base layer deposited prior to the catalytic multilayers improves the performance even more by facilitating the transfer of photogenerated holes for water oxidation through modification of the flat band potential of the underlying photoelectrode. This approach utilizing polymeric base and catalytic multilayers provides an insight into the design of highly efficient photoelectrodes and devices for artificial photosynthesis.
关键词： photocatalysis,graphene oxide,layer-by-layer assembly,artificial photosynthesis,polyoxometalate
更新于2025-09-10 09:29:36
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Hierarchical organization of perylene bisimides and polyoxometalates for photo-assisted water oxidation
摘要： The oxygen in Earth’s atmosphere is there primarily because of water oxidation performed by photosynthetic organisms using solar light and one specialized protein complex, photosystem II (PSII). High-resolution imaging of the PSII ‘core’ complex shows the ideal co-localization of multi-chromophore light-harvesting antennas with the functional reaction centre. Man-made systems are still far from replicating the complexity of PSII, as the majority of PSII mimetics have been limited to photocatalytic dyads based on a 1:1 ratio of a light absorber, generally a Ru–polypyridine complex, with a water oxidation catalyst. Here we report the self-assembly of multi-perylene-bisimide chromophores (PBI) shaped to function by interaction with a polyoxometalate water-oxidation catalyst (Ru4POM). The resulting [PBI]5Ru4POM complex shows a robust amphiphilic structure and dynamic aggregation into large two-dimensional paracrystalline domains, a redshifted light-harvesting efficiency of >40% and favourable exciton accumulation, with a peak quantum efficiency using ‘green’ photons (λ?>?500?nm). The modularity of the building blocks and the simplicity of the non-covalent chemistry offer opportunities for innovation in artificial photosynthesis.
关键词： polyoxometalates,water oxidation,artificial photosynthesis,photo-assisted,perylene bisimides
更新于2025-09-10 09:29:36
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Exploration of highly efficient blue-violet light conversion agents for agricultural film based on structure optimization of TPA
摘要： To obtain highly efficient blue-violet light conversion agents used for agricultural film, six triarylacrylonitrile derivatives and their doping films were prepared. Further, the luminogens have the ability to convert UV light into blue-violet light, and exhibit aggregation dependent fluorescence emission and high-contrast fluorescence quantum yields from 0.004 to 0.833. Based on X-ray single crystal diffraction analysis and aggregation-induced emission activity tests, the variant fluorescence quantum yields are attributed to intermolecular π-π stacking and phase transition between crystalline state and amorphous state. In simulated greenhouse environment, the luminogens exhibit excellent photostability. However, their fluorescence intensity drop to 17%-40% of prime intensity after outdoor radiation for one month due to the ring-closing oxidation reaction (In summer). By comprehensively considering the above photophysical properties and mechanical properties of the doping film, Ph4TPA is a potential light conversion agent for agricultural film in winter. More importantly, the results indicate the properties of the light conversion films are expected to be further improved by molecular design inhibiting the ring-closing oxidation reaction and dispersion of crystalline nanoparticles in the doping film.
关键词： Light conversion film,Light conversion agents,Fluorescence,Photosynthesis,Acrylonitrile derivatives
更新于2025-09-09 09:28:46
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Fundamental molecules of life are pigments which arose and co-evolved as a response to the thermodynamic imperative of dissipating the prevailing solar spectrum
摘要： The driving force behind the origin and evolution of life has been the thermodynamic imperative of increasing the entropy production of the biosphere through increasing the global solar photon dissipation rate. In the upper atmosphere of today, oxygen and ozone derived from life processes are performing the short-wavelength UV-C and UV-B dissipation. On Earth’s surface, water and organic pigments in water facilitate the near-UV and visible photon dissipation. The first organic pigments probably formed, absorbed, and dissipated at those photochemically active wavelengths in the UV-C and UV-B that could have reached Earth’s surface during the Archean. Proliferation of these pigments can be understood as an autocatalytic photochemical process obeying non-equilibrium thermodynamic directives related to increasing solar photon dissipation rate. Under these directives, organic pigments would have evolved over time to increase the global photon dissipation rate by (1) increasing the ratio of their effective photon cross sections to their physical size, (2) decreasing their electronic excited state lifetimes, (3) quenching radiative de-excitation channels (e.g., fluorescence), (4) covering ever more completely the prevailing solar spectrum, and (5) proliferating and dispersing to cover an ever greater surface area of Earth. From knowledge of the evolution of the spectrum of G-type stars, and considering the most probable history of the transparency of Earth’s atmosphere, we construct the most probable Earth surface solar spectrum as a function of time and compare this with the history of molecular absorption maxima obtained from the available data in the literature. This comparison supports the conjecture that many fundamental molecules of life are pigments which arose, proliferated, and co-evolved as a response to dissipating the solar spectrum, supports the thermodynamic dissipation theory for the origin of life, constrains models for Earth’s early atmosphere, and sheds some new light on the origin of photosynthesis.
关键词： photosynthesis,thermodynamic dissipation,UV-C,solar spectrum,UV-B,Archean,organic pigments,origin of life
更新于2025-09-09 09:28:46
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Investigating Forest Photosynthetic Response to Elevated CO<inf>2</inf> Using Uav-Based Measurements of Solar Induced Fluorescence
摘要： The response of ecosystems to increasing atmospheric CO2 will have significant, but still uncertain, impacts on the global carbon and water cycles. A lot of information has been gained from Free Air CO2 Enrichment (FACE) experiments, but the response of mature forest ecosystems remains a significant knowledge gap. One of the challenges in FACE studies is obtaining an integrated measure of canopy photosynthesis at the scale of the treatment ring. A new remote sensing approach for measuring photosynthetic activity is based on Solar Induced Fluorescence (SIF), which is emitted by plants during photosynthesis, and is closely linked to the rates and regulation of photosynthesis. We proposed that UAV-based SIF measurements, that enable the spectrometer field of view to be targeted to the treatment ring, provide a unique opportunity for investigating the dynamics of photosynthetic responses to elevated CO2. We have successfully tested this approach in a new FACE site, located in a mature oak forest in the UK. We flew a series of flights across the experiment arrays, collecting a number of spectra. We combined these with ground-based physiological and optical measurements, and see great promise in the use of UAV-based SIF measurements in FACE and other global change experiments.
关键词： Piccolo Doppio,photosynthesis,Solar Induced Fluorescence,UAV,global change
更新于2025-09-09 09:28:46
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Extending the SCOPE model to combine optical reflectance and soil moisture observations for remote sensing of ecosystem functioning under water stress conditions
摘要： A radiative transfer and process-based model, called Soil-Canopy-Observation of Photosynthesis and Energy fluxes (SCOPE), relates remote sensing signals with plant functioning (i.e., photosynthesis and evapotranspiration). Relying on optical remote sensing data, the SCOPE model estimates photosynthesis and evapotranspiration, but these ecosystem-level fluxes may be significantly overestimated if water availability is the primary limiting factor for vegetation. Remedying this shortcoming, additional information from extra sources is needed. In this study, we propose considering water stress in SCOPE by incorporating soil moisture data in the model, besides using satellite optical reflectance observations. A functional link between soil moisture, soil surface resistance, leaf water potential and carboxylation capacity is introduced as an extra element in SCOPE, resulting in a soil moisture integrated version of the model, SCOPE-SM. The modified model simulates additional state variables: (i) vapor pressure (ei), both in the soil pore space and leaf stomata in equilibrium with liquid water potential; (ii) the maximum carboxylation capacity (Vcmax) by a soil moisture dependent stress factor; and (iii) the soil surface resistance (rss) through approximation by a soil moisture dependent hydraulic conductivity. The new approach was evaluated at a Fluxnet site (US-Var) with dominant C3 grasses and covering a wet-to-dry episode from January to August 2004. By using the original SCOPE (version 1.61), we simulated half-hourly time steps of plant functioning via locally measured weather data and time series of Landsat (TM and ETM) imagery. Then, SCOPE-SM was similarly applied to simulate plant functioning for three cases using Landsat imagery: (i) with modeled ei; (ii) with modeled ei and Vcmax; and (iii) with modeled ei, Vcmax, and rss. The outputs of all four simulations were compared to flux tower plant functioning measurements. The results indicate a significant improvement proceeding from the first to the fourth case in which we used both Landsat optical imagery and soil moisture data through SCOPE-SM. Our results show that the combined use of optical reflectance and soil moisture observations has great potential to capture variations of photosynthesis and evapotranspiration during drought episodes. Further, we found that the information contained in soil moisture observations can describe more variations of measured evapotranspiration compared to the information contained in thermal observations.
关键词： SCOPE-SM model,Landsat,Evapotranspiration,Vegetation properties,Water stress,Remote sensing,Soil moisture,Vegetation functioning,Vapor pressure,Photosynthesis,Maximum carboxylation capacity,Soil surface resistance,Reflectance
更新于2025-09-09 09:28:46
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Light regulation of vitamin C in tomato fruit is mediated through photosynthesis
摘要： Higher levels of irradiance result in higher accumulation of ascorbate in leaves and fruits. Photosynthesis and respiration are an integral part of the physiological mechanism of light regulation of ascorbate in leaves, but little is known about the light regulation of ascorbate in fruit. The aim of this study was to investigate whether fruit illumination alone is sufficient for ascorbate increase in tomato fruit and whether this light signal is mediated by respiration and photosynthesis. First the changes of ascorbate with the progress of fruit development were investigated and subsequently detached fruit of different tomato genotypes were exposed to different irradiances and spectra. Measurements were performed on ascorbate, respiration, photosynthesis and chlorophyll content of the fruit. When attached to the plant, there was no effect of development on ascorbate from the mature green to the red stage. Detached fruit stored in darkness did not accumulate ascorbate. However, when exposed to 300-600 μmol m-2 s-1 light detached mature green fruit (photosynthetically active) substantially accumulated ascorbate, while mature red fruit (non-photosynthetically active) did not respond to light. Photosynthesis correlated with this increase of ascorbate while no correlation between respiration and ascorbate was found. Spectral effects on ascorbate in detached tomato fruit were limited. These results indicate that the signal for light regulation of ascorbate is perceived locally in the fruit and that fruit illumination alone is sufficient for a considerable increase in ascorbate levels for as long as the fruit contains chlorophyll. It is shown that photosynthetic activity of the fruit is an integral part of the response of ascorbate to light in tomato fruit. The light induced increase in ascorbate levels occurred in a range of genotypes, indicating a universal effect of light to ascorbate in tomato fruit.
关键词： photosynthesis,respiration,vitamin C,irradiance,ascorbic acid,spectrum
更新于2025-09-04 15:30:14
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Photosynthetic Machineries in Nano-Systems
摘要： Photosynthetic reaction centres are membrane-spanning proteins, found in several classes of autotroph organisms, where a photoinduced charge separation and stabilization takes place with a quantum efficiency close to unity. The protein remains stable and fully functional also when extracted and purified in detergents thereby biotechnological applications are possible, for example, assembling it in nano-structures or in optoelectronic systems. Several types of bio-nanocomposite materials have been assembled by using reaction centres and different carrier matrices for different purposes in the field of light energy conversion (e.g., photovoltaics) or biosensing (e.g., for specific detection of pesticides). In this review we will summarize the current status of knowledge, the kinds of applications available and the difficulties to be overcome in the different applications. We will also show possible research directions for the close future in this specific field.
关键词： Bio-nanocomposite,reaction centre,nanosystems,photosynthesis
更新于2025-09-04 15:30:14
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Physiological Response to Different Irradiation Regimes during Barley Seedlings Growth Followed by Drought Stress under Non-Photoinhibitory Light
摘要： Differences in physiological response of barley seedlings cultivated under low (LI, ~65 μmol m-2 s-1) and elevated irradiation (EI, ~450 μmol m-2 s-1) to upcoming drought were evaluated. After ten days of cultivation, drought stress was induced under LI by withholding water and was defined as: mild stress (MS), severe stress (SS), extreme stress (ES) and control (C, well watered). Decreased relative water content (RWC) in both LI and EI grown plants was associated with increased lipid peroxidation (TBARS) and electrolyte leakage (%EL) as well as with decreased total chlorophylls content at SS and ES. Antioxidative response to drought was, generally, indicated by higher accumulation of free proline, increased activities of catalase (CAT), guaiacol peroxidase (GPOD) and ascorbate peroxidase (APX). Even the majority of estimated physiological and biochemical parameters showed no differences between investigated light regimes before drought stress induction, the LI grown plants responded on drought by adjustment of the photosynthetic apparatus to prevent photoinhibitory oxidative damage. Photosynthesis downregulation in EI grown plants under ES was revealed due to reduced values of maximum quantum yield of photosystem II (Fv/Fm) and performance index (PIABS) showing that acclimatization to EI conditions lowered their tolerance to the following drought stress although it was applied under low irradiation (LI). Therefore, those plants had reduced capability to cope with the challenge of upcoming drought stress showing more pronounced cellular oxidative damage (SS and ES), less efficient and almost dysfunctional photosynthetic apparatus in extreme drought (ES).
关键词： antioxidative response,photosynthesis,Hordeum vulgare,light regime,drought stress,lipid peroxidation
更新于2025-09-04 15:30:14