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Michael De Volder, Engineering Department - IfM

Tue 05 Mar 14:15: Control of Uncertainty or Control with Uncertainty? A New Control Design Paradigm for Autonomous Stochastic Systems

Control of Uncertainty or Control with Uncertainty? A New Control Design Paradigm for Autonomous Stochastic Systems

Uncertainty propagation and mitigation is at the core of all robotic and control systems. The standard approach so far has followed the spirit of control of a system “with uncertainties,” as opposed to direct control “of uncertainties.” Recent advances from the controllability of higher order moments of the distribution of the state trajectories provide us with a new tool to control stochastic systems with strict performance guarantees. In this talk I will review some recent results on covariance and distribution control for discrete stochastic systems, subject to probabilistic (chance) constraints, and will demonstrate the application of the approach on control and robot motion planning problems under uncertainty. The resulting theory has close connections to the classical Optimal Mass Transport (OMT) problem and is numerically efficient (often resulting in a convex program). I will also discuss some current trends and potential directions for future work.

The seminar will be held in the Board Room, Baker Building, Department of Engineering, and online (zoom):

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Enhancing Light Outcoupling Efficiency via Anisotropic Low Refractive Index Electron Transporting Materials for Efficient Perovskite Light‐Emitting Diodes


Thanks to the extensive efforts toward optimizing perovskite crystallization properties, high-quality perovskite films with near-unity photoluminescence quantum yield have been successfully achieved. However, the light outcoupling efficiency of perovskite light-emitting diodes (PeLEDs) is impeded by insufficient light extraction, which poses a challenge to the further advancement of PeLEDs. Here, an anisotropic multifunctional electron transporting material, 9,10-bis(4-(2-phenyl-1H-benzo[d]imidazole-1-yl)phenyl) anthracene (BPBiPA), with a low extraordinary refractive index (n e) and high electron mobility is developed for fabricating high-efficiency PeLEDs. The anisotropic molecular orientations of BPBiPA can result in a low n e of 1.59 along the z-axis direction. Optical simulations show that the low n e of BPBiPA can effectively mitigate the surface plasmon polariton loss and enhance the photon extraction efficiency in waveguide mode, thereby improving the light outcoupling efficiency of PeLEDs. Additionally, the high electron mobility of BPBiPA can facilitate balanced carrier injection in PeLEDs. As a result, high-efficiency green PeLEDs with a record external quantum efficiency of 32.1% and a current efficiency of 111.7 cd A−1 are obtained, which provides new inspirations for the design of electron transporting materials for high-performance PeLEDs.

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Moiré Pattern Controlled Phonon Polarizer Based on Twisted Graphene


Atomically twisted van der Waals materials featuring Moiré patterns present new design possibilities and demonstrate unconventional behaviors in electrical, optical, spintronic, and superconducting properties. However, experimental exploration of thermal transport across Moiré patterns has not been as extensive, despite its critical role in nanoelectronics, thermal management, and energy conversion. Here, we conduct the first experimental investigation into thermal transport across twisted graphene, demonstrating the concept of a phonon polarizer achieved by manipulating the rotational misalignment between adjacent stacked layers. Our approach includes thorough structural characterizations and atomistic modeling of various twisted graphene configurations, along with direct measurements of thermal and acoustic transport using ultrafast spectroscopies. For the first time, we have measured a significant modulation – up to 631% – in the thermal conductance of twisted graphene by reducing phonon transmissions as a function of Moiré angles, while a high acoustic transmission maintains across all twist configurations. By comparing experiments with first-principles calculations using density functional theory and molecular dynamics simulations, mode-dependent phonon transmission between monolayer graphene are quantified based on the angle alignment of phonon band structures. We investigate mode-specific phonon transmission and attribute the pronounced polarizing effect to the distortion over the coupling phase space especially from flexural phonon modes. The modeling results agree with experimental data, verifying the dominant tuning mechanisms in adjusting phonon transmission from high-frequency thermal modes while negligible effects on low-frequency acoustic modes near Brillouin zone center. This study offers crucial insights into the fundamental thermal transport in Moiré structures, opening avenues for the invention of advanced thermal devices and new design methodologies based on manipulations of vibrational band structures and phonon spectra.

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Mechanical Properties of Conducting Printed Nanosheet Network Thin Films Under Uniaxial Compression

Printed thin film nanosheet networks show remarkable promise for a range of electrical applications. Their conductivity relies heavily on their morphology, which may be altered via compression. This work provides the first exploration of the compressive properties of printed networks of graphene and MoS2 to explore properties of elastic modulus, plastic yield, viscoelasticity, tensile failure, and sheet bending versus slippage.


Thin film networks of solution processed nanosheets show remarkable promise for use in a broad range of applications including strain sensors, energy storage, printed devices, textile electronics, and more. While it is known that their electronic properties rely heavily on their morphology, little is known of their mechanical nature, a glaring omission given the effect mechanical deformation has on the morphology of porous systems and the promise of mechanical post processing for tailored properties. Here, this work employs a recent advance in thin film mechanical testing called the Layer Compression Test to perform the first in situ analysis of printed nanosheet network compression. Due to the well-defined deformation geometry of this unique test, this work is able to explore the out-of-plane elastic, plastic, and creep deformation in these systems, extracting properties of elastic modulus, plastic yield, viscoelasticity, tensile failure and sheet bending vs. slippage under both out of plane uniaxial compression and tension. This work characterizes these for a range of networks of differing porosities and sheet sizes, for low and high compression, as well as the effect of chemical cross linking. This work explores graphene and MoS2 networks, from which the results can be extended to printed nanosheet networks as a whole.

Ultraconfined Plasmons in Atomically Thin Crystalline Silver Nanostructures

Ultrathin crystalline silver structures of <3 nm in thickness are fabricated by lighographically prepatterning a silicon wafer and subsequently depositing a few atomic layers of metal under ultrahigh vacuum conditions. The method has great flexibility regarding the size and morphology of the structures, which are demonstrated to sustain plasmon resonances with quality factors as high as ten.


The ability to confine light down to atomic scales is critical for the development of applications in optoelectronics and optical sensing as well as for the exploration of nanoscale quantum phenomena. Plasmons in metallic nanostructures with just a few atomic layers in thickness can achieve this type of confinement, although fabrication imperfections down to the subnanometer scale hinder actual developments. Here, narrow plasmons are demonstrated in atomically thin crystalline silver nanostructures fabricated by prepatterning silicon substrates and epitaxially depositing silver films of just a few atomic layers in thickness. Specifically, a silicon wafer is lithographically patterned to introduce on-demand lateral shapes, chemically process the sample to obtain an atomically flat silicon surface, and epitaxially deposit silver to obtain ultrathin crystalline metal films with the designated morphologies. Structures fabricated by following this procedure allow for an unprecedented control over optical field confinement in the near-infrared spectral region, which is here illustrated by the observation of fundamental and higher-order plasmons featuring extreme spatial confinement and high-quality factors that reflect the crystallinity of the metal. The present study constitutes a substantial improvement in the degree of spatial confinement and quality factor that should facilitate the design and exploitation of atomic-scale nanoplasmonic devices for optoelectronics, sensing, and quantum-physics applications.

Self‐Adaptive Perception of Object's Deformability with Multiple Deformation Attributes Utilizing Biomimetic Mechanoreceptors

A novel tactile sensor, which integrates biomimetic slow-adapting mechanoreceptors in a soft medium, enables self-decoupled sensing of local pressure and strain at the contact surface. In robotic manipulation, the sensor can achieve the self-adaptive perception of material softness and enhance tactile perception by establishing two relevant deformation attributes (material softness and compliance) for an object.


The perception of object's deformability in unstructured interactions relies on both kinesthetic and cutaneous cues to adapt the uncertainties of an object. However, the existing tactile sensors cannot provide adequate cutaneous cues to self-adaptively estimate the material softness, especially in non-standard contact scenarios where the interacting object deviates from the assumption of an elastic half-infinite body. This paper proposes an innovative design of a tactile sensor that integrates the capabilities of two slow-adapting mechanoreceptors within a soft medium, allowing self-decoupled sensing of local pressure and strain at specific locations within the contact interface. By leveraging these localized cutaneous cues, the sensor can accurately and self-adaptively measure the material softness of an object, accommodating variations in thicknesses and applied forces. Furthermore, when combined with a kinesthetic cue from the robot, the sensor can enhance tactile expression by the synergy of two relevant deformation attributes, including material softness and compliance. It is demonstrated that the biomimetic fusion of tactile information can fully comprehend the deformability of an object, hence facilitating robotic decision-making and dexterous manipulation.

In Situ Engineering of Inorganic‐Rich Solid Electrolyte Interphases via Anion Choice Enables Stable, Lithium Anodes

Tetrahydrofuran-based electrolyte systems have demonstrated success in enabling high-stability lithium anodes by encouraging the decomposition of anions (instead of organic solvent) and thus generating inorganic-rich solid electrolyte interphases (SEIs). By employing a variety of different lithium salts (i.e., LiPF6, LiTFSI, LiFSI, and LiDFOB), it is demonstrated that electrolyte anions can improve the inorganic composition and resulting properties of the SEI.


The discovery of liquid battery electrolytes that facilitate the formation of stable solid electrolyte interphases (SEIs) to mitigate dendrite formation is imperative to enable lithium anodes in next-generation energy-dense batteries. Compared to traditional electrolyte solvents, tetrahydrofuran (THF)-based electrolyte systems have demonstrated great success in enabling high-stability lithium anodes by encouraging the decomposition of anions (instead of organic solvent) and thus generating inorganic-rich SEIs. Herein, by employing a variety of different lithium salts (i.e., LiPF6, LiTFSI, LiFSI, and LiDFOB), it is demonstrated that electrolyte anions modulate the inorganic composition and resulting properties of the SEI. Through novel analytical time-of-flight secondary-ion mass spectrometry methods, such as hierarchical clustering of depth profiles and compositional analysis using integrated yields, the chemical composition and morphology of the SEIs generated from each electrolyte system are examined. Notably, the LiDFOB electrolyte provides an exceptionally stable system to enable lithium anodes, delivering >1500 cycles at a current density of 0.5 mAh g−1 and a capacity of 0.5 mAh g−1 in symmetrical cells. Furthermore, Li//LFP cells using this electrolyte demonstrate high-rate, reversible lithium storage, supplying 139 mAh g(LFP) −1 at C/2 (≈0.991 mAh cm−2, @ 0.61 mA cm−2) with 87.5% capacity retention over 300 cycles (average Coulombic efficiency >99.86%).

Retarding Ion Migration for Stable Blade‐Coated Inverted Perovskite Solar Cells

A bifunctional molecule, p-aminobenzoic acid (PABA), increases ion migration barrier, induces (100) facet perovskite grain growth, and yields defect-reduced, homogeneous films. The blade-coated PABA-based inverted PSC achieves an impressive PCE of 23.32% and maintains 93.8% of its initial efficiency after 1000 hours under 1-sun illumination at 75 °C and 10% relative humidity.


The fabrication of perovskite solar cells (PSCs) through blade coating is seen as one of the most viable paths toward commercialization. However, relative to the less scalable spin coating method, the blade coating process often results in more defective perovskite films with lower grain uniformity. Ion migration, facilitated by those elevated defect levels, is one of the main triggers of phase segregation and device instability. Here, a bifunctional molecule, p-aminobenzoic acid (PABA), which enhances the barrier to ion migration, induces grain growth along the (100) facet, and promotes the formation of homogeneous perovskite films with fewer defects, is reported. As a result, PSCs with PABA achieved impressive power conversion efficiencies (PCEs) of 23.32% and 22.23% for devices with active areas of 0.1 cm2 and 1 cm2, respectively. Furthermore, these devices maintain 93.8% of their initial efficiencies after 1 000 h under 1-sun illumination, 75 °C, and 10% relative humidity conditions.

Rejuvenating Aged Bone Repair through Multihierarchy Reactive Oxygen Species‐Regulated Hydrogel

The multihierarchy reactive oxygen species regulated system, PEGS-PGA/SeSe/Rapa hydrogel (PSeR) for aged bone regeneration can effectively delay senescence and restore the regenerative function of senescent BMSCs by maintaining the levels of ROS intracellularly and extracellularly. Additionally, the PSeR hydrogel can be injected and rapidly crosslinked in the site of bone defects, presenting a novel therapeutic strategy for addressing age-related bone injuries.


Aging exacerbates the dysfunction of tissue regeneration at multiple levels and gradually diminishes individual's capacity to withstand stress, damage, and disease. The excessive accumulation of reactive oxygen species (ROS) is considered a hallmark feature of senescent stem cells, which causes oxidative stress, deteriorates the host microenvironment, and eventually becomes a critical obstacle for aged bone defect repair. Till now, the strategies cannot synchronously and thoroughly regulate intracellular and extracellular ROS in senescent cells. Herein, a multihierarchy ROS scavenging system for aged bone regeneration is developed by fabricating an injectable PEGylated poly(glycerol sebacate) (PEGS-NH2)/poly(γ-glutamic acid) (γ-PGA) hydrogel containing rapamycin-loaded poly(diselenide-carbonate) nanomicelles (PSeR). This PSeR hydrogel exhibits highly sensitive ROS responsiveness to the local aged microenvironment and dynamically releases drug-loaded nanomicelles to scavenge the intracellular ROS accumulated in senescent bone mesenchymal stem cells. The PSeR hydrogel effectively tunes the antioxidant function and delays senescence of bone mesenchymal stem cells by safeguarding DNA replication in an oxidative environment, thereby promoting the self-renewal ability and enhancing the osteogenic capacity for aged bone repair in vitro and in vivo. Thus, this multihierarchy ROS-regulated hydrogel provides a new strategy for treating degenerative diseases.

Dual‐Responsive Nanorobot‐Based Marsupial Robotic System for Intracranial Cross‐Scale Targeting Drug Delivery

A marsupial robotic system combining a continuum robot (mother robot) with nanorobots (child robots) is developed for cross-scale targeting drug delivery. The robotic system improves the targeting rate and therapeutic efficacy in brain tumor treatment with the hierarchical targeting strategy spanning targeting scale from centimeters to nanometers.


Nanorobots capable of active movement are an exciting technology for targeted therapeutic intervention. However, the extensive motion range and hindrance of the blood–brain barrier impeded their clinical translation in glioblastoma therapy. Here, a marsupial robotic system constructed by integrating chemical/magnetic hybrid nanorobots (child robots) with a miniature magnetic continuum robot (mother robot) for intracranial cross-scale targeting drug delivery is reported. For primary targeting on macroscale, the continuum robot enters the cranial cavity through a minimally invasive channel (e.g., Ommaya device) in the skull and transports the nanorobots to pathogenic regions. Upon circumventing the blood–brain barrier, the released nanorobots perform secondary targeting on microscale to further enhance the spatial resolution of drug delivery. In vitro experiments against primary glioblastoma cells derived from different patients are conducted for personalized treatment guidance. The operation feasibility within organisms is shown in ex vivo swine brain experiments. The biosafety of the treatment system is suggested in in vivo experiments. Owing to the hierarchical targeting method, the targeting rate, targeting accuracy, and treatment efficacy have improved greatly. The marsupial robotic system offers a novel intracranial local therapeutic strategy and constitutes a key milestone in the development of glioblastoma treatment platforms.

Water‐Mediated Selectivity Control of CH3OH versus CO/CH4 in CO2 Photoreduction on Single‐Atom Implanted Nanotube Arrays

Fe-TiO2/SrTiO3 nanotube arrays are constructed with both Fe single atom reduction centers and dominant oxidation facets (001) for efficiently driving CO2 photoreduction and water oxidation. The amount of water can be facilely adjusted to selectively control CH3OH production from ≈0% (above H2O) to 98.90% (in H2O) via slowly immersing the catalyst into water.


Controllable methanol production in artificial photosynthesis is highly desirable due to its high energy density and ease of storage. Herein, single atom Fe is implanted into TiO2/SrTiO3 (TSr) nanotube arrays by two-step anodization and Sr-induced crystallization. The resulting Fe-TSr with both single Fe reduction centers and dominant oxidation facets (001) contributes to efficient CO2 photoreduction and water oxidation for controlled production of CH3OH and CO/CH4. The methanol yield can reach to 154.20 µmol gcat −1 h−1 with 98.90% selectivity by immersing all the catalyst in pure water, and the yield of CO/CH4 is 147.48 µmol gcat −1 h−1 with >99.99% selectivity when the catalyst completely outside water. This CH3OH yield is 50 and 3 times higher than that of TiO2 and TSr and stands among all the state-of-the-art catalysts. The facile gas–solid and gas–liquid–solid phase switch can selectively control CH3OH production from ≈0% (above H2O) to 98.90% (in H2O) via slowly immersing the catalyst into water, where abundant •OH and H2O around Fe sites play important role in selective CH3OH production. This work highlights a new insight for water-mediated CO2 photoreduction to controllably produce CH3OH.

Dendrite‐Free and High‐Rate Potassium Metal Batteries Sustained by an Inorganic‐Rich SEI

A 3D porous Al current collector decorated with N-doped graphene affording electronic structure modulation, giving rise to an inorganic-rich SEI architecture to expedite ion transport and guide dendrite-free potassium deposition.


Potassium metal battery is an appealing candidate for future energy storage. However, its application is plagued by the notorious dendrite proliferation at the anode side, which entails the formation of vulnerable solid electrolyte interphase (SEI) and non-uniform potassium deposition on the current collector. Here, this work reports a dual-modification design of aluminum current collector to render dendrite-free potassium anodes with favorable reversibility. This work achieves to modulate the electronic structure of the designed current collector and accordingly attain an SEI architecture with robust inorganic-rich constituents, which is evidenced by detailed cryo-EM inspection and X-ray depth profiling. The thus-produced SEI manages to expedite ionic conductivity and guide homogeneous potassium deposition. Compared to the potassium metal cells assembled using typical aluminum current collector, cells based on the designed current collector realize improved rate capability (maintaining 400 h under 50 mA cm−2) and low-temperature durability (stable operation at −50 °C). Moreover, scalable production of the current collector allows for the sustainable construction of high-safety potassium metal batteries, with the potential for reducing the manufacturing cost.

Intelligent Size‐Switchable Iron Carbide‐Based Nanocapsules with Cascade Delivery Capacity for Hyperthermia‐Enhanced Deep Tumor Ferroptosis

Killing tumor cells in deep tumor regions with ferroptosis agents is still challenging because of distinct size requirements for intratumoral accumulation and deep tumor penetration. This study presents an intelligent formulation based on iron carbide for achieving deep tumor ferroptosis through size-switchable cascade delivery, thereby advancing the comprehension of ferroptosis in the context of tumor theranostics.


The ferroptosis pathway is recognized as an essential strategy for tumor treatment. However, killing tumor cells in deep tumor regions with ferroptosis agents is still challenging because of distinct size requirements for intratumoral accumulation and deep tumor penetration. Herein, intelligent nanocapsules with size-switchable capability that responds to acid/hyperthermia stimulation to achieve deep tumor ferroptosis are developed. These nanocapsules are constructed using poly(lactic-co-glycolic) acid and Pluronic F127 as carrier materials, with Au–Fe2C Janus nanoparticles serving as photothermal and ferroptosis agents, and sorafenib (SRF) as the ferroptosis enhancer. The PFP@Au–Fe2C–SRF nanocapsules, designed with an appropriate size, exhibit superior intratumoral accumulation compared to free Au–Fe2C nanoparticles, as evidenced by photoacoustic and magnetic resonance imaging. These nanocapsules can degrade within the acidic tumor microenvironment when subjected to laser irradiation, releasing free Au–Fe2C nanoparticles. This enables them to penetrate deep into tumor regions and disrupt intracellular redox balance. Under the guidance of imaging, these PFP@Au–Fe2C–SRF nanocapsules effectively inhibit tumor growth when exposed to laser irradiation, capitalizing on the synergistic photothermal and ferroptosis effects. This study presents an intelligent formulation based on iron carbide for achieving deep tumor ferroptosis through size-switchable cascade delivery, thereby advancing the comprehension of ferroptosis in the context of tumor theranostics.

Functionalized MXene Films with Substantially Improved Low‐Voltage Actuation

The simple tetrabutylammonium (TBA)-functionalization of MXene improves the in-plane actuation strain over three times and enhances the mechanical property and stability in air. In situ and ex situ characterizations reveal that the co-insertion/de-insertion of TBA ions with Li ions into/from MXene interlayer galleries and inter-edge gaps causes a large in-plane sliding of MXene sheets under negative/positive polarizations.


Ti3C2Tx MXene film is promising for low-voltage electrochemical actuators (ECAs) due to its excellent electrical conductivity, volumetric capacitance, and mechanical properties. However, its in-plane actuation is limited to little intralayer strain of MXene sheets under polarization. Here it is demonstrated that a simple tetrabutylammonium (TBA) functionalization of MXene improves the in-plane actuation strain by 337% and also enhances the mechanical property and stability in air and the electrolyte. Various in situ characterizations reveal that the improved actuation is ascribed to the co-insertion/desertion of TBA and Li ions into/from MXene interlayer galleries and inter-edge gaps that causes a large in-plane sliding of MXene sheets under negative/positive polarizations. The assembled bending actuator has a high strength and modulus and generates a peak-to-peak strain difference of 0.771% and a blocking force up to 51.5 times its own weight under 1 V. The designed soft robotic tweezer can grasp an object under 1 V and hold it firmly under 0 V. The novel sheet sliding mechanism resembling the filament sliding theory in skeletal muscles may inspire the design of high-performance actuators with other nanomaterials.

Mid‐IR Light‐Activatable Full Spectrum LaB6 Plasmonic Photocatalyst

A plasmonic LaB6 photocatalyst can be excited by mid-IR (3900 nm) light and thermal radiation from hot/warm objects to generate reactive oxygen species and exert photodegradation of organic pollutants, as well as disinfection of multidrug-resistant bacteria.


Photocatalysts as long-lasting, benign reagents for disinfection of bacteria in hospitals and public areas/facilities/transportation vehicles are strongly needed. A common limitation for all existing semiconductor photocatalysts is the requirement of activation by external UV–vis-near-infrared (NIR) light with wavelengths shorter than ≈1265 nm. None of the existing photocatalysts can function during nighttime in the absence of external light. Herein, an unprecedented LaB6 plasmonic photocatalyst is reported, which can absorb UV–vis-NIR light and mid-IR (3900 nm) light to split water and generate hydrogen and hydroxyl radicals for the decomposition of organic pollutants, as well as kill multidrug-resistant Escherichia coli bacteria. Mid-IR light (≈2–50 µm) is readily available from the natural environments via thermal radiation of warm/hot objects on the earth including human bodies, animals, furnances, hot/warm electrical devices, and buildings.

Deformation‐Induced Photoprogrammable Pattern of Polyurethane Elastomers Based on Poisson Effect

A straightforward yet powerful strategy to fabricate micropatterns with high aspect ratio on polyurethane elastomers is developed by spatially regulating the photodimerization and the distribution of internal stress. This technology integrates the characteristics of top-down and bottom-up methods, providing a versatile basis for applications in stretchable strain sensors, anticounterfeiting devices, and functional systems.


Elastomers with high aspect ratio surface patterns are a promising class of materials for designing soft machines in the future. Here, a facile method for fabricating surface patterns on polyurethane elastomer by subtly utilizing the Poisson effect and gradient photocrosslinking is demonstrated. By applying uniaxial tensile strains, the aspect ratio of the surface patterns can be optionally manipulated. At prestretched state, the pattern on the polyurethane elastomer can be readily constructed through compressive stress, resulting from the gradient photocrosslinking via selective photodimerization of an anthracene-functionalized polyurethane elastomer (referred to as ANPU). The macromolecular aggregation structures during stretching deformation significantly contribute to the fabrication of high aspect ratio surface patterns. The insightful finite element analysis well demonstrates that the magnitude and distribution of internal stress in the ANPU elastomer can be regulated by selectively gradient crosslinking, leading to polymer chains migrate from the exposed region to the unexposed region, thereby generating a diverse array of surface patterns. Additionally, the periodic surface patterns exhibit tunable structural color according to the different stretching states and are fully reversible over multiple cycles, opening up avenues for diverse applications such as smart displays, stretchable strain sensors, and anticounterfeiting devices.

Self‐Standing Metal Foam Catalysts for Cathodic Electro‐Organic Synthesis

This work develops leaded foam-type electrodes through the dynamic hydrogen bubble template (DHBT) method and tests them in electro-organic reductions using an oxime to nitrile transformation for synthesis of fine chemicals. All developed catalysts outperformed both Pb and CuSn7Pb15 in terms of chemical yields and energy efficiency. The latter material is deemed the best replacement for Pb in reductive organo-electrosynthesis.


Although electro-organic synthesis is currently receiving renewed interest because of its potential to enable sustainability in chemical processes to value-added products, challenges in process development persist: For reductive transformations performed in protic media, an inherent issue is the limited choice of metallic cathode materials that can effectively suppress the parasitic hydrogen evolution reaction (HER) while maintaining a high activity toward the targeted electro-organic reaction. Current development trends are aimed at avoiding the previously used HER-suppressing elements (Cd, Hg, and Pb) because of their toxicity. Here, this work reports the rational design of highly porous foam-type binary and ternary electrocatalysts with reduced Pb content. Optimized cathodes are tested in electro-organic reductions using an oxime to nitrile transformation as a model reaction relevant for the synthesis of fine chemicals. Their electrocatalytic performance is compared with that of the model CuSn7Pb15 bronze alloy that has recently been endorsed as the best cathode replacement for bare Pb electrodes. All developed metal foam catalysts outperform both bare Pb and the CuSn7Pb15 benchmark in terms of chemical yield and energetic efficiency. Moreover, post-electrolysis analysis of the crude electrolyte mixture and the cathode's surfaces through inductively coupled plasma mass spectrometry (ICP-MS) and scanning electron microscopy (SEM), respectively, reveal the foam catalysts’ elevated resistance to cathodic corrosion.

Rejoint of Carbon Nitride Fragments into Multi‐Interfacial Order‐Disorder Homojunction for Robust Photo‐Driven Generation of H2O2

Herein, a directed healing process is employed to splice carbon nitride pieces into a carbon nitride homojunction with multiple order-disorder interfaces. The resultant catalyst exhibits boosted charge dynamics and more spatially and orderly separated redox centers, resulting in a remarkable yield, an excellent selectivity, and a prominent solar-to-chemical conversion efficiency in photosynthesis of H2O2.


Photocatalytic technology based on carbon nitride (C3N4) offers a sustainable and clean approach for hydrogen peroxide (H2O2) production, but the yield is severely limited by the sluggish hot carriers due to the weak internal electric field. In this study, a novel approach is devised by fragmenting bulk C3N4 into smaller pieces (CN-NH4) and then subjecting it to a directed healing process to create multiple order-disorder interfaces (CN-NH4-NaK). The resulting junctions in CN-NH4-NaK significantly boost charge dynamics and facilitate more spatially and orderly separated redox centers. As a result, CN-NH4-NaK demonstrates outstanding photosynthesis of H2O2 via both two-step single-electron and one-step double-electron oxygen reduction pathways, achieving a remarkable yield of 16675 µmol h–1 g–1, excellent selectivity (> 91%), and a prominent solar-to-chemical conversion efficiency exceeding 2.3%. These remarkable results surpass pristine C3N4 by 158 times and outperform previously reported C3N4-based photocatalysts. This work represents a significant advancement in catalyst design and modification technology, inspiring the development of more efficient metal-free photocatalysts for the synthesis of highly valued fuels.

A Soft, Adhesive Self‐Healing Naked‐Eye Strain/Stress Visualization Patch

A novel naked-eye strain/stress visualization (NSV) patch is developed based on a bio-inspired force-responsive hydrogel. Reversible generation of light scattering mechano-iridophore is regulated by local deformations, serving as the sensing mechanism. NSV patches feature fast response, high resolution, wide dynamic range, great adhesiveness, and self-healing material capability. Their optical output can be directly read by naked eyes or smartphone apps.


Learning about the strain/stress distribution in a material is essential to achieve its mechanical stability and proper functionality. Conventional techniques such as universal testing machines only apply to static samples with standardized geometry in laboratory environment. Soft mechanical sensors based on stretchable conductors, carbon-filled composites, or conductive gels possess better adaptability, but still face challenges from complicated fabrication process, dependence on extra readout device, and limited strain/stress mapping ability. Inspired by the camouflage mechanism of cuttlefish and chameleons, here an innovative responsive hydrogel containing light-scattering “mechano-iridophores” is developed. Force induced reversible phase separation manipulates the dynamic generation of mechano-iridophores, serving as optical indicators of local deformation. Patch-shaped mechanical sensors made from the responsive hydrogel feature fast response time (<0.4 s), high spatial resolution (≈100 µm), and wide dynamic ranges (e.g., 10–150% strain). The intrinsic adhesiveness and self-healing material capability of sensing patches also ensure their excellent applicability and robustness. This combination of chemical and optical properties allows strain/stress distributions in target samples to be directly identified by naked eyes or smartphone apps, which is not yet achieved. The great advantages above are ideal for developing the next-generation mechanical sensors toward material studies, damage diagnosis, risk prediction, and smart devices.

Crystallization Control Based on the Regulation of Solvent–Perovskite Coordination for High‐Performance Ambient Printable FAPbI3 Perovskite Solar Cells

A weak coordination solvent strategy is developed to tailor solvent–perovskite coordination. This strategy promotes the direct crystallization from sol–gel phases to α-formamidinium lead iodide (FAPbI3), leads to more balanced nucleation–growth kinetics, and restrains the formation of defects and microstrains in situ. The corresponding ambient-printed FAPbI3 perovskite solar cells exhibit a remarkable power conversion efficiency of 24%.


The critical requirement for ambient-printed formamidinium lead iodide (FAPbI3) lies in the control of nucleation–growth kinetics and defect formation behavior, which are extensively influenced by interactions between the solvent and perovskite. Here, a strategy is developed that combines a cosolvent and an additive to efficiently tailor the coordination between the solvent and perovskite. Through in situ characterizations, the direct crystallization from the sol–gel phase to α-FAPbI3 is illustrated. When the solvent exhibits strong interactions with the perovskite, the sol–gel phases cannot effectively transform into α-FAPbI3, resulting in a lower nucleation rate and confined crystal growth directions. Consequently, it becomes challenging to fabricate high-quality void-free perovskite films. Conversely, weaker solvent–perovskite coordination promotes direct crystallization from sol–gel phases to α-FAPbI3. This process exhibits more balanced nucleation–growth kinetics and restrains the formation of defects and microstrains in situ. This strategy leads to improved structural and optoelectronic properties within the FAPbI3 films, characterized by more compact grain stacking, smoother surface morphology, released lattice strain, and fewer defects. The ambient-printed FAPbI3 perovskite solar cells fabricated using this strategy exhibit a remarkable power conversion efficiency of 24%, with significantly reduced efficiency deviation and negligible decreases in the stabilized output.

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