Programmable patterning fabrication of laser-induced graphene-MXene composite electrodes for flexible planar supercapacitors.

The development of laser-induced graphene (LIG) has been regarded as an effective method for satisfying the substantial requirements for the scalable fabrication of graphene-based electrode materials. Despite the rapid progress in fabricating LIG-based supercapacitors, the incompatibility between material modification and the device planarization process remains a challenging problem to be resolved. In this study, we demonstrate the attributes of novel LIG-MXene (LIG-M) composite electrodes for flexible planar supercapacitors fabricated by direct laser writing (DLW) of MXene-coated polyimide (PI) films. During the DLW process, PI was transformed into LIG, while MXene was simultaneously introduced to produce LIG-M. Combining the porous structure of LIG and the high conductivity of MXene, the as-prepared LIG-M-based supercapacitor exhibited superior specific capacitance, five times higher than that of the pristine LIG-based supercapacitor. The enhanced capacitance of LIG-M also benefited from the pseudocapacitive performance of the abundant active sites offered by MXene. Moreover, the planar LIG-M-based device delivered excellent cycling stability and flexibility. No significant performance degradation was observed after bending tests. Arbitrary electrode patterns could be obtained using the DLW technique. The patterned in-series LIG-M supercapacitor was able to power a light-emitting diode, demonstrating significant potential for practical applications.

Hierarchically structuring and synchronous photoreduction of graphene oxide films by laser holography for supercapacitors.

Herein, we report a simple laser holography technology for hierarchically structuring and synchronous photoreduction of graphene oxides (GO), toward the development of efficient graphene-based electrodes for supercapacitor applications in cost effectively manners. Hierarchical micro-nanostructures, formed due to laser treatment induced photoreduction and ablation effect. Interestingly, both the morphology and reduction degree of the laser holography reduced GO (LHRGO) show strong dependence on the laser intensity, providing the feasibility for controlling the micro-nanostructures, chemical composition, and the conductivity of the graphene electrodes. Furthermore, the supercapacitors based on LHRGO show higher capacitance values and better electrochemical performance compared to that based on thermal reduced GO (TRGO) of same reduction level. Photoredution and micro-nanostructuring of GO using laser holography may hold great promise for production of effective carbon-based electrodes towards practical applications in energy storage devices.

Direct laser writing of flexible planar supercapacitors based on GO and black phosphorus quantum dot nanocomposites.

The research interest in wearable electronics has continuously stimulated the development of flexible energy storage systems with high performance and robustness. However, open problems with respect to energy storage efficiency and device integration are still challenging. Here, we demonstrate the laser fabrication of flexible planar supercapacitors based on graphene oxide (GO) and black phosphorus quantum dot (BPQD) nanocomposites. By combining graphene and BPQDs, the resultant supercapacitors feature high conductivity and activity, demonstrating enhanced specific capacity and superior rate performance, compared to those based on reduced GO (RGO) alone. Furthermore, the as-obtained devices present outstanding flexibility. Their performance shows unobvious degradation after repeated cycles of bending and straightening. Additionally, with the help of direct laser writing (DLW) technology, integration of the supercapacitors has been achieved without the need for any metal interconnection. The integrated devices delivered reasonable performance uniformity with a voltage extension of 3 V, which could easily power a LED. The supercapacitor-based RGO and BPQD nanocomposites demonstrate great potential for practical applications in flexible and wearable electronics.

Reed Leaf-Inspired Graphene Films with Anisotropic Superhydrophobicity.

Controlling the wettability of graphene and its derivatives is critical for broader applications. However, the dynamic dewetting performance of graphene is usually overlooked. Currently, superhydrophobic graphene with an anisotropic wettability is rare. Inspired by natural reed leaves, we report an ingenious fabrication process combining photolithography and laser holography technologies to create biomimetic graphene surfaces that demonstrate anisotropic wettability along two directions of grooved hierarchical structures, which are similar to reed leaf veins. Microgrooved structures with a period of 200 µm were fabricated via photolithography to endow the substrate with an obvious anisotropic wettability. Two-beam laser interference treatments of the graphene oxide (GO) film on the grooved substrate removed most of the hydrophilic oxygen-containing groups on the GO sheets and increased the surface roughness by introducing additional hierarchical micro-nanostructures. The combined effects endowed the resultant graphene films with a unique anisotropic superhydrophobicity similar to that of reed leaves. Superhydrophobic graphene surfaces with anisotropic antiwetting behavior might allow further innovations based on graphene in the fields of bionics and electronics.

Improved NO2 Gas Sensing Properties of Graphene Oxide Reduced by Two-beam-laser Interference.

We report on the fabrication of a NO2 gas sensor from room-temperature reduction of graphene oxide(GO) via two-beam-laser interference (TBLI). The method of TBLI gives the distribution of periodic dissociation energies for oxygen functional groups, which are capable to reduce the graphene oxide to hierarchical graphene nanostructures, which holds great promise for gaseous molecular adsorption. The fabricated reduced graphene oxide(RGO) sensor enhanced sensing response in NO2 and accelerated response/recovery rates. It is seen that, for 20 ppm NO2, the response (Ra/Rg) of the sensor based on RGO hierarchical nanostructures is 1.27, which is higher than that of GO (1.06) and thermal reduced RGO (1.04). The response time and recovery time of the sensor based on laser reduced RGO are 10 s and 7 s, which are much shorter than those of GO (34 s and 45 s), indicating that the sensing performances for NO2 sensor at room temperature have been enhanced by introduction of nanostructures. This mask-free and large-area approach to the production of hierarchical graphene micro-nanostructures, could lead to the implementation of future graphene-based sensors.

Flame treatment of graphene oxides: cost-effective production of nanoporous graphene electrode for Lithium-ion batteries.

A facile production of highly porous graphene foam by using flame treatment of graphene oxide (GO) is proposed. Highly porous architectures with randomly distributed micro-crack and micro-slit were produced due to the high temperature induced ruinous reduction and rapid expansion of GO. Synchronously, abundant oxygen-containing groups (OCGs) on GO sheets could be effectively removed after flame treatment, which renders significantly increased conductivity to the resultant flame reduced GO (FR-GO). The synergistic effect of micro/nanostructuring and the OCGs removal makes FR-GO a promising candidate for electrode materials. Compared with chemically reduced GO (CR-GO), FR-GO delivers much higher specific capacity. It gives us some hints that flame treatment of graphene-based material is a smart strategy for cost-effective production of anode materials for commercial application.

Superhydrophobic SERS Substrates Based on Silver-Coated Reduced Graphene Oxide Gratings Prepared by Two-Beam Laser Interference.

Reported here is the fabrication of reduced graphene oxide (RGO) grating structures by two-beam laser interference (TBLI) for the development of highly efficient SERS substrates via simple physical vapor deposition (PVD) coating of silver. TBLI has been utilized to make hierarchical RGO grating structures with microscale gratings and nanoscale folders through a laser treatment induced ablation and photoreduction process. The hierarchical structures contribute to the formation of plasmonic structures after silver coating, giving rise to the formation of plenty of SERS "hot spots", while the RGO substrate would provide chemical enhancement of Raman signal through interaction with analytes molecules. The significantly increased roughness with respect to the hierarchical structures in combination with the removal of hydrophilic oxygen-containing groups endow the resultant substrates with unique superhydrophobicity, which leads to the enrichment of analytes and further lowers the detection limit. The synergistic effects make the silver coated RGO gratings a highly efficient SERS substrate; in the detection of Rhodamine B, our SERS substrates showed high SERS enhancement and good reproducibility, a detection limit of 10(-10) M has been achieved.

Bioinspired Underwater Superoleophobic Membrane Based on a Graphene Oxide Coated Wire Mesh for Efficient Oil/Water Separation.

Inspired from fish scales that exhibit unique underwater superoleophobicity because of the presence of micronanostructures and hydrophilic slime on their surface, we reported here the facile fabrication of underwater superoleophobic membranes by coating a layer of graphene oxide (GO) on commercially available wire meshes with tunable pore sizes. Using the wire mesh as a ready-made mask, GO-embellished mesh with open apertures (GO@mesh) could be readily fabricated after subsequent O2 plasma treatments from the back side. Interestingly, the congenital microstructures of the crossed microwires in combination with the abundant hydrophilic oxygen-containing groups of the GO layer endow the resultant GO@mesh with unique underwater superoleophobic properties. The antioil tests show that the underwater contact angles of various oils including both organic reagents (undissolved in water) and vegetable oil on GO@mesh exceed 150°, indicating the superoleophobic nature. In a representative experiment, a mixture of bean oil and water that imitates culinary sewage has been well separated with the help of our GO@mesh. GO-embellished wire meshes may find broad applications in sewage purification, especially for the treatment of oil contaminations.

[Decreased mRNA expressions of T-type channel alpha1H and alpha1G in the sperm of varicocele patients and their implication].

OBJECTIVE: To study the relationship of varicocele (VC) with the expressions of T-type channel alpha1H and alpha1G in the sperm of VC patients. METHODS: Based on the WHO criteria, we examined the semen samples by computer-aided sperm analysis (CASA), and divided the samples into groups A (normal semen from volunteers, n = 20), B (normal semen from VC patients, n = 16) and C (abnormal semen from VC patients, n = 44). We optimized the semen by discontinuous Percoll grade centrifugation, and determined the mRNA expressions of T-type channel alpha1H and alpha1G in the three groups using using reverse transcription polymerase chain reaction (RT-PCR). RESULTS: Compared with group A, the mRNA expressions of alpha1H and alpha1G showed with no significant decrease in group B (P>0.05), but were remarkably reduced in group C (P<0.01). CONCLUSION: The abnormal mRNA expressions of T-type channel alpha1H and alpha1G may be one of the causes of declined semen quality and consequently infertility in VC patients, which has pointed out a new direction for the studies of the causes and treatment of VC-related infertility.