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A facile and feasible method for decoration of iron oxide (Fe3O4) submicron-sized particles on carbon paper at room temperature in a short time of 10 min is demonstrated in this work. The Fe3O4-particles decorated carbon papers were used as the negative electrode for an Fe-air rechargeable battery in both an alkaline aqueous solution system and an all-solid-state system. As for the all-solid-state Fe-air rechargeable battery, KOH-ZrO2 electrolyte powder developed by our group was used in the battery fabrication. In the alkaline aqueous solution based Fe-air rechargeable battery, a high initial discharge capacity of 460 mAh g−1(Fe) was achieved. Meanwhile, in the novel all-solid-state Fe-air rechargeable battery system, an initial discharge capacity of 70 mAh g−1(Fe) was obtained demonstrating the feasibility of this system that could be further developed towards a practical Fe-air rechargeable battery for portable and lightweight device application.

paper-like films of reduced graphene oxide with controllable shapes and thickness were prepared via funnel filtration and thermal reduction of graphene oxide (GO), which could work as flexible surface-enhanced Raman scattering (SERS) substrates to detect Rhodamine 6G (R6G) molecules. The SERS signal intensity of R6G on annealed films was found to be related with the annealling temperature. The most intense signal was observed for the film obtained at 800 °C. While for the sample annealed at 1000 °C, no SERS signal could be detected. The underlying mechanism for the difference was discussed. The reported preparation process of flexible rGO paper is simple and cost-effective, which shows great potential in rapid biochemical analysis of agricultural products with irregular surfaces.

Nanoparticles are used in several applications due to the unique properties they possess compared to bulk materials. Production techniques have continuously evolved over the years. Recently, there has been emphasis on environmentally friendly manufacturing processes. Substrate properties often limit the possible production techniques and, for example; until recently, it has been difficult to incorporate nanoparticles into paper. Chemical reduction of a precursor in the presence of paper changes the bulk properties of paper, which may limit intended end-use. In this study, we present a novel technique for incorporating silver nanoparticles into paper surface using a flame pyrolysis procedure known as Liquid Flame Spray. Papers precoated with mineral pigments and plastic are used as substrates. Silver nanoparticles were analyzed using SEM and XPS measurements. Results show a homogeneous monolayer of silver nanoparticles on the surface of paper, which demonstrated antibacterial properties against E. coli . Paper precoated with plastic showed more nanoparticles on the surface compared to pigment coated paper samples except for polyethylene-precoated paper. The results demonstrate a dry synthesis approach for depositing silver nanoparticles directly onto paper surface in a process which produces no effluents. The production technique used herein is up scalable for industrial production of antibacterial paper.

As a typical membrane matrix with attractive flexibility, paper has exhibited great feasibility to serve as surface-enhanced Raman scattering (SERS) substrate in the environmental monitoring and surveillance. In this research, we have designed and fabricated a distinctive hydrophilic-hydrophobic SERS substrate utilizing several ordinary papers loaded with Ag nanowires (Ag NWs). Remarkable SERS activities with an enhancement factor (EF) up to 2.63 × 106 was successfully achieved in the assembly Ag NWs with the optimal amount of nanotips and overlaps. The hydrophilic-hydrophobic strategy could contribute to anchoring microdroplets and thus enrich analytes to improve the homogeneity of substrate with a low relative standard deviation of 10.6%. Furthermore, the sophisticated SERS substrate was also applied in the in-situ detection of trace furazolidone on fish under the interference of malachite green and the reliable recovery rates were demonstrated as well.

We presented a three-step method for the preparation of superhydrophobic cellulose filter paper. It involved ZnCl2 pre-treatment to activate the cellulose fibers, a SiO2 sol-gel process to increase surface roughness and grafting of hexadecyl trimethoxysilane groups to chemically enhance the water repellency. The water contact angle of the modified paper reached 154.8°. XRD analysis confirmed silica as the product from the sol-gel process. EDS and SEM analysis showed that pre-treatment results in greater silica adhesion and retention on the paper surface. The modified paper proved to be self-cleaning and resistant to staining. Further tests under various conditions showed that ZnCl2 pre-treatment improved the durability of the superhydrophobic paper. It was concluded that pre-treatment of the filter paper prior to superhydrophobic coating results in a disruption in the cellulose crystalline structure that favours greater silica adhesion and retention.

In this work, a facile method was developed to prepare reactive superhydrophobic paper by the attachment of 10-undecylenoyl chloride onto homogenized α-cellulose followed by one-step spray-coating of the resulting cellulose derivative (α-cellulose 10-undecylenoyl ester, CUE) onto filter paper. By spray-coating a CUE suspension with a concentration of 1.04 wt% for at least 6 mL, the paper surface became superhydrophobic, which had a water contact angle of 152 ± 2° with the advancing and receding angles of 165 ± 2° and 144 ± 2° and the slide angle of 6°. Additionally, the resulting surface showed a good durable stability, acid-base stability and thermal stability. More interestingly, an obvious photoclick thiol-ene reaction could be conducted on such superhydrophobic paper, which would further enlarge the application fields of superhydrophobic surfaces.

In this paper, an effective strategy using potassium dichromate lotion to activate surfaces of commercial carbon papers leading to enhanced electrochemical capacitances was reported. It is revealed that surfaces of activated carbon papers became rougher and their specific surface areas enlarged after treatment. Further, surface hydrophilicity of the treated carbon papers enhanced due to the generation of hydrophilic groups such as hydroxyl (–OH), carbonyl (〉C O) and carboxyl (–COOH) and they act as strong polar sites to absorb water molecules. With the synergistic effect of enlarged specific surface area and enhanced surface hydrophilicity, the activated carbon papers provide high areal capacitances. In general, this strategy offers a feasible pathway to make commercial carbon paper a promising candidate for practical supercapacitors and is expected to extend to other carbon based electrode materials.

In the current efficient energy focused society, metal–air batteries (MAB), which have high theoretical energy densities in comparison with other batteries have attracted tremendous attention for electronics and electric vehicle applications. Efficient utilization of the active material in the negative electrode with oxygen from air as the positive electrode could enable the development of a lightweight and portable metal-air battery with large energy density. Zinc (Zn), which is an abundant and inexpensive material that exhibits small voltage fluctuation during discharge as well as large discharge capacity in a liquid electrolyte-based battery system, is a good candidate as the active material in a MAB. Therefore, in this work, a Zn-air battery is fabricated and characterized using electroplated metallic Zn on carbon paper in order to increase the working contact area between Zn and the carbon paper which serves as the current collector. A near theoretical discharge capacity of 814 mAh g−1 (Zn) was achieved in an aqueous KOH liquid electrolyte system. Meanwhile, an all-solid-state Zn-air battery using a sol-gel-derived KOH-ZrO2 solid electrolyte was also fabricated which demonstrated an initial discharge capacity of 30 mAh g−1 (Zn).

Ag triangular nanoplates have been widely used as the SERS substrate due to their anisotropic morphology and sharp corners. In this work, SERS activity of Ag triangular nanoplates on glass and paper substrates was investigated with different concentration and size. A tiny triangular nuclei based synthesis method was employed to produce Ag triangular nanoplates with different size. And the extinction coefficients of Ag triangular nanoplates with different size were quantified by inductively coupled plasma mass spectrometry (ICP-MS) and transmission electron microscopy (TEM). With definite concentration, Ag triangular nanoplates with small size showed stronger SERS intensity on glass substrate at high concentrations, while large Ag triangular nanoplates exhibited better SERS effect on paper substrate at low concentrations. The possible reasons for distinct SERS activity of Ag triangular nanoplates on glass and paper were discussed with scanning electron microscope (SEM) characterization. These results exhibited important implications for fabricating Raman substrates using Ag triangular nanoplates and could be applied to the SERS sensing with flexile substrate.

Flexible nanohybrid paper electrode (termed as C-I) consisting of multi-walled carbon nanotubes (MWCNTs) and indium sulfide (In2S3) nanoplates is formed via a simple vacuum-assisted assembly and used as an anode for sodium-ion batteries (SIBs). In2S3 nanoplates which are well distributed on and bound to the MWCNTs provide a high Na storage capacity of the nanohybrid electrode as high as 410 mAh g−1 at a specific current of 50 mA g−1 over 100 charge/discharge cycles and ∼97% of rate-retention capability over the specific currents of 50 mA g−1 to 1 A g−1 for at least 50 charge/discharge cycles. Particularly, when In2S3 in the form of nanoplates was added to MWCNTs, the electrochemical performances are considerable as compared to those of bulk In2S3 or MWCNTs film electrodes. This highlights the importance of nanohybrid approach in overcoming the intrinsic complication of In2S3, i.e., the agglomeration of In2S3 into bulk form during assembly, followed by annealing. For C-I nanohybrid electrode, capacitive contribution (∼95%) rather than insertion contribution (∼5%) is predominant during charge/discharge process. The nanohybrid paper electrode is robust and thus retains capacity even under repeated mechanical deformation (flat-bent-flat cycles), demonstrating the potential of the electrode being used for flexible and wearable energy storage.

Here, a novel, simple, cost-effective, environment-friendly, non-invasive and mediator free, reduced graphene oxide (RGO) modified paper-based biosensing platform was reported. A conductive platform was generated over the ivory paper sheet via in-situ reduction of graphene oxide. The conductivity of the RGO paper was found as 0.86 S cm−1. This substrate was used for deposition of cysteine capped gold nanoparticles (Cys-AuNPs) using electrophoretic deposition technique at 60 V for biosensing application. Scanning electron microscopic images show the deposition of Cys-AuNPs in the spherical bunch on the RGO paper. The Cys-AuNPs deposition on RGO paper was confirmed by energy-dispersive x-ray spectroscopy and X-ray photoelectron spectroscopy and used for immobilization of monoclonal antibodies. This paper-based immunosensor based on chronoamperometry technique has the ability of direct electron transfer without using any mediator. This platform can replace commercially available electrodes [Indium Tin Oxide (ITO) and fluorine-doped tin oxide (FTO)] coated glass substrate, glassy carbon and gold] for electronic and electrochemical applications including point-of-care (POC) devices.