Reduced Graphene Oxide and Pd Nanocomposite as a Catalyst for Oxygen Reduction Reaction in Rechargeable Li-Oxygen Battery

摘要

abstract_textpPd+2 ions are reduced on two-dimensional reduced graphene oxide nanosheets in aqueous phase by NaBH4 as reducing agent. Pd nanoparticles are uniformly grown on graphene sheets in 5-15 nm range, verified by TEM investigation. Oxygen reduction reaction (ORR) is carried in nonaqueous medium by using rotating disk electrode technique. For comparison, ORR activity of pure RGO is also studied; ORR follows one e- pathway (O-2 + e-=O2-) in non-aqueous electrolyte. Pd-RGO has ORR activity five times more as compared to pure RGO in 0.10 M TBAP-DMSO solution. Pd-RGO catalyst is used to assemble the non-aqueous Li-O-2 batteries and charge-discharge cycling is carried out. At 0.20 mA cm-2 the discharge capacity of 8192 mAh g-1 is obtained. Overpotential for ORR (or discharge) step is 260 mV. This is first report on reaction chemistry in Li-O-2 battery using Pd nanoparticles. Li2O2 and Li2O are confirmed as discharged products by ex-situ XRD studies./p/abstract_text