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Low energy storage performance of aqueous flow batteries is the main limitation in commercialization and worldwide implementation. The effect of nanofluids on the electrochemical behaviour of electrolytes to alleviate this problem has been rarely studied in contrast with the extensive heat-transfer-related literature on nanofluids from the field of thermal science. Therefore, this study aims to experimentally investigate the long-term effect of using reduced graphene oxide (rGO) nanofluidic electrolyte on vanadium redox flow battery performance, placing it amongst the very few studies on the effectiveness of nanofluids in flow batteries. Scanning Electron Microscopy (SEM), EDS elemental mapping, X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) characterizations reveal changes in morphology, structural and elemental properties of the carbon felt electrodes due to the presence of suspended nano catalysts in the electrolyte. Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) exhibited significant improvements of 36 % and 26 % in oxidation/reduction peaks, ~ 95 % of reduction in charge transfer resistance, and enhanced redox reactions reversibility of the optimum concentration of nanofluidic electrolyte (0.1 wt%). Moreover, active surface area of the electrodes were determined to be increased by ~130 % and ~ 135 % for positive and negative 1.0 wt% nanofluid-affected electrode samples compared to pure electrolyte-affected electrode. In addition, considering the optimum nanoparticle concentration of 0.1 wt%, charge, and discharge capacities of the flow battery outperformed where pure electrolyte was applied in different current densities. These enhancements show considerable increase in energy storage of the VRFB. Furthermore, energy efficiency and voltage efficiency of the flow cell were observed to be increased respectively by 15 % to 24 % and 8 % to ~21 % for the current densities from 25 to 150 mAcm−2when the optimum concentration of nanoparticles was applied. This study gives new insight into the rarely studied applicability of nanofluids in vanadium flow batteries.

•Newly developed nanofluid electrolyte which significantly enhanced anodic and cathodic peaks•Reversibility of the electrochemical reactions was improved in the proposed nanofluid electrolyte•The diffusivity of the ions was improved using the nanofluid electrolyte•Charge resistance of the nanofluid electrolyte in different concentrations was significantly decreased

•The effect of nanofluid stability and synthesizing methods on the performance of PV/T was evaluated.•The effect of flow regime in different types of nanofluids on PV/T system was assessed.•Energy and exergy analysis by considering each preparation method was conducted.•The maximum efficiencies were obtained from turbulent flow regime and one-step method prepared nanofluid.•EEW method as the one-step procedure in this study showed excellent stability for a longer time than that using ultrasonication process.

Financial Technology (FinTech) is a combination of Internet-based technology and the existing financial services. FinTech is an innovation that aims at competing with traditional financial methods in the delivery of financial services. FinTech is an excellent example of Industrial Integration and Innovation. Currently, FinTech is changing the traditional financial services and will have a significant impact on financial operations on a global scale. Iranian Fintech market, as a part of Western Asian Fintech market, can be considered as a growing new market. This research introduces the Iranian FinTech development trend as well as the existing barriers and challenges.