Light Utilization Research Articles

Photothermal Catalytic Removal of 1,2-DCE with High HCl Selectivity over the Brønsted Acid-Enriched Sulfur-Doped MOFs.

Chlorinated volatile organic compounds come from a wide range of sources and are highly toxic, posing a serious threat to biological health and the environment. Herein, a high-efficiency and energy-saving photothermal synergistic catalytic oxidation method was developed for the removal of 1,2-dichloroethane (1,2-DCE). Compared to traditional thermocatalysis, the 1,2-DCE conversion over Ru-U6S in photothermal synergistic catalysis at 340 °C increased by approximately 44% not only reducing energy consumption but also avoiding the instability of MOF structure caused by high reaction temperature. The excellent photothermal catalytic oxidation activity was derived from the synergistic effect of photo- and thermocatalysis. Ru-U6S demonstrated excellent 1,2-DCE adsorption capacity and stronger light utilization and could produce more reactive oxygen species (•OH and •O2-) after light illumination, which participated in the oxidation reaction, promoting the release of the active site of the catalyst. The results of H2O-TPD and NH3-DRIFTS exhibited that the use of S-containing ligands in the synthesis process increased the hydroxyl groups and Brønsted acid sites, significantly improved the selectivity of CO2 and HCl in the oxidation process, and reduced the release of chlorine-containing byproducts. This work provides a high-efficiency and energy-saving strategy for removing chlorinated volatile organic compounds and increasing the selectivity of ideal products directly with MOFs directly.

Disinfection of bacteria and viruses under near infrared light by tunable self-assembled nanomaterial NH2-MIL-101-xAu based on photothermal and photodynamic mechanisms

In response to the threat posed by multi-drug resistant "superbugs", a synergistic approach of photothermal therapy (PTT) and photodynamic therapy (PDT) has been developed. In this work, NH2-MIL-101-xAu was prepared by introducing Au nanoparticles on the surface of NH2-MIL-101 n-type semiconductor by means of self-assembly. The introduction of Au nanoparticles greatly improves the light absorption and utilization of nanomaterials. Based on the surface plasma response (SPR), NH2-MIL-101-xAu has an efficient photothermal conversion ability, and under the irradiation of 808 nm (1 W/cm2), NH2-MIL-101–5.0Au (0.50 mg/mL) can be heated to 60℃ in 3 min. And the synergistic effect of plasma-induced interfacial charge-transfer transition and Schottky barriers dramatically enhances the photogenerated carrier separation of NH2-MIL-101-xAu, which in turn generates a large number of reactive oxygen species (ROS). Under the experimental conditions, NH2-MIL-101-xAu with the synergistic effect of PTT and PDT had the sterilization rate of 99.99999 % against Escherichia coli and Staphylococcus aureus, and the inactivation rate of Bacteriophage MS2 was more than 99.9 %. This study shows that NH2-MIL-101-xAu possessing a high degree of tunability is an effective PTT and PDT synergistic means of destroying pathogens, which is very helpful in the application of eliminating drug-resistant bacteria.

Higher phosphorus and water use efficiencies and leaf stoichiometry contribute to legume success in drylands

Abstract Legumes are essential plants in dryland ecosystems worldwide because they increase nitrogen availability, so their understanding is vital for improving knowledge and modelling in the face of climate change. This work studies the differences in resource use efficiency and their relationship with photosynthetic, photochemical, bioelemental, and stoichiometric traits of coexistent legumes and non‐legumes in a Sonoran Desert ecosystem. We found that legumes had higher photosynthetic rates, intrinsic and seasonal water use efficiency (WUE), phosphorus use efficiency (PPUE), and higher light utilisation mediated by chlorophyll content and active reaction centers, which may increase their photoprotection. Legumes can increase their WUE and PPUE with no changes in nitrogen use efficiency (PNUE). Consequently, observed trait relationships between studied traits in these legumes have significant differences with the non‐legume species in the study. Stoichiometry is helpful, in some cases, as an indicator of nutrient use efficiency and enables functional group differentiation. Our results strongly relate legumes' higher resource use efficiency with their success in dryland ecosystems. Read the free Plain Language Summary for this article on the Journal blog.

Nanoarchitectonics of MIL-101(Fe)/g-C3N4 S-Scheme heterojunction for photocatalytic nitrogen fixation: Mechanisms and performance

Recently, there has been a growing interest in the fundamental understanding of the mechanism of how MIL-101(Fe)/g-C3N4 heterojunctions facilitate the occurrence of photocatalytic nitrogen fixation reactions, especially the electron transfer mechanism has attained increasing attention in photocatalysis. Herein, we implemented a "triple win scenario" strategy to fabricate the S-scheme MIL-101(Fe)/g-C3N4 heterojunction through a straightforward solvothermal process. The MC-6 heterojunction minimizes the recombination of photogenerated carriers, enhances light utilization efficiency, and activates the N≡N bond, thus boosting photocatalytic nitrogen fixation efficiency. The transition metal iron activates the N≡N bond, while S-scheme heterojunctions reduce the photogenerated carrier recombination. In addition, the decrease in band gap (Eg) leads to an increase in visible light utilization efficiency. ISIXPS proved the mechanism of interelectron transfer of MIL-101(Fe)/g-C3N4 heterojunction under illumination. Upon the creation of the heterojunction, electrons migrate from g-C3N4 to MIL-101(Fe), establishing an inherent electric field due to the disparate Fermi levels between the two materials. The electrons (e-) on the g-C3N4 CB with a more negative reduction potential and the holes (h+) on the MIL-101(Fe) VB are retained, which increased the redox capacity to a great extent required for the reduction of N2 to NH3. The ammonia production efficiency of MC-6 photocatalyst was 160 µmol gcat-1 h-1, representing an 8-fold and 2.8-fold improvement over pristine g-C3N4 (20 µmol gcat-1 h-1) and MIL-101(Fe) (57 µmol gcat-1 h-1), respectively.

ZnO/Gra/Si structure to improve photoelectric properties

To enhance the interface bonding and optoelectronic properties of ZnO/Si, we employed graphene (Gra) as a buffer layer to mitigate lattice mismatch. Density functional theory (DFT) was utilized to analyze the impact of graphene insertion on the interface structure and optoelectronic properties of ZnO/Si. Our findings indicate strong covalent bonds within the ZnO/Si interface, whereas the ZnO/Gra/Si interface exhibits van der Waals interactions. Additionally, the incorporation of graphene shifts the valence band of ZnO/Gra/Si closer to the conduction band, significantly improving its conductivity. Moreover, ZnO/Gra/Si demonstrates a 74 % increase in visible light utilization compared to ZnO/Si, highlighting the substantial potential of this sandwich structure in solar cell applications.

Enhanced Photocatalytic Properties and Photoinduced Crystallization of TiO2-Fe2O3 Inverse Opals Fabricated by Atomic Layer Deposition.

The use of solar energy for photocatalysis holds great potential for sustainable pollution reduction. Titanium dioxide (TiO2) is a benchmark material, effective under ultraviolet light but limited in visible light utilization, restricting its application in solar-driven photocatalysis. Previous studies have shown that semiconductor heterojunctions and nanostructuring can broaden the TiO2's photocatalytic spectral range. Semiconductor heterojunctions are interfaces formed between two different semiconductor materials that can be engineered. Especially, type II heterojunctions facilitate charge separation, and they can be obtained by combining TiO2 with, for example, iron(III) oxide (Fe2O3). Nanostructuring in the form of 3D inverse opals (IOs) demonstrated increased TiO2 light absorption efficiency of the material, by tailoring light-matter interactions through their photonic crystal structure and specifically their photonic stopband, which can give rise to a slow photon effect. Such effect is hypothesized to enhance the generation of free charges. This work focuses on the above-described effects simultaneously, through the synthesis of TiO2-Fe2O3 IOs via multilayer atomic layer deposition (ALD) and the characterization of their photocatalytic activities. Our results reveal that the complete functionalization of TiO2 IOs with Fe2O3 increases the photocatalytic activity through the slow photon effect and semiconductor heterojunction formation. We systematically explore the influence of Fe2O3 thickness on photocatalytic performance, and a maximum photocatalytic rate constant of 1.38 ± 0.09 h-1 is observed for a 252 nm template TiO2-Fe2O3 bilayer IO consisting of 16 nm TiO2 and 2 nm Fe2O3. Further tailoring the performance by overcoating with additional TiO2 layers enhances photoinduced crystallization and tunes photocatalytic properties. These findings highlight the potential of TiO2-Fe2O3 IOs for efficient water pollutant removal and the importance of precise nanostructuring and heterojunction engineering in advancing photocatalytic technologies.

Fluorine Doping Mediated Epitaxial Growth of NaREF4 on TiO2 for Boosting NIR Light Utilization in Bioimaging and Photodynamic Therapy.

By integrating TiO2 with rare earth upconversion nanocrystals (NaREF4), efficient energy transfer can be achieved between the two subunits under near-infrared (NIR) excitation, which hold tremendous potential in the fields of photocatalysis, photodynamic therapy (PDT), etc. However, in the previous studies, the combination of TiO2 with NaREF4 is a non-epitaxial random blending mode, resulting in a diminished energy transfer efficiency between the NaREF4 and TiO2. Herein, we present a fluorine doping-mediated epitaxial growth strategy for the synthesis of TiO2-NaREF4 heteronanocrystals (HNCs). Due to the epitaxial growth connection, NaREF4 can transfer energy through phonon-assisted pathway to TiO2, which is more efficient than the traditional indirect secondary photon excitation. Additionally, F doping brings oxygen vacancies in the TiO2 subunit, which further introduces new impurity energy levels in the intrinsic band gap of TiO2 subunit, and facilitates the energy transfer through phonon-assisted method from NaREF4 to TiO2. As a proof of concept, TiO2-NaGdF4 : Yb,Tm@NaYF4@NaGdF4 : Nd@NaYF4 HNCs were rationally constructed. Taking advantage of the dual-model up- and downconversion luminescence of the delicately designed multi-shell structured NaREF4 subunit, highly efficient photo-response capability of the F-doped TiO2 subunit and the efficient phonon-assisted energy transfer between them, the prepared HNCs provide a distinctive nanoplatform for bioimaging-guided NIR-triggered PDT.

Effect of surfactant PEG on the property control of Bi2O3 and its photocatalytic activity

A detailed investigation into the effect of the poly(ethylene glycol) (PEG) addition mass on the bismuth (III) oxide (Bi2O3) photocatalyst is limited but necessary. Bismuth (III) oxide/PEG photocatalysts with different morphologies were prepared with different PEG mass via the solvothermal method and characterized for phase, morphology, optical absorption properties, elemental composition and specific surface area. The results indicated that all bismuth (III) oxide photocatalysts with different additions (Bi2O3/PEG-m x ) were pure β-bismuth (III) oxide phases, comprising larger platelike and smaller particle-like particles. Enhanced photocatalytic activity was attributed to increased larger specific surface area with PEG below 10 g. With 12 g of PEG, the formation of surface pores on plate-like bismuth (III) oxide impoved light penetration and utilization. Bi2O3/PEGm12 exhibited optimal photocatalytic activity, achieving over 90% bisphenol A(BPA) degradation after 180 min at 0.6 g·L−1 under visible light. Bismuth (III) oxide /PEG-ty prepared below 140°C showed poor activity, while above 160°C, high activity was observed. Bismuth (III) oxide/PEG effectively mineralize over 80% of bisphenol A into inorganic molecules and water under the co-oxidation of superoxide radicals (·O2 −) and holes (h+). This is the first detailed research on the regulation and modification of β-bismuth (III) oxide by PEG, which may provide new insights into the photocatalytic technology.

Optimizing radiation capture in machine-harvested cotton: A functional-structural plant modelling approach to chemical vs. manual topping strategies

Topping and planting density are key agronomic management practices to optimize cotton plant structure for machine harvesting and light capture. However, modelling the effects of these practices on canopy light utilization in the field, in order to improve cotton management, remains challenging. Functional-structural plant modelling is a computational approach to explore the effects of agronomic practices on shaping plant architecture and thus light interception. This study, for the first time, utilizes the CottonXL model to quantify the significant impact of chemical topping compared to manual topping on radiation interception on machine-harvested cotton in China at different planting densities, providing new management strategies for cotton production. A more compact plant structure is shaped by chemical topping through inhibiting leaf expansion and shortening internodes of both the main stem and fruiting branches, thereby allowing more PAR interception by middle and lower leaves. Simulation results showed that the total PAR intercepted by the canopy over entire growth season was increased by 11.3 % under chemical topping compared to manual topping. This positive effect became even more pronounced with increasing plant density. These results indicate that chemical topping could be beneficial for optimizing canopy structure, enhancing light interception and lint yield, especially at higher plant densities. The results illustrate the importance of shaping plant structure for improving radiation resource capture and exemplify the potential of optimizing topping strategy and plant density to enhance crop performance. They also demonstrate the utility of a functional-structural plant model for guiding crop management.

Co-regulation of microstructure and intrinsic groups in carbon nitride to achieve high-efficient pollutant degradation under visible light: Roles of N species

Owing to the drawback of the lower separation and shorter lifetime of carriers in carbon nitride (CN), this study reported that the CN composites with different morphologies and the N species were successfully synthesized through the regulation of intrinsic functional groups. Results showed that the formed tubular structure in 1D CN nanotubes (1D CNNTs) could intensify the utilization of visible light (Vis) because of the multiple diffraction or scattering of light, bridge the mass transfer distance and provide more active sites. Meanwhile, 1D CNNTs showed excellent TC degradation rates (0.3777 min-1) under Vis, which were 13, 630 and 6-36 times higher than these of two-dimensional CN nanosheets, three-dimensional CN microspheres and reported CN based catalysts, respectively. The analysis of active species showed O2·- and h+ were the main active species for TC degradation. The degradation pathways and comprehensive toxicities of TC were also comprehensively analyzed. Theoretical calculation exhibited that the introduction of N vacancy and -NHx groups effectively accelerating separation of carriers, prolonging carrier lifetime and enhancing the adsorption ability and relative electron transfer of O2 to the production of O2·-. In addition, the prepared catalysts presented better stability and anti-interference ability. Therefore, this study would provide a new view for regulation of intrinsic functional groups in CN to achieve efficient pollutant degradation under Vis.

A temperature-insensitivity multi-channel strain sensor based on chirped fiber grating loop ring-down structure

This study proposes a novel multi-channel strain sensor, which combines the chirped fiber grating loop ring-down (CFGLRD) structure and time division multiplexing (TDM) technology. Each channel contains a CFGLRD cavity based on overlapping spectrum demodulation, which can convert measurements into ring-down spectra. All cavities are connected in series by delay fiber. The advantages of the sensor include simple structure, high light utilization, and temperature insensitive. A two-channel strain experimental setup is used in performance testing of the sensor. The strain measurement ranges of both channels extend from 0 to 3000 με. The resolutions of two channels are 18.3 με and 27.9 με, the linear correlation coefficients R2 are 0.997 and 0.996, the strain sensitivities are about 112.97 μs/ε and 280.03 μs/ε, and the temperature sensitivities are 0.37 ns/°C and 0.72 ns/°C. The experimental results show the structure has good performances on linearity of curve, measurement range, and temperature robustness.

Theoretical Study on Photocatalytic Reduction of CO2 on Anatase/Rutile Mixed-Phase TiO2.

The construction of anatase/rutile heterojunctions in TiO2 is an effective way of improving the CO2 photoreduction activity. Yet, the origin of the superior photocatalytic performance is still unclear. To solve this issue, the band edges between anatase and rutile phases were theoretically determined based on the three-phase atomic model of (112)A/II/(101)R, and simultaneously the CO2 reduction processes were meticulously investigated. Our calculations show that photogenerated holes can move readily from anatase to rutile via the thin intermediated II phase, while photoelectrons flowing in the opposite direction may be impeded due to the electron trapping sites at the II phase. However, the large potential drop across the anatase/rutile interface and the strong built-in electric field can provide an effective driving force for photoelectrons' migration to anatase. In addition, the II phase can better enhance the solar light utilization of (112)A/(100)II, including a wide light response range and an intensive optical absorption coefficient. Meanwhile, the mixed-phase TiO2 possesses negligible hydrogenation energy (CO2 to COOH*) and lower rate-limiting energy (HCOOH* to HCO*), which greatly facilitate CH3OH generation. The efficient charge separation, strengthened light absorption, and facile CO2 reduction successfully demonstrate that the anatase/rutile mixed-phase TiO2 is an efficient photocatalyst utilized for CO2 conversion.

Synergistic interplay of photobioreactor mixing and static mixer configuration on Rhodoseupdomonas palustris’s growth and biohydrogen production

Inducing light/dark (L/D) cycles through mixing or recirculating the media in a photobioreactor improves light utilization for biohydrogen production during photoferentation. However, the mutual shading effect is a key challenge for photofermentation using purple non-sulphur bacteria (PNSB). In this study, mixing was explored as a mitigating methodology through the investigation of three different static mixer configurations: concentric, spiral, and half-moon, across four laminar flowrates: 1.2 L/min, 0.71 L/min, 0.31 L/min and 0.15 L/min. At 0.15 L/min, the half-moon and spiral static mixers significantly improved specific and cumulative hydrogen production by 11.2-fold and 114 %, respectively. Also, recirculating the fluid via a peristaltic pump resulted in a significant shearing effect, impacting cell viability. Inducing L/D cycles via a static mixer was thus beneficial for hydrogen production over an increased flow rate. Additionally, biomass productivity increased by up to 70 %, reaching a cell dry weight of 7.0 g/L with the spiral static mixer configuration at 0.15 L/min flow rate. Interestingly, this study found that the static mixers only significantly increased specific hydrogen production and light conversion efficiency at the lowest flow rate of 0.15 L/min, beyond which they showed no significant improvement in biohydrogen production. This indicates that high L/D cycling frequencies are unnecessary to alleviate the mutual shading effect for R. palustris, which is advantageous for upscaling. These findings emphasise the potential of static mixers as an alternative to increase light conversion efficiency and industrial hydrogen production.

Initializing Compression Stress to Stabilize the Phase Homogeneity in Bifacial Semitransparent Perovskite Solar Cells

AbstractSemitransparent perovskite solar cells (ST‐PSCs) hold great promise for various commercial applications, including building integrated photovoltaics and tandem solar cells. The all‐inorganic perovskite, known for its outstanding optical transparency and thermal stability, emerges as a top contender for ST‐PSCs. However, challenges persist due to phase segregation, which hampers charge carrier transport and operational stability. In this study, an approach is proposed to address these challenges by employing strain engineering to reconstruct the perovskite texture, eliminating inhomogeneities within the perovskite film. The crucial role of compressive strain in stabilizing lattice rigidity and suppressing light‐induced ion migration is demonstrated. Furthermore, a transparent light‐harvesting architecture is devised utilizing a sandwiched layer of gold embedded between MoO3. This design enhances power generation by efficiently harnessing incident light from both the front and rear panel surfaces. Therefore, bifacial ST‐PSCs achieve an equivalent efficiency (ηeq) of 13.97% with an average visible light transmittance of 41.58%, yielding an outstanding light utilization efficiency of up to 5.8%. This research not only advances the understanding of perovskite material phase‐segregation behavior but also introduces an effective strategy for enhancing optical gain without compromising the semitransparent characteristics.

Small molecule π-π stacking promotes efficient photoelectrocatalytic splitting of aqueous hydrogen production from polyaniline.

The efficiency of photoelectrocatalysis is fundamentally dependent on the sufficient absorption of light and efficient utilisation of photogenerated carriers, but is largely limited by the reactivity from the inefficient charge transfer and surface sites of the catalyst. In this study, π-π stacking of polar small molecules on aromatic ring-rich polyaniline (PANI) was carried out to improve its photoelectrocatalytic splitting of water for hydrogen production. Detailed photoelectrochemical experiments and density-functional theory (DFT) calculations show that small molecules of p-aminobenzoic acid (PABA) and PANI have the best π-π stacking (compared to p-toluenesulfonic acid (PTA)), which promotes the separation of carriers on the PANI surface. In addition, the polar effect of the small molecules also improves the reactivity of the PANI surface and also reduces the potential barrier for H2 evolution. The current density of PANI-PABA reached -0.12 mA/cm2 (1.23 V vs. RHE) 2.53 times higher than that of pure PANI in linear voltammetric scanning tests under light. This strategy of introducing polar small molecules into organocatalysts via π-π stacking will provide new ideas for the preparation of efficient organic photoelectrocatalysis.

A sandwich-type photoelectrochemical biosensor based on anthocyanin-sensitized ZnO/P5FIn heterojunction for the sensitive detection of CYFRA21-1.

. A sandwich-type photoelectrochemical (PEC) immunosensor based on a ZnO/poly(5-formylindole) (P5FIn)/anthocyanin heterostructure was developed to achieve sensitive background-free detection ofthe tumor marker CYFRA21-1. ZnO with good photovoltaic properties is combined with narrow bandgap P5FIn to form a p-n type heterojunction. This structure reduces the electron-hole pair recombination, thereby enhancing the photocurrent response of the composite. Anthocyanidins are environmentally friendly natural compounds with excellent antioxidant, redox properties, and remarkable electrochemical activity. After sensitization by anthocyanins, the absorption and utilization of visible light in the composites are enhanced, further improving the PEC luminescence efficiency of the materials. Additionally, boron nitride quantum dots (BN QDs) are combined with Ab2 via polydopamine (PDA) as a secondary antibody marker, enhancing its sensitivity. The biosensor exhibited a linear detection range of 0.001-100ngmL-1 with a limit of detection (LOD) of 0.00033ngmL-1. Furthermore, this biosensor demonstrates excellent selectivity, reproducibility, and stability, as well as successful results in analyzingactual human serum samples. This approach provides a feasible method for tumor marker detection.

Integral morphology and structure design of poly (heptazine imide) for efficient utilization of visible light generated charge carriers in proton reduction reactions

AbstractSufficient utilization of visible‐light generated charge carriers in proton reduction reactions is of great significance for the development of effective solar‐fuel technologies. Achieving simultaneous bulk rapid transfer and surface efficient extraction of charge carriers is still very challenging. Herein, it is found for the first time ammonium persulfate (APS) can significantly influence polymerization processes of C3N4 (CN) from melamine to poly (heptazine imide) (PHI) under the simultaneous oxygen doping and etching effect of SO42−. PHI with high crystallinity, porous structure, and in‐situ oxygen doping was therefore obtained through one‐step APS‐assisted salt strategy. Benefiting from sufficient visible‐light absorption and upshifted conduction band originating from regulated electronic structure and optimized morphology through APS modification, the as‐prepared PHI achieved a H2 evolution activity of 3274.23 μmol h−1 g−1 (λ > 420 nm), which is appropriately 148 and 19 times that of conventional and crystalline CN. This work opens up new opportunities for efficient photocatalysis.

The alleviating effect on the growth, chlorophyll synthesis, and biochemical defense system in sunflowers under cadmium stress achieved through foliar application of humic acid

BackgroundWith the progress of industrialization and urbanization, cadmium (Cd) pollution in farmland is increasingly severe, greatly affecting human health. Sunflowers possess high resistance to Cd stress and great potential for phytoremediation of Cd-contaminated soil. Previous studies have shown that humic acid (HA) effectively mitigates plant damage induced by Cd; however, its alleviating effects on sunflower plants under Cd stress remain largely unknown.ResultsWe employed four different concentrations of HA (50, 100, 200, and 300 mg L−1) via foliar application to examine their ability to alleviate Cd stress on sunflower plants' growth, chlorophyll synthesis, and biochemical defense system. The results revealed that Cd stress not only reduced plant height, stem diameter, fresh and dry weight, and chlorophyll content in sunflower plants but also altered their chlorophyll fluorescence characteristics compared to the control group. After Cd stress, the photosynthetic structure was damaged and the number of PSII reactive centers per unit changed. Application of 200 mg L−1 HA promotes sunflower growth and increases chlorophyll content. HA significantly enhances antioxidant enzyme activities (SOD, POD, CAT, and APX) and reduces ROS content (O2−, H2O2 and −OH). Totally, Application of 200 mg L−1 HA had the best effect than other concentrations to alleviate the Cd-induced stress in sunflower plants.ConclusionsThe foliar application of certain HA concentration exhibited the most effective alleviation of Cd-induced stress on sunflower plants. It can enhance the light energy utilization and antioxidant enzyme activities, while reduce ROS contents in sunflower plants. These findings provide a theoretical basis for using HA to mitigate Cd stress in sunflowers.

Light footprint of microalgae cultivation system addressed by modified Cornet model

The cultivation of microalgae is significantly influenced by light intensity and utilization efficiency. This study developed a modified Cornet (M−Cornet) model to assess the distribution of light intensity and flux in microalgae cultivation systems. Algal biofilm cultivation represents a more concentrated approach of algal suspension cultivation. Both follow the M−Cornet model and exhibit the same growth rates when cultured under identical conditions. Algal pigments and morphologies greatly impact the light absorption and scattering, resulting in light attenuation in intensity, penetration distance and light flux distribution. Algae varieties exhibit diverse light flux characteristics. 37% − 90% of the incident light is absorbed, of which, 80% to 90% is dissipated as heat. 10% to 63% of the incident light is scattered off the photobioreactor. The overall light utilization efficiency ranges 6% to 13%. The light footprint using the M−Cornet model offers valuable insights for photobioreactors designing and cultivation operating.

Fluorescence and electron transfer of Limnospira indica functionalized biophotoelectrodes

Cyanobacteria play a crucial role in global carbon and nitrogen cycles through photosynthesis, making them valuable subjects for understanding the factors influencing their light utilization efficiency. Photosynthetic microorganisms offer a promising avenue for sustainable energy conversion in the field of photovoltaics. It was demonstrated before that application of an external electric field to the microbial biofilm or cell improves electron transfer kinetics and, consequently, efficiency of power generation. We have integrated live cyanobacterial cultures into photovoltaic devices by embedding Limnospira indica PCC 8005 cyanobacteria in agar and PEDOT:PSS matrices on the surface of boron-doped diamond electrodes. We have subjected them to varying external polarizations while simultaneously measuring current response and photosynthetic performance. For the latter, we employed Pulse-Amplitude-Modulation (PAM) fluorometry as a non-invasive and real-time monitoring tool. Our study demonstrates an improved light utilization efficiency for L. indica PCC 8005 when immobilized in a conductive matrix, particularly so for low-intensity light. Simultaneously, the impact of electrical polarization as an environmental factor influencing the photosynthetic apparatus diminishes as matrix conductivity increases. This results in only a slight decrease in light utilization efficiency for the illuminated sample compared to the dark-adapted state.