Oxygen reduction reaction (ORR) is an important electrochemical reaction in fuel cells (FCs). Until now, Pt and its alloys are still the best materials for ORR. However, the problem lies on how to prepare a high- performance catalyst with the lowest usage of Pt. Metal organic frameworks (MOFs) that represented by Zeolitic imidazolate framework(ZIFs) have been used as precursors for efficient transition metal-nitrogen- carbon (M-N-C, M=Fe, Co, Mn, et. al) catalysts ORR catalysts. However, these catalysts are generally reported to suffer from poor activity. In this paper, a low Pt catalyst Pt-NC-900 was synthesized by dispersing Pt on cubic ZIF-8 with highly usage for Pt. Cetyltrimethylammonium bromide (CTAB) was used to control synthesize cubic ZIF-8 in the aqueous phase. This synthesis method was a green process because no methanol was required. As synthesized ZIF-8 displayed a large specific surface area of 1870 m2/g. Subsequently, Pt was loaded on the carbon support with high pyridinic N content that obtained through heat treatment atmosphere and temperature optimization. The sample was treated under N2 atmosphere at 900â„ƒ to obtain Pt-NC-900. It showed an optimal electrochemical performance with a half-wave potential (E1/2) of 0.84 V, which is 10 mV higher than Pt/C20% catalyst. and the Pt-NC-900 also showed a higher mass activity (0.207 A/mgPt) than Pt/C20%. The excellent ORR performance could be attributed to the Pt active centers, large specific surface area, rich pore structure, and high pyridinic-N content.
Keywords low Pt; oxygen reduction reaction; metal organic framework; catalyst