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Zn/Ce redox flow battery (ZRFB) is emerging as a promising technology to store large amount of energy economically and efficiently, wherein a highly efficient positive electrode with a continuous and fast electronic and ionic transportation path is urgently desired. The unique nanostructure of reduced graphene oxide (RGO) paper electrode is prepared by a simply chemical reduction method, which facilitates transference of the electron and Ce3+/Ce4+ at the electrolyte/electrode interface. Thus ZRFB exhibits superior extent of charge (81.0%) and energy efficiency (71.3%). The results show RGO paper is a good candidate for positive electrode of ZRFB.

The oil pollution is an increasing threat to nature and human health. Therefore, effective separation of oil from the oily wastewater is a challenging task. Through the nonsolvent vapor method, a superhydrophobic paper can be self-assembled by dropping the conjugated poly-p-phenylenes solution on the commercial filter paper in a nonsolvent vapor atmosphere. The numerous nano-mircostructral particles composed of polymer nanowires covered on the filter paper, just like the morphology of lotus leaves, lead to the excellent superhydrophobic effect. Moreover, the polymer-coated filter paper not only exhibits good mechanical stability, long-term durability, self-cleaning, but also has superhydrophobicity and superoleophilicity. The as-prepared paper possess remarkable oil/water separation ability for a variety of oil/water mixtures, including bromoethane, hexane, cyclohexane, petroleum ether, gasoline, dodecane, and the mixed oil of gasoline and diesel, demonstrating that it can be a good candidate for the treatment of industrial oil-polluted water.

In this study, copper sulfate was successfully embedded in filter paper through soaking and copper oxide was successfully embedded in filter paper via in situ technique using the copper sulfate-embedded paper as the starting material. Using color analysis, the filter paper soaked with copper sulfate solution was observed to change color from white to blue, indicating the presence of embedded copper sulfate salts. Furthermore, upon soaking this filter paper with sodium hydroxide solution, the color changed from blue to brown, indicating the presence of copper oxide. X-ray diffraction (XRD) spectroscopy confirms the observed results of the color analysis. Scanning electron microscopy (SEM) and electron dispersive x-ray (EDX) spectroscopy were used to determine the surface morphology and elemental composition of the samples, respectively. The antimicrobial property of the filter paper with copper-based particles was tested against Gram-negative bacterium (Escherichia coli) and Gram-positive bacterium (Staphylococcus aureus), and two species of fungi (Candida albicans and Aspergillus niger) using disc diffusion method. The reactivity of the copper sulfate-embedded filter paper against E. coli was found to be severe, whereas that against S. aureus was moderate. The reactivity of the samples against the two fungi was mild, having a relatively small zone of inhibition. For the copper oxide-embedded paper, the reactivity of the paper to both bacteria was moderate, whereas it shows no reactivity to C. albicans and only a mild reactivity to A. niger. After 60 min of contact with Escherichia coli, both the copper sulfate-embedded and copper oxide-embedded filter papers reduced the amount of colony forming unit to more than 99.9%.

A paper-based colorimetric sensor was fabricated using polymethylacrylic acid-templated silver nanoclusters (AgNCs) as a sensing probe for the detection of Fe 2+ and employing an ion exchange polymeric membrane as a coating layer. AgNCs were impregnated on a cellulose filter paper. The AgNC-impregnated filter paper was then lacquered with a hydrophobic membrane of polyvinyl chloride plasticized with o -NPOE incorporating a hydrophobic cation exchanger. Due to the ion exchange phenomenon at the membrane surface, Fe 2+ was extracted into the paper layer, and the bound Ag + on the AgNCs was reduced by Fe 2+ . The growth of the cluster could be observed by measuring the increase in the silver nanoparticle (AgNP) plasmon band. The maximum plasmon band on the paper at 447 nm increased as a linear function of the increasing Fe 2+ concentration. The proposed sensor was highly selective to Fe 2+ over Fe 3+ and other cations. The proposed sensor was optimized and could be used to detect Fe 2+ solution concentrations as low as 50 μM, with a wide working linear concentration range of 0.2–1.0 mM. The sensor was applied to determine Fe 2+ in iron supplement tablet samples with satisfactory results.