Redox flow battery (RFB) has received tremendous attention as energy storage system coupled with renewable energy sources. In this paper, a low-cost alizarin red S (ARS) organic dye is proposed to serve as the active material for the negative electrode reaction for organic redox flow batteries. Cyclic voltammetry has been conducted under a number of operating conditions to reveal the electrochemical performance of this molecule. The results suggest that ARS is highly reversible at low electrode potential (c.a. 0.082 V vs. standard hydrogen electrode), indicating that ARS is a promising negative electrode material for organic redox flow batteries. The diffusion coefficient of ARS is calculated in the range of 6.424 x 10-4 cm2 s-1, This has indicated fast diffusion rate and electrochemical kinetics for oxidation and reduction in higher concentration of ARS. It has been found out that the higher concentration of ARS in base electrolyte cause lowest diffusion coefficient due to solubility issue of ARS.

In the last few years, low molecular organogels (LMWG) have attracted much interest due to their unique properties, including high adsorption capacity, high specific surface area, high porosity and rich functional groups binding with other guest species. LMWG based materials have wide applications in various field, such as separation technologies, tissue engineering, sensors, catalysis [1-4]. LMWGs are usually obtained by self-assembly of low molecular(typically with a molecular weight < 1000 Da)weight gelators in organic solvents or in water, to form fibrous structure through non-covalent interactions such as hydrogen bonding, π-π stacking, metal coordination, coulomb forces, and van der Waals interactions[5] . C2-symmetric benzene-based hydrogel (C2-BHG) is a new type of LMWGs with a 1,4-dimine benzene as the symmetric structure which can provide strong parallel interactions between hydrogen-bonding amide moieties. The C2-BHG has been used as an adsorbent to remove the toxic materials due to its strong adsorption ability [5]. The C2-BNG can self-assemble on many surfaces to form fibrous network structure through the π–π stacking between the adjacent phenyl groups or hydrogen bonding. In this report, the C2-BHG modified glassy carbon electrode (C2-BHG/GCE) was fabricated by self assembly at a suitable assembly temperature. The gelation and self-assembly of C2-GHB can occur simultaneously on the carbon surface with a uniform film thickness. The film properties were studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in the presence of redox probes. The morphology of C2-GHB-modified layer was characterized by atomic force microscopy (AFM). The porous membrane structure with a high surface area could provide rich active sites to interact with the target substance. In addition, the C2-GHB-modified layer contains a large amount of hydroxyl group on the hydrophilic chain. The sensing properties of the C2-BHG/GCE to Cu(II) ions were investigated with sensitive response. Under the optimized conditions (such as preconcentration time, preconcentration potential and electrolyte type), the linear range of Cu(II) ions was determined between 1ppt-800ppt and 1ppb-100ppb, with a detection limit down to 0.5 ppt. The complex interaction of C2-BHG with Cu2+ was confirmed by UV-Vis characterization. As a new kind of low molecular organogel modifier, C2-GHB is a promising material in the development of a new type of chemical modified electrode for sensor application. References [1] Tian Y, Zhang L, Duan P, et al. Fabrication of organogels composed from carbon nanotubes through a supramolecular approach. New Journal of Chemistry, 2010, 34(12): 2847-2852. [2] Ono Y, Nakashima K, Sano M, et al. Organic gels are useful as a template for the preparation of hollow fiber silica[J]. Chemical Commununications, 1998 (14): 1477-1478. [3] Li Y, Liu M. Fabrication of chiral silver nanoparticles and chiral nanoparticulate film via organogel. Chemical Commununications,, 2008 (43): 5571-5573. [4] Motulsky A, Lafleur M, Couffin-Hoarau A C, et al. Characterization and biocompatibility of organogels based on L-alanine for parenteral drug delivery implants. Biomaterials, 2005, 26(31): 6242-6253. [5] Dou X, Li P, Zhang D, et al. C2-symmetric benzene-based hydrogels with unique layered structures for controllable organic dye adsorption. Soft Matter, 2012, 8(11): 3231-3238.