Guomin Ding

Self‐assembled graphene films at air‐liquid interface have great potential for multiple applications. However, the large size and ultrathin thickness for graphene‐based films are hardly achieved simultaneously because of poor assembly ability of graphene oxide (GO) and cautious film transfer process (FTP). Herein, the ethanol‐based binary solution with supramolecular clusters and weak polarity is introduced to enhance the assembly performance of GO. In this regime, GO film is formed within 52 s, and its formation temperature can be as low as −20 °C. More importantly, the attractive force between the formed GO film and this binary solution is 62% lower than that between GO film and traditional aqueous solution. On this basis, for the first time a spontaneous separation of the self‐assembled GO film from solution is reported, and the air‒floating graphene films (AGFs) with nanoscale thickness and centimeter‐scale diameter are prepared without FTP. By means of this separation behavior, the in situ growth AGFs sensors are fabricated, and they express fast response and ultrahigh sensitivity to imperceptible change in temperature and disturbances that are hardly recognized by common sensors. Therefore, a new accessible strategy is demonstrated to prepare ultrathin graphene macrofilms, which can be the excellent candidates for multifunctional, ultrasensitive sensors.

Development of high-performance graphene-based microwave absorbing materials with low density and strong absorption is of great significance to solve the growing electromagnetic pollution. Herein, a controllable open-cell structure is introduced into graphene aerogels by the graphene oxide (GO) Pickering emulsion. The open-cell graphene aerogel (OCGA) with multiple microstructures shows a significantly enhanced microwave absorption ability without any additions. A high microwave absorption performance with the minimum value of reflection loss (RL_min) of −51.22 dB was achieved, while the material density was only 4.81 mg/cm³. Moreover, by means of centrifugation, the graphene cells were arranged by their diameter, and a gradient, open-cell graphene structure was first fabricated. Based on this unique structure, an amazing microwave absorption value of −62.58 dB was reached on a condition of ultra-low graphene content of 0.53 wt%. In our opinion, such excellent microwave absorption performance results from multiple reflection and well-matched impedance brought by the open-cell and gradient structure, respectively. In addition, the structural strength of the OCGA is greatly improved with a maximum increase of 167% due to the introduction of cell structure. Therefore, the OCGAs with the gradient structure can be an excellent candidate for lightweight, efficient microwave absorption materials.

The percolation thresholds of poly ether ether ketone/graphene (PEEK/Gr) composites in most studies are high due to the random distribution of Gr in the matrix. Here, aminated poly-ether-ether-ketone/graphene network (PEEK-NH ₂ /GN) nanocomposites were prepared by electrostatic adsorption of PEEK-NH ₂ with positive charges and graphene oxide with negative charges, followed by in -situ reduction and hot-pressing. The GN structure of composites was well presented in the images of scanning electron microscope. The PEEK-NH ₂ /GN nanocomposites exhibited excellent electrical conductivity with a maximum conductivity of 0.0634 S·cm ⁻¹ and a percolation threshold as low as 0.25 vol%. In addition, the maximum tensile strength of nanocomposites was reached at 93 MPa when the Gr content was 0.5 wt%. We believe that this approach is a new avenue for the production of low filler high conductive polymer composites with potential commercial prospects in various fields.

The as-fabricated encapsulated photodetectors at the neutral mechanical plane are supposed to perform stably during the bending process no matter how large the strain of the outside surface is. Meanwhile, they show an ultra-stable performance with almost unvaried photoresponse properties after 10 000 bending cycles or a bending duration of 1000 h with a radius of curvature of 5 mm. Furthermore, they can work as long-term stable rollable photodetectors.

Smart materials with underwater motion detection have become a popular research topic with the development of ocean exploration. Herein, a heterogeneous polydimethylsiloxane/open-cell graphene network (PDMS/OCGN) with a micro–nanoscale hierarchical structure is fabricated via a simple inverse drying method. The PDMS/OCGN has a special microstructure due to the PDMS-coated surface and the uncoated interior, which enables the material to exhibit both strong superhydrophobicity and high electrical conductivity simultaneously. In addition, the adhesive force of PDMS/OCGNs for water droplets can easily be controlled from 70.6 μN to 34.0 μN by adjusting the coating content. On this basis, the lossless transportation of water microdroplets is achieved in this paper. By means of the typical underwater state and deformable network of PDMS/OCGNs, for the first time, a superhydrophobic material with rapid sensing capability for immersion and emersion processes, owing to the abrupt change in its resistance, is reported. More importantly, the vertical dive and horizontal movement in water can also be detected in real time. Furthermore, the PDMS/OCGN can identify the diving depth and moving speed via the degree of change in resistance. Therefore, this multifunctional PDMS/OCGN may be an excellent candidate for the fabrication of underwater sensing devices.

SnS ₂ /rGO gas sensors were developed, with P–N transition response for room temperature ppb-level NO ₂ detection and visible light illumination enhancement behavior.

Multifunctional surfaces with special wettability and sensing capabilities have attracted the interest of researchers because of their wide application prospects. Herein, based on octadecylamine (ODA) and carboxylic carbon nanotubes (cCNTs), a conductive composite coating (ODA/cCNT) with a micro–nanoscale hierarchical structure is fabricated by a simple one-step method. The wettability of ODA/cCNT can be controlled, ranging from strong hydrophilicity to superhydrophobicity, by changing the content of ODA, and the adhesive force of the superhydrophobic coating is adjustable over a large range, spanning from 71.4 μN to 30.9 μN. Using the ODA/cCNTs with adjustable adhesion behavior, the lossless transportation of water microdroplets has been achieved. Furthermore, due to its conductivity and special microstructure, the superhydrophobic ODA/cCNT can sense bending deformation via changing resistance and shows a higher sensitivity than other coatings. More importantly, by means of the strong water repellence and the gas sensing property of cCNTs, we report for the first time an underwater, self-sensing, superhydrophobic material with enhanced sensitivity. The change degree of its resistance in water is more than twice as large as that in air for the same deformation. The water level can also be detected by the superhydrophobic coating due to its unique underwater state. Therefore, the multifunctional ODA/cCNT can be an excellent candidate for the fabrication of underwater smart devices.

Smart superhydrophobic surfaces with controllable adhesion behavior or sensing capability have become a research hotspot in many areas, such as self-cleaning and microdroplet transportation. Herein, we design and fabricate a superhydrophobic, open-cell graphene network with a polypropylene coating (PP/OCGN) via a new method of boiling coating. The adhesive force of PP/OCGN for water droplets can be controlled easily from 66.8 μN to 32.3 μN by adjusting the soaking time. Using the PP/OCGN with controllable adhesion behavior, the lossless transportation of water microdroplets has been achieved. What's more, because of the boiling coating process, the PP/OCGN exhibits a heterogeneous network, which has the coated graphene on the surface and the uncoated graphene in the inner part. By means of the special network and strong water repellency of PP/OCGN, we report for the first time a conductive, superhydrophobic graphene material with a self-sensing capability for continuously falling water droplets. When the water droplets fall on the surface, the PP/OCGN with low adhesive force not only makes the droplets bounce off successfully, but also has a rapid response to the bouncing process through changing the resistance. The size of falling water droplets can also be determined. Therefore, our multifunctional superhydrophobic PP/OCGN can meet multiple needs simultaneously, such as self-cleaning and detecting raindrops, and it has great application prospects in the future.