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There has been a significant shift in research focus in recent years toward laser-induced graphene (LIG), which is a high-performance material with immense potential for use in energy storage, ultrahydrophobic water applications, and electronic devices. In particular, LIG has demonstrated considerable potential in the field of high-precision human motion posture capture using flexible sensing materials. In this study, we investigated the surface morphology evolution and performance of LIG formed by varying the laser energy accumulation times. Further, to capture human motion posture, we evaluated the performance of highly accurate flexible wearable sensors based on LIG. The experimental results showed that the sensors prepared using LIG exhibited exceptional flexibility and mechanical performance when the laser energy accumulation was optimized three times. They exhibited remarkable attributes, such as high sensitivity (~41.4), a low detection limit (0.05%), a rapid time response (response time of ~150 ms; relaxation time of ~100 ms), and excellent response stability even after 2000 s at a strain of 1.0% or 8.0%. These findings unequivocally show that flexible wearable sensors based on LIG have significant potential for capturing human motion posture, wrist pulse rates, and eye blinking patterns. Moreover, the sensors can capture various physiological signals for pilots to provide real-time capturing. [ABSTRACT FROM AUTHOR]

Inorganic halide perovskite CsPbI3 is highly promising in the photocatalytic field for its strong absorption of UV and visible light. Among the crystal phases of CsPbI3, the δ-phase as the most aqueous stability; however, directly using it in water is still not applicable, thus limiting its dye photodegradation applications in aqueous solutions. Via adopting nitrogen-doped graphene quantum dots (NGQDs) as surfactants to prepare δ-phase CsPbI3 nanocrystals, we obtained a water-stable material, NGQDs-CsPbI3. Such a material can be well dispersed in water for a month without obvious deterioration. High-resolution transmission electron microscopy and X-ray diffractometer characterizations showed that NGQDs-CsPbI3 is also a δ-phase CsPbI3 after NGQD coating. The ultraviolet-visible absorption spectra indicated that compared to δ-CsPbI3, NGQDs-CsPbI3 has an obvious absorption enhancement of visible light, especially near the wavelength around 521 nm. The good dispersity and improved visible-light absorption of NGQDs-CsPbI3 benefit their aqueous photocatalytic applications. NGQDs-CsPbI3 alone can photodegrade 67% rhodamine B (RhB) in water, while after compositing with TiO2, NGQDs-CsPbI3/TiO2 exhibits excellent visible-light photocatalytic ability, namely, it photodegraded 96% RhB in 4 h. The strong absorption of NGQDs-CsPbI3 in the visible region and effective transfer of photogenerated carriers from NGQDs-CsPbI3 to TiO2 play the key roles in dye photodegradation. We highlight NGQDs-CsPbI3 as a water-stable halide perovskite material and effective photocatalytic adjuvant. [ABSTRACT FROM AUTHOR]

Fluorinated graphene quantum dots (F-GQDs) were prepared by mixing GQDs and XeF2 in a facile gaseous phase heating method. The F-GQDs with excellent water solubility have a F/C atomic ratio of 84.25% and a diameter of 2–6 nm. The photoluminescence (PL) properties of GQDs and F-GQDs were investigated systematically. The results showed that the PL emission of the F-GQDs exhibited an obvious blue-shift of 90 nm compared to that of the GQDs. [ABSTRACT FROM AUTHOR]

High-photoluminescence (PL) graphene quantum dots (GQDs) were synthesized by a simple one-pot hydrothermal process, then separated by dialysis bags of different molecular weights. Four separated GQDs of varying sizes were obtained and displayed different PL intensities. With the decreasing size of separated GQDs, the intensity of the emission peak becomes much stronger. Finally, the GQDs of the smallest size revealed the most energetic PL intensity in four separated GQDs. The PL energy of all the separated GQDs shifted slightly, supported by density functional theory calculations. [ABSTRACT FROM AUTHOR]

Inducing magnetic moments in graphene is very important for its potential application in spintronics. Introducing sp3-defects on the graphene basal plane is deemed as the most promising approach to produce magnetic graphene. However, its universal validity has not been very well verified experimentally. By functionalization of approximately pure amino groups on graphene basal plane, a spin-generalization efficiency of ~1 μB/100 NH2 was obtained for the first time, thus providing substantial evidence for the validity of inducing magnetic moments by sp3-defects. As well, amino groups provide another potential sp3-type candidate to prepare magnetic graphene. [ABSTRACT FROM AUTHOR]

Inducing robust magnetic moments on the basal plane of the graphene sheet is very difficult, and is one of the greatest challenges in the study of physical chemistry of graphene materials. Theoretical studies predicted that introduction of a kind of sp3-type defects formed by OH groups is an effective pathway to achieve this goal [Boukhvalov, D. W. &Katsnelson, M. I. ACS Nano 5, 2440-2446 (2011)]. Here we demonstrate that OH groups can efficiently induce robust magnetic moments on the basal plane of the graphene sheet. We show that the inducing efficiency can reach as high as 217 μB per 1000 OH groups. More interestingly, the magnetic moments are robust and can survive even at 900°C. Our findings highlight the importance of OH group as an effective sp3-type candidate for inducing robust magnetic moments on the basal plane of the graphene sheet. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nitrogen-doping enhances the H+ and D+ permeability of graphene. • D+ permeates across pyridinic-N defects faster than H+, showing an inverse KIE (0.75). • A normal KIE (1.56) is observed in pyrrolic-N defects. • KIE is influenced by the chemisorption and effective size imparted by defects. Graphene is becoming an increasingly popular platform for developing high-efficiency hydrogen isotope separation technologies operated at room temperature. However, its performance can be strongly affected by contributions from atomic defects. Understanding the influence of defects on the hydrogen isotope selectivity of graphene is thus imperative but remains elusive. In this work, we investigated the electrically driven proton/deuteron permeation through nitrogen-doped graphene membranes with varying N concentrations and configurations. The results show that N-doping significantly enhances the proton and deuteron permeability of graphene (by one order of magnitude). More importantly, deuterons are found to permeate faster through pyridinic N-containing defects than protons, demonstrating a pronounced inverse kinetic isotope effect (KIE) with k H / k D of 0.75. Conversely, pyrrolic N-containing defects exhibit a normal KIE (k H / k D = 1.56). The exclusive contribution of the pyridinic N to the inverse KIE is confirmed by the reversed KIE factor of the pyridinic N-dominated sample subjected to modification. Theoretical calculations indicate that the explicit dependence of KIE on N configuration originates from the different leading mechanisms of proton/deuteron permeation through these N-containing defects, which is governed by the size and the chemisorption imparted by defects. These findings provide fundamental insights into the correlation between defect characteristics and proton/deuteron transport in graphene, and contribute to developing economical hydrogen isotope separation technologies through the defect engineering of graphene. [ABSTRACT FROM AUTHOR]

Nitrogen-doped graphene quantum dots (N-GQDs) exhibit exciting properties in the oxygen reduction reaction (ORR) for ample electrocatalytic edging and N-doped active sites. However, low yield and high dispersity of N-GQDs prohibit their direct application as the electrocatalyst. In this paper, two facile hydrothermal progress were developed to synthesize the high-yield N-GQDs with the diameter of ca. 2–6 nm and the hybrid of N-GQDs/Reduced Graphene Oxide (N-GQDs/r-GO). The results demonstrated that the N-GQDs/r-GO display remarkable electrocatalytic activity. Moreover, it can be found that the pyridinic-N plays a major role in ORR. Both the average electron transfer number and the onset potential depend on the content of pyridinic-N. The proposed synthesis strategy is facile and low-cost, serving as a feasible method for the development of highly efficient electrocatalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Auxetic PU/PDA/GR composite foam with high EMI SE was prepared via simple method. • The relationship between EMI SE and reentrant structure was studied at first time. • The high EMI SE of auxetic foam results from the reentrant structure and high SE A. • The auxetic foam is promising as temperature-regulated EMI shielding material. In this work, two kinds of auxetic composite foams of polyurethane (PU) with polydopamine (PDA) and graphene (GR) (PU/PDA/GR) were prepared by dip-coating and ultrasonic immersing, then followed by triaxial compression-heating process. The electromagnetic interference (EMI) shielding effectiveness (SE) value of the PU/PDA/GR auxetic composite foam with a Poisson's ratio of −2.36 from PU foam with open cellular structure reaches 59.75 dB, which is 8.9 times of the positive Poisson's ratio composite foam with the same GR content. Furthermore, the relationship of the EMI shielding performance of auxetic foam with different forms of reentrant structure was studied for the first time, in which the absolute value of negative Poisson's ratio was used to quantitatively describe the difference of the reentrant structure in the obtained auxetic foam. The larger the absolute value of negative Poisson's ratio is, the better the EMI shielding performance of the composite foam is. The high absorption EMI SE and the existence of reentrant structure are the key factors for the high EMI shielding performance of the auxetic composite foam. In addition, it is found that the EMI SE of the auxetic foam can be adjusted via simple heating treatment, showing that the auxetic composite foam may be used as a temperature-regulated EMI shielding material in the future. [ABSTRACT FROM AUTHOR]

New carbon allotropes can be designed by combining sp, sp2 and sp3 three hybridization states. And the hybridization states or coordination numbers of carbon atoms can be changed by applying high pressure on carbon materials. In this study, a common high pressure phase (named as TBBC) transformed from AB-stacking graphyne or THD-graphene is predicted. Its kinetic stability is examined using finite displacement method. We find that the sp2 and sp3 hybridized carbon atoms behave different vibration features at high frequency region. Both graphene-like and diamond-like vibration peaks occurs. Phase transition energy barriers from both graphyne and THD-graphene to TBBC are estimated. Electronic structure calculations show that the TBBC is an indirect semiconductor with a bandgap of 0.66 eV. The ideal tensile strength of TBBC is high in [0001] and [ 1 1 ¯ 00 ] directions, but is weak along [ 1 2 ¯ 10 ] direction. [ABSTRACT FROM AUTHOR]