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Laser-engraved graphene (LEG) has been applied increasingly in flexible electronics over the past decade owing to its unique physical and chemical properties, and has shown great promise in energy controls, chemical and physical sensing, and telemedicine. In situ laser engraving has empowered graphene with additional versatilities such as miniaturized patterning, tunable composition, controllable morphology, and environmental friendliness. In this review, the technological advances of LEG from synthesis to applications in flexible and wearable electronic devices are summarized. Specifically, the use of LEG in designing next-generation nanogenerators, batteries, supercapacitors, physical sensors, gas sensors, biosensors, and wearable/telemedicine systems is discussed. An outlook related to LEG-based flexible electronics and key technological bottlenecks is identified.

Understanding and assessing endocrine response to stress is crucial to human performance analysis, stress-related disorder diagnosis, and mental health monitoring. Current approaches for stress monitoring are largely based on questionnaires, which could be very subjective. To avoid stress-inducing blood sampling and to realize continuous, non-invasive, and real-time stress analysis at the molecular levels, we investigate the dynamics of a stress hormone, cortisol, in human sweat using an integrated wireless sensing device. Highly sensitive, selective, and efficient cortisol sensing is enabled by a flexible sensor array that exploits the exceptional performance of laser-induced graphene for electrochemical sensing. Herein, we report the first cortisol diurnal cycle and the dynamic stress response profile constructed from human sweat. Our pilot study demonstrates a strong empirical correlation between serum and sweat cortisol, revealing exciting opportunities offered by sweat analysis toward non-invasive dynamic stress monitoring via wearable and portable sensing platforms.

Monitoring superoxide anions in living cells have attracted much academic and biomedical interest due to their important role in metabolic processes. Herein, we confined ultra-small nano-Mn3(PO4)2 in chitosan and designed a unique puffy woven sphere consisted by nanowires. Further constructed an effective in situ detection chip using the as-synthesized nano-Mn3(PO4)2-chitosan for electrochemical sensing of superoxide anions from murine breast tumor cells (4T1). The excellent biocompatibility of chitosan and large size of the Mn3(PO4)2-chitosan spheres greatly reduced the damage and toxicity of the detection interface to the living cells, while the ultra-small nano-Mn3(PO4)2 in chitosan could effectively catalyze the superoxide anions released from cells. The nano-Mn3(PO4)2-chitosan-based sensor exhibited high sensitivity (1.6 μA μM−1), low detection limit (9.4 nM at S/N = 3) and good selectivity for O2•−. After cell culture on the surface of nano-Mn3(PO4)2-chitosan based electrode. As a miniature analytical and sensing platform, results further suggest that the prepared chip offers a more sensitive detective superoxide anions (O2•−) released from 4T1 cell lines than traditional electron paramagnetic resonance (EPR) analysis.

Wearable sweat sensors have the potential to provide continuous measurements of useful biomarkers. However, current sensors cannot accurately detect low analyte concentrations, lack multimodal sensing or are difficult to fabricate at large scale. We report an entirely laser-engraved sensor for simultaneous sweat sampling, chemical sensing and vital-sign monitoring. We demonstrate continuous detection of temperature, respiration rate and low concentrations of uric acid and tyrosine, analytes associated with diseases such as gout and metabolic disorders. We test the performance of the device in both physically trained and untrained subjects under exercise and after a protein-rich diet. We also evaluate its utility for gout monitoring in patients and healthy controls through a purine-rich meal challenge. Levels of uric acid in sweat were higher in patients with gout than in healthy individuals, and a similar trend was observed in serum.

Despite being pursued for a long time, hydrogen production via water splitting is still a huge challenge mainly due to a lack of durable and efficient catalysts. Molybdenum phosphide (MoP) is theoretically capable of efficient hydrogen evolution reaction (HER) catalysis, however, there is still room for further improvement in its performance. Herein, we propose a design for MoP with a P-rich outermost atomic layer for enhancing HER via complementary theoretical and experimental validation. The correlation of computational results suggests that the P-terminated surface of MoP plays a crucial role in determining its high-efficiency catalytic properties. We fabricated a P-rich outermost atomic layer of MoP nanoparticles by using N-doped porous carbon (MoP@NPCNFs) to capture more P on the surface of MoP and limit the growth of nanoparticles. Further, the as-prepared material can be directly employed as a self-supported electrocatalyst, and it exhibits remarkable electrocatalytic activity for HER in acidic media; it also reveals excellent long-term durability for up to 5,000 cycles with negligible loss of catalytic activity.

Air pollution poses a serious threat to public health, especially in developing countries, and how to reduce it has gained great attention over the past decades. In this work, a hierarchical-structured composite, ultrafine TiO 2 encapsulated in a nitrogen-doped porous carbon framework, was fabricated and used as a photocatalyst to degrade ammonia gas. In addition, a gas sensor test system lined with a photocatalytic apparatus was proposed to estimate the degradation of ammonia gas, which allowed for facile in situ analysis and assessment of the photodegradation process of the toxic gas. Due to the large surface area, abundant pore structure, good gas adsorption property, extended light harvesting capacity and charge transfer capability of the nitrogen-doped porous carbon, the as-prepared ultrafine TiO 2 encapsulated in the nitrogen-doped porous carbon framework displayed excellent photocatalytic activity and degraded ammonia gas with 100% efficiency after only 5 min of light irradiation.

Since visible-light (VL) accounting for massive solar radiation energy, a large amount of attention has been paid to the development of highly efficient visible-light-driven (VLD) semiconductor materials. However, despite recent efforts to construct VL active material, hollow structure-based silver iodide (AgI) with appropriate band gap and a large surface area are limited because of lack of a proper synthesis method. Herein, hollow AgI with p-type semiconductor behavior is constructed on the basis of micro-emulsion strategy, which enables admirable cathode photoelectrochemical (PEC) response. The as-prepared hollow AgI is applied to fabricate the PEC sensing platform and reveals a low limit of detection of 0.04 fM and a wide dynamic range up to 5 orders of magnitude toward H2S. The PEC sensing mechanism is supposed to the 'signal-off' pattern on account of the ultralow solubility product (Ksp) of Ag2S, derived from the precipitation reaction due to the high affinity between sulfide ion and Ag+. Besides, the hollow structure of AgI provides sufficient surface area forin situproducing Ag2S that serves as recombination center of carrier, thus causing the efficient quenching of photocurrent signals. This work broadens the horizon of structuring VLD semiconductor nanomaterials andKsp-based H2S sensing.

Monitoring superoxide anion radicals in living cells has been attracting much academic and industrial interest due to the dual roles of the radicals. Herein, we synthesized a novel nanostructured cobalt phosphate nanorods (Co3(PO4)2 NRs) with tunable pore structure using a simple and effective micro-emulsion method and explored their potential utilization in the electrochemical sensing of superoxide anions. As an analytical and sensing platform, the nanoscale biomimetic enzymes Co3(PO4)2 NRs exhibited excellent selectivity and sensitivity towards superoxide anion (O2•-) with a low detection limit (2.25nM), wide linear range (5.76-5396nM), and long-term stability. Further, the nanoscale biomimetic enzyme could be efficiently applied in situ to electrochemically detect O2•- released from human malignant melanoma cells and normal keratinocyte, showing excellent real time quantitative detection capability. This material open up exciting opportunities for implementing biomimetic enzymes in nanoscale transition metal phosphates and designing enzyme-free biosensors with much higher sensitivity and durability in health and disease analysis than those of natural one.

In this work, ultrathin graphene-like carbon nitride nanosheets with rich nanoporous and excellent hydrophilic characteristics were synthesized by a simple and effective thermal exfoliation of bulk g-C3N4. In order to fully understand the effect of thermal exfoliation conditions on the texture, surface state, and photocatalytic activity of the resulting g-C3N4, a series of exfoliated g-C3N4 were prepared by adjusting the thermal exfoliation temperature and time. The detailed characterization and analysis distinctly suggested that increasing exfoliation temperature led to a large number of nitrogen vacancies and increased specific surface area, further prolonging exfoliation time, the thermal exfoliation degree was enhanced, more carbon vacancies and enlarged pore volume formed in the resulting products. Further, the exfoliation degree and photocatalytic ability of the resultant products were enhanced by increasing thermal exfoliation temperature and time. The optimized ultrathin graphene-like carbon nitride nanosheets exhibited a 89.6% degradation efficiency for Rh6G only in 10 min, which was much faster than other such nanosheets reported in previous literature.

A novel MnO@Amorphous C-Carbon nanotubes (MnO@C-CNTs) composite is prepared by chemical vapor deposition (CVD). When used as an anode material for Li-ion batteries, the MnO@C-CNTs composite exhibits an initial discharge capacity of 1164 mA h g −1 at 100 mA g −1 and the discharge capacity gradually increased from 571.7 mA h g −1 to 654 mA h g −1 after 100 cycles at 1 A g −1 , which shows an increase of the capacity rather than attenuation. Furthermore, the MnO@C-CNTs electrode can deliver a capacity of up to 228 mA h g −1 at 5 A g −1 . These results indicate that the three-dimensional conductive network of the MnO@C-CNTs composite could prevent the aggregation of MnO particles, and its open structure allows electrolyte penetration, and reduces the diffusion path of the lithium ions, hence maximizes utilization of the electrochemically active MnO particles, while enhances the conductivity of electrode material and Li + transport. This work offers a universal approach to design various metal oxides@C-CNTs composite.

Since the oxygen evolution catalysis process is vital yet arduous in energy conversion and storage devices, it is highly desirous but extremely challenging to engineer earth-abundant, noble-metal-free nanomaterials with superior electrocatalytic activity toward effective oxygen evolution reactions (OERs). Herein, we construct a prismlike cobalt–iron layered double hydroxide (Co–Fe LDH) with a Co/Fe ratio of 3:1 utilizing a facile self-templated strategy. Instead of carbon-species-coupled treatment, we focus on ameliorating the intrinsic properties of LDHs as OER electrocatalysts accompanied by the hierarchical nanoflake shell, well-defined interior cavity, and numerous microporous defects. In contrary to conventional LDHs synthesized via a one-pot method, Co–Fe LDHs fabricated in this work possess a huge specific surface area up to 294.1 m^2 g^(–1), which not only provides abundant active sites but also expedites the kinetics of the OER process. The as-prepared Co–Fe LDH electrocatalysts exhibit advanced electrocatalytic performance and a dramatic stability of the OER in an alkaline environment. In particular, the contribution of micropore defects is clearly discussed according to the electrochemical impedance spectroscopy analysis, in which the time constant of the OER at the micropore defect is several orders of magnitude smaller than that at the exterior of Co–Fe LDHs, forcefully verifying the intrinsic catalytic activity enhancement derived from the micropore defects. This work provides a promising model to improve OER electrocatalyst activity via produce defects and research the contribution of micropore defects.

Monitoring superoxide anions in living cells have attracted much academic and biomedical interest due to their important role in metabolic processes. Herein, we confined ultra-small nano-Mn

Correction for ‘Synthesis and model simulation of the hexagonal to circular transition of perovskite cesium lead halide nanosheets by rapidly changing the temperature’ by Zhong-Hai Lin et al., RSC Adv., 2020, 10, 4211–4217, DOI: 10.1039/C9RA10312K.

One-dimensional Pd-Au nanowires (Pd-Au NWs) were prepared and applied to fabricate an electrochemiluminescence (ECL) biosensor for the detection of acetylcholinesterase (AChE) activity. Compared with single-component of Pd or Au, the bimetallic nanocomposite of Pd-Au NWs offers a larger surface area for the immobilization of enzyme, and displays superior electrocatalytic activity and efficient electron transport capacity. In the presence of AChE and choline oxidase (ChOx), acetylcholine (ATCl) is hydrolyzed by AChE to generate thiocholine, then thiocholine is catalyzed by ChOx to produce H2O2 in situ, which serves as the coreactant to effectively enhance the ECL intensity in luminol-ECL system. The detection principle is based on the inhibited AChE and reactivated AChE as dual biomarkers, in which AChE was inhibited by organophosphorus (OP) agents, and then reactivated by obidoxime. Such dual biomarkers method can achieve credible evaluation for AChE activity via providing AChE activity before and after reactivation. The liner range for AChE activity detection was from 0.025 U L(-1) to 25 KU L(-1) with a low detection limit down to 0.0083 U L(-1).

Well-cubic perovskite lanthanum aluminate (LaAlO(3)) film on (110) silicon substrate was fabricated by sol-gel method with corresponding inorganic salts. Lanthanum acetate and aluminum acetate glacial acetic acid solutions were prepared via ligand exchange starting from lanthanum nitrate hexahydrate and aluminum nitrate hexahydrate after being refluxed. (CH(3)CO)(2)O removed nitrates and the crystallized H(2)O completely, acetylacetone (AcAc) was partially bidentated with metallic ion of the metallic acetates and formed La(OAc)(3-x)(AcAc)(x), which were hydrolyzed into La(AcAc)(3-x)(OH)(x) by adding 10 ml 0.4% methyl cellulose (MCL) solution. The La(AcAc)(3-x)(OH)(x), polymerizing and combining with MCL, formed the LaAlO(3) sol precursor with heteropolymeric structure and formed film easily. The epitaxial LaAlO(3) film on Si(110) substrate was crystallized after being annealed in thermal annealing furnace for 650-750 degrees C/30 min. The mor-phologies and microstructures were characterized. The refractive index of the LAO film was 1.942 to 2.007; the dielectric constant and the dissipation factors were estimated to be 23-26 and 2.1x10(-4) - 2.4x10(-4) respectively.