Graphene, because of its excellent mechanical, electrical, chemical, physical properties, sparked great interest to develop and extend its applications. Particularly, graphene based field-effect transistors (GFETs) present exciting and bright prospects for sensing applications due to their greatly higher sensitivity and stronger selectivity. This Review highlights a selection of important topics pertinent to GFETs and their application in electronic sensors. This article begins with a description of the fabrications and characterizations of GFETs, and then introduces the new developments in physical, chemical, and biological electronic detection using GFETs. Finally, several perspective and current challenges of GFETs development are presented, and some proposals are suggested for further development and exploration.

Three-dimensional graphene foam (3DGF) is a superior sensing material because of its high conductivity, large specific surface area and wide electrochemical potential windows. In this work, hexagonal Ni(OH)2 nanosheets are deposited on the surface of chemical vapor deposition-grown 3DGF through a facial hydrothermal process without any auxiliary reagents. The morphology and structure of the composite are characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), Raman spectroscopy, and X-ray diffraction (XRD). Based on the Ni(OH)2/3DGF composite, a free-standing electrochemical electrode is fabricated. Being employed as a nonenzymatic glucose detection electrochemical electrode, it exhibits a high sensitivity (∼2.65 mA mM(-1) cm(-2)), low detection limit (0.34 μM) and excellent selectivity with a linear response from 1 μM to 1.17 mM. The excellent sensing properties of the Ni(OH)2/3DGF electrode may be attributed to the synergistic effect of the high electrocatalytic activity of Ni(OH)2 nanosheets and the high conductivity and large surface area of 3DGF.

Nanostructured Co3O4 materials attracted significant attention due to their exceptional electrochemical (pseudo-capacitive) properties. However, rigorous preparation conditions are needed to control the size (especially nanosize), morphology and size distribution of the products obtained by conventional methods. Herein, we describe a novel one step shape-controlled synthesis of uniform Co3O4 nanocubes with a size of 50 nm with the existence of mesoporous carbon nanorods (meso-CNRs). In this synthesis process, meso-CNRs not only act as a heat receiver to directly obtain Co3O4 eliminating the high-temperature post-calcination, but also control the morphology of the resulting Co3O4 to form nanocubes with uniform distribution. More strikingly, mesoporous Co3O4 nanocubes are obtained by further thermal treatment. The structure and morphology of the samples were characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. A possible formation mechanism of mesoporous Co3O4 nanocubes is proposed here. Electrochemical tests have revealed that the prepared mesoporous Co3O4 nanocubes demonstrate a remarkable performance in supercapacitor applications due to the porous structure, which endows fast ion and electron transfer.

Fluorescent hydrogels have recently become one of the most prominent materials for smart confidential information protection. But it is still quite challenging to develop a 3D anticounterfeiting platform with on‐demand information decryption and transmission capacities, which are of great importance to achieve high‐level data protection security. Herein, robust aggregation‐induced emissive polymeric hydrogels with thermo‐triggered multistate fluorescence switching, shape memory, and self‐healing properties based on supramolecular dynamic lanthanide coordination interactions are presented. By a collective action of these promising properties, a fluorescent hydrogel‐based 3D information encoding platform is demonstrated for on‐demand information decryption, in which information pre‐encrypted in 3D hydrogel structures is stepwise decrypted by the control of external stimuli. Such unique on‐demand information decryption features are further expanded to the transmission of manifold customized messages to multiple receivers. Herein, the possibility of utilizing 3D fluorescent hydrogel structures for high‐level information encryption and on‐demand decryption is opened up.

A facile strategy has been developed to synthesize sliver nanoparticles (Ag NPs) decorated three-dimensional graphene (3DG) through hydrothermal process. The AgNPs-3DG composites are directly fabricated into a free standing sensing electrode for electrochemical detection of hydrogen peroxide (H2O2) in phosphate buffered solutions. Various techniques equipments including scanning electron microscopy, X-ray diffraction, and Raman spectroscopy are used to characterize the morphology and structure of the as-prepared composite. The electrochemical experiments reveal the AgNPs-3DG based biosensor exhibits fast amperometric sensing, low detection limitation, wide linear responding range, and perfect selectivity for non-enzyme H2O2 detection, indicating the well synergistic effect of Ag NPs high electrocatalytic activity and 3DG high conductivity and large surface area.

Substituted naphthalimide (NI) moieties are highly versatile and newly recognized aggregation‐induced emission (AIE) building blocks for many potentially useful smart molecules, polymers, and nanoparticles. However, the introduction of NI fluorophore into cross‐linked polymeric networks to prepare AIE‐active hydrogels still remains underdeveloped. Herein, a novel naphthalimide‐based aggregation‐induced emissive polymeric hydrogel is reported, followed by its proof‐of‐concept applications as fluorescence pattern switch and biomimetic actuator. The hydrogel, bearing semi‐interpenetrating polymer networks, is synthesized starting from N‐isopropylacrylamide, hydroxyethyl methacrylate, and a newly designed NI monomer (4‐phenoxy‐N‐allyl‐1,8‐naphthalimide, PhAN). Rational molecular design for AIE‐active PhAN monomer lies in modification of the NI core with rigid and bulky phenoxy group to break its planarity to produce desirable propeller‐shaped molecular conformation. The as‐prepared hydrogel is proved to be a aggregation‐induced blue‐light‐emitting hydrogel. It also shows volume phase transition behavior and is endowed with thermally responsive synergistic emission and transmittance change, thus enabling simultaneous regulation of two optical properties merely by one single stimulus. These useful advantages further encourage fabrication of several proto‐type fluorescence pattern switching and biomimetic actuating devices. This study may not only enlarge the list of fluorescent hydrogels but also serve as a novel smart optical platform for potential anticounterfeiting, sensing, displaying, or actuating applications.

A novel Ni x Co y O z -C composite has been synthesized by a one pot in situ hydrothermal method with rodlike Ni@C (Ni nanoparticles wrapped by C) as support. The structure and morphology of the composites are characterized by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. As supercapacitor electrodes, the as-prepared composites present good electrochemical performance with a high specific capacitance (975 F g À1 at the current density of 1.0 A g À1 ) and good cycling stability (79% of capacitance still maintained after 1000 cycles). The electrochemical performance is mainly due to the active redox reaction provided by the polytype metal oxide and the faster electron transfer supplied by the conductive carbon support. These results indicate that Ni x Co y O z -C composites have promising applications as supercapacitor electrode materials.

Using surface active agents, three-dimensional (3D) self-standing graphene/Ni(OH)2 composites with different morphologies, such as nanoflowers, nanoslices and nanoparticles, are directly synthesized by a facile in situ electrodeposition method.