Chun-Yu Lin1 Zhenhai Xia1

1, Materials Science and Engineering, University of North Texas, Denton, Texas, United States

Clean energy technologies such as fuel cells, rechargeable metal-air batteries, and water splitting, are promising for future energy sources owning to their nature of no pollution and greenhouse gas emission. The key reactions in this technologies are the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) that generate power. The state-of-the-art electrocatalyst in OER is RuO2 and in ORR is Pt, but their high cost and poor durability hindered their application in clean energy technologies. Zeolitic imidazolate frameworks (ZIFs), a subclass of metal organic frameworks (MOFs), mainly composed of a transition metal (TM) center and organic ligands, exhibits the excellent ability as electrochemical catalysts in clean energy conversion and storage. However, their ligand or coordination of metal ions must be modified to enhance their catalytic activities. To rationally design the ZIF catalysts, we have calculated the OER and ORR activities of TM-ZIFs and found an intrinsic descriptor which can describe the catalytic activities of the TM-ZIFs by density-functional theory (DFT) method. Our DFT calculations show that the unsaturated metal sites show high catalytic activities comparable to that of RuO2 / Pt electrocatalyst. This theoretical result was confirmed by the experiment.