High Aspect Ratio Carbon Nanotube Membranes Decorated with Pt Nanoparticle Urchins for Micro Underwater Vehicle Propulsion via H2O2 Decomposition

Experimental and Theoretical Investigation of the Mechanism of the Reduction of O2 from Air to O22- by VIVO2+-N,N,N-Amidate Compounds and Their Potential Use in Fuel Cells

The two-electron reductive activation of O2 to O22- is of particular interest to the scientific community mainly due to the use of peroxides as green oxidants and in powerful fuel cells. Despite of the great importance of vanadium(IV) species to activate the two-electron reductive activation of O2, the mechanism is still unclear. Reaction of VIVO2+ species with the tridentate-planar N,N,N-carboxamide (ΗL) ligands in solution (CH3OH:H2O) under atmospheric O2, at room temperature, resulted in the quick formation of [VV(═O)(η2-O2)(κ3-L)(H2O)] and cis-[VV(═O)2(κ3-L)] compounds. Oxidation of the VIVO2+ complexes with the sterically hindered tridentate-planar N,N,N-carboxamide ligands by atmospheric O2 gave only cis-[VV(═O)2(κ3-L)] compounds. The mechanism of formation of [VV(═O)(η2-O2)(κ3-L)(H2O)] (I) and cis-[VV(═O)2(κ3-L)] (II) complexes vs time, from the interaction of [VIV(═O)(κ3-L)(Η2Ο)2]+ with atmospheric O2, was investigated with 51V, 1H NMR, UV-vis, cw-X-band EPR, and 18O2 labeling IR and resonance Raman spectroscopies revealing the formation of a stable intermediate (Id). EPR, MS, and theoretical calculations of the mechanism of the formation of I and II revealed a pathway, through a binuclear [VIV(═O)(κ3-L)(H2O)(η1,η1-O2)VIV(═O)(κ3-L)(H2O)]2+ intermediate. The results from cw-EPR, 1H NMR spectroscopies, cyclic voltammetry, and the reactivity of the complexes [VIV(═O)(κ3-L)(Η2Ο)2]+ toward O2 reduction fit better to an intermediate with a binuclear nature. Dynamic experiments in combination with computational calculations were undertaken to fully elucidate the mechanism of the O2 reduction to O22- by [VIV(═O)(κ3-L)(Η2Ο)2]+. The galvanic cell {Zn|VIII,VII||Id, [VIVO(κ3-L)(H2O)2]+|O2|C(s)} was manufactured, demonstrating the important applicability of this new chemistry to Zn|H2O2 fuel cells technology generating H2O2 in situ from the atmospheric O2.

Intelligent Micro-/Nanorobots for Cancer Theragnostic

Cancer is one of the most intractable diseases owing to its high mortality rate and lack of effective diagnostic and treatment tools. Advancements in micro-/nanorobot (MNR)-assisted sensing, imaging, and therapeutics offer unprecedented opportunities to develop MNR-based cancer theragnostic platforms. Unlike ordinary nanoparticles, which exhibit Brownian motion in biofluids, MNRs overcome viscous resistance in an ultralow Reynolds number (Re << 1) environment by effective self-propulsion. This unique locomotion property has motivated the advanced design and functionalization of MNRs as a basis for next-generation cancer-therapy platforms, which offer the potential for precise distribution and improved permeation of therapeutic agents. Enhanced barrier penetration, imaging-guided operation, and biosensing are additionally studied to enable the promising cancer-related applications of MNRs. Herein, the recent advances in MNR-based cancer therapy are comprehensively addresses, including actuation engines, diagnostics, medical imaging, and targeted drug delivery; promising research opportunities that can have a profound impact on cancer therapy over the next decade is highlighted.

Micro and Nano Interdigitated Electrode Array (IDEA)-Based MEMS/NEMS as Electrochemical Transducers: A Review

Micro and nano interdigitated electrode array (µ/n-IDEA) configurations are prominent working electrodes in the fabrication of electrochemical sensors/biosensors, as their design benefits sensor achievement. This paper reviews µ/n-IDEA as working electrodes in four-electrode electrochemical sensors in terms of two-dimensional (2D) planar IDEA and three-dimensional (3D) IDEA configurations using carbon or metal as the starting materials. In this regard, the enhancement of IDEAs-based biosensors focuses on controlling the width and gap measurements between the adjacent fingers and increases the IDEA's height. Several distinctive methods used to expand the surface area of 3D IDEAs, such as a unique 3D IDEA design, integration of mesh, microchannel, vertically aligned carbon nanotubes (VACNT), and nanoparticles, are demonstrated and discussed. More notably, the conventional four-electrode system, consisting of reference and counter electrodes will be compared to the highly novel two-electrode system that adopts IDEA's shape. Compared to the 2D planar IDEA, the expansion of the surface area in 3D IDEAs demonstrated significant changes in the performance of electrochemical sensors. Furthermore, the challenges faced by current IDEAs-based electrochemical biosensors and their potential solutions for future directions are presented herein.

Self-Healing Approach toward Catalytic Soft Robots

Soft robotics is a rapidly evolving research field that focuses on developing robots with bioinspired actuation/sensing mechanisms and highly flexible soft materials, some of which are similar to those found in living organisms. The hydrogel has the characteristics of excellent biocompatibility, softness, and elasticity, which makes it an ideal candidate material for the preparation of soft robots. Here we utilized a self-healing approach to develop a catalytically driven soft robot, which was constructed by dynamic imine bonds between modular hydrogels. One of the modules was a hydrogel formed by dynamic aldimine cross-linking of chitosan and glutaraldehyde, and the other module was a hydrogel embedded with catalase. The soft hydrogel robot moved because of catalytic reactions between the robot and environment [hydrogen peroxide (H₂O₂) fuel], giving rise to a fluidic release that supports propulsion, as inspired by the jet-propulsive mechanism in swimming dragonfly larvae. The speed of the soft robot can be mediated by adjusting the concentration of H₂O₂ and enable/disable movement based on the folding and unfolding of enzymes. In addition, the hydrogel formed by replacing glutaraldehyde with dialdehyde-functionalized PEG₂₀₀₀ had excellent elastic properties, and the soft robot based on PEG₂₀₀₀ had a higher movement speed than that based on glutaraldehyde under the same H₂O₂ concentration. Moreover, the addition of iron oxide nanoparticles can realize the magnetic guidance of the soft robot and the combination of different modules can realize different motion modes. The highly configurable self-healing catalytic soft robot holds great potential for a variety of interesting applications, including swimming robots, robot-assisted water treatment, and drug release.

A flexible optical gas pressure sensor as the signal readout for point-of-care immunoassay

Inspired by the concept of pneumatic micro/nanoscale surface morphing, an optical flexible gas pressure immunosensor constructed with an optical Ag/PDMS BGPS and a SiO2/Pt immunocomplex induced gas-generated reaction element for the sensitive detection of AFP was proposed.

Laser-induced graphene electrodes for electrochemical ion sensing, pesticide monitoring, and water splitting

Laser-induced graphene (LIG) has shown to be a scalable manufacturing route to create graphene electrodes that overcome the expense associated with conventional graphene electrode fabrication. Herein, we expand upon initial LIG reports by functionalizing the LIG with metallic nanoparticles for ion sensing, pesticide monitoring, and water splitting. The LIG electrodes were converted into ion-selective sensors by functionalization with poly(vinyl chloride)-based membranes containing K⁺ and H⁺ ionophores. These ion-selective sensors exhibited a rapid response time (10-15 s), near-Nernstian sensitivity (53.0 mV/dec for the K⁺ sensor and - 56.6 mV/pH for the pH sensor), and long storage stability for 40 days, and were capable of ion monitoring in artificial urine. The pesticide biosensors were created by functionalizing the LIG electrodes with the enzyme horseradish peroxidase and displayed a high sensitivity to atrazine (28.9 nA/μM) with negligible inference from other common herbicides (glyphosate, dicamba, and 2,4-dichlorophenoxyacetic acid). Finally, the LIG electrodes also exhibited a small overpotential for hydrogen evolution reaction and oxygen evolution reaction. The oxygen evolution reaction tests yielded overpotentials of 448 mV and 995 mV for 10 mA/cm² and 100 mA/cm², respectively. The hydrogen evolution reaction tests yielded 35 mV and 281 mV for the corresponding current densities. Such a versatile LIG platform paves the way for simple, efficient electrochemical sensing and energy harvesting applications.

Unravelling the cooperative role of lattice strain on MnO2/TiO2 and MnO2/ZnO catalysts for the fast decomposition of hydrogen peroxide

The rate of decomposition of hydrogen peroxide was directly correlated with lattice strain, as derived from strain calculations.

Hollow micro and nanostructures for therapeutic and imaging applications

Hollow particles have been extensively used in bioanalytical and biomedical applications for almost two decades due to their unique and tunable optoelectronic properties as well as their significantly high loading capacities. These intrinsic properties led them to be used in various bioimaging applications as contrast agents, controlled delivery (i.e. drugs, nucleic acids and other biomolecules) platforms and photon-triggered therapies (e.g. photothermal and photodynamic therapies). Since recent studies showed that imaging-guided targeted therapeutics have higher success rates, multimodal theranostic platforms (combination of one or more therapy and diagnosis modality) have been employed more often and hollow particles (i.e. nanoshells) have been one of the most efficient candidates to be used in multiple-purpose platforms, owing to their intrinsic properties that enable synergistic multimodal performance. In this review, recent advances in the applications of such hollow particles fabricated with various routes (either inorganic or organic based) were summarized to delineate strategies for tuning their properties for more efficient biomedical performance by overcoming common biological barriers. This review will pave the ways for expedited progress in design of next generation of hollow particles for clinical applications.

A zinc-quinone battery for paired hydrogen peroxide electrosynthesis

Hydrogen peroxide is a commodity chemical with immense applications as an environmentally benign disinfectant for water remediation, a green oxidant for synthetic chemistry and pulp bleaching, an energy carrier molecule and a rocket propellant. It is typically synthesized by indirect batch anthraquinone process, where sequential hydrogenation and oxidation of anthraquinone molecules generates H₂O₂. This highly energy demanding catalytic sequence necessitates the advent of new reaction pathways with lower energy expenditure. Here we demonstrate a Zn-quinone battery for paired H₂O₂ electrosynthesis at the three phase boundary of its cathodic half-cell during electric power generation. The catalytic quinone half-cell of the Zn-quinone battery, mediates proton coupled electron transfer with molecular oxygen during its chemical regeneration thereby pairing peroxide electrosynthesis with electricity generation. Hydrogen peroxide synthesizing Zn-quinone battery (HPSB) demonstrated a peak power density of ~90 mW/cm² at a peak current density of ~145 mA/cm² while synthesizing ~230 mM of H₂O₂. HPSB offers immense opportunities as it distinctly couples electric power generation with peroxide electrosynthesis which in-turn transforms energy conversion in batteries truly multifunctional.

Bilayer Tubular Micromotors for Simultaneous Environmental Monitoring and Remediation

There are two main aspects of environmental governance including monitoring and remediation, both of which are essential for environmental protection. Self-propelled micro/nanomotors (MNM) have shown promising potential for achieving on-demand tasks in environmental field, including environmental sensing and pollutant removal or degradation. However, most of the current MNM used in environmental protection can hardly accomplish the two major tasks of both monitoring and pollutant degradation. Hereby, we present a bubble-propelled mesoporous silica-coated titania (TiO₂@mSiO₂) bilayer tubular micromotor with platinum (Pt) and magnetic Fe₃O₄ nanoparticles modified on their inner walls. The outer mesoporous silica (mSiO₂) layer can effectively adsorb and collect the pollutants, and the adsorption capacity of the TiO₂@mSiO₂ tube is about 3 times higher than that of the TiO₂ tube due to the presence of mSiO₂ shell. By magnetic manipulation, the micromotors can be recovered to release the collected pollutant for precise analysis of the composition of the pollutants, such us pollutant molecule identification by surface-enhanced Raman scattering. The active motion and photocatalytic TiO₂ inner layer of the micromotors can greatly enhance the degradation rate of the model pollutant rhodamine 6G (R6G). Our results show that within 30 min, up to 98% of R6G can be degraded by the motors. The successful demonstration of the TiO₂@mSiO₂ bilayer tubular motors for simultaneous environmental monitoring and pollutant degradation paves the way for future development of active and intelligent micro/nanorobots for advanced environmental governance.

Electrochemical Glucose Sensors Enhanced by Methyl Viologen and Vertically Aligned Carbon Nanotube Channels

Freestanding, vertically aligned carbon nanotubes (VACNTs) were patterned into 16 μm diameter microchannel arrays for flow-through electrochemical glucose sensing. Non-enzymatic sensing of glucose was achieved by the chemical reaction of glucose with methyl viologen (MV) at an elevated temperature and pH (0.1 M NaOH), followed by the electrochemical reaction of reduced-MV with the VACNT surface. The MV sensor required no functionalization (including no metal) and was able to produce on average 3.4 electrons per glucose molecule. The current density of the MV sensor was linear with both flow rate and glucose concentration. Challenges with interference chemicals were mitigated by operating at a low potential of -0.2 V vs Ag/AgCl. As a comparison, enzymatic VACNT sensors with platinum nano-urchins were functionalized with glucose oxidase by covalent binding (1-ethyl-3-(-3-dimethylaminopropyl)carbodiimide/ N-hydroxysuccinimide) or by polymer entrapment [poly(3,4-ethylene-dioxythiophene)] and operated in phosphate buffered saline. With normalization by the overall cross-sectional area of the flow (0.713 cm²), the sensitivity of the MV, enzyme-in-solution, and covalent sensors were 45.93, 18.77, and 1.815 mA cm^-2 mM^-1, respectively. Corresponding limits of detection were 100, 194, and 311 nM glucose. The linear sensing ranges for the sensors were 250 nM to 200 μM glucose for the MV sensor, 500 nM to 200 μM glucose for the enzyme-in-solution sensor, and 1 μM to 6 mM glucose for the covalent sensor. The flow cell and sensor cross-sectional area were scaled down (0.020 cm²) to enable detection from 200 μL of glucose with MV by flow injection analysis. The sensitivity of the small MV sensor was 5.002 mA cm^-2 mM^-1, with a limit of detection of 360 nM glucose and a linear range up to at least 150 μM glucose. The small MV sensor has the potential to measure glucose levels found in 200 μL of saliva.

Mechanism and Kinetics of Hydrogen Peroxide Decomposition on Platinum Nanocatalysts

The decomposition of H₂O₂ to H₂O and O₂ catalyzed by platinum nanocatalysts controls the energy yield of several energy conversion technologies, such as hydrogen fuel cells. However, the reaction mechanism and rate-limiting step of this reaction have been unsolved for more than 100 years. We determined both the reaction mechanism and rate-limiting step by studying the effect of different reaction conditions, nanoparticle size, and surface composition on the rates of H₂O₂ decomposition by three platinum nanocatalysts with average particle sizes of 3, 11, and 22 nm. Rate models indicate that the reaction pathway of H₂O₂ decomposition is similar for all three nanocatalysts. Larger particle size correlates with lower activation energy and enhanced catalytic activity, explained by a smaller work function for larger platinum particles, which favors chemisorption of oxygen onto platinum to form Pt(O). Our experiments also showed that incorporation of oxygen at the nanocatalyst surface results in a faster reaction rate because the rate-limiting step is skipped in the first cycle of reaction. Taken together, these results indicate that the reaction proceeds in two cyclic steps and that step 1 is the rate-limiting step. Step 1: Pt + H₂ O₂ → H₂ O + Pt( O). Step 2: Pt( O) + H₂ O₂ → Pt + O₂ + H₂ O. Overall: 2 H₂ O₂ → O₂ + 2 H₂ O. Establishing relationships between the properties of commercial nanocatalysts and their catalytic activity, as we have done here for platinum in the decomposition of H₂O₂, opens the possibility of improving the performance of nanocatalysts used in applications. This study also demonstrates the advantage of combining detailed characterization and systematic reactivity experiments to understand property-behavior relationships.

Emulsion Hydrogel Soft Motor Actuated by Thermal Stimulation

An emulsion hydrogel motor (E-H motor), constituted by low-boiling-point oil fuel and a hydrogel matrix, is prepared through a simple yet versatile oil-in-water (O/W) emulsion template method. The E-H motor can be efficiently propelled by the bubbles generated under a thermal stimulus. As thermally induced explosion occurs inside the E-H motor (diameter ∼4.0 mm and length ∼6.0 mm), the gas bubbles resulting from thermotropic phase transition are violently ejected from one side, leading to a fast speed of 14.78 ± 4.82 mm s^-1 in a 60 °C aqueous solution. Additionally, multiple water-insoluble organic solvents can serve as the fuel for self-propulsion, which demonstrates the favorable universality of the E-H motor. The magnetic navigation and near-infrared propulsion can be realized through incorporating hydrophilic iron oxide (Fe₃O₄) nanoparticles and graphene oxide (GO) into the aqueous phase. Moreover, the synchronous integration of GO and enrofloxacin bactericide can enable intelligent targeted cargo transportation and delivery. The attractive self-propulsion performance, precise locomotion control, and formidable integration ability of the emulsion hydrogel-based miniaturized soft motor hold great promise for numerous practical applications.

Enabling Inkjet Printed Graphene for Ion Selective Electrodes with Postprint Thermal Annealing

Inkjet printed graphene (IPG) has recently shown tremendous promise in reducing the cost and complexity of graphene circuit fabrication. Herein we demonstrate, for the first time, the fabrication of an ion selective electrode (ISE) with IPG. A thermal annealing process in a nitrogen ambient environment converts the IPG into a highly conductive electrode (sheet resistance changes from 52.8 ± 7.4 MΩ/□ for unannealed graphene to 172.7 ± 33.3 Ω/□ for graphene annealed at 950 °C). Raman spectroscopy and field emission scanning electron microscopy (FESEM) analysis reveals that the printed graphene flakes begin to smooth at an annealing temperature of 500 °C and then become more porous and more electrically conductive when annealed at temperatures of 650 °C and above. The resultant thermally annealed, IPG electrodes are converted into potassium ISEs via functionalization with a poly(vinyl chloride) (PVC) membrane and valinomycin ionophore. The developed potassium ISE displays a wide linear sensing range (0.01-100 mM), a low detection limit (7 μM), minimal drift (8.6 × 10^-6 V/s), and a negligible interference during electrochemical potassium sensing against the backdrop of interfering ions [i.e., sodium (Na), magnesium (Mg), and calcium (Ca)] and artificial eccrine perspiration. Thus, the IPG ISE shows potential for potassium detection in a wide variety of human fluids including plasma, serum, and sweat.

Free-Standing Networks of Core-Shell Metal and Metal Oxide Nanotubes for Glucose Sensing

Nanotube assemblies represent an emerging class of advanced functional materials, whose utility is however hampered by intricate production processes. In this work, three classes of nanotube networks (monometallic, bimetallic, and metal oxide) are synthesized solely using facile redox reactions and commercially available ion track membranes. First, the disordered pores of an ion track membrane are widened by chemical etching, resulting in the formation of a strongly interconnected pore network. Replicating this template structure with electroless copper plating yields a monolithic film composed of crossing metal nanotubes. We show that the parent material can be easily transformed into bimetallic or oxidic derivatives by applying a second electroless plating or thermal oxidation step. These treatments retain the monolithic network structure but result in the formation of core-shell nanotubes of altered composition (thermal oxidation: Cu₂O-CuO; electroless nickel coating: Cu-Ni). The obtained nanomaterials are applied in the enzyme-free electrochemical detection of glucose, showing very high sensitivities between 2.27 and 2.83 A M^-1 cm^-2. Depending on the material composition, varying reactivities were observed: While copper oxidation reduces the response to glucose, it is increased in the case of nickel modification, albeit at the cost of decreased selectivity. The performance of the materials is explained by the network architecture, which combines the advantages of one-dimensional nano-objects (continuous conduction pathways, high surface area) with those of a self-supporting, open-porous superstructure (binder-free catalyst layer, efficient diffusion). In summary, this novel synthetic approach provides a fast, scalable, and flexible route toward free-standing nanotube arrays of high compositional complexity.

Synthesis of new photosensitive H2BBQ2+[ZnCl4]2−/[(ZnCl)2(μ-BBH)] complexes, through selective oxidation of H2O to H2O2

A two-electron photosensitive H₂O to H₂O₂ oxidizer, H₂BBQ²⁺[ZnCl₄]²⁻/[(ZnCl)₂(μ-BBH)], has been synthesized. An aqueous {[(ZnCl)₂(μ-BBH)]||H₂O₂} solar rechargeable galvanic cell has been constructed.

Platinum Nanoparticle Decorated SiO2 Microfibers as Catalysts for Micro Unmanned Underwater Vehicle Propulsion

Micro unmanned underwater vehicles (UUVs) need to house propulsion mechanisms that are small in size but sufficiently powerful to deliver on-demand acceleration for tight radius turns, burst-driven docking maneuvers, and low-speed course corrections. Recently, small-scale hydrogen peroxide (H₂O₂) propulsion mechanisms have shown great promise in delivering pulsatile thrust for such acceleration needs. However, the need for robust, high surface area nanocatalysts that can be manufactured on a large scale for integration into micro UUV reaction chambers is still needed. In this report, a thermal/electrical insulator, silicon oxide (SiO₂) microfibers, is used as a support for platinum nanoparticle (PtNP) catalysts. The mercapto-silanization of the SiO₂ microfibers enables strong covalent attachment with PtNPs, and the resultant PtNP-SiO₂ fibers act as a robust, high surface area catalyst for H₂O₂ decomposition. The PtNP-SiO₂ catalysts are fitted inside a micro UUV reaction chamber for vehicular propulsion; the catalysts can propel a micro UUV for 5.9 m at a velocity of 1.18 m/s with 50 mL of 50% (w/w) H₂O₂. The concomitance of facile fabrication, economic and scalable processing, and high performance-including a reduction in H₂O₂ decomposition activation energy of 40-50% over conventional material catalysts-paves the way for using these nanostructured microfibers in modern, small-scale underwater vehicle propulsion systems.

3D nanostructured inkjet printed graphene via UV-pulsed laser irradiation enables paper-based electronics and electrochemical devices

Emerging research on printed and flexible graphene-based electronics is beginning to show tremendous promise for a wide variety of fields including wearable sensors and thin film transistors. However, post-print annealing/reduction processes that are necessary to increase the electrical conductivity of the printed graphene degrade sensitive substrates (e.g., paper) and are whole substrate processes that are unable to selectively anneal/reduce only the printed graphene-leaving sensitive device components exposed to damaging heat or chemicals. Herein a pulsed laser process is introduced that can selectively irradiate inkjet printed reduced graphene oxide (RGO) and subsequently improve the electrical conductivity (Rsheet∼0.7 kΩ□(-1)) of printed graphene above previously published reports. Furthermore, the laser process is capable of developing 3D petal-like graphene nanostructures from 2D planar printed graphene. These visible morphological changes display favorable electrochemical sensing characteristics-ferricyanide cyclic voltammetry with a redox peak separation (ΔEp) ≈ 0.7 V as well as hydrogen peroxide (H2O2) amperometry with a sensitivity of 3.32 μA mM(-1) and a response time of <5 s. Thus this work paves the way for not only paper-based electronics with graphene circuits, it enables the creation of low-cost and disposable graphene-based electrochemical electrodes for myriad applications including sensors, biosensors, fuel cells, and theranostic devices.

A paper based graphene-nanocauliflower hybrid composite for point of care biosensing

We demonstrate the first report of graphene paper functionalized with fractal platinum nanocauliflower for use in electrochemical biosensing of small molecules (glucose) or detection of pathogenic bacteria (Escherichia coli O157:H7). Raman spectroscopy, scanning electron microscopy and energy dispersive spectroscopy show that graphene oxide-coated nanocellulose was partially reduced by both thermal treatment, and further reduced by chemical treatment (ascorbic acid). Fractal nanoplatinum with cauliflower-like morphology was formed on the reduced graphene oxide paper using pulsed sonoelectrodeposition, producing a conductive paper with an extremely high electroactive surface area (0.29±0.13cm(2)), confirmed by cyclic voltammetry and electrochemical impedance spectroscopy. The platinum surface was functionalized with either glucose oxidase (via chitosan encapsulation) or a RNA aptamer (via covalent linking) for demonstration as a point of care biosensor. The detection limit for both glucose (0.08±0.02μM) and E. coli O157:H7 (≈4 CFUmL(-1)) were competitive with, or superior to, previously reported devices in the biosensing literature. The response time (6s for glucose and 12min for E. coli) were also similar to silicon biochip and commercial electrode sensors. The results demonstrate that the nanocellulose-graphene-nanoplatinum material is an excellent paper-based platform for development of electrochemical biosensors targeting small molecules or whole cells for use in point of care biosensing.

Self-Propelling Hydrogel/Emulsion-Hydrogel Soft Motors for Water Purification

We fabricate a kind of catalytic self-propelling hydrogel soft motor (H-motor) via a facile injection loading method with low energy consumption. The factors influencing the practicability of H-motors, including locomotive ability and reusability, are investigated. The succession of rapid bubble evolution and propulsion endows the millimeter-sized columnar H-motors with length/diameter of 1 a remarkable speed of 3.84 mm s(-1) in 10% (w/w) hydrogen peroxide (H2O2) solution. Moreover, the H-motors maintain undiminished propulsion capability and functionality even after repeated loading for 6 times. Additionally, we also fabricate emulsion-hydrogel soft motors (E-H-motors) templated from the oil/water (O/W) emulsion for the first time, which exhibit a faster speed of 4.33 mm s(-1) under the same conditions. It can be ascribed to the additional liberation of low-boiling oil phase stored in the emulsion-hydrogels caused by catalytic reaction heat, which is appropriate for larger propulsive situations. The stabilized, efficient, and reusable H-motors are selected for industrial effluents purification to fit the imperious demands about the disposal of organic pollutants in water. The synergy effect between catalytic degradation and enhanced intermixing of the fluid flow around the miniaturized soft motors gives rise to an effective and exhaustive removal of organic contaminants.

pulSED: pulsed sonoelectrodeposition of fractal nanoplatinum for enhancing amperometric biosensor performance

A technique for deposition of fractal nanometal as a transducer in electrochemical sensing is described. The effect(s) of duty cycle and deposition time were explored, and two sensors are demonstrated.