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Tremendous attention has been paid on high efficiency, readily available and stability of electrocatalysts. Herein, we ingenious report a one-step reaction strategy synthesis of CoFe/CP grown on three-dimensional (3D) nanoarray carbon paper (CP) containing non-precious metals for oxygen evolution reaction (OER) with low-cost and unique hierarchical porous structure. This amorphous CoFe/CP hybrid exhibits commendable electrocatalytic performance in the OER process, requiring only overpotential of 278 mV to achieve 10 mAcm−2 in 1.0 M KOH solution and a lower Tafel slope of 49.12 mVdec-1. In addition, this sample shows a long-term durability even at 200 mAcm−2 without obvious decay, which attributes to peculiar multistage graded nano structure and the change of composition at the interface of CP. Therefore, the remarkable OER activity can provide a new strategy to construct potential candidates, which will replace the state-of-the-art precious metals for OER in the future.

Cobalt(ii) phthalocyanine (CoPc) was suspended in aqueous medium and the colloidal system was used as catalyst for the electrochemical determination of hydrogen peroxide on paper-based electrodes modified with carbon nanomaterials. H2O2 was oxidised at 0.275 V vs. Ag pseudoreference electrode. This system was adapted to develop a glucose sensor with glucose oxidase immobilized on the cellulose electrode. CoPc suspended nanoparticles acted as nanoenzyme mimicking peroxidase activity and were combined with different carbon nanomaterials to form hybrids with optimised catalytic performance. GO-CoPc paper-based electrodes yielded the best results with a linear range of ∼12 μM to 49 mM for H2O2 and 0.1 mM to 1 mM for glucose. Glucose was determined in physiological serum and juice samples with recoveries of 93.3 and 94.2% respectively. CoPc could replace HRP for the catalytic sensing of H2O2, without the need to be dissolved. This material can be used in situ in a simple protocol with other nanomaterials for electrode modification. The sensor described has the advantage of easy preparation, using the catalyst in colloidal form, long term stability, and versatility to be adapted to other low cost and disposable enzymatic systems.

Vanadium-doped porous Cosub3/subOsub4/sub(V-porous Cosub3/subOsub4/sub) was synthesized via a simple soft-templating method and used as a superior peroxidase mimic for the simultaneous colorimetric determination of glucose and total cholesterol (TC) in whole blood samples on a two-dimensional microfluidic paper-based analytical device (2D-μPAD). The large surface area and the presence of two metals in V-porous Cosub3/subOsub4/subcontributed to its excellent catalytic activity toward 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) and 3,3',5,5'- tetramethylbenzidine (TMB) with Michaelis-Menten constants (iK/isubM/sub) of 0.1301 and 0.0141 mM, respectively. The 2D-μPAD was fabricated using simple wax screen-printing and cutting techniques. The colorimetric reactions of both glucose and TC on 2D-μPAD were simultaneously performed by adding a single drop of a whole blood sample on the sample zone made of the LF1 membrane. After the enzymatic reactions, the generated hydrogen peroxide (Hsub2/subOsub2/sub) was oxidized by V-porous Cosub3/subOsub4/subto produce hydroxy radicals (sup•/supOH), inducing ABTS and TMB to generate colored products. The generated Hsub2/subOsub2/subwas proportional to the intensities of the green and blue products of the glucose and TC systems, respectively. The developed 2D-μPAD required a short analysis time (∼5 min) with small volumes of samples (15 μL of whole blood) whereby no sample preparation was needed. Owing to several advantages including simplicity, low cost, long-term stability, and simultaneous readout, the novel V-porous Cosub3/subOsub4/subcoupled with 2D-μPAD proved to be promising for practical uses as a pioneering portable device for the determination of glucose, TC, and other important biomarkers without the need of technical supports.

Disposable ion-selective electrodes of high reproducibility of recorded potentials between different sensors have been prepared using carbon-nanotubes modified paper as the transducer and electrical lead, and a poly(vinyl chloride) ion-selective membrane. The conducting paper was obtained using carboxymethylcellulose stabilized carbon nanotubes suspension – combination found to result in high stability of conventional sensors. It was shown for the first time that change of the amount of conducting material used to prepare sensor, from conventional (where it is used as transducer) to disposable sensors (where it is used as transducer and electrical lead), requiring application of much higher amount of carbon nanotubes significantly affects performance of the sensors. Presence of ions in the suspension used results in occurrence of super-Nernstian range on the potentiometric calibration curve of potassium-selective sensor, below 10−5 M KCl. Highly reproducible potential values, between sensors as well as between different calibrations, were achieved introducing mixture of cobalt(II) porphyrin/cobalt(III) corrole to the carbon nanotubes layer, at the back side of the membrane. Presence of porphyrinoids not only stabilizes potential values obtained for the sensors but also tailors ion transport through the membrane, resulting in stable potential of the sensors, although a super-Nernstian region is present on the calibration line.

Paper bleaching effluent was treated by catalytic wet oxidation method and the effect of the type of the catalyst on the efficiency was investigated. Cerium oxide, cobalt oxide and copper oxide based (CuOx-CoOx-CeO2) composite catalysts which were varying with regard to CuOx, CoOx and CeO2 compositions were prepared by co-precipitation method. The efficiency of the process was determined by measuring the chemical oxygen demand (COD), total organic carbon (TOC), adsorbable organic halides (AOX) and Cl− removal yields. When the COD, TOC and AOX removal yields were considered, better results were achieved with copper and ceria based catalysts than the cobalt based catalysts. At the optimum reaction conditions (T—473 K, t—120 min, P—130–250 psig), the maximum removal yields obtained by the 50% CuOx–50% CeO2 catalyst. When the wastewater of the I stage of paper bleaching process was treated, removal yields of TOC, COD and AOX were detected as 89; 94 and 95%, respectively Whereas, removal yields of 53% COD, 84% TOC, 90% AOX and 76% Cl− were achieved for the III stage wastewater. It was shown that removal of the toxicity of wastewater samples that were collected from the paper bleaching process by the proposed treatment methods.

The catalytic combustion of diesel soot is addressed with flexible and structured “paper catalysts”. Two different series of catalysts were prepared either by drip impregnation or by a spray method to deposit a mixture of Co, Ba, and K or a mixture of Co and Ce onto SiO2-Al2O3 ceramic paper matrixes. In every case, CeO2 nanoparticles were added to bind the ceramic fibers. SEM images showed that the impregnation method generated catalytic particles concentrated as large chunks (> 10 μm), mainly at ceramic fiber crossings, whereas the spray method produced smaller catalytic particles (< 1 μm) well distributed throughout the ceramic paper. Besides, Co-Ba-K particles appeared better dispersed on the surface of ceramic fibers than Co-Ce due to the presence of K. Additionally, FTIR spectra showed the formation of O2 2− and O2 − species associated with CeO2 (binder) on the samples containing potassium which gave the Co-Ba-K-ceramic paper good catalytic properties, thus making the Co-Ba-K drop impregnated the best catalyst both considering activity and stability. Successive temperature programmed oxidation (TPO) runs up to 700 °C caused the formation of cobalt silicates in the catalytic ceramic paper prepared by the spray method, as indicated by TPR. The formation of these species was probably favored by the smaller size of cobalt particulates and their higher dispersion in the catalysts prepared by the spray method. This provoked the partial loss of the redox properties of Co3O4. TPR experiments also indicated the formation of BaCoO3 in Ba-containing ceramic paper, which could help in maintaining the catalyst activity after several TPO runs through the capacity of this mixed perovskite-type oxide to trap and release NOx. Fil: Leonardi, Sabrina Antonela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina Fil: Tuler, Fernando Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina Fil: Gaigneaux, Eric M.. Université Catholique de Louvain; Bélgica Fil: Debecker, Damien P.. Université Catholique de Louvain; Bélgica Fil: Miro, Eduardo Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina Fil: Milt, Viviana Guadalupe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina

Paper industries are water-intensive industries that produce large amount of wastewater containing dyes, toxicity and high nutrient content. These industries require sustainable technology for their waste disposal and MEC could be one of them. However, effective MEC operation at neutral pH and ambient temperature requires economical and efficient cathodes that are capable to treat indusial wastewater along with recovery of energy/biohydrogen. Co-deposits of Nickel, Nickel–Cobalt and Nickel–Cobalt–Phosphorous on the surface of SS and Cu base metals distinctly were used as cathodes in MEC for the concurrent treatment of real paper industry wastewater and biohydrogen production. MECs were utilized in batch mode at neutral pH, applied voltage of 0.6 V and 30 ± 2 °C temperature with paper industry wastewater and activated sludge as microbial sources. The fabricated Nickel–Cobalt–Phosphorous gives the higher hydrogen production rate of 0.16 ± 0.002 m3(H2) m−3d−1 and 0.14 ± 0.002 m3(H2) m −3d −1 respectively, with ~33–42 % treatment efficiency for a 500 ml wastewater in 7-day batch cycle in both the cases; while it is lowest in the case of the control cathodes (SS1 (0.07 ± 0.002 m3(H2) m−3d−1) & Cu1 (0.06 ± 0.004 m3(H2) m−3d−1)). It was also found that fabricated cathodes have the capability to treat industrial wastewater at ambient conditions efficiently with higher energy recovery. Prepared cathodes show enhanced hydrogen production and treatment efficiency as well as are competitive to some reported literature.

In this work, a new chemiluminescence (CL) system of Co-Fe prussian blue analogs nanocubes (Co-Fe PBA NCs) that can catalyze luminol to produce strong CL in the absence of H2O2 was established. Co-Fe PBA NCs have the property of oxidase-like activity, and it can catalyze the generation of active oxygen radicals in a dissolved oxygen system. Since caffeic acid (CA) can remove reactive oxygen species in the system, a sensitive detection method for CA on a paper-based chip was developed. Under the optimal conditions, this method showed a good linear response to CA in the range of 10 - 800 ng mL-1 with a limit of 3 ng mL-1. The proposed method had been used for the determination of CA in tea samples. The results may open a new avenue for the catalytic property on luminol CL system without extra oxidants.

As a renewable resource, waste paper cannot only be recycled to paper, but also can be used as a new carbon source in the material field. In the present study, starting from the abundant and inexpensive materials, the three-dimensional (3D) framework cobalt (Co) and nitrogen (N) doped (Cox–N–C) electrocatalyst was successfully prepared using waste paper and urea via a facile hydrothermal treatment and ion adsorption process, followed by a further pyrolysis step. The experimental results show that the as-prepared Cox–N–C materials exhibit excellent electrocatalytic performance for hydrogen evolution reaction (HER). Especially, Co1.2–N–C sample has an outstanding HER catalytic activity with a 223 mV overpotential (at j = 10 mA cm−2), 91 mV dec−1 Tafel slope, and a remarkable long-term stability in 0.5 M H2SO4. Note that the abundant Co–N active sites are responsible for enhancing HER activity of Cox–N–C sample. It is expected that the low cost and highly efficient Co1.2–N–C electrocatalyst is a promising candidate to replace Pt noble catalysts.

Ceramic paper discs were made by employing a dual papermaking technique and by partially substituting cellulosic fibres by SiO2-Al2O3ceramic ones. Ulexite (NaCaB5O6(OH)6�5(H2O)), extracted from the natural mineral, was added as a binder to give ceramic paper the necessary strength for its manipulation and catalytic use. Either La,Co or Ba,Co was incorporated in order to give ceramic paper the capability of trapping NOx and oxidizing soot particles. Structured catalysts were characterised by SEM, FTIR and XRD, and the mechanical properties were also determined. Lanthanum was deposited on ceramic fibres as La2O2CO3aggregates and barium as BaCO3filaments, being cobalt deposited as Co3O4flakes. Mechanical properties indicated that the ceramic paper obtained from natural ulexite proved to be stronger, though less flexible than those prepared using colloidal suspensions as a binder. Diesel soot oxidation activity was determined by TPO either adding or not 0.1% NO into the feeding stream. The thus prepared systems resulted in being active towards soot oxidation, being the value of maximum combustion rate 420 �C, which is within the temperature range of diesel exhaust gases. Fil: Leonardi, Sabrina Antonela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina Fil: Zanuttini, Miguel Angel Mario. Universidad Nacional del Litoral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Miro, Eduardo Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina Fil: Milt, Viviana Guadalupe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina

Sulfur quantum dots are promising alternatives for traditional heavy metal-containing quantum dots due to their benign chemical properties and low cytotoxicity. Herein, cysteine-decorated sulfur dots were prepared from facile modification of pristine sulfur dots and can be acted as a chemosensor for the fluorometric and colorimetric dual-channel detection of cobalt (Co2+) with high sensitivity and selectivity. Visual colors of the as-prepared chemosensor in the presence of Co2+ changed from blue to colorless under UV light and also can transform from colorless to yellow under sunlight based on the photoinduced electron transfer effect. The detection limit of cysteine-decorated sulfur dots toward Co2+ was determined as low as 0.16 μM with a wide detection range, which is lower than the permitted guideline level by Department of Environmental Protection for drinking water (1.7 μM). Furthermore, portable paper sensor-based cysteine-decorated sulfur dots were fabricated for Co2+ detection and showed superior detection ability. Aided by a common smartphone as detector, the rapid, on-site and accurate quantification of Co2+ in real water samples can be accomplished. Our research has provided a novel chemosensor based on sulfur dots for dual-channel detection of Co2+, which would expand applications of sulfur dots in environmental monitoring, diseases diagnosis, cell imaging, light-emitting diodes, etc. Cysteine-decorated sulfur dots were acted as a chemosensor for fluorometric and colorimetric dual channel detection of Co2+ based on the photoinduced electron transfer effect.

The cobalt triphosphide (CoP3) was grew on carbon paper (CP) by using a hydrothermal method and served as counter electrode (CE) catalyst in dye-sensitized solar cells (DSSCs). The morphology of the CoP3/CP CE exhibits a regular fibrous structure, which provides a guarantee for its good electrochemical performance of the CE made from the cyclic voltammetry, Tafel test, etc. Various photoelectric performance tests also show that the DSSCs with CoP3/CP CE achieves good photoelectric conversion efficiency of 6.84% under 100 mW·cm−2 illumination, which can compare to that of the DSSC assembled with the Pt (6.79%) CE. Metal phosphides are rarely used as CEs in DSSCs, and they will have a good promising alternative to the Pt electrode in the future.

Nickel (Ni), cobalt (Co) and Ni-Co nanosheets were successfully grown on carbon fiber paper (CFP) via hydrothermal method for hydrogen evolution reaction (HER). The interconnected Ni, Co and Ni-Co nanosheets have thickness in the range of 8.42 to 21.78 nm. However, all samples are poorly crystalline as evident from their diffused diffraction patterns. The Ni-Co nanocomposite exhibited the largest HER activity having the lowest overpotential of -0.313 V (vs RHE) at a current density of 10 mA/cm2, compared to pure Ni and Co samples having overpotential values of -0.632 V (vs RHE) and -0.441 V (vs RHE), respectively. This is attributed to the synergistic effect between the intrinsic HER catalytic property of Ni and high hydrogen adsorption of Co

Eosin Y is a potential new color test for use in detecting illicit drugs that has not been extensively studied. In the present study, a variety of drugs of abuse and fentanyl analogues were tested to determine which drugs will bind to eosin Y, which functional groups are capable of binding and eliciting a color change, and a mechanism for eosin Y binding to fentanyl. Further, these agents were combined with common cutting agents and other drugs of abuse in order to determine the fentanyl detection limit in a drug mixture using an eosin Y test strip. Additionally, cobalt thiocyanate was used to determine whether the combination of cobalt thiocyanate and eosin Y has the potential to identify fentanyl. Through the testing performed, we concluded that (i) Eosin Y is capable of detecting low amounts of fentanyl down to 1%, (ii) Eosin Y binds to select tertiary amines to produce an orange to pink color change, and (iii) Eosin Y binds to the nonpiperidine ring nitrogen of fentanyl as a primary binding site and the piperidine ring nitrogen as a secondary binding site. While the cobalt thiocyanate assay detected 1% fentanyl in some of the mixtures, eosin Y detected 1% fentanyl in all mixtures. Finally, eosin Y was able to detect fentanyl in forensic case samples containing heroin and various cutting agents. Based on our results, eosin Y has the potential to screen for fentanyl and fentanyl analogues and can detect fentanyl in low amounts when mixed with common cutting agents.

A cost-efficient and environmentally benign strategy for large-scale production of metal oxide/metal-decorated 3D porous graphene directly converted from waste papers with a cobalt(II) complex was successfully developed. The resulting Co3O4/Co immobilized in porous graphene served as a spacer to prevent restacking of graphene and also provided more accessible active sites. As a demonstration, the oxygen reduction reaction (ORR) was chosen to show the catalytic activity of the high-added-value Co3O4/Co@graphene composite. Due to the synergistic catalytic effects between Co3O4 and graphene combined with a hierarchical porous structure, the synthesized 3D functional porous graphene can function as an efficient ORR catalyst with comparable performance to that of a Pt/C catalyst, which shows its potential application in fuel cells.

The key to improving water oxidation is to develop efficient and earth-abundant catalysts for the oxygen evolution reaction (OER). Herein, a new amorphous cobalt iron borate supported on 3D carbon paper integrated electrode is reported as a precatalyst for the OER, which was synthesized by using a one-pot hydrothermal method. An optimum OER activity was obtained at 25 % Fe doping by screening the compositions of the Co and Fe. The best synthesized catalyst needs an overpotential of 227 mV to deliver a current density of 10 mA cm-2 and also exhibits a long-term durability of 24 h. Impressively, we find that CoFe oxyhydroxide was formed in situ in the OER process, which serves as the real catalytic active species for OER. Moreover, the direct conversion from CoFe borate to CoFe oxyhydroxide is reported for the first time in metal borate OER catalysts. The discovery in this work, that is, that metal borate as a precursor can efficiently catalyze the OER in alkaline media, significantly widens the family of OER catalysts.

Remediation of engineered-nanomaterials is an up-coming major environmental concern. This study demonstrates adsorptive-remediation of cobalt oxide nanoparticles (CoO NPs) from the water. The α-cellulose-fibers were extracted from waste-paper biomass (WP-αCFs) and magnetized with Fe3O4 NPs (M-WP-αCFs). The XRD, FT-IR, and TGA were performed for detailed characterization of the newly developed bioadsorbent. The M-WP-αCFs was then applied for adsorptive remediation of CoO NPs. The adsorptive kinetics of CoO NPs adsorption onto the M-WP-αCFs reveals the pseudo-second-order model. The various adsorption isotherm studies revealed Langmuir is a best-fit isotherm. A prominently high adsorption capacity qm (1567 mg/g) corroborated extraordinary adsorptive potential of M-WP-αCFs. Furthermore, CoO NPs were adsorbed onto M-WP-αCFs were analyzed by the XPS, VSM, and TEM. Therefore, this study gave rise WP biomass extracted and rapidly-separable nano-biocomposite of ‘M-WP-αCFs’ with a high-capacity for CoO NPs remediation and can be further applied in remediation of several other engineered-nanomaterials.

An electrochemical paper-based analytical device (ePAD) using an electrocatalytic cobalt(II) phthalocyanine-modified screen-printed carbon electrode (CoPc-SPCE) was first developed for the determination of 8-hydroxyquinoline (8-HQ). The electrochemical behavior of 8-HQ on the CoPc-modified electrode was investigated by cyclic voltammetry (CV) and square-wave voltammetry (SWV). The obtained results demonstrated that the CoPc-SPCE shows high electrocatalytic activity toward the oxidation of 8-HQ. The oxidation potential was shifted to a negative value compared to those obtained from the unmodified electrode. Under the optimized experimental conditions, a good linear relationship between the 8-HQ concentration and the peak current was obtained within the range of 10–250 μM with a detection limit of 0.89 μM. Furthermore, the method was successfully applied for the determination of 8-HQ in cosmetic samples. According to a paired t-test, the results were in good agreement with results from the standard HPLC-UV method. The benefits of this proposed device are that it is easily fabricated, low cost, disposable, highly sensitive and reproducible.

Electrode materials as an important component for the supercapacitors (SC) mainly undertake energy storage. Hence, the research hotspots in the SC fields are focused on the active materials of the electrode. In this study, we have provided a facile synthesis method to prepare reduced graphene oxide (RGO) and cobalt carbonate hydroxide (Co(CO3)0.5(OH)0.11·H2O) nanorod composites. The RGO films were obtained by vacuum filtration of GO papers and hydrothermal method. And during this hydrothermal, Co(CO3)0.5(OH)0.11·H2O nanorods also grow on the surface of RGO films. The as-fabricated RGO/Co(CO3)0.5(OH)0.11·H2O composites are characterized by SEM, EDS, XRD measurement. According to the electrochemical research results, the RGO/Co(CO3)0.5(OH)0.11·H2O electrodes own an ultrahigh volumetric capacitance of 1627 F cm−3 at a current density of 0.5 A g−1. Besides, the energy density of the symmetrical supercapacitor (SSc) assembled with the RGO/Co(CO3)0.5(OH)0.11·H2O electrode material is 9.22 mW h cm−3, and the capacity can be maintained 100.0% after 10,000 cycles when the composite material at the current density of 1 A g−1, these promote an efficient electrode material for electrochemical supercapacitor applications.

A simple strategy is here described for assembling graphite-based pencil leads doped with electrode modifiers suitable for drawing electrochemical devices on porous materials such as paper in a very reproducible and easy way. They were prepared by mixing controlled amounts of the chosen modifier with different quantities of carbon powder (conductive material), sodium bentonite (binding agent) and sodium silicate (hardening agent). After pressurisation, these mixtures were extruded at room temperature from a suitable die in thin rods which were then inserted in commercial lead holders to facilitate their use for drawing electrodes on paper. Lead composition (80% graphite powder; 8% sodium bentonite; 12% potassium silicate) and their fabrication procedure were optimised by drawing working electrodes for paper-based electrochemical cells with leads prepared with different contents of their components and evaluating their performance by voltammetric measurements conducted on hexacyanoferrate(II). Two prototype species (decamethylferrocene and cobalt(II) phtalocyanine, chosen as model compounds displaying a reversible redox process and versatile electrocatalytic properties, respectively) were assayed for doping leads. A quite satisfactorily reversible electrochemical behaviour was observed for decamethylferrocene incorporated into graphite-based working electrodes drawn on paper-based cells (RSD% for peak height and peak potential of 4.1 and 2.4, respectively) and a good electrocatalytical activity towards cysteine and hydrogen peroxide was displayed by graphite-based working electrodes modified by cobalt(II) phtalocyanine.

A facile approach utilizing synthesis of cobalt nanoparticles in green polymers of chitosan (CS) coating layer on high surface area cellulose microfibers of filter paper (CFP) is described for the catalytic reduction of nitrophenol and an organic dye using NaBH 4 . Simple steps of CFP coating with 1 wt% CS aqueous solution followed by Co 2+ ions adsorption from 0.2 M CoCl 2 aqueous solution were carried out to prepare pre-catalytic strips. The Co 2+ loaded pre-catalytic strips of CS-CFP were treated with 0.19 M NaBH 4 aqueous solution to convert the ions into nanoparticles. Successful Co nanoparticles formation was assessed by various characterization techniques of FESEM, EDX and XRD analyzes. TGA analyses were carried out on CFP, CS-CFP, and Co-CS-CFP for the determination of the amount of Co particles formed on the CS-FP, and to track their thermal properties. Furthermore, we demonstrated that the Co-CS-CFP showed an excellent catalytic activity and reusability in the reduction reactions a nitroaromatic compound of 2,6-dintirophenol (2,6-DNP) and brilliant cresyl blue (BCB) dye by NaBH 4 . The Co-CS-CFP catalyzed the reduction reactions of 2,6-DNP and BCB by NaBH 4 with psuedo-first order rate constants of 0.0451 and 0.1987 min −1 , respectively.

The successful attempt to solve the crystal structure of Co(CO3)0.5(OH)·0.11H2O (denotedCCH), based on synchrotron powder diffraction data, leads to a drastic revision of the chemical formula to Co6(CO3)2(OH)8·H2O [hexacobalt(II) bis(carbonate) octahydroxide monohydrate] and to a hexagonal cell instead of the orthorhombic cell suggested previously [Portaet al.(1992).J. Chem. Soc. Faraday Trans.88, 311–319]. This results in a new structure-type related to malachite involving infinite chains of [CoO6] octahedra sharing edges along a shortcaxis, delimiting tunnels having a three-branched star section. All reports discussing cobalt hydroxycarbonates (CCH) without any structural knowledge and especially its topotactic decomposition into Co3O4have, as a result, to be reconsidered.

Point-of-care (POC) diagnostic devices play significant roles in delivering vital surveillance information and providing proper and timely care to patients. There is a challenge in the development of new diagnostic tools to overcome their current shortcomings in terms of cost issues, accuracy and performance. Herein, a highly efficient paper-based analytical device based on a 2D metal-organic framework (MOF) has been reported for the colorimetric/fluorometric monitoring of glucose. Because of the inherent bifunctional activity of cobalt-terephthalate MOF (CoMOF) nanosheets, great improvements were made to the stability and performance of glucose oxidase (GOX) and to its catalytic effect on the reaction of o-phenylenediamine (OPD) and H2O2. The exceptional behavior of 2D CoMOF, along with a precise smartphone readout, led to the rapid and sensitive colorimetric/fluorometric detection of glucose in biological samples. Paper modified by CoMOF and GOX was stable for a long time, and a yellow-brown color and a high fluorescence emission were observed after the addition of a low volume of sample and OPD solutions. The probe showed a wide linear effectiveness range of 50 μM-15 mM, with colorimetric and fluorometric detection limits of 16.3 and 3.2 μM, respectively. Despite its great simplicity, the developed probe showed high performance and accuracy for the quantification of glucose.

We report the design, structure, and performance of a planar paper-based ion-sensing platform that utilizes colloid-imprinted mesoporous (CIM) carbon as a solid contact, with a redox buffer as the internal reference. This device contains an all-solid-state ion-selective electrode and an all-solid-state reference electrode that are integrated into the paper substrate with a symmetrical cell design. To ensure calibration-free sensor operation, each interfacial potential within the device is well-defined by the use of a redox buffer added to the sensing and reference membranes that controls the interfacial potentials at the CIM carbon/sensing membrane and CIM carbon/reference membrane interfaces. Two types of redox buffers were evaluated for this purpose, i.e., one based on the tetrakis(pentafluorophenyl)borate salts of cobalt(II/III) tris(4,4′-dinonyl-2,2′-bipyridyl) and one consisting of 7,7,8,8-tetracyanoquinodimethane and its corresponding anion radical. The feasibility of the design was demonstrated wit...

Filter paper has been sequentially enchased with titania (TiO2) nanoparticles and coated by a cobalt-porphyrin/dansyl piperazine complex. A series of “turn on” fluorescence sensors are demonstrated to show high sensitivity and fast response for ammonia gas.

The oxygen reduction reaction (ORR) is a vitally important process in fuel cells. The development of high-performance and low-cost ORR electrocatalysts with outstanding stability is essential for the commercialization of the electrochemical energy technology. Herein, we report a facile synthesis of cobalt (Co) and nitrogen (N) co-doped carbon nanotube@porous carbon (Co/N/CNT@PC-800) electrocatalyst through a one-step pyrolysis of waste paper, dicyandiamide, and cobalt(II) acetylacetonate. The surface of the hierarchical porous carbon supported a large number of carbon nanotubes (CNTs), which were derived from dicyandiamide through the catalysis of Co. The addition of Co resulted in the formation of a hierarchical micro/mesoporous structure, which was beneficial for the exposure of active sites and rapid transportation of ORR-relevant species (O2, H+, OH−, and H2O). The doped N and Co formed more active sites to enhance the ORR activity of the electrocatalyst. The Co/N/CNT@PC-800 material exhibited optimal ORR performance with an onset potential of 0.005 V vs. Ag/AgCl and a half-wave potential of –0.173 V vs. Ag/AgCl. Meanwhile, the electrocatalyst showed an excellent methanol tolerance and a long-term operational durability than that of Pt/C, as well as a quasi-four-electron reaction pathway. The low-cost and simple synthesis approach makes the Co/N/CNT@PC-800 a prospective electrocatalyst for the ORR. Furthermore, this work provides an alternative approach for exploring the use of biomass-derived electrocatalysts for renewable energy applications.

Molybdenum disulfide (MoS2) is considered as a promising candidate to Pt-based catalysts. Literatures report the active centers of MoS2 locate at its edges, while the perfect in-plane domains are not active. In this study, a simple Co Mo S precursor decomposition approach is used to synthesize Co-doped MoS2 in-situ grown graphite paper (GP) substrate. Electrochemical analyses reveal the Co-doped MoS2 possesses excellent electrocatalytic activity comparable to Pt. Density functional theory (DFT) calculations indicate the inert in-plane S atoms neighboring the doped Co atoms become active towards triiodide reduction, as revealed by the adsorption energies (Ead) of iodine atom decreasing from 0.36 eV to −0.52 eV, identical with value obtained from Pt (−0.52 eV). Due to increased active sites, highly conductive of GP, and excellent electrical connection between Co-doped MoS2 and GP substrate, the dye-sensitized solar cell fabricated using Co-doped MoS2/GP as counter electrode (CE) shows higher photoelectric conversion efficiency (7.26%) than those based on MoS2/GP CE (6.57%) and platinized F-doped tin oxide (Pt/FTO) electrode (6.87%).

In this work, a highly sensitive colorimetric paper-based optode for the determination of thiocyanate in urine samples was developed for the first time. The cocktail solution of the optode was composed of 5,10,15,20-tetrakis(4-octyloxyphenyl)porphyrin cobalt(II) complex (L), tridodecylmethylammonium chloride (TDMACl), 2-nitrophenyl octyl ether, and polyvinyl chloride as an ionophore, an ion exchanger, a plasticizer, and a polymer, respectively. The paper-based optode responded to thiocyanate by increasing the blue component in the RGB index and a visible change, with the naked-eye, of the optode color from pink to green was observed. From the central composite design, the optimized conditions that yielded the highest sensitivity were 4.70 mmol/kg TDMACl and 13.75 mmol/kg L. The developed optode sensor was highly selective and responded to thiocyanate over other anions, with a working range of 0.001–5 mM and with a coefficient of determination (R2) of 0.9915. The limits of detection using naked-eye and camera were determined to be 50.0 μM and 1.26 μM, respectively. In addition, the LOD and LOQ estimated from the standard deviation of the blank were 0.65 and 1.87 μM, respectively. Furthermore, this sensor was successfully applied to the detection of thiocyanate in urine samples from non-smokers and smokers. The results were in good agreement with the standard ion chromatography (IC) technique. This developed paper-based optode sensor was simple, low-cost, portable, and easy to use as a sensing device without any complicated instrument.

As one of the most toxic contaminants, arsenic (As) is well-known for diverse types of adversary effects on the life of living beings. Unfortunately, as the conventional methods of its detection generally suffer from several demerits (e.g., long duration, high cost, and complexity), the engineering of advanced materials could be a solution for the development of next generation sensors. In an effort to validate such proposition, we developed a molybdenum based metal–organic framework (Mo-MOF) by modifying a common form of [(Mo2O6)(4,4′–bpy)]n) as a new sensing platform for As. We have successfully developed and characterized a mixed metal (Co/Mo) MOF for the specific, sensitive, and expeditious detection of As(V) metal ions. The color changing capacity (from purple to blue) of Co/Mo-MOF is found to maintain a good linear relationship with changes in the concentration of As(V) from 0.05 ppb to 1000 ppm. This Mo-based MOF sensor, when bound with spectroscoptic and paper-based methods, offered exceptionally low limits of detection (LOD) for As(V) ions such as 0.02 and 0.04 ppb, respectively.

Fabricating low-cost and high-efficiency oil-water separation superwetting materials for the demand of oil spilling treatment remains a great challenge. Herein, a superwetting aluminosilicate fiber paper decorated by flower-like nickel-cobalt carbonate hydroxide (NiCo-CH) nanostructures was prepared via the hydrothermal method and chemical modification with stearic acid (SA) or 1H, 1H, 2H, 2H-Perfluoroalkyltriethoxysilane (FAS-17). The superhydrophilic multi-layers nanoflowers combing with nanoflakes were uniformly distributed on the surface of aluminosilicate fiber. The superhydrophilic aluminosilicate fiber was then modified by the SA to obtain the superhydrophobic aluminosilicate fiber (SA-NiCo-CH@Al2SiO5 FP). The SA-NiCo-CH@Al2SiO5 FP revealed high separation efficiency (> 95.4%) for both light oils and heavy oils, and high oil flux (417 L m−2 h−1–71,656 L m−2 h−1). Furthermore, the SA-NiCo-CH@Al2SiO5 FP can also remain superhydrophobicity under various harsh conditions, such as dust, sand impact, acid or alkali, and low-temperature environments. This study revealed an inexpensive and simple-fabricated multifunctional superwetting material, which provides promising avenue for future applications in oil-water separation.

Cobalt-based nanomaterials have received considerable attention in electric energy-storage devices due to their outstanding electrochemical characteristics. However, multiple time- and energy-consuming steps and complex reduction processes for producing cobalt and cobalt oxide nanostructures are disrupting their substantive commercialization. Here, we propose a facile, ultra-fast, and versatile method for the fabrication of cobalt and cobalt oxide nanostructures using an intense pulsed white light (IPWL) photothermal reduction technique. The mechanism of the IPWL photothermal reduction of cobalt and cobalt oxide is firstly studied by measuring the in-situ temperature of the Co(NO3)2-coated carbon fiber paper (CFP) substrate during IPWL irradiation and analyzing the crystal structures of the IPWL-irradiated samples. Cobalt nanoflakes and cobalt oxide nanoparticles are synthesized on the surface of the CFP substrate by irradiating IPWL for 10 ms at ambient temperature and pressure with various energy densities from 10 to 30 J cm−2. The Co3O4 nanoparticle/CFP and Co nanoflake/CFP samples are further utilized as an electrode, and each electrode exhibits high specific capacity of 29 and 73 mA h g−1, respectively, at a current density of 1 A g−1. Since this novel photothermal reduction technique is applicable to other transition metals and metal oxides, it is a promising method for not only energy storage systems, but also for energy generation applications, filters, sensors, and catalysis systems.

We present a high-capacity pseudocapacitor based on a hierarchical network architecture consisting of Co(3)O(4) nanowire network (nanonet) coated on a carbon fiber paper. With this tailored architecture, the electrode shows ideal capacitive behavior (rectangular shape of cyclic voltammograms) and large specific capacitance (1124 F/g) at high charge/discharge rate (25.34 A/g), still retaining ~94% of the capacitance at a much lower rate of 0.25 A/g. The much-improved capacity, rate capability, and cycling stability may be attributed to the unique hierarchical network structures, which improves electron/ion transport, enhances the kinetics of redox reactions, and facilitates facile stress relaxation during cycling.

A new chemosensor 1 was synthesized by reacting rhodamine B hydrazide and 2,3,4-trihydroxybenzaldehyde, which was then characterized by spectroscopic techniques and single crystal X-ray crystallography. Sensor 1 has the ability to sense Co2+/Cu2+ ions by “naked-eye” with an apparent colour change from colourless to pink in different solvent system, MeCN and DMF respectively. Furthermore, it can selectively detect Co2+/Cu2+ among wide range of different metal ions, and it exhibits low detection limit of 4.425 × 10−8 M and 1.398 × 10−7 M respectively. Binding mode of the two complexes were determined to be 1:1 stoichiometry for Co2+ complex and 1:2 stoichiometry for Cu2+ complex through Job’s plot, IR spectroscopy, mass spectrometry and 1H NMR spectroscopy. Moreover, reversibility of the sensor 1 as copper (II) ion detector was determined by using EDTA and the results showed that sensor 1 can be reused for at least 6 cycles. Other than that, a low cost chemosensor test strips were fabricated for the convenient “naked-eye” detection of Co2+ and Cu2+ in pure aqueous media. The MTT assay was conducted in order to determine the cytotoxicity of sensor 1 towards human cell lines.

Catalytic performances of isopropanol combustion and bed pressure drop in structured fixed bed reactor composed of cobalt oxides modified ZSM-5 zeolite membrane catalysts on paper-like stainless steel fibers (Co/ZSM-5/PSSF) and traditional granular ZSM-5 zeolites catalysts were investigated in this paper. Both of the catalyst samples were fabricated by wetness impregnation method and were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectrometer (EDS) mapping and the N 2 adsorption/desorption isotherm analyses. The result of EDS mapping revealed that cobalt oxides dispersed well on ZSM-5/PSSF. The Co/ZSM-5/PSSF catalyst display superior catalytic activity to granular Co/ZSM-5 catalyst, 50% and 90% isopropanol conversion temperatures over Co/ZSM-5/PSSF reduced 107 °C and 51 °C, respectively, compared with those over granular Co/ZSM-5 catalysts. The apparent activation energy for isopropanol combustion over Co/ZSM-5/PSSF (90 kJ/mol) was much lower than that over granular Co/ZSM-5 (134 kJ/mol). When the face velocity increased to 14.9 cm/s, the bed pressure drop of reactor filled with only Co/ZSM-5/PSSF catalysts was 9.5% of that of reactor filled with only granular Co/ZSM-5 catalysts. The ZSM-5 zeolite membrane on paper-like stainless steel fibers support provide good dispersion for cobalt oxides and Co/ZSM-5/PSSF show superior catalytic efficiency of isopropanol combustion and produced lower bed pressure drop in reactor compared with granular ZSM-5 zeolites.

This paper describes the synthesis of novel material and its application to fabricate a sensing tool for the diagnosis of vitamin D deficiency. A simple and economical route for the synthesis of novel composite material based on silver-cobalt (Co-Ag) doped polyaniline-polypyrrole (PANI-PPY) copolymer and ionic liquid (IL) has been described and used as sensing material for vitamin D3 detection. The synthesized composite was characterized using structural, morphological and electrochemical techniques. Co-Ag/PANI-PPY/IL was first used to modify the glassy carbon electrode (GCE) and applied for vitamin D3 detection. Later a conductive ink of the proposed material was prepared and a handmade paper sensor was fabricated. Co-Ag/PANI-PPY/IL@GCE and paper electrode showed excellent electrochemical behavior towards vitamin D3 oxidation within the concentration range of 0.0125–22.5 µM and 0.025–0.125 µM with the acceptable detection limit of 0.0073 µM and 0.015 µM respectively. Co-Ag/PANI-PPY/IL@GCE and paper electrode were successfully applied for the detection of vitamin D3 in serum and urine samples.

The properties of the interlayer and outer layer of Ti/Co/SnO2-Sb2O5 electrode were studied, and the electrochemical behavior was examined as well. As a result of unsatisfactory treatment using Ti/Co/SnO2-Sb2O5 electrode, electrochemical disposal of paper mill wastewater employing three-dimensional electrodes, combining active carbon granules serving as packed bed particle electrodes, with Ti/Co/SnO2-Sb2O5 anode, was performed. The outcome demonstrates that efficient degradation was achieved. The residual dimensionless chemical oxygen demand (COD) concentration reached 0.137, and color removal 75% applying 167 mA cm(-2) current density at pH 11 and 15 g l(-1) NaCl. The instant current efficiency, energy cost, electrochemical oxidation index (EOI) and kinetic constant of the reaction were calculated. At the same time, the influence of pH and current density on COD abatement and decolorization was also investigated, respectively.

The electrochemical oxidation of pulp and paper making wastewater assisted by transition metal (Co, Cu) modified kaolin in a 200 ml electrolytic batch reactor with graphite plate as electrodes was investigated. H(2)O(2), which produced on the surface of porous graphite cathode, would react with the catalysts to form strong oxidant (hydroxyl radicals) that can in turn destroy the pollutants adsorbed on the surface of kaolin. The transition metal (Co, Cu) modified kaolin was also characterized by XRD and SEM before and after the modification and the results showed that the transition metals were completely supported on kaolin and formed a porous structure with big BET surface. The mechanism was proposed on the basis of XPS analysis of the catalyst after the degradation process. Series of experiments were also done to prove the synergetic effect of the combined oxidation system and to find out the optimal operating parameters such as initial pH, current density and amount of catalyst. From the results it can be founded that when the initial pH was at 3, current density was 30 mA cm(-2); catalyst dose was 30 g dm(-3), COD (chemical oxygen demand) removal could reach up to 96.8% in 73 min.

Water splitting associated with the conversion and storage of renewable energy is considered to be the most significant strategy to create hydrogen. Herein, an efficient self-supported electrode was developed by in-situ growth of interlayer expanded lamellar cobalt diselenide (CoSe2) nanosheets (NS) on carbon paper (CP) substrate (CoSe2 NS@CP). The analyses of TEM, SEM and XRD confirmed that the CP is homogeneously coated by few stacking layers of interlayer expanded lamellar structured CoSe2. This rationally designed nanostructure can provide more active sites for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The bifunctional electrode exhibits high electrocatalytic performance with −128 mV vs. RHE onset potential for the HER in 0.5 mol dm−3 H2SO4 and +1521 mV vs. RHE for the OER in 1.0 mol dm−3 KOH. Besides, small electrolysis potentials of −201.1 mV vs. RHE and +1636 mV vs. RHE are needed to drive the HER and OER at current density of 100 mA cm−2. Finally, a small overall cell voltage (ca. +1.75 V) was used to drive the water splitting reaction in 1.0 mol dm−3 KOH. The CoSe2 NS@CP electrode showed both excellent catalytic activity with overall current density of 100 mA cm−2 at 2.13 V and tremendous durability with negligible decrease in potential at a constant current of 20 mA cm−2 for more than 30 hours. Thus this rationally designed electrode material can be readily applied for large-scale water splitting process.

Here, we demonstrate that nonprecious CoFe-based oxide nanoarrays exhibit excellent electrocatalytic activity and superior stability for electrochemical oxygen evolution reaction (OER) at large current densities (>500 mA cm-2). Carbon fiber paper (CFP) with three-dimensional macroporous structure, excellent corrosion resistance, and high electrical properties is used as the support material to prevent surface passivation during the long-term process of OER. Through a facile method of hydrothermal synthesis and thermal treatment, vertically aligned arrays of spinel Co xFe3- xO4 nanostructures are homogeneously grown on CFP. The morphology and the Fe-doping content of the CoFe oxide nanoarrays can be controlled by the Fe3+ concentration in the precursor solution. The arrays of CoFe oxide nanosheets (NSs) grown on CFP (Co2.3Fe0.7O4-NSs/CFP) deliver lower Tafel slope (34.3 mV dec-1) than CoFe oxide nanowire (NW) arrays grown on CFP (Co2.7Fe0.3O4-NWs/CFP) in alkaline solution, owing to higher Fe-doping content and larger effective specific surface area. The Co2.3Fe0.7O4-NSs/CFP electrode exhibits excellent stability for OER at large current densities in alkaline solution. Moreover, the morphology and structure of CoFeO nanoarrays are well preserved after long-term testing, indicating the high stability for OER.

The high-energy Li S battery suffers from poor cycling performance due to the shuttle effect of the polysulfides. Strategies must be adopted to suppress the diffusion of polysulfides into the electrolyte in Li S battery. In this work, for the first time, we adopt hydrophilic carbon paper anchored by hierarchically porous cobalt disulfides as the interlayer for capturing polysulfides through physical absorption and chemical bonding. Hierarchical pores can physically adsorb polysulfides, and moreover cobalt disulfide can trap the polysulfides by forming strong chemical interaction. The sulfur-graphene composite with a sulfur content of 70.5% delivers a high initial capacity of 1239.5 mAh g−1 at 0.2 C and retains a reversible capacity of 818 mAh g−1 after 200 cycles. In spite of a little capacity contribution by the insertion of lithium ions into cobalt disulfide for the initial cycles, it disappears in the subsequent cycling. Therefore, the as-developed porous transition metal disulfides on carbon paper as the interlayer could significantly enhance the cycling performance of Li S batteries.

The self-standing electrode materials with large surface area and high electronic conductivity have attracted intensive attention in energy storage devices. Herein, the expanded graphite paper (EGP) is fabricated via a controlled cathodic expansion in acetonitrile with tetrabutylammonium bromide at 10 V. The as-prepared EGP exhibits a three-dimensional porous structure with large specific surface area and high electronic conductivity, which is a favorable support for in situ growing nickel cobalt carbonate hydroxide (NiCo-CH) nanowires via a simple hydrothermal method. The as-prepared NiCo-CH@EGP composite achieves high areal capacity of 2.55 C cm−2 at 0.5 mA cm−2, and still remains 1.38 C cm−2 even at 60 mA cm−2. The assembled NiCo-CH@EGP//activated carbon asymmetric supercapacitor exhibits the maximum energy density of 0.30 mWh cm−2 at a power density of 0.92 mW cm−2, and a suitable cyclic stability with the capacity retention of 78.1 % after 10,000 cycles at 20 mA cm−2. The results indicate that the self-standing NiCo-CH@EGP is a potential electrode material for energy storage devices.

Cobalt telluride branched nanostructures on carbon fiber paper (CFP) with two different morphologies were synthesized via solution-based conversion reaction. Both the CoTe2 with nanodendrite and CoTe with nanosheet morphologies on the CoTe2 nanotube (CoTe2 NDs/CoTe2 NTs and CoTe NSs/CoTe2 NTs) supported by CFP exhibit high activities toward hydrogen evolution reaction (HER). Particularly, the CoTe NSs/CoTe2 NTs only require an overpotential of 230.0 mV to deliver the current density of 100 mA cm(-2) in acid solution. After cycling for 5000 cycles or 20 h continual electrolysis, only a small performance loss is observed.

Paper folding techniques are used in order to compact a Li-ion battery and increase its energy per footprint area. Full cells were prepared using Li4Ti5O12 and LiCoO2 powders deposited onto current collectors consisting of paper coated with carbon nanotubes. Folded cells showed higher areal capacities compared to the planar versions with a 5 × 5 cell folded using the Miura-ori pattern displaying a ∼14× increase in areal energy density.

Catalytic co-pyrolysis of biomass and plastics (HDPE (high density polyethylene), PP (polypropylene) and PET (polyethylene terephthalate)) has been performed in a fixed-bed reactor in presence of cobalt based alumina, ceria and ceria-alumina catalysts to analyze the product distribution and selectivity. Catalysts are synthesized using co-precipitation method and characterized by BET (Brunauer-Emmett-Teller) surface area and XRD analysis. The effect of catalytic co-pyrolysis at different temperature with product distribution has been evaluated. The results have clearly shown the synergistic effect between biomass and plastics, the liquid products gradually increases forming with rise in the plastic content in the blend. Gaseous products have yielded most during pyrolysis of blend having biomass/plastics ratio of 5:1 with the presence of 40% Co/30% CeO2/30% Al2O3 catalyst with hydrogen gas production touched its peak of 47 vol%. Catalytic performance enhanced with increase with the cobalt loading, with best performance attributing to 40% Co/30% CeO2/30% Al2O3 catalyst. (C) 2016 Elsevier Ltd. All rights reserved.

A novel and binder free Co@graphite/paper electrode is prepared by electrodeposition Co nano-sheet on the surface of a graphite layer modified paper substrate. The morphology and phase structure of the Co@graphite/paper electrode are characterized by scanning electron microscopy equipped with energy dispersive X-ray spectrometer, transmission electron microscope and X-ray diffractometer. The catalytic activity of the Co@graphite/paper electrode for H 2 O 2 electrooxidation is investigated by means of cyclic voltammetry and chronoamperometry. The catalyst combines tightly with the paper and exhibits a good stability. The oxidation current density reaches to 580 mA cm −2 in 2 mol dm −3 NaOH and 0.5 mol dm −3 H 2 O 2 at 0.5 V. Besides, we illustrate the reaction mechanization of the H 2 O 2 electrooxidation on the Co film.

A low-cost and binder-free cobalt electrode is prepared by the electrodeposition of Co nanoplates onto a flexible conductive substrate, which is prepared simply by scratching a piece of A4 paper with a common 8B pencil. The morphology and phase structure of the cobalt–graphite–paper (CGP) electrode are characterized by scanning electron microscopy, transmission electron microscopy and an X-ray diffractometer. The catalytic activity of the CGP electrode for NaBH4 electro-oxidation is investigated by cyclic voltammetry and chronoamperometry. The catalyst combines tightly with the paper and exhibits a good stability. The oxidation current density reaches up to 180 mA cm−2 in 1 mol dm−3 NaOH and 0.10 mol dm−3 NaBH4 at −0.4 V.