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Iron-chromium redox flow batteries (ICRFBs) have the advantages of high safety, long cycle life, flexible design, and low maintenance costs. Polyacrylonitrile-based graphite felt composite material has good temperature resistance, corrosion resistance, large surface area and excellent electrical conductivity, and is often used as the electrode material of ICRFB, but its chemical activity is poor. In order to improve the activity of the graphite felt electrode, In3+ was used for modification in this paper, and the modified graphite felt was used as the electrode material for iron-chromium batteries. The structure and surface morphology of the modified graphite felt were analyzed by the specific surface area analyzer and scanning electron microscope; the electrochemical impedance spectroscopy and cyclic voltammetry experiments were carried out on the electrochemical workstation to study the electro catalytic activity of In3+ modified graphite felt and its performance in ICRFBS. The results show that the graphite felt electrode modified with a concentration of 0.2 M In3+ was activated at 400°C for 2 h, and its surface showed a lot of grooves, and the specific surface area reached 3.889 m2/g, while the specific surface area of the untreated graphite felt was only 0.995 m2/g significantly improved. Electrochemical tests show that the electrochemical properties of graphite felt electrodes are improved after In3+ modification. Therefore, the In3+ modified graphite felt electrode can improve the performance of ICRFB battery, and also make it possible to realize the engineering application of ICRFB battery.

Iron-chromium redox flow battery（ICRFB） is a secondary battery capable of deep charge and discharge. It is a novel electrochemistric equipment for energy storage. ICRFB has around wide concern as it possesses advanced characteristics such as high energy, long cycle life, and environmental friendly. Graphite felt is a common electrode material for ICRFB because of its high temperature resistance, corrosion resistance, infinite specific surface area, and admirable electroconductibility. However, poor hydrophilicity and electrochemical activity lead to the graphite felt to be modified to be better applied in ICRFB. To improve the electrochemical activity of graphite felt, the PAN-based graphite felt was activated by boric acid thermal etching, and tested with SEM analysis, electrochemical analysis, and charge-discharge test. The results showed that the electrochemical activity and reversibility of boric acid thermal etching graphite felt impregnated with 25% boric acid solution were significantly improved after thermal treatment at 500℃ for 5 hours. The Energy Efficiency of boric acid thermal etching graphite felt impregnated with 25% boric acid solution in ICRFB could reach more than 85%, which was about 9.5% higher than that of ICRFB with untreated graphite felt (1#) as electrode.

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ZIF-67@Ta2O5 graded hetero-structure material was designed and prepared using F-Ta2O5 as a raw material and Zeolite imidazole ester(ZIF-67) as framework structure material. The hetero-structure Ta2O5 and ZIF-67@Ta2O5 were annealing 6 hours at 900°C in nitrogen ambience. The photolysis properties of the Ta2O5 and ZIF-67@Ta2O5 materials as catalysts for photocatalytic decomposition of water to hydrogen were characterized. The results show that the heterogeneous composite structure formed by cobalt-tantalum oxide and tantalum pentoxide can significantly improve the hydrogen production performance of tantalum pentoxide samples, and the properties of samples obtained under nitrogen atmosphere are better. Among them, the N-50 sample (F-Ta2O5 is 50mg, Cobalt nitrate dosage is 6ml, annealing 6 hours at 900°C in nitrogen ambience) has the best hydrogen production performance, and the hydrogen production rate is 116μmol/g/h.