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Developing low-cost electrocatalysts for the nitrate reduction reaction (NO3RR) with superior performance is of great significance for wastewater treatment. Herein, we synthesized bimetal Cu/Fe nanoparticles encased in N-doped carbon nanofibers (Cu/Fe@NCNFs) through simple electrospinning followed by a pyrolysis reduction strategy. Metallic copper is beneficial for reducing nitrate to nitrite, and the existence of Fe is conducive to convert nitrate and nitrite into nitrogen. Additionally, the nitrogen-doped carbon nanofibers also facilitate the adsorption of nitrate, and the continuous and complete fiber structure enhances the stability of the catalyst and prevents the corrosion of the active sites. Therefore, the synergetic effect of bimetal Cu/Fe and N-doped carbon fiber plays a key role in promoting the efficiency of nitrate reduction. The obtained Cu/Fe@NCNF catalyst exhibits a satisfactory nitrate conversion efficiency of 76%, removal capacity of 5686 mg N g-1 Cu/Fe and nitrogen selectivity of 94%.

A novel, stable and sensitive non-enzymatic glucose sensor was developed by potentiostatically electrodepositing metallic Cu nanoparticles on a linear graphene edge nanoelectrode (Cu–GNE). The electrochemical performance of the Cu–GNE for the detection of glucose was investigated by cyclic voltammetry and chronoamperometry. The Cu–GNE displayed a synergistic effect of copper nanoparticles and the edge plane of the graphene sheet towards the oxidation of glucose in alkaline solution, showing a large oxidation current and negative shift in peak potential. At a detection potential of 0.5 V, the Cu–GNE sensor exhibited a wide linear range up to 1 mM glucose, with a detection limit of 0.12 μM (S/N = 3). In addition, the sensor responded very quickly (

As ionic liquid analogues or quasi-ionic liquids, deep eutectic solvents (DESs) have been applied in many fields in the past few years. Herein, a novel PEGylated DES composed of PEG 200 and thiourea was formed for the first time and used for solvothermal synthesis of nickel cobalt sulfides. The structure and composition of the as-synthesized sulfides can be tuned by adjustment of the ratio of the reactants. The PEGylated DES plays multiple roles as a solvent, a shape-control agent, and a sulfur source in the synthesis of sulfides. Compared with traditional sulfuration routes, this proposed route is cost-effective and energy-efficient by combining solvothermal synthesis and the sulfuration process. The prepared sulfides were used as catalysts for electrochemical water oxidation and they exhibited excellent oxygen evolution reaction (OER) performance, especially for NiCo2S4 with hierarchical pores. The overpotential (η) demand was 337 mV for the current density reaching 10 mA cm−2 and the Tafel slope was 64 mV dec−1 in an alkaline medium (1 M KOH) for NiCo2S4. In addition, NiCo2S4 demonstrated long-term stability with little deactivation after either thirty hours of continuous operation or two thousand cycles and a high faradaic efficiency of 95.8%. Synergistic effects including a relatively high Brunauer–Emmett–Teller area, abundant active sites, easy diffusion of electrolytes and oxygen gas, and strong structural integrity contribute to the high activity and long-term stability of the catalyst for OER. This study provides a new method for the synthesis of hierarchically structured metal sulfides for energy conversion and storage applications.

A graphene platform electrode (GPE) was prepared directly by transferring chemical vapor deposited (CVD) graphene films from Cu foils to polyethylene terephthalate substrates with the aid of polymethyl-methacrylate, a distinct advantage over previously developed methods. L-Cysteine (L-Cys) was polymerized on the GPE by using a one-step electrodeposition technique to form a poly-L-Cys/GPE. As a negatively charged polymer, the poly-L-Cys could adsorb positively charged dopamine (DA) and repel negatively charged ascorbic acid (AA) under optimum conditions. As a result, a novel electrochemical sensor for the simultaneous determination of DA and AA was developed. The electrochemical behaviors of DA and AA were investigated by cyclic voltammetry. Differential pulse voltammetry was used for determining DA and AA in their mixture, where the separation between oxidation peak potentials of DA and AA was about 163 mV. The broad linear responses to DA and AA were determined by chronoamperometry, which were 0.2 to 423 μM and 1 to 580 μM with detection limits (S/N = 3) of 0.0531 μM and 0.2031 μM, respectively. In addition, the as-obtained sensor delivered good stability as well as high resistance to interference, and was successfully utilized in determining real samples. Consequently, the poly-L-Cys/GPE could be considered as a new promising DA and AA sensor, strongly indicating that CVD graphene could be used successfully as a material in electrochemistry.

The rational design and construction of carbon nanostructures, particularly those assembled from carbon nanotubes (CNTs) and graphene because of their superior synergistic advantages, are of significance for the development of metal-free electrocatalysts with low cost and high activity in energy conversion and storage fields. Herein, we report a highly efficient oxygen reduction reaction (ORR) catalyst based on a three dimensional nitrogen-doped CNTs–holey graphene framework (N-CNTs–HGF) formed by the in situ, precisely positioned growth of nitrogen-doped CNTs on the holey-edges of porous graphene sheets. Benefiting from the unique hierarchical structure of CNTs and graphene with the merits of fast charge and mass transport along the interfaces of holes, the resultant catalyst exhibits superior capability towards catalyzing oxygen reduction, which affords a positive onset potential of 1.08 V vs. RHE, small Tafel slope of 72 mV dec−1 and half-peak potential of 0.85 V vs. RHE. Furthermore, its potential practical application is also evidenced by simply integrating it into an all-solid-state Zn–air battery.

Intramolecular photoinduced charge-separation and charge-recombination processes in two C60-spacer-TTF dyads, in which C60 and TTF (tetrathiafulvalene) are connected through a flexible spacer of different lengths, have been investigated in polar solvents by time-resolved absorption and fluorescence techniques. Weak interaction between the C60-moiety and TTF-moiety in the ground state was suggested by the steady-state absorption spectra; the dyad with the shorter spacer shows slightly stronger interaction than that with the longer spacer. The observed short fluorescence lifetimes of these dyads, compared with that of their precursor fullerene derivative in THF and benzonitrile indicate that the charge separation takes place via the singlet excited state of the C60-moiety, producing the ion pairs (C60˙−-spacer-TTF˙+) as shown from the transient absorption spectra in the 800–1100 nm region. In polar benzonitrile solvent, the ion-pair state with the long flexible chain shows longer lifetime than that with the short chain, suggesting that weaker interaction between C60 and TTF moieties is preferred to the long ion-pair lifetime. These observations were compared with other reported data for C60-TTF dyads.

The urgent need for sustainable energy development depends on the progress of green technologies, which have steered hot research areas into environmentally benign approaches via inexpensive precursors and abundant resources obtained directly from nature for energy devices such as fuel cells and supercapacitors. By using fermented rice as starting materials, we herein demonstrate a facile, green and scalable approach to synthesize porous N-doped carbon spheres characterised by high specific surface areas (2105.9 m2 g−1) and high porosity (1.14 cm3 g−1), which exhibit not only excellent electrocatalytic activity toward the four-electron oxygen reduction reaction with long-term stability for fuel cells, but also have excellent resistance to crossover effects and CO poisoning superior to that of the commercial Pt/C catalyst. Furthermore, the naturally derived porous N-doped carbon spheres, used as the active electrode materials, present superior performance for capacitors with a capacitance of 219 F g−1 at a high discharge current density of 15 A g−1 and good cycling stability for over 4400 cycles. This work shows a good example for taking advantage of the abundant resources provided by nature, and opening the door for the creation of functional materials with promising applications in high-performance renewable devices related to energy conversion and storage.

A simple but effective method has been developed to controllably extract carbon nanotubes (CNTs) from their vertically aligned arrays on growth substrates. The intrinsic micron-scale roughness of the CNT surface enables the protruding nanotubes to make good contact with an adhesive layer which can then remove them from the array on the growth substrate. This approach allows us to manage and tailor the surface morphologies and related surface properties of CNT arrays. The patterned structure of CNT arrays with region-selective control over the density has been achieved. The ability of this process to tailor spacing between vertically aligned CNTs, as demonstrated, opens a new pathway to fabricate the CNT nanoelectrode arrays for applications in electroanalysis.