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Robotic harvesting is challenging manipulation task as it requires dexterity and robustness to handle delicate crops that can show complex structure and variable form. A compounding challenge is that the research and development methodology currently relies upon extensive field testing, which is inefficient and can also only happen during the harvesting season. With an urgent need to develop robotic solutions for harvesting to avoid crops being left in the fields unpicked, we explore how the research methodology for harvesting robots can be accelerated by learning the required interactions with delicate crops through human demonstration. Specifically, we focus on raspberry harvesting, a fruit which is challenging to harvest due to its fragility, and also which has a very narrow harvesting window limiting field trials. We propose leveraging soft robotic technologies to create a physical twin of the harvesting environment. This twin is a sensorized physical and visual simulator of the real raspberry plant with tuneable mechanical properties. This physical twin can be used to develop and optimize the harvesting robot and associated controller through human demonstrations. Furthermore, the robot can autonomously harvest the sensorized physical twin repetitively and use its sensor feedback to update and optimize its control parameters to best imitate a human harvester. We hypothesize, that by closing the reality gap between our physical twin and real world raspberry plants, the ability to achieve direct lab2field transfer increases, such that zero or minimal trials and adaptations in the field area is required. When the fully lab trained robot was tested in the field without any modifications, a 80\% successful harvesting success rate was achieved. We conclude the robot performs successfully under conditions simulated by the physical twin, while it is limited by unmodeled environmental conditions. Using this approach we demonstrate a new methodology for robotic harvesting research.

Decreasing the catalytic loading and complexity of electrocatalysts for the reduction of CO2 is a critical necessity towards globally generating carbon-negative synthons. This effort therefore calls for the development of not only more active catalysts per employed g but also for more financially sound ones. Notably, molecular electrocatalysts allow for tuning the electronic and geometric environment around single-atom catalytic centers. Nevertheless, synthetic complexity, cost and electrochemical instability still hamper their large-scale implementation. With industrial application in mind, we herein present a holistic design approach starting from different Ag(I) N,N´-bis(arylimino)acenaphtene complexes to sophisticated architectures of electrolyzer components. Performed in industrially applicable cells at 60°C, this approach allows us to reach catalytic activity for CO formation close to 1 A cm-2, while achieving the highest mass activity reported for CO at 100.000 A gAg-1, accompanied by cost decreases up to a factor of 80 against the current heterogeneous standards. This study thus represents an unprecedented example to show the applicability of homogenous catalysts under industrially relevant conditions.

Electrifying the chemical industry is a key step towards the generation of green and sustainable chemical products. Electrochemical hydrogenations have gained a central role in this effort, generating important synthons in compact and modular zero-gap electrolyzers. Despite the significant achievements in recent years, clear guidelines to improve the efficiency and selectivity of zero-gap electrolyzers are still missing. Herein, by means of the hydrogenation of 2-methyl-3-butyn-2-ol (MBY), we present a holistic investigation for understanding the role of the anode porous transport layer and employed membrane on the efficiency of a zero-gap electrolyzer. Alongside, we provide a series of optimization steps, demonstrating that ECH electrolyzers can efficiently operate electrochemical hydrogenations at IrO2 loadings below 1 mg cm-2. We believe our results provide a crucial step towards accelerating the establishment of electrochemical methods in the chemical industry.

Holistic pathway for the sustainable electrochemical hydrogenation of alkynols – from robust metal sulphides to scalable zero-gap electrolysers.

Biology provides many examples of how body adaption can be used to achieve a change in functionality. The feather star, an underwater crinoid that uses feather arms to locomote and feed, is one such system; it releases its arms to distract prey and vary its maneuverability to help escape predators. Using this crinoid as inspiration, we develop a robotic system that can alter its interaction with the environment by changing its morphology. We propose a robot that can actuate layers of flexible feathers and detach them at will. We first optimize the geometric and control parameters for a flexible feather using a hydrodynamic simulation followed by physical experiments. Second, we provide a theoretical framework for understanding how body change affects controllability. Third, we present a novel design of a soft swimming robot ( Figure 1 ) with the ability of changing its morphology. Using this optimized feather and theoretical framework, we demonstrate, on a robotic setup, how the detachment of feathers can be used to change the motion path while maintaining the same low-level controller.

Cell reports / Physical science 3(4), 100825 (2022). doi:10.1016/j.xcrp.2022.100825, Published by Cell Press, Maryland Heights, MO

The conversion of CO2 is an attractive strategy towards the mitigation of environmental pollution, and the production of bulk chemicals and fuels by renewables. In the field of CO2 electroreduction, copper constitutes the most versatile catalyst, being able to generate CO, C2H4, CH4, as well as alcohols and acids from CO2. Lately, research on Cu-based CO2 electroreduction has focused on two main topics: firstly, the operation under elevated current densities through the development of stable and selective gas diffusion electrodes (GDEs), and electrolyzers; secondly, the tuning of the selectivity of Cu-catalysts towards a specific product. Regarding the latter, common methods, include doping with other metals and heteroatoms, alloying, as well as creating electrode architectures consisting often of Cu/Ag and Cu/Zn structures. Contrary to Cu, only a few heterogeneous electrocatalysts have shown the ability to generate more complex molecules beyond CO and HCOOH, such as hydrocarbons and alcohols. Among these catalysts, the chemically robust and synthetically scalable, boron phosphide (BP) has shown the ability to favor the production of CH3OH from CO2 under low current densities of ca. 2 mA cm-2. Aiming to achieve a synergistic effect between Cu and BP, we herein investigate the role of electrode characteristics versus material properties in gas diffusion electrodes under industrially relevant current densities > 100 mA cm-2. Starting from GDE-properties, we report on the influence of the layer arrangement of Cu and BP on the surface of the GDL, their mixing ratio as well as the deposition method and cell type on the CO2 electroreduction. Furthermore, in order to elucidate the role of material properties towards deciding the product spectrum, we compared the activity of B-compounds with different structural characteristics, possessing cubic as well as hexagonal structures. Concretely, cubic boron nitride (c-BN), and phosphide (BP) as well as hexagonal boron carbon nitride (h-BCN), and hexagonal BN (h-BN) are evaluated in a series of Cu-based GDEs. Depending on the selected layer arrangement, material combination and mixing ratio we are able to steer the main CO2RR product to either CO, C2H4 or CH4 at 200 mA cm-2. Beyond Cu-BX GDEs, our results demonstrate that in the case of synergistic effects, material/electrocatalyst development and electrode/electrolyzer architecture must go hand-in-hand, providing important strategies towards the optimization of composite electrocatalysts. Figure 1

Electrosynthetic methods are considered to be crucial in the sustainable transformation of the chemical industry. Being an integral part of many synthetic pathways, the electrification of hydrogenation reactions gained increasing interest in recent years. However, for the large-scale industrial application of electrochemical hydrogenations, low-resistance zero-gap electrolyzers operating at high current densities and high substrate concentrations, ideally applying noble-metal-free catalyst systems, are required. In this work, we demonstrate the successful development of an electrochemical hydrogenation process towards application at the example of the semi-hydrogenation of alkynols. Because of their conductivity, stability, and stoichiometric flexibility, transition metal sulfides were thoroughly investigated as promising electrocatalysts for electrochemical hydrogen evolution but remain scarcely investigated for electrochemical hydrogenations. An initial screening of a series of first-row transition metal sulfides of the pentlandite class revealed promising activity for the electrochemical hydrogenation of alkynols in water and methanol. Based on these findings, selected catalysts were incorporated into a zero-gap electrolyzer, thereby enabling the hydrogenation of alkynols at current densities of up to 1 A cm-2, Faraday efficiencies of up to 75 %, and an alkene selectivity of 90 %. In this scalable setup we demonstrate high stability of the catalyst and the electrode for at least 100 h. Altogether, we illustrate the successful integration of a sustainable catalyst into a scalable zero-gap electrolyzer establishing electrosynthetic methods in an application-oriented manner. Figure 1

Electrocatalytic hydrogenation reactions (ECH) increasingly emerge as promising methods in the reductive production of base- and fine-chemicals. When driven by renewable energies, it constitutes a sustainable option circumventing the need for gaseous hydrogen, high pressure conditions as well as stoichiometric reducing agents which are associated with surplus waste formation. Furthermore, ECH processes can be operated under mild conditions close to room temperature and using green solvents such as water as proton source. Beyond these substantial advantages, an ideal ECH-process requires readily available, cheap and durable electrocatalysts capable of preplacing predominant noble metals to become industrially competitive. Along this line, much can be learned from natural enzymatic systems handling hydrogen. Inspired by the active sites of hydrogenases, which feature abundant transition metals in a sulfidic environment, we employed highly conductive 3d-metal chalcogenides of pentlandite type as highly efficient and cheap electrocatalysts for the ECH of unsaturated organic chemicals. Based on this inspiring compound class we demonstrate the relevant parameters to suppress the formation of parasitic hydrogen in favor for hydrogenations. Additionally, we outline the necessary interplay of material science as well as reactor engineering all the way from an initially promising catalytic material to a scalable sustainable electrochemical cell with industrial potential. Figure 1

The efficient reduction of protons by non-noble metals under mild conditions is a challenge for our modern society. Nature utilises hydrogenases, enzymatic machineries that comprise iron- and nickel- containing active sites, to perform the conversion of protons to hydrogen. We herein report a straightforward synthetic pathway towards well-defined particles of the bio-inspired material FexNi9−xS8, a structural and functional analogue of hydrogenase metal sulfur clusters. Moreover, the potential of pentlandites to serve as photocatalysts for solar-driven H2-production is assessed for the first time. The FexNi9−xS8 materials are visible light responsive (band gaps between 2.02 and 2.49 eV, depending on the pentlandite’s Fe : Ni content) and display a conduction band energy close to the thermodynamic potential for proton reduction. Despite the limited driving force, a modest activity for photocatalytic H2 has been observed. Our observations show the potential for the future development of pentlandites as photocatalysts. This work provides a basis to explore powerful synergies between biomimetic chemistry and material design to unlock novel applications in solar energy conversion.

The electrocatalytic reduction of carbon dioxide (CO2) by means of renewable energies is widely recognized as a promising approach to establish a sustainable closed carbon cycle economy. However, widespread application is hampered by the inherent difficulty in suppressing the hydrogen evolution reaction and controlling the overall process selectivity. Further critical parameters are the limited solubility of CO2 in many electrolytes and its hindered mass transport to the electrodes. Herein we report on a series of nanoparticle Cu electrocatalysts on different carbon supports and their potential to perform the electrochemical CO2 reduction under supercritical conditions (scCO2). Herein, CO2 serves as the reaction medium and reactant alike. By a detailed comparison to ambient conditions we show that scCO2 conditions largely suppress the undesirable hydrogen evolution and favor the production of formic acid by the Cu electrodes. Furthermore, we show that scCO2 conditions significantly prevent Cu nanoparticle agglomeration during electrocatalysis.

We have developed a scalable platform that employs electrolysis for an in vitro synthetic enzymatic cascade in a continuous flow reactor. Both H2 and O2 were produced by electrolysis and transferred through a gas‐permeable membrane into the flow system. The membrane enabled the separation of the electrolyte from the biocatalysts in the flow system, where H2 and O2 served as electron mediators for the biocatalysts. We demonstrate the production of methylated N‐heterocycles from diamines with up to 99 % product formation as well as excellent regioselective labeling with stable isotopes. Our platform can be applied for a broad panel of oxidoreductases to exploit electrical energy for the synthesis of fine chemicals., A bioelectrochemical flow system has been developed to power enzymatic cascades in vitro. H2 and O2 are generated by electrolysis and serve as electron mediators for oxidoreductases. Methylated N‐heterocycles were generated from diamines with up to 99 % product formation and a labeling regioselectivity of up to 99 %.

Inspired by our recent finding that Fe4.5Ni4.5S8 rock is a highly active electrocatalyst for HER, we set out to explore the influence of the Fe:Ni ratio on the performance of the catalyst. We herein describe the synthesis of (FexNi1–x)9S8 (x = 0–1) along with a detailed elemental composition analysis. Furthermore, using linear sweep voltammetry, we show that the increase in the iron or nickel content, respectively, lowers the activity of the electrocatalyst toward HER. Electrochemical surface area analysis (ECSA) clearly indicates the highest amount of active sites for a Fe:Ni ratio of 1:1 on the electrode surface pointing at an altered surface composition of iron and nickel for the other materials. Specific metal–metal interactions seem to be of key importance for the high electrocatalytic HER activity, which is supported by DFT calculations of several surface structures using the surface energy as a descriptor of catalytic activity. In addition, we show that a temperature increase leads to a significant...

The efficient reduction of protons by non-noble metals under mild conditions is a challenge for our modern society. Nature utilises hydrogenases, enzymatic machineries that comprise iron- and nickel- containing active sites, to perform the conversion of protons to hydrogen. We herein report a straightforward synthetic pathway towards well-defined particles of the bio-inspired material FexNi9-xS8, a structural and functional analogue of hydrogenase metal sulfur clusters. Moreover, the potential of pentlandites to serve as photocatalysts for solar-driven H2-production is assessed for the first time. The FexNi9-xS8 materials are visible light responsive (band gaps between 2.02 and 2.49 eV, depending on the pentlandite's Fe : Ni content) and display a conduction band energy close to the thermodynamic potential for proton reduction. Despite the limited driving force, a modest activity for photocatalytic H2 has been observed. Our observations show the potential for the future development of pentlandites as photocatalysts. This work provides a basis to explore powerful synergies between biomimetic chemistry and material design to unlock novel applications in solar energy conversion.

The electrocatalytic reduction of carbon dioxide (CO2RR) to valuable bulk chemicals is set to become a vital factor in the prevention of environmental pollution and the selective storage of sustainable energy. Inspired by structural analogues to the active site of the enzyme CODHNi, we envisioned that bulk Fe/Ni sulfides would enable the efficient reduction of CO2. By careful adjustment of the process conditions, we demonstrate that pentlandite (Fe4.5Ni4.5S8) electrodes, in addition to HER, also support the CO2RR reaching a peak faradaic efficiency of 87% and 13% for the formation of CO and methane, respectively at 3 mA cm−2. The choice of solvent, the presence of water/protons and CO2 solubility are identified as key-properties to adjust the balance between HER and CO2RR in favour of the latter. Such experiments can thus serve as model reactions to elucidate a potential catalyst within gas diffusion electrodes.

The efficient reduction of protons and CO2 under mild conditions is a current challenge for modern society. Nature utilizes enzymatic machineries that comprise iron- and nickel- containing active sites to perform these transformations.1 Recently, we reported on the formidable HER activity of bulk Fe4.5Ni4.5S8 electrodes as a bio-inspired material revealing similar structural and functional properties of [FeNi] hydrogenases.2,3,4 We herein set out to explore the influence of the Fe : Ni ratio on the performance of the electrocatalyst.5 Using linear sweep voltammetry, we show that the increase in the Fe or Ni content, respectively, lowers the activity of the bulk electrocatalyst towards HER. Comparable to the enzymes, specific Fe-Ni interactions seem to be the key for the observed HER activity. Furthermore, due to the resemblance of such sulfides with CO2 converting enzymes, we likewise investigated Fe4.5Ni4.5S8 electrodes to perform the reduction of CO2. In non-aqueous conditions, this material is indeed a potential catalyst affording CO as main product with high Faradaic yields. 1F. Möller, S. Piontek, R. G. Miller, U.-P. Apfel, Chem. Eur. J. 2017, DOI: 10.1002/chem.201703451. 2B. Konkena, K. junge Puring, O. Khavryuchenko, I. Sinev, S. Piontek, M. Muhler, W. Schuhmann, U.-P. Apfel, Nature Commun. 2016, 7:12269, DOI: 10.1038/ncomms12269. 3K. junge Puring, S. Piontek, M. Smialkowski, J. Burfeind, S. Kaluza, C. Doetsch, U.-P. Apfel, J. vis. Exp. 2017, 124, DOI:10.3791/56087. 4I. Zegkinoglou, A. Zendegani, I. Sinev, S. Kunze, H. Mistry, J. Zhao, M. Y. Hu, E. E. Alp, S. Piontek, M. Smialkowski, U.-P. Apfel, T. Hickel, J. Neugebauer, B. Roldan Cuenya, J. Am. Chem. Soc. 2017, 139, 14360. 5S. Piontek, C. Andronescu, A. Zaichenko, B. Konkena, K. junge Puring, B. Marler, H. Antoni, I. Sinev, M. Muhler, D. Mollenhauer, B. Roldan Cuenya, W. Schuhmann, U.-P. Apfel, ACS Catalysis, 2018, 8, 987. Figure 1

A series of six cobalt ketoiminates, of which one was previously reported but not explored as a chemical vapor deposition (CVD) precursor, namely, bis(4-(isopropylamino)pent-3-en-2-onato)cobalt(II) ([Co( ipki)2], 1), bis(4-(2-methoxyethylamino)pent-3-en-2-onato)cobalt(II) ([Co(meki)2], 2), bis(4-(2-ethoxyethylamino)pent-3-en-2-onato)cobalt(II) ([Co(eeki)2], 3), bis(4-(3-methoxy-propylamino)pent-3-en-2-onato)cobalt(II) ([Co(mpki)2], 4), bis(4-(3-ethoxypropylamino)pent-3-en-2-onato)cobalt(II) ([Co(epki)2], 5), and bis(4-(3-isopropoxypropylamino)pent-3-en-2-onato)cobalt(II) ([Co( ippki)2], 6) were synthesized and thoroughly characterized. Single-crystal X-ray diffraction (XRD) studies on compounds 1-3 revealed a monomeric structure with distorted tetrahedral coordination geometry. Owing to the promising thermal properties, metalorganic CVD of CoO x was performed using compound 1 as a representative example. The thin films deposited on Si(100) consisted of the spinel-phase Co3O4 evidenced by XRD, Rutherford backscattering spectrometry/nuclear reaction analysis, and X-ray photoelectron spectroscopy. Photoelectrochemical water-splitting capabilities of spinel CoO x films grown on fluorine-doped tin oxide (FTO) and TiO2-coated FTO revealed that the films show p-type behavior with conduction band edge being estimated to -0.9 V versus reversible hydrogen electrode. With a thin TiO2 underlayer, the CoO x films exhibit photocurrents related to proton reduction under visible light.

The rock material pentlandite with the composition Fe(4.5)Ni(4.5)S(8) was synthesized via high temperature synthesis from the elements. The structure and composition of the material was characterized via powder X-ray diffraction (PXRD), Mössbauer spectroscopy (MB), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and energy dispersive X-ray spectroscopy (EDX). Two preparation methods of pentlandite bulk electrodes are presented. In the first approach a piece of synthetic pentlandite rock is directly contacted via a wire ferrule. The second approach utilizes pentlandite pellets, pressed from finely ground powder, which is immobilized in a Teflon casing. Both electrodes, whilst being prepared by an additive-free method, reveal high durability during electrocatalytic conversions in comparison to common drop-coating methods. We herein showcase the striking performance of such electrodes to accomplish the hydrogen evolution reaction (HER) and present a standardized method to evaluate the electrocatalytic performance by electrochemical and gas chromatographic methods. Furthermore, we report stability tests via potentiostatic methods at an overpotential of 0.6 V to explore the material limitations of the electrodes during electrolysis under industrial relevant conditions.

The need for sustainable catalysts for an efficient hydrogen evolution reaction is of significant interest for modern society. Inspired by comparable structural properties of [FeNi]-hydrogenase, here we present the natural ore pentlandite (Fe4.5Ni4.5S8) as a direct ‘rock' electrode material for hydrogen evolution under acidic conditions with an overpotential of 280 mV at 10 mA cm−2. Furthermore, it reaches a value as low as 190 mV after 96 h of electrolysis due to surface sulfur depletion, which may change the electronic structure of the catalytically active nickel–iron centres. The ‘rock' material shows an unexpected catalytic activity with comparable overpotential and Tafel slope to some well-developed metallic or nanostructured catalysts. Notably, the ‘rock' material offers high current densities (≤650 mA cm−2) without any loss in activity for approximately 170 h. The superior hydrogen evolution performance of pentlandites as ‘rock' electrode labels this ore as a promising electrocatalyst for future hydrogen-based economy., There are comparable structural properties between the natural enzyme [FeNi]-hydrogenase and the natural ore, pentlandite. Here the authors, inspired by these similarities, use the mineral as a ‘rock' electrode, and evaluate its electrocatalytic hydrogen evolution performance.

Although often regarded a childhood toy, the design of paper airplanes is subtly complex. The design space and mapping from geometry to distance flown is highly nonlinear and probabilistic where a single airplane design exhibits a multitude of trajectory forms and flight distances. This makes optimization and understanding of their behavior challenging for humans. By understanding the behavior of paper airplanes and predicting flight behavior, there is a potential to improve the design of aerial vehicles that operate at low Reynolds numbers. By developing a robotic system that can fabricate, test, analyze, and model the flight behavior in an unsupervised fashion, a wide design space can be reliably characterized. We find there are discrete behavioral groups that result in different trajectories: nose dive, glide, and recovery glide. Informed by this characterization we propose a method of using Gaussian mixture models to extract the clusters of the design space that map to these different behaviors. This allows us to solve both the forward and reverse design problem for paper airplanes, and also to perform efficient optimization of the geometry for a given target flight distance.

In the quest to develop large-area soft sensors, we can look to nature for many examples. Spiderwebs show many fascinating properties that we can seek to understand and replicate in order to develop large-area, soft, and deformable sensing structures. Spiders’ webs are used not only to capture prey, but also to localize their prey through the vibrations that they feel through their legs. Inspired by spiderwebs, we developed a large-area tactile sensor for localizing contact points through vibration sensing. We hypothesize that the structure of a web can be leveraged to amplify, filter, or otherwise morphologically tune vibrations to improve sensing capabilities. To explore this design space, we created a means of computationally designing and 3D printing web structures. By using vibration sensors mounted on the edges of webs to simulate a spider monitoring vibrations, we show how varying the structural properties affects the localization performance when using vibration sensors and long short-term memory (LSTM)-based neural network classifiers. We seek to explain the classification performance seen in different webs by considering various metrics of information content for different webs and, hence, provide insight into how bio-inspired spiderwebs can be used to assist large-area sensing structures.

The use of robotic systems for harvesting of crops is a growing application domain in the agriculture sector. A key challenge is to develop robotic systems to harvest soft fruits such as raspberries which require delicate handling as they are easily damaged. Designing and optimizing a robotic harvesting setup by testing on real raspberry crops can be challenging due to the short natural harvesting period and the cost and logistical challenges of running experiments in the field. To solve this problem, we present a sensorized physical twin of a raspberry which can be used to develop robotic harvesting systems before deploying in the field. The sensorized raspberry has the capability of measuring the applied forces before and after it has been picked off the plant with a high sensitivity. The mechanical design was optimized and a material with properties similar to the real fruit was chosen, in order to achieve similar mechanical properties to a real raspberry, specifically the stiffness before and after picking and the pulling force. The paper concludes with a harvesting demonstration performed by a robotic gripper, where the sensorized raspberry is used to assess the quality of the picking action. This work aims to lay the groundwork for accelerating the future development of robotic harvesting systems to enable robust development in a lab before deployment in the field.