Description
Date/Time: 04-04-2018 - Wednesday - 05:00 PM - 07:00 PM
Bahareh Golrokh Amin1 Jahangir Masud1 Manashi Nath1

1, Missouri Science and Technology, Rolla, Missouri, United States

During the last decade, the quest for a durable, highly efficient, sustainable, nonprecious metal based electrocatalyst for water splitting with minimal environmental impact has intensified. In that regards, chalcogenide electrocatalysts have recently made a promising impact based on their high activity towards oxygen evolution reaction (OER), one of the major roadblocks towards overall water splitting. In this presentation we will discuss the electrocatalytic activity of ternary CoNi2Se4 nanoflakes, with special emphasis on the effect of anion coordination, crystal structure and morphology on the OER catalytic activity. Ternary CoNi2Se4 was prepared by direct electrodeposition on carbon fiber paper (CFP) and gold coated glass (Au/glass) electrodes. Such electrodeposition directly on the electrodes produces a binder-free film which can utilize full potential of the catalyst. CoNi2Se4 crystallizes in a vacancy-ordered spinel structure type. Through detailed XPS analysis it was determined that the as-deposited film contains Ni in the +3 oxidation state. This is very important since it has been known that Ni3+ is the actual catalytically active species for OER in alkaline medium, and in Ni-based electrocatalysts, Ni3+ is generated through oxidation of Ni2+ visible as a pre-oxidation peak. Having Ni3+ is the as-synthesized catalyst expectedly can reduce the onset potential for OER activity. Detailed electrochemical studies showed that CoNi2Se4 on CFP needs an overpotential of only 160 mV to reach 10 mA cm-2 for OER, which is one of the lowest overpotentials reported thus far. Moreover, this catalyst was also active for hydrogen evolution reaction (HER) in the same medium, showing an overpotential of only 220 mV to deliver 10 mA cm-2. This bifunctional catalyst could eventually split water delivering a current density of 10 mA cm-2 at a very low cell voltage of 1.61 V in 1.0 M KOH. Through detailed SEM, XPS, pxrd, EDS, and TEM studies, we have shown that the composition of the catalyst remains unaltered even after prolonged periods of catalytic activity under conditions of OER. The functional stability of the catalyst was also measured through chronoamperometric studies. In this presentation we will discuss the OER and HER catalytic activity of CoNi2Se4 nanoflakes along with establishing the compositional and functional stability under conditions of continuous OER/HER.

Meeting Program
poster-icon

5:00 PM–7:00 PM Apr 4, 2018 (America - Denver)

PCC North, 300 Level, Exhibit Hall C-E