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Since hydrophobicity can improve the usability and functionality of materials in humid condition, enhancing the hydrophobic behavior of starch films or papers is of importance. In this work, ZnO nanoparticles (NPs) were introduced into the starch solution under ultrasonic and magnetic-stirring, followed by cast filming and paper coating. The contact angles of resulting film and coated paper containing 2% (wt) NPs were increased from 85.73° to 121.45°, 64.47° to 103.94°, respectively. The results from comprehensive characterizations confirmed the hierarchical structure created by ZnO nanoparticles on the surface of starch film as well as the formation of intact layers on coated paper. The excellent miscibility between starch and ZnO NPs was also achieved. The approach developed is promising and facilitates the hydrophobic modification of green-based materials.

Filter paper (FP) with superhydrophobicity and high water adhesion was prepared by adsorption and simple immersion process. The surface morphologies displayed the micro-nano structure of FP. The surfaces composition was investigated by Fourier transform IR, X-ray photoelectron spectrum and X-ray diffractometer. The superhydrophobic surfaces with a water contact angle of 153° benefited from the Fe(OH)3 nanostructure formed on FP and subsequent stearic acid (STA) modification. The as-prepared superhydrophobic surfaces could firmly pin the water droplet even when the surfaces turned upside down. The wettability properties of the FP surfaces could be repaired by immersing the damaged samples into the solution again.

Sandwich-type hybrid structure consisting of etched nitrogen-doped graphene paper (ENGP) and flower-like MnO2 are fabricated through a three-step method. The ENGP were synthesized by vacuum assisted flow-filtration of the dicyandiamide (DCD) and graphene oxide (GO) aqueous solution through filter membrane, followed by a carbonization process, and then by an electrochemical etching method to improve the surface active-sites and wettability. The MnO2 nanoflowers consisting of multiple thin MnO2 nanosheets were anchored on both side of ENGP by electrodeposition techniques. The optimized hybrid electrodes exhibited a high specific capacitance of 368.3 F/g at 0.2 A/g, and excellent cycling performance of 98.4% capacitance retention over 3000 cycles.

A novel filter paper (FP) with superhydrophobicity and superoleophilicity was prepared via adsorption and immersion process for the separation of surfactant-stabilized water-in-oil emulsions. The realization of superhydrophobicity with a water contact angle of 153° benefits from the Cu(OH)2 nanostructure formed on FP and subsequent stearic acid (STA) modification. The three-dimensional network of FP as well as superhydrophobic and superoleophilic property can facilitate the demulsification of emulsified oil, thus the only gravity-driven separations of various water-in-oil emulsions with high oil flux and good recyclability have been achieved. The superhydrophobic FP can be massively applied in emulsion separation due to its facile preparation and superior performance.

Novel and flexible Mn3O4 nanosheets/reduced graphene oxide nanosheets (Mn3O4 NSs/rGO NSs) paper-like electrodes have been developed by a feasible method. The rGO works as a flexible substrate and an electron conductor. The synergetic effect of interconnected nanosheet structure can effectively depress self-agglomeration of rGO, which displays eminent conductivity. Moreover, the crumpled surface with more active sites are more convenient for the ion and electron insertion/desertion in the reversible reactions. So flexible Mn3O4 NSs/rGO NSs electrode exhibited a high specific capacitance of 409 F g−1 at a current density of 0.5 A g−1, superior cycling stability of 92% after 3000 charge-discharge cycles. More importantly, the composite material was first applied in 3D printing and screen printing of micro-patterns because of the desirable processability. It is anticipated that the high-performance Mn3O4 NSs/rGO NSs composites are a promising electrode material in printable energy storage and wearable electronic equipment.

Effect of 1 MeV electron irradiation with the dose up to 160 × 1015 cm−2 on the electrical properties of reduced graphene oxide paper (rGOP) was investigated in a temperature range of 8–300 K. It was found that rGOP has fairly high irradiation stability, but sufficiently high dose causes nonmonotonic changes in the resistivity. The effect of electron irradiation on the resistivity is more substantial under the low temperatures of electrical measurements. It was assumed that the modification of electrical properties is due to the effect of electron irradiation on the ensembles of the sp3-hybridized carbon atoms. It was shown that in the studied rGOP, the transport of charge carriers occurs by variable range hopping conductivity in the wide temperature range and conduction mechanism remains the same after electron irradiation.

Reduced graphene oxide (rGO) papers prepared by simple self-assembly process were used as electrode material for the fabrication of bimorphic electrical actuators. Initially, the structural studies of the rGO paper confirmed the formation of graphitic structure. The ionic gel electrolyte was prepared separately and used to couple the two rGO paper electrodes. This forms the tri-layered structure as an actuator, the displacement was measured by varying the applied potential with respect to time. The actuation properties were extended for both photon as well as electronic conducting gel electrolyte. The experimental results suggest that the flexible rGO paper can be used for electronic actuators.

Porous foams from cellulose nanofibres (CNF) and poly-vinyl alcohol CNF/PVA were prepared by uni-directional freezing to create a homogeneous pore structure. The CNF was derived from paper mills sludge (PMS), a by-product of paper manufacturing waste-water treatment. Sodium tetraborate decahydrate (borax) was used as a crosslinking agent. The density of the CNF/PVA foams were 0.03 g cm−3 with a compressive strength of 116 kPa at 20% strain. The foams were competitive to commercial expanded polystyrene (EPS) foam.