Artificial Leaf Research Articles

Soil salinization disrupts plant-plant signaling effects on extra-floral nectar induction in wild cotton.

Plant-plant interactions via volatile organic compounds (VOCs) have received much attention, but how abiotic stresses affect these interactions is poorly understood. We tested the effect of VOCs exposure from damaged conspecifics on the production of extra-floral nectar (EFN) in wild cotton plants (Gossypium hirsutum), a coastal species in northern Yucatan (Mexico), and whether soil salinization affected these responses. We placed plants in mesh cages, and within each cage assigned plants as emitters or receivers. We exposed emitters to either ambient or augmented soil salinity to simulate a salinity shock, and within each group subjected half of the emitters to no damage or artificial leaf damage with caterpillar regurgitant. Damage increased the emission of sesquiterpenes and aromatic compounds under ambient but not under augmented salinity. Correspondingly, exposure to VOCs from damaged emitters had effect on receiver EFN induction, but this effect was contingent on salinization. Receivers produced more EFN in response to damage after being exposed to VOCs from damaged emitters when the latter were grown under ambient salinity, but not when they were subjected to salinization. These results suggest complex effects of abiotic factors on VOC-mediated plant interactions.

Solar-driven liquid multi-carbon fuel production using a standalone perovskite–BiVO4 artificial leaf

Solar-driven liquid multi-carbon fuel production using a standalone perovskite–BiVO4 artificial leaf

Z-Schematic Artificial Leaf Structure for Biosolar Oxyfunctionalization of Hydrocarbons

The natural Z-schematic photosynthesis is a promising catalytic model for solar-to-chemical conversion. Here, we construct a Z-schematic, wireless photoelectrocatalytic (PEC) system (i.e., artificial leaf) for biocatalytic oxyfunctionalization of hydrocarbons. The monolithic leaf structure consists of a tandem photoanode|photocathode configuration that uses sunlight as the sole energy source to drive redox reactions. Under solar light, the ferric oxyhydroxide-coated, molybdenum-doped bismuth vanadate (FeOOH|Mo:BVO) photoanode extracts electrons from H2O electron feedstock and transfers the electrons to the conjugated polyterthiophene (pTTh) photocathode. Meanwhile, the pTTh photocathode absorbs FeOOH|Mo:BVO-filtered light for O2 reduction to H2O2. The in situ generated H2O2 activates unspecific peroxygenases (UPOs) to drive enantioselective C–H oxyfunctionalization (e.g., hydroxylation and epoxidation). Furthermore, we solve HO•-mediated inactivation of UPOs using a cellulose membrane, which increases enzymatic productivity with a benchmark total turnover number of 193 000 among PEC and photocatalytic platforms that trigger UPO-mediated synthesis.

Ingenious Artificial Leaf Based on Covalent Organic Framework Membranes for Boosting CO2 Photoreduction.

Covalent organic frameworks (COFs) hold the potential in converting CO2 with water into value-added fuels and O2 to save the deteriorating ecological environment. However, reaching high yield and selectivity is a grand challenge under metal-, photosensitizer-, or sacrificial reagent-free conditions. Here, inspired by microstructures of natural leaves, we designed triazine-based COF membranes with the integration of steady light-harvesting sites, efficient catalytic center, and fast charge/mass transfer configuration to fabricate a novel artificial leaf for the first time. Significantly, a record high CO yield of 1240 μmol g-1 in a 4 h reaction, approximately 100% selectivity, and a long lifespan (at least 16 cycles) were achieved under gas-solid conditions without using any metal, photosensitizer, or sacrificial reagent. Unlike the existing knowledge, the chemical structural unit of triazine-imide-triazine and the unique physical form of the COF membrane are predominant for such a remarkable photocatalysis. This work opens a new pathway to simulating photosynthesis in leaves and may motivate relevant research in the future.

Inexpensive DIY Bioprinting in a Secondary School Setting.

Bioprinting is a technique that allows custom printing of cell-laden tissue using the principle of three-dimensional (3D) printing. The technique has various applications, ranging from tissue engineering to materials science. Bioprinting is an attractive topic for science, technology, engineering, and math education due to its novelty and interdisciplinary nature. Nonetheless, a basic commercial bioprinter could cost several thousand U.S. dollars. There have been attempts to construct low-cost do-it-yourself bioprinters for research purpose. However, those methods required expertise, uncommon reagents, and professional equipment, making it difficult for teachers and students in secondary schools to replicate. Here, we demonstrate how teachers and students in a secondary school can convert a 3D printer into a bioprinter for conducting a hands-on bioprinting activity using secondary school-available resources. Briefly, an open-source Creality Ender 3 V2 3D printer in a school was converted into a bioprinter using 3D-printed parts and other readily available materials. Cell-laden bioink and support medium were made using school-available reagents. The bioprinter can be easily constructed and operated by teachers and students who do not have prior knowledge in coding and engineering. We used the bioprinter to print a coronary artery model and an algae-laden artificial leaf. The photosynthetic activity of the artificial leaf could be observed and investigated using a hydrogen carbonate indicator. The work described in this paper could make bioprinting available, comprehensible, and enjoyable to secondary school students, opening a door for inexpensive innovative teaching and learning activities using bioprinting in secondary schools.

Wind energy harvesting inspired by Palm leaf flutter: Observation, mechanism and experiment

Environmental adaptation of wind energy harvester (WEH) would be improved by mimicking the leaf flutter in Mother Nature. This study presents aeroelastic modelling and laboratory testing of Palm leaves to understand the mechanism of leaf flutter, furtherly designs an artificial leaf WEH and tests it in wind tunnel. Three modes of investigation are fulfilled: (1) Observation: Palm leaf flutter is observed in urban wind. The material properties of Palm leaves are measured by microscopic images or tensile tests. (2) Modelling: The aeroelastic model is established using finite element method and doublet-lattice aerodynamics to determine the flutter boundary of Palm leaves. The mechanism of mode coalescence between bending and twisting is found, and the model is further applied in designing the artificial leaf. (3) Experiments: Palm leaf oscillations under several flow speeds are measured with ultra-high-speed laser displacement sensor in wind tunnel. The critical speed and frequency of Palm leaf flutter are then obtained. Furthermore, the artificial leaf is mounted on the piezoelectric cantilever and evaluated in wind tunnel. At preliminary trial, the leaf harvester starts working at as low wind speed as 2 m/s, with stable frequency of 3.56 Hz. It reaches output power density of 1.238 µW/cm3 in our laboratory. The study highlights the bio-inspired design of wind energy harvester with low cut-in wind speed and stable output frequency.

Device for Simultaneous Wind and Raindrop Energy Harvesting Operating on the Surface of Plant Leaves

Soft (bio)hybrid robotics aims at interfacing living beings with artificial technology. It was recently demonstrated that plant leaves coupled with artificial leaves of selected materials and tailored mechanics can convert wind-driven leaf fluttering into electricity. Here, we significantly advance this technology by establishing the additional opportunity to convert kinetic energy from raindrops hitting the upper surface of the artificial leaf into electricity. To achieve this, we integrated an extra electrification layer and exposed electrodes on the free upper surface of the wind energy harvesting leaf that allow to produce a significant current when droplets land and spread on the device. Single water drops create voltage and current peaks of over 40V and 15µA and can directly power 11 LEDs. The same structure has the additional capability to harvest wind energy using leaf oscillations. This shows that environment-responsive biohybrid technologies can be tailored to produce electricity in challenging settings, such as on plants under motion and exposed to rain. The devices have the potential for multisource energy harvesting and as self-powered sensors for environmental monitoring, pointing at applications in wireless sensor networks (WSNs), the internet of things (IoT), smart agriculture, and smart forestry.

Metabonomic Analysis of Silkworm Midgut Reveals Differences between the Physiological Effects of an Artificial and Mulberry Leaf Diet.

Bombyx mori is a model lepidopteran insect of great economic value. Mulberry leaves are its only natural food source. The development of artificial diets can not only resolve the seasonal shortage of mulberry leaves but also enable changes to be made to the feed composition according to need. Metabolomic differences between the midguts of male and female silkworms fed either on fresh mulberry leaves or an artificial diet were studied using liquid chromatography-mass spectrography (LC-MS/MS) analysis. A total of 758 differential metabolites were identified. Our analysis showed that they were mainly involved in disease resistance and immunity, silk quality, and silkworm growth and development. These experimental results provide insights into the formulation of optimized artificial feed for silkworms.

Renewable formic acid production from CO2 reduction using green ZnO nanoarchitectures

In order to create an artificial leaf to photoconvert CO2 into fuels, this work describes the syntheses of ZnO with the use of natural and food wastes (nonedible) as biotemplates. The goal was to obtain various nanoarchitectures and produce renewable formic acid from CO2 reduction under visible light. Pea shells, jalapeño stems, egg membranes, and shrub leaves were selected as biotemplates for the syntheses of ZnO with different morphologies such as erythrocytes, macarons, hexagonal discs, and spheres, to enhance light harvesting in the visible region. The biotemplates enhanced charge transfer and provided active sites in the zinc interstitial spaces that increased the efficiency of CO2 photoreduction. Formic acid was the main product obtained from CO2 reduction under visible light; the highest yield (185 μmol; S = 95% in 3 h) was reached with a sample prepared by using egg membranes as template, and the catalyst showed remarkable stability over time. Other products with low-carbon contents, e.g., methanol and ethanol, were generated in lower proportions.

Hybrid Perovskite-Based Wireless Integrated Device Exceeding a Solar to Hydrogen Conversion Efficiency of 11.

A wireless solar water splitting device provides a means to achieve an inexpensive and highly distributed solar-to-fuel system owing to its portability, flexible scale, and simple design. Here, a highly efficient hydrogen-generating artificial leaf is introduced, which is a wireless configuration for converting solar energy into chemical energy, by integrating ahybrid perovskite (PSK) as the light absorber with catalysts for electrochemical reaction. First, a single integrated photoelectrochemical photocathode, and a spatially decoupled hydrogen evolution reaction catalyst, are fabricated. A decoupled geometry is adopted to enable the physical protection of the PSK layer from the electrolyte, thus allowing excellent stability for over 85h. Additionally, an efficient dual photovoltaicmodule photocathode is fabricatedto produce sufficient photovoltage to drive water splitting reactions, as well as a high photocurrent to achieve the applied-bias photoconversion efficiency (13.5%). To investigate the overall water splitting performance, a NiFe-OH catalyst is employed, and the device with a wired configuration achieves a photocurrent density of 9.35mA cm-2 , corresponding to a solar to hydrogen (STH) efficiency of 11.5%. The device with a fully integrated wireless artificial leaf configuration exhibited a similar STH efficiency of over 11%, demonstrating the effectiveness of this cell design.

Artificial Leaf for Solar‐Driven Ammonia Conversion at Milligram‐Scale Using Triple Junction III‐V Photoelectrode

Developing a green and energy-saving alternative to the traditional Haber-Bosch process for converting nitrogen into ammonia is urgently needed. Imitating from biological nitrogen fixation and photosynthesis processes, this work develops a monolithic artificial leaf based on triple junction (3J) InGaP/GaAs/Ge cell for solar-driven ammonia conversion under ambient conditions. A gold layer serves as the catalytic site for nitrogen fixation with photogenerated electrons. The Au/Ti/3J InGaP/GaAs/Ge photoelectrochemical (PEC) device achieves high ammonia production rates and Faradaic efficiencies in a two-electrode system without applying external potential. For example, at 0.2 sunlight intensity, the solar-to-ammonia (STA) conversion efficiency reaches 1.11% and the corresponding Faradaic efficiency is up to 28.9%. By integrating a Ni foil on the anode side for the oxygen evolution reaction (OER), the monolithic artificial leaf exhibits an ammonia production rate of 8.5µg cm-2 h at 1.5 sunlight intensity. Additionally, a 3× 3cm unassisted wireless PEC device is fabricated that produces 1.0039mg of ammonia in the 36-h durability test. Thus, the new artificial leaf can successfully and directly convert solar energy into chemical energy and generate useful products in an environmentally friendly approach.

Water Responsive Fabrics with Artificial Leaf Stomata

Due to fiber swelling, textile fabrics containing hygroscopic fibers tend to decrease pore size under wet or increasing humidity and moisture conditions, the reverse being true. Nevertheless, for personal thermal regulation and comfort, the opposite is desirable, namely, increasing the fabric pore size under increasing humid and sweating conditions for enhanced ventilation and cooling, and a decreased pore size under cold and dry conditions for heat retention. This paper describes a novel approach to create such an unconventional fabric by emulating the structure of the plant leaf stomata by designing a water responsive polymer system in which the fabric pores increase in size when wet and decrease in size when dry. The new fabric increases its moisture permeability over 50% under wet conditions. Such a water responsive fabric can find various applications including smart functional clothing and sportswear.Graphical

Germination Development of Powdery Mildew on Natural and Artificial Wheat Leaf Surfaces: A Study to Investigate Plant Wax Signals

Germination Development of Powdery Mildew on Natural and Artificial Wheat Leaf Surfaces: A Study to Investigate Plant Wax Signals

Enabling unassisted solar water splitting with concurrent high efficiency and stability by robust earth-abundant bifunctional electrocatalysts

Hydrogen production from solar water splitting, especially via photovoltaic-electrocatalysis, has been regarded as a promising approach for the conversion of abundant but intermittent solar energy into storable chemical fuels. Despite much progress, conventional combined photoelectrochemical devices usually suffer from severe instability issues, which largely inhibit them for practical applications and may also lead to the uncertain efficiency value for true overall water splitting. Here, we report an unassisted solar water splitting device with concurrent high efficiency and stability, which is constructed by spatial coupling of tandem III-V-based GaInP/GaAs/Ge light absorber and robust earth-abundant Ni foil-based MoNi4/MoO2 bifunctional electrocatalysts. Remarkably, apart from the outstanding hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performance, bifunctional MoNi4/MoO2 electrocatalysts also largely avoid electrode contamination issues, while the robust Ni substrate protects III-Vs from conventional corrosion problems. Consequently, this integrated photovoltaic-electrolysis system device exhibits a high solar-to-hydrogen (STH) conversion efficiency of 17.6 % in alkaline electrolytes with long-term stability of up to 845 h. Further construction into a wireless unassisted monolithic device could lead to an artificial leaf with an STH efficiency of 4.28 %, holding great promise in future solar fuel production with concurrent high efficiency, good stability as well as low cost.

Maize Disease Detection using Color Cooccurrence Features

The Ethiopian economy is based primarily on agriculture. Furthermore, due to Ethiopia's predominately agricultural economy, most Ethiopians are dependent on agriculture in some way. In Ethiopia, traditional dishes including bread, injera, and soup are commonly made from one of the plants, maize. Although growing maize, Wollo farmers experience low levels of yield due to a variety of problems. This study examines the features of color co-occurrence to identify Maize illness. Although it has not been proven, several diseases may occur in Ethiopia. In this research features from the images are retrieved, while the texture feature from the color co-occurrence matrix is used. Artificial Neural Networks and Leaf Color Analysis are used to categorize the diseases classified as Maize Blast, Brown Spot, Narrow Spot, and Normal Maize Leaf. Analyze and classify the Maize disease, the process entails acquiring, evaluating, and classifying images. The entire Maize sample goes through the leaf color analysis before moving on to the artificial neural network.. All samples are subjected to a leaf color analysis throughout the testing step in order to identify the leaf diseases. If the sample's RGB values fall within a predetermined range, it is automatically classified as a normal Maize leaf; nevertheless, all diseased samples undergo image processing in order to get the features that utilized to train and evaluate an artificial neural network. The generated model is then discovered when an artificial neural network is trained using these features. As a result, the artificial neural network technique is used to identify the Maize diseases with an accuracy rate of roughly 86%.

Electron-Rich Bi Nanosheets Promotes CO2•- Formation for High-Performance and pH-Universal Electrocatalytic CO2 Reduction.

Electrochemical CO2 reduction reaction (CO2RR) to chemical fuels such as formate offers a promising pathway to carbon-neutral future, but its practical application is largely inhibited by the lack of effective activation of CO2 molecules and pH-universal feasibility. Here, we report an electronic structure manipulation strategy to electron-rich Bi nanosheets, where electrons transfer from Cu donor to Bi acceptor in bimetallic Cu-Bi, enabling CO2RR towards formate with concurrent high activity, selectivity and stability in pH-universal (acidic, neutral and alkaline) electrolytes. Combined in situ Raman spectra and computational calculations unravel that electron-rich Bi promote CO2•- formation to activate CO2 molecules, and enhance the adsorption strength of *OCHO intermediate with an up-shifted p-band center, thus leading to its superior activity and selectivity of formate. Further integration of the robust electron-rich Bi nanosheets into III-V-based photovoltaic solar cell results in an unassisted artificial leaf with a high solar-to-formate (STF) efficiency of 13.7%.

Electron‐Rich Bi Nanosheets Promote CO2⋅− Formation for High‐Performance and pH‐Universal Electrocatalytic CO2 Reduction

AbstractElectrochemical CO2 reduction reaction (CO2RR) to chemical fuels such as formate offers a promising pathway to carbon‐neutral future, but its practical application is largely inhibited by the lack of effective activation of CO2 molecules and pH‐universal feasibility. Here, we report an electronic structure manipulation strategy to electron‐rich Bi nanosheets, where electrons transfer from Cu donor to Bi acceptor in bimetallic Cu−Bi, enabling CO2RR towards formate with concurrent high activity, selectivity and stability in pH‐universal (acidic, neutral and alkaline) electrolytes. Combined in situ Raman spectra and computational calculations unravel that electron‐rich Bi promotes CO2⋅− formation to activate CO2 molecules, and enhance the adsorption strength of *OCHO intermediate with an up‐shifted p‐band center, thus leading to its superior activity and selectivity of formate. Further integration of the robust electron‐rich Bi nanosheets into III–V‐based photovoltaic solar cell results in an unassisted artificial leaf with a high solar‐to‐formate (STF) efficiency of 13.7 %.

Tailored BiVO4/In2O3 nanostructures with boosted charge separation ability toward unassisted water splitting

AbstractThe development of new heterostructures with high photoactivity is a breakthrough for the limitation of solar‐driven water splitting. Here, we first introduce indium oxide (In2O3) nanorods (NRs) as a novel electron transport layer for bismuth vanadate (BiVO4) with a short charge diffusion length. In2O3 NRs reinforce the electron transport and hole blocking of BiVO4, surpassing the state‐of‐the‐art photoelectrochemical performances of BiVO4‐based photoanodes. Also, a tannin–nickel–iron complex (TANF) is used as an oxygen evolution catalyst to speed up the reaction kinetics. The final TANF/BiVO4/In2O3 NR photoanode generates photocurrent densities of 7.1 mA cm−2 in sulfite oxidation and 4.2 mA cm−2 in water oxidation at 1.23 V versus the reversible hydrogen electrode. Furthermore, the “artificial leaf,” which is a tandem cell with a perovskite/silicon solar cell, shows a solar‐to‐hydrogen conversion efficiency of 6.2% for unbiased solar water splitting. We reveal significant advances in the photoactivity of TANF/BiVO4/In2O3 NRs from the tailored nanostructure and band structure for charge dynamics.

Germination Development of Powdery Mildew on Natural and Artificial Wheat Leaf Surfaces: A Study to Investigate Plant Wax Signals

Wax chemistry, especially long‐chain aldehydes, and surface wettability are discussed to have a stimulating effect on the development of Blumeria graminis, the pathogen of powdery mildew on wheat. Here, these specific surface properties are investigated on leaves of different wheat varieties and on developed test systems coated with plant wax and wax components. So far, the wettability of leaves has not been achieved by artificial substrates used in in vitro studies. With the test systems developed here, a wettability comparable to that on leaf surfaces and the signal character of wax chemistry could be investigated individually and in combination. The results show that wax morphology and chemistry (analyzed by scanning electron microscopy and gas chromatography) as well as wettability of leaves have no differences that would suggest a relationship with variety susceptibility. Furthermore, the influence of wax chemistry and wettability on the process of prepenetration of B. graminis on leaves and test systems is investigated. Germination and differentiation are not stimulated on any of the test systems compared to surfaces without the signals offered. Wettability, wax chemistry, and components such as long‐chain aldehydes could not be identified as decisive signals for the germination development of B. graminis.

Nutritional Enrichment of Plant Leaves by Combining Genes Promoting Tocopherol Biosynthesis and Storage.

The enrichment of plant tissues in tocochromanols (tocopherols and tocotrienols) is an important biotechnological goal due to their vitamin E and antioxidant properties. Improvements based on stimulating tocochromanol biosynthesis have repeatedly been achieved, however, enhancing sequestering and storage in plant plastids remains virtually unexplored. We previously showed that leaf chloroplasts can be converted into artificial chromoplasts with a proliferation of plastoglobules by overexpression of the bacterial crtB gene. Here we combined coexpression of crtB with genes involved in tocopherol biosynthesis to investigate the potential of artificial leaf chromoplasts for vitamin E accumulation in Nicotiana benthamiana leaves. We show that this combination improves tocopherol levels compared to controls without crtB and confirm that VTE1, VTE5, VTE6 and tyrA genes are useful to increase the total tocopherol levels, while VTE4 further leads to enrichment in α-tocopherol (the tocochromanol showing highest vitamin E activity). Additionally, we show that treatments that further promote plastoglobule formation (e.g., exposure to intense light or dark-induced senescence) result in even higher improvements in the tocopherol content of the leaves. An added advantage of our strategy is that it also results in increased levels of other related plastidial isoprenoids such as carotenoids (provitamin A) and phylloquinones (vitamin K1).