▎ 摘　　要

Fuel cells which use hydrogen peroxide as oxidant have been widely studied and presents good development foreground. As a liquid fuel, H2O2 possesses advantages of easily storage and transportation which make it can be widely used in underwater and space as a power source. At present, the most widely used catalysts for H2O2 electroreduction are noble metal catalysts. Compared with noble metals, transition metal oxides possess advantages of low cost and extensive sources. However, the catalytic activity of transition metal oxides is still much lower than noble metals. Therefore, many efforts should be made to improve the electrochemical performance of transition metal oxides. In this work, rGO is used as an additive to improve the electrochemcial performance of MnO2. An original electrode of MnO2 in-situ supported on reduced graphene oxide modified Ni foam (MnO2/rGO@Ni foam) is prepared through two-step hydrothermal methods. Primarily, the novel current collector of rGO@Ni foam is obtained with larger surface area which is beneficial to the next loading of MnO2. Secondly, MnO2 is grown on the rGO@Ni foam also by a hydrothermal treatment. Besides large surface area, the addition of rGO can provide more channels for electron transfer and then accelerate the reaction rate of H2O2 reduction. The morphology and phase composition of the as-prepared electrode are investigated by measurements of X-ray diffractometer (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM). It can be concluded from SEM and TEM images, both rGO and MnO2 exhibit sheet-like structure and there are many gaps existing between these sheets. Especially, the as-prepared MnO2 nanosheets builds a honeycomb structure which makes positive effects on the contact between H2O2 and catalyst. And XRD and HRTEM results show that MnO2 and rGO are successfully prepared on Ni foam. The electrochemical performance of the MnO2/rGO@Ni foam electrode toward H2O2 reduction is investigated by cyclic voltammetry and chronoamperometry in a three-electrode system in solutions of NaOH and H2O2. Results reveal that the reduction current density of H2O2 reduction on the MnO2/rGO@Ni foam electrode reaches 240 mA/cm(2) in a solution of 1.0 mol/L H2O2 and 3 mol/L NaOH at -0.8 V which is much higher than that on MnO2 directly supported on Ni foam (MnO2@Ni foam). At the same time, a better stability is also achieved on the MnO2/rGO@Ni foam electrode. Generally speaking, the addition of rGO highly improves the electrocatalytic activity and stability of the as-prepared electrode indicating great application prospect in the future.