Similar to the paper-making process, the efficient flame retardant graphene paper is conveniently obtained by using graphene oxide (GO) and hexachlorocyclotriphosphazene (HCCP) aqueous pulp. The “paper pulp” can also conceivably be used as ink to make other hydrophilic films become flame retardant paper. Further, the as-prepared reduced GO-HCCP paper (RGO-HCCP paper), compared with GO-HCCP paper, can maintain its intact structure for a longer time in an ethanol flame. As a consequence of these preparation methods, the bearing temperature of the as-prepared graphene papers shows a significant increase.

An interconnected framework of mesoporous graphitic-C₃N₄ nanofibers merged with in situ incorporated nitrogen-rich carbon has been prepared. The unique composition and structure of the nanofibers as well as strong coupling between the components endow them with efficient light-harvesting properties, improved charged separation, and a multidimensional electron transport path that enhance the performance of hydrogen production. The as-obtained catalyst exhibits an extremely high hydrogen-evolution rate of 16885 μmol h⁻¹ g⁻¹, and a remarkable apparent quantum efficiency of 14.3 % at 420 nm without any cocatalysts, which is much higher than most reported g-C₃N₄-based photocatalysts even in the presence of Pt-based cocatalysts.

An interconnected framework of mesoporous graphitic-C₃N₄ nanofibers merged with in situ incorporated nitrogen-rich carbon has been prepared. The unique composition and structure of the nanofibers as well as strong coupling between the components endow them with efficient light-harvesting properties, improved charged separation, and a multidimensional electron transport path that enhance the performance of hydrogen production. The as-obtained catalyst exhibits an extremely high hydrogen-evolution rate of 16885 μmol h⁻¹ g⁻¹, and a remarkable apparent quantum efficiency of 14.3 % at 420 nm without any cocatalysts, which is much higher than most reported g-C₃N₄-based photocatalysts even in the presence of Pt-based cocatalysts.

Recently, macroporous graphene monoliths (MGMs), with ultralow density and good electrical conductivity, have been considered as excellent pressure sensors due to their excellent elasticity with a rapid rate of recovery. However, MGMs can only exhibit good sensitivity when the strain is higher than 20%, which is undesirable for touch-type pressure sensors, such as artificial skin. Here, an innovative method for the fabrication of freestanding flexible graphene film with bubbles decorated on honeycomb-like network is demonstrated. Due to the switching effect depended on “point-to-point” and “point-to-face” contact modes, the graphene pressure sensor has an ultrahigh sensitivity of 161.6 kPa⁻¹ at a strain less than 4%, several hundred times higher than most previously reported pressure sensors. Moreover, the graphene pressure sensor can monitor human motions such as finger bending and pulse with a very low operating voltage of 10 mV, which is sufficiently low to allow for powering by energy-harvesting devices, such as triboelectric generators. Therefore, the high sensitivity, low operating voltage, long cycling life, and large-scale fabrication of the pressure sensors make it a promising candidate for manufacturing low-cost artificial skin.

Controllable and sensitive perception of environmental changes is essential for the development of smart material and device systems. Herein, a multi-stimuli sensitive responsor has been fabricated on the base of the established double-helix core-sheath graphene-based microfibers (GFs). By combining the tunable conductivity and mechanical robustness of GF coated with graphitic carbon nitride (GF@GCN), a fibriform smart environmental responsor (SER) is prepared by water-assisted GFs-twisting strategy, which can accordingly present conductive state-dependent current responses upon exposure to a variety of stimuli. More importantly, this SER exhibits high current response to small perturbations induced by temperature variations, mechanical interactions, and relative humidity changes, thereby achieving an environmental perceptibility. Based on this finding, a multi-functional respiratory monitor has been built under the stimuli of the human breath.

Controllable and sensitive perception of environmental changes is essential for the development of smart material and device systems. Herein, a multi-stimuli sensitive responsor has been fabricated on the base of the established double-helix core-sheath graphene-based microfibers (GFs). By combining the tunable conductivity and mechanical robustness of GF coated with graphitic carbon nitride (GF@GCN), a fibriform smart environmental responsor (SER) is prepared by water-assisted GFs-twisting strategy, which can accordingly present conductive state-dependent current responses upon exposure to a variety of stimuli. More importantly, this SER exhibits high current response to small perturbations induced by temperature variations, mechanical interactions, and relative humidity changes, thereby achieving an environmental perceptibility. Based on this finding, a multi-functional respiratory monitor has been built under the stimuli of the human breath.

A seaweed-like graphitic-C₃N₄ (g-C₃N₄ “seaweed”) architecture has been prepared by direct calcination of the freeze-drying-assembled, hydrothermally treated dicyandiamide fiber network. The seaweed network of mesoporous g-C₃N₄ nanofibers is favorable for light harvesting, charge separation and utilization of active sites, and has highly efficient photocatalytic behavior for water splitting. It exhibits a high hydrogen-evolution rate of 9900 μmol h⁻¹ g⁻¹ (thirty times higher than that of its g-C₃N₄ bulk counterpart), and a remarkable apparent quantum efficiency of 7.8 % at 420 nm, better than most of the g-C₃N₄ nanostructures reported. This work presents a very simple method for designing and developing high-performance catalysts for hydrogen evolution.

A seaweed-like graphitic-C₃N₄ (g-C₃N₄ “seaweed”) architecture has been prepared by direct calcination of the freeze-drying-assembled, hydrothermally treated dicyandiamide fiber network. The seaweed network of mesoporous g-C₃N₄ nanofibers is favorable for light harvesting, charge separation and utilization of active sites, and has highly efficient photocatalytic behavior for water splitting. It exhibits a high hydrogen-evolution rate of 9900 μmol h⁻¹ g⁻¹ (thirty times higher than that of its g-C₃N₄ bulk counterpart), and a remarkable apparent quantum efficiency of 7.8 % at 420 nm, better than most of the g-C₃N₄ nanostructures reported. This work presents a very simple method for designing and developing high-performance catalysts for hydrogen evolution.

Pseudocapacitors bridge the gap between supercapacitors and batteries. Controllable microstructures grown on substrates have achieved success with regard to energy storage. However, traditional designs have only focused on the surface of scaffolds, which results in high specific capacitance values for the electroactive material rather than the electrodes. Inspired by slurry-casting, a dual-scale shell-structured NiCo₂O₄ on nickel foam was assembled by using a simple and flexible solution-based strategy. First, NiCo₂O₄ nanosheets covering the Ni foam skeleton surface loosely (the sample is denoted as ′pasted′) is obtained by a solution-grown and ′dip-and-dry′ process (in a cobalt–nickel hydroxide solution) followed by annealing. Secondly, the NiCo₂O₄ nanosheets are filled in the pores of the Ni scaffold (the obtained material is denoted as ′tailored′) through chemical bath deposition process followed by annealing. The capacitance per weight of electroactive materials is not outstanding (1029 F g⁻¹ at 10 mA cm⁻²), but is competitive with regard to area (3.23 F cm⁻² at 10 mA cm⁻²). However, features in the cycling performance imply that the electrode exhibits a hybrid supercapacitor–battery behavior and that thermodynamic hysteresis promotes the ’breaking’ and ’fusing’ behavior of the material. The overall design highlights a new pathway to step out from surface to space.

The development of new promising metal-free catalysts is of great significance for the electrocatalytic hydrogen evolution reaction (HER). Herein, a rationally assembled three-dimensional (3D) architecture of 1D graphitic carbon nitride (g-C₃N₄) nanoribbons with 2D graphene sheets has been developed by a one-step hydrothermal method. Because of the multipathway of charge and mass transport, the hierarchically structured g-C₃N₄ nanoribbon–graphene hybrids lead to a high electrocatalytic ability for HER with a Tafel slope of 54 mV decade⁻¹, a low onset overpotential of 80 mV and overpotential of 207 mV to approach a current of 10 mA cm⁻², superior to those non-metal materials and well-developed metallic catalysts reported previously. This work presents a great advance for designing and developing highly efficient metal-free catalyst for hydrogen evolution.

The development of new promising metal-free catalysts is of great significance for the electrocatalytic hydrogen evolution reaction (HER). Herein, a rationally assembled three-dimensional (3D) architecture of 1D graphitic carbon nitride (g-C₃N₄) nanoribbons with 2D graphene sheets has been developed by a one-step hydrothermal method. Because of the multipathway of charge and mass transport, the hierarchically structured g-C₃N₄ nanoribbon–graphene hybrids lead to a high electrocatalytic ability for HER with a Tafel slope of 54 mV decade⁻¹, a low onset overpotential of 80 mV and overpotential of 207 mV to approach a current of 10 mA cm⁻², superior to those non-metal materials and well-developed metallic catalysts reported previously. This work presents a great advance for designing and developing highly efficient metal-free catalyst for hydrogen evolution.