Preparation Of Non-Precious Metal Electriccatalyst And Their Oxygen Reduction/Evolution Preformance

Li-air battery, which has high theoretical specific energy and is environment friendly has become a new hotspot in the field of energy storage and conversion technology. However, the core reactions of secondary Li-air batteries are the oxygen reduction reaction （ORR） and the oxygen evolution reaction （OER）, and ORR and OER are kinetically sluggish, leading to Li-air battery at present can not meet the requirements of actual use. Therefore, it is vital to develop bifunctional electic catalyst with low price and excellent property to improve the performance of Li-air battery, thus meeting the actual application requirements.In this paper, graphite oxide was modified and reducted by a hydrothermal method, and the effect of glucose and polyethylene glycol on the OER/ORR of modified graphite oxide is studied. And the result showed the less glucose and polyethylene glycol, the higher the degree of reduction of graphite oxide, and the better OER and ORR catalytic activity. N-rGO-15 with 13% glucose and polyethylene glycol has a good OER/ORR catalytic activity relatively, its OER current density is 0.91 mA·cm^-2 at 0.8 V （vs. Ag/AgCl） and the ORR onset potentials is -0.117 V.Co-Mn layered double hydroxides （Co-Mn-LDHs） intercalated by different anions (Cl-, Mo₇O₂₄^6-and C₂₄H₃₉O_5-) were prepared by co-precipitation. Among them, Co-Mn-LDHSs intercalated by Cl- has the best ORR activity and the best bifunctional catalysis acticity. Its ORR onset potentials and AE （the gap （AE=Ej=10-Ej=-3） between the Ej=10 （the potential at 10 mA/cm² in OER） and Ej=-3 （the potential at -3 mA/cm² in ORR） is an important metric for evaluating the overall bifunctional activity） is-0.16 V and 1.13 V. Co-Mn-LDHs intercalated by Mo₇O₂₄ has the best OER activity, its OER current density at 0.8 V （vs. Ag/AgCl） is 35.5 mA·cm^-2.In view of the excellent conductivity of graphite oxide and the excellent catalytic activity of cobalt and manganese oxide, a series of Co₃O₄-MnCo₂O₄/rGO nanocomposite with different graphite oxide content were synthesized by a hydrothermal method. The results showed that the crystalline structure of the sample was MnCo₂O₄ without GO, the crystalline structure of the sample is Co₃O₄-MnCo₂O₄ composite structure after adding GO. Co₃O₄-MnCo₂O₄/rGO composites have a good ORR/OER bifunctional electric catalytic performance in alkaline electrolyte. Furthermore the catalytic performance is related to N content, Co²⁺/Co³⁺ratio, Mn³⁺/Mn⁴⁺ratio and the interaction between rGO and the oxides. MCO/20rGO with 20 wt% GO has the best ORR/OER bifunctional electric catalytic performance in MCO/rGO composites. Its OER current density at 0.8 V （vs. Ag/AgCl） is up to 35.5 mA·cm^-2, its onset potentials and △E is -0.03 V and 0.91 V.