In Situ Self-Assembly of Nitrogen-Doped 3D Flower-like Hierarchical Porous Carbon and Its Application for Supercapacitors.

The hierarchical porous carbon-based materials derived from biomass are beneficial for the enhancement of electrochemical performances in supercapacitors. Herein, we report the fabrication of nitrogen-doped 3D flower-like hierarchical porous carbon (NPC) assembled by nanosheets using a mixture of urea, ZnCl2, and starch via a low-temperature hydrothermal reaction and high-temperature carbonization process. As a consequence, the optimized mass ratio for the mixture is 2:2:2 and the temperature is 700 °C. The NPC structures are capable of electron transport and ion diffusion owing to their high specific surface area (1498.4 m2 g-1) and rich heteroatoms. Thereby, the resultant NPC electrodes display excellent capacitive performance, with a high specific capacitance of 249.7 F g-1 at 1.0 A g-1 and good cycling stability. Remarkably, this implies a superior energy density of 42.98 Wh kg-1 with a power density of 7500 W kg-1 in organic electrolyte for the symmetrical supercapacitor. This result verifies the good performance of as-synthesized carbon materials in capacitive energy storage applications, which is inseparable from the hierarchical porous features of the materials.

Nanocellulose-mediated bilayer hydrogel actuators with thermo-responsive, shape memory and self-sensing performances.

Inspired by creatures, abundant stimulus-responsive hydrogel actuators with diverse functionalities have been manufactured for applications in soft robotics. However, constructing a shape memory and self-sensing bilayer hydrogel actuator with high mechanical strength and strong interfacial bonding still remains a challenge. Herein, a novel bilayer hydrogel with a stimulus-responsive TEMPO-oxidized cellulose nanofibers/poly(N-isopropylacrylamide) (TOCN/PNIPAM) layer and a non-responsive TOCN/polyacrylamide (TOCN/PAM) layer is proposed as a thermosensitive actuator. TOCNs as a nano-reinforced phase provide a high mechanical strength and endow the hydrogel actuator with a strong interfacial bonding. Due to the incorporation of TOCNs, the TOCN/PNIPAM hydrogel exhibits a high compressive strength (~89.2 kPa), elongation at break (~170.7 %) and tensile strength (~24.0 kPa). The prepared PNIPAM/TOCN/PAM hydrogel actuator performs the roles of an encapsulation, jack, temperature-controlled fluid valve and temperature-control manipulator. The incorporation of Fe3+ further endows the bilayer hydrogel actuator with a synergistic performance of shape memory and temperature-driven, which can be used as a temperature-responsive switch to detect ambient temperature. The PNIPAM/TOCN/PAM-Fe3+ conductive hydrogel can be assembled into a flexible sensor and generate sensing signals when driven by temperature changes to achieve real-time feedback. This research may lead to new insights into the design and manufacturing of intelligent flexible soft robots.

CoO supported NiFe layered double hydroxide sandwich-like nanosheets on hierarchical carbon framework for efficient electrocatalytic oxygen evolution.

Exploration of greatly efficient and steady non-noble oxygen evolution reaction (OER) electrocatalysts is of great significance in improving the overall efficiency of energy density systems such as regenerative fuel cells, water electrolyzes, and metal-air batteries. Herein, inspired by hierarchical 3D porous structures with open microchannels of natural wood, CoO@NiFe LDH sandwich-like nanosheets were anchored on the carbonized wood (CW) via electrodeposition and calcination strategies. The strong interactions between CoO nanosheets and NiFe LDH nanosheets endow CoO@NiFe LDH/CW electrocatalyst with high catalytic properties toward the OER comparable to CoO/CW and NiFe LDH/CW. The optimized CoO@NiFe LDH/CW electrocatalyst demonstrates good OER catalytic performance with an overpotential of 230 mV at 100 mA cm-2. This work presents an innovative approach to utilize renewable resources for constructing advanced free-standing catalysts.

Nanocellulose-based nanogenerators for sensor applications: A review.

With the rapid development of the Internet of Things, nanogenerator as a green energy collection technology has attracted great attention in various fields. Specifically, the natural renewable nanocellulose as a raw material can significantly improve the environmental friendliness of the nanocellulose-based nanogenerators, which also makes the nanocellulose based nanogenerators expected to further develop in areas such as wearable devices and sensor networks. This paper mainly reports the application of nanocellulose in nanogenerator, focusing on the sensor. The types, sources and preparation methods of nanocellulose are briefly introduced. At the same time, the special structure of nanocellulose highlights the advantages of nanocellulose in nanogenerators. Then, the application of nanocellulose-based nanogenerators in sensors is introduced. Finally, the future development prospects and shortcomings of this nanogenerator are discussed.

Hierarchically core-shell structured nanocellulose/carbon nanotube hybrid aerogels for patternable, self-healing and flexible supercapacitors.

The flexible and self-healing supercapacitors (SCs) are considered to be promising smart energy storage devices. Nevertheless, the SCs integrated with flexibility, lightweight, pattern editability, self-healing capabilities and desirable electrochemical properties remain a challenge. Herein, an all-in-one self-healing SC fabricated with the free-standing hybrid film (TCMP) composed of the 2,2,6,6-tetramethylpiperidin-1-yloxy-oxidized cellulose nanofibers (TOCNs) carried carbon nanotubes (CNTs), manganese dioxide (MnO2) and polyaniline (PANI) as the electrode, polyvinyl alcohol/sulfuric acid (PVA/H2SO4) gel as the electrolyte and dynamically cross-linked cellulose nanofibers/PVA/sodium tetraborate decahydrate (CNF/PB) hydrogel as the self-healing electrode matrix is developed. The TCMP film electrodes are fabricated through a facile in-situ polymerization of MnO2 and PANI in TOCNs-dispersed CNTs composite networks, exhibiting lightweight, high electrical conductivity, flexibility, pattern editability and excellent electrochemical properties. Benefited from the hierarchically porous structure and high mechanical properties of TOCNs, excellent electrical conductivity of CNTs and the desirable synergistic effect of pseudocapacitance induced by MnO2 and PANI, the assembled SC with an interdigital structure demonstrated a high areal capacitance of 1108 mF cm-2 at 2 mA cm-2, large areal energy density of 153.7 µWh cm-2 at 1101.7 µW cm-2. A satisfactory bending cycle performance (capacitance retention up to 95 % after 200 bending deformations) and self-healing characteristics (∼90 % capacitance retention after 10 cut/repair cycles) are demonstrated for the TCMP-based symmetric SC, delivering a feasible strategy for electrochemical energy storage devices with excellent performance, designable patterns and desirable safe lifespan.

Construction of smartphone-adapted signal visualization platform for dual-mode detection of H2S based on integrated metal-organic framework nanoprobes.

Hydrogen sulfide (H2S) is a toxic contaminant and has great influence on many physiological processes. Due to various pathophysiological roles and environmental pollution problems, it is necessary to construct and develop simple and portable monitoring sensors for the precise detection of H2S. Herein, we developed a smartphone-adapted dual-mode detection platform by integrating the colorimetric and photothermal imaging analysis into a metal-organic framework-based chip (ZIF-8/Cu). Due to the nanoconfinement effect of ZIF-8, small-sized plasmonic CuS could be in-situ formed during the detection procedure of H2S and endowed the chips with excellent photothermal properties. By constructing a smartphone-adapted photothermal imager, the metal-organic framework-based chip could achieve a portable photothermal imaging analysis of H2S. Moreover, as the formed CuS was a good peroxidase-like nanozyme, the chips could also be used to trigger the enzymic catalytic reaction toward the chromogenic reaction of 3,3',5,5'-tetramethylbenzidine (TMB)-H2O2, thus providing another colorimetric sensing mode by using a smartphone App. In this smartphone-adapted visualization platform, the portable chemosensors could simultaneously achieve double detection modes at one electrode, which provided a new pathway for the accurate detection of H2S and circumvented the false-positive or negative errors during the detection process. Besides, by using the finite difference time domain (FDTD) simulation method, the in-depth mechanism, including the plasmonic effect and spatial electromagnetic field distribution, was explored to provide a possible reason for the excellent sensing performance of the dual-mode visualization platform. This work provides a new insight into the construction of the accurate, portable and smart sensing platform in the visual screening of H2S.

High Rate Performance Supercapacitors Based on N, O Co-Doped Hierarchical Porous Carbon Foams Synthesized via Chemical Blowing and Dual Templates.

N, O Co-Doped porous carbon materials are promising electrode materials for supercapacitors. However, it is still a challenge to prepare high capacitance performance N, O Co-Doped porous carbon materials with balanced pore structure. In this work, a simple chemical blowing method was developed to produce hierarchal porous carbon materials with Zn(NO3)2·6H2O and Fe(NO3)3·9H2O as the foaming agents and precursors of dual templates. Soybean protein isolate served as a self-doping carbon source. The amount of Fe(NO3)3·9H2O influenced the microstructure, element content and capacitance performance of the obtained porous carbon materials. The optimized sample CZnFe-5 with the addition of 5% Fe(NO3)3·9H2O displayed the best capacitance performance. The specific capacitance reached 271 F g-1 at 0.2 A g-1 and retained 133 F g-1 at 100 A g-1. The CZnFe-5//CZnFe-5 symmetric supercapacitors delivered a maximum energy density of 16.83 Wh kg-1 and good stability with capacitance retention of 86.33% after 40,000 cycles tests at 50 A g-1. The symmetric supercapacitors exhibited potential applications in lighting LED bulbs with a voltage of 3 V. This work provides a new strategy for the synthesis of hierarchical porous carbon materials for supercapacitors from low-cost biomass products.

Functionalized antibacterial peptide with DNA cleavage activity for enhanced bacterial disinfection.

Antibiotics are commonly used to treat bacterial infections, but the misuse and abuse of antibiotics have given rise to a severe problem of the drug resistance of bacteria. Solving this problem has been a vitally important task in the modern medical arena. Antibacterial peptide (AMPs) has become a promising candidate drug to replace antibiotics because of their broad-spectrum antibacterial activity and their difficulty in making bacteria resistant. However, its wider clinical application is limited by the shortcomings of high cytotoxicity and low antibacterial efficiency. In this paper, we constructed an antibacterial peptide (Cu-GGH-KKLRKIAFK, abbreviated as Cu-GGH-AMP) with a DNA cleavage function. The peptide has two functional regions, the C-terminal antibacterial peptide PaDBS1R6F10 (KKLRLKIAFK) and the N-terminal Cu-GGH complex. PaDBS1R6F10 is a unique antibacterial peptide, which shows lower tendency to produce bacterial resistance than traditional antibiotics. Cu-GGG complexes are formed by chelating Cu with the classical amino terminal Cu (II)- and Ni (II) -Binding (ATCUN) motif GGH. In the presence of ascorbic acid, Cu-GGH can efficiently catalyze the oxidative cleavage of bacterial DNA, thus playing a synergistic antibacterial role with antibacterial peptides. The in vitro and in vivo experiments demonstrated this functionalized antibacterial peptide possesses excellent antibacterial and anti-skin infection capability, as well as the activity of promoting wound healing.

Inspired by Wood: Thick Electrodes for Supercapacitors.

The emergence and development of thick electrodes provide an efficient way for the high-energy-density supercapacitor design. Wood is a kind of biomass material with porous hierarchical structure, which has the characteristics of a straight channel, uniform pore structure, good mechanical strength, and easy processing. The wood-inspired low-tortuosity and vertically aligned channel architecture are highly suitable for the construction of thick electrochemical supcapacitor electrodes with high energy densities. This review summarizes the design concepts and processing parameters of thick electrode supercapacitors inspired by natural woods, including wood-based pore structural design regulation, electric double layer capacitances (EDLCs)/pseudocapacitance construction, and electrical conductivity optimization. In addition, the optimization strategies for preparing thick electrodes with wood-like structures (e.g., 3D printing, freeze-drying, and aligned-low tortuosity channels) are also discussed in detail. Further, this review presents current challenges and future trends in the design of thick electrodes for supercapacitors with wood-inspired pore structures. As a guideline, the brilliant blueprint optimization will promote sustainable development of wood-inspired structure design for thick electrodes and broaden the application scopes.

Perylene derivative and persulfate as highly efficient electrochemical system for constructing sensitive amperometric aptasensor.

To design highly efficient electrochemistry system was important for construct simple and sensitive biosensors, which was crucial in clinical diagnosis and therapy. In this work, a novel electrochemistry probe N,N'-di (1-hydroxyethyl dimethylaminoethyl) perylene diimide (HDPDI) with positive charges was reported to show two-electron redox behavior in neutral phosphate buffer solution between 0 and -1.0 V. And K2S2O8 in solution could significantly increase the reduction current of HDPDI at -0.29 V, which was interpreted with cyclic catalysis mechanism of K2S2O8. Moreover, HDPDI as electrochemical probe and K2S2O8 as signal enhancer was used to design aptasensors for protein detection. Thrombin was used as target model protein. Thiolate ssDNA with thrombin-binding sequence was immobilized on gold electrode to selectively capture thrombin and adsorb HDPDI. The thiolate ssDNA without binding with thrombin was with random coil structure and could adsorb HDPDI through electrostatic attraction interaction. However, the thiolate ssDNA binding with thrombin became G-quadruplex structure and hardly adsorbed HDPDI. Thus, with increasing the concentration of thrombin, the current signal stepwisely decreased and was taken as detection signal. Compared with other aptasensors based on electrochemistry molecules without signal enhancer, the proposed aptasensors exhibited wider linear response for thrombin between 1 pg mL-1 and 100 ng mL-1 with lower detection limit 0.13 pg mL-1. In addition, the proposed aptasensor showed good feasibility in human serum samples.

Orthogonal light-triggered multiple effects based on photochromic nanoparticles for DNA cleavage and beyond.

Efficient and spatiotemporally controllable cleavage of deoxyribonucleic acid (DNA) is of great significance for both disease treatment (e.g. tumour, bacterial infection, etc) and molecular biology applications (e.g. gene editing). The recently developed light-induced cleavage strategy based on catalytic nanoparticles has been regarded as a promising strategy for DNA controllable cleavage. Although the regulation based on orthogonal light in biomedical applications holds more significant advantages than that based on single light, nanoparticle-mediated DNA cleavage based on orthogonal light has yet to be reported. In this article, for the first time, we demonstrated an orthogonal light-regulated nanosystem for efficient and spatiotemporal DNA cleavage. In this strategy, tungsten oxide (WO3) nanoparticles with photochromic properties were used as nano-antennae to convert the photoenergy from the orthogonal visible light (405 nm) and near-infrared light (808 nm) into chemical energy for DNA cleavage. We verified that only the orthogonal light can trigger high cleavage efficiency on different types of DNA. Moreover, such an orthogonal light-response nano-system can not only induce significant apoptosis of tumour cells, but also effectively eliminate bacterial biofilms.

Al Foil-Supported Carbon Nanosheets as Self-Supporting Electrodes for High Areal Capacitance Supercapacitors.

Self-supporting electrode materials with the advantages of a simple operation process and the avoidance of the use any binders are promising candidates for supercapacitors. In this work, carbon-based self-supporting electrode materials with nanosheets grown on Al foil were prepared by combining hydrothermal reaction and the one-step chemical vapor deposition method. The effect of the concentration of the reaction solution on the structures as well as the electrochemical performance of the prepared samples were studied. With the increase in concentration, the nanosheets of the samples became dense and compact. The CNS-120 obtained from a 120 mmol zinc nitrate aqueous solution exhibited excellent electrochemical performance. The CNS-120 displayed the highest areal capacitance of 6.82 mF cm-2 at the current density of 0.01 mA cm-2. Moreover, the CNS-120 exhibited outstanding rate performance with an areal capacitance of 3.07 mF cm-2 at 2 mA cm-2 and good cyclic stability with a capacitance retention of 96.35% after 5000 cycles. Besides, the CNS-120 possessed an energy density of 5.9 µWh cm-2 at a power density of 25 µW cm-2 and still achieved 0.3 µWh cm-2 at 4204 µW cm-2. This work provides simple methods to prepared carbon-based self-supporting materials with low-cost Al foil and demonstrates their potential for realistic application of supercapacitors.

Paired electrocatalysis in 5-hydroxymethylfurfural valorization.

5-Hydroxymethylfurfural (HMF) has aroused considerable interest over the past years as an important biomass-derived platform molecule, yielding various value-added products. The conventional HMF conversion requires noble metal catalysts and harsh operating conditions. On the other hand, the electrocatalytic conversion of HMF has been considered as an environmentally benign alternative. However, its practical application is limited by low overall energy efficiency and incomplete conversion. Paired electrolysis and highly efficient electrocatalysts are two viable strategies to address these limitations. Herein, an overview of coupled electrocatalytic HMF hydrogenation or hydrogen evolution reaction (HER) with HMF oxidation as well as the associated electrocatalysts are reviewed and discussed. In this mini-review, a brief introduction of electrocatalytic HMF upgrading is given, followed by the recent advances and challenges of paired electrolysis with an emphasis on the integration HMF electrohydrogenation with HMF electrooxidation. Finally, a perspective for a future sustainable biomass upgrading community based on electrocatalysis is proposed.

Enhanced Electrochemiluminescence of A Macrocyclic Tetradentate Chelate Pt(II) Molecule through Its Collisional Interactions with the Electrode.

A macrocyclic tetradentate chelate Pt(II) molecule (Pt1) served as an excellent luminophore in electrochemiluminescence (ECL) processes. The blue ECL of Pt1/S2 O8 2- coreactant system in N,N'-dimethylformamide was found to be 46 times higher than that of the Ru(bpy)2+ /S2 O8 2- system or 30 times higher than that of the 9,10-diphenylanthracene/S2 O8 2- system. The unprecedented high ECL quantum efficiencies were caused by the cyclic generation of monomer excited states through collisional interactions of Pt1 molecules with the electrode at an elevated frequency. The ECL is tunable from bright blue to pure white by simply changing the solvent from N,N'-dimethylformamide to dichloromethane. The white ECL of Pt(II) molecule was reported for the first time and the mechanism was proposed to be the simultaneous emissions from the monomer excited state (blue) and excimer (red).

Facile Electrodeposition of NiCo2O4 Nanosheets on Porous Carbonized Wood for Wood-Derived Asymmetric Supercapacitors.

Multichannel-porous carbon derived from wood can serve as a conductive substrate for fast charge transfer and ion diffusion, supporting the high-theory capacitance of pseudocapacitive materials. Herein, NiCo2O4 nanosheets, which are hierarchically porous, anchored on the surface of carbonized wood via electrodeposition for free-binder high-performance supercapacitor electrode materials, were proposed. Benefiting from the effectively alleviated NiCo2O4 nanosheets accumulation and sufficient active surface area for redox reaction, a N-doped wood-derived porous carbon-NiCo2O4 nanosheet hybrid material (NCNS-NCW) electrode exhibited a specific electric capacity of 1730 F g-1 at 1 A g-1 in 1 mol L-1 KOH and splendid electrochemical firmness with 80% capacitance retention after cycles. Furthermore, an all-wood-based asymmetric supercapacitor based on NCNS-NCW//NCW was assembled and a high energy density of 56.1 Wh kg-1 at a watt density of 349 W kg-1 was achieved. Due to the great electrochemical performance of NCNS-NCW, we expect it to be used as an electrode material with great promise for energy storage equipment.

Progress in the use of organic potassium salts for the synthesis of porous carbon nanomaterials: microstructure engineering for advanced supercapacitors.

Porous carbon nanomaterials (PCNs) are widely applied in energy storage devices. Traditionally, PCNs were mainly synthesized by activation and templating methods, which are time-consuming, tedious, corrosive and relatively high cost. Therefore, the development of easier and greener methods to produce PCNs is of great significance. Recently, organic potassium salts (OPSs) emerged as versatile reagents for synthesizing PCNs. The OPS-based synthesis of PCNs can avoid the use of large amounts of corrosive chemical agents. Potassium carbonate generated in situ from the decomposition of OPSs could serve as both a green activation agent and a water-removable template to produce nanopores. Potassium oxide and potassium formed at higher temperature could generate additional porosity, contributing to a highly porous architecture. The carbon-rich organic moiety could function as a carbon precursor and chemical blowing agent. This review aims to elucidate the multifunctionality of OPSs in the synthesis of PCNs and the capacitive performance of the corresponding PCNs. To this end, recent progress on the capacitive performance of PCNs synthesized from OPSs is summarized. This review provides constructive viewpoints for the cost-effective and green synthesis of PCNs with the aid of OPSs for application in supercapacitors.

Wood-Derived High-Mass-Loading MnO2 Composite Carbon Electrode Enabling High Energy Density and High-Rate Supercapacitor.

The simple design of a high-energy-density device with high-mass-loading electrode has attracted much attention but is challenging. Manganese oxide (MnO2 ) with its low cost and excellent electrochemical performance shows high potential for practical application in this regard. Hence, the high-mass-loading of the MnO2 electrode with wood-derived carbon (WC) as the current collector is reported through a convenient hydrothermal reaction for high-energy-density devices. Benefiting from the high-mass-loading of the MnO2 electrode (WC@MnO2 -20, ≈14.1 mg cm-2 ) and abundant active sites on the surface of the WC hierarchically porous structure, the WC@MnO2 -20 electrode shows remarkable high-rate performance of areal/specific capacitance ≈1.56 F cm-2 /45 F g-1 , compared to the WC electrode even at the high density of 20 mA cm-2 . Furthermore, the obtained symmetric supercapacitor exhibits high areal/specific capacitances of 3.62 F cm-2 and 87 F g-1 at 1.0 mA cm-2 and high energy densities of 0.502 mWh cm-2 /12.2 Wh kg-1 with capacitance retention of 75.2% after 10 000 long-term cycles at 20 mA cm-2 . This result sheds light on a feasible design strategy for high-energy-density supercapacitors with the appropriate mass loading of active materials and low-tortuosity structural design while also encouraging further investigation into electrochemical storage.

Peroxidase-like activity of Ru-N-C nanozymes in colorimetric assay of acetylcholinesterase activity.

Herein, the Ru-N-C nanozymes with abundant active Ru-Nx sites have been successfully prepared by pyrolyzing Ru(acac)3 trapped zeolitic-imidazolate-frameworks (Ru(acac)3@ZIF-8). Taking advantages of the remarkable peroxidase-mimicking activity, outstanding stability and reusability of Ru-N-C nanozymes, a novel biosensing system with explicit mechanism is strategically fabricated for sensitively determining acetylcholinesterase (AChE) and tacrine. The limit of detection for AChE activity can achieve as low as 0.0433 mU mL-1, and the IC50 value of tacrine for AChE is about 0.190 µmol L-1. The robust analytical performance in serums test verifies the great application potential of this assay in real matrix. Furthermore, "INH" and "IMPLICATION-AND" logic gates are rationally constructed based on the proposed colorimetric sensor. This work not only provides one sustainable and effective avenue to fabricate Ru-N-C-based peroxidase mimic with high catalytic performance, and also gives new impetuses for developing novel biosensors by applying Ru-N-C-based enzyme mimics as substitutes for the natural enzyme.

Anisotropic cellulose nanofibril composite sponges for electromagnetic interference shielding with low reflection loss.

With the development of the electronic industry bringing convenience to people, a series of caused electromagnetic pollution problems (e.g., electromagnetic interference (EMI)) have recently also become urgent tasks. In this work, an anisotropic composite sponge consisting of cellulose nanofibrils (CNFs) and chemical co-precipitated silver nanowire (AgNW)@Fe3O4 composites was successfully prepared. Due to the introduction of anisotropic structures and the synergistic effect among CNFs, AgNWs, and Fe3O4, this composite sponge exhibited low density (16.76 mg/cm3), good saturation magnetization (4.21 emu/g) and electrical conductivity (0.02 S/cm), and anisotropic EMI shielding ability. By adjusting the proportion (1:0.3) between AgNWs and Fe3O4 and their loading (0.15 vol%) inside the sponge, the reflection loss of the sponge with the improved interface impedance mismatch was only 2.3 dB, accounting for 7.2% of the total loss. It is expected to become a promising EMI shielding material, especially for effectively alleviating the secondary reflection EM pollution.