Monday, 14 May 2018
Ballroom 6ABC (Washington State Convention Center)
Solar-chemical production inspired from nature has attracted substantial attention due to a need for developing sustainable future energy as well as chemical resources. Water oxidation catalyst is a vital element for achieving photoelectrochemical solar-chemical production system. In this study, we demonstrate a highly efficient and scalable water oxidation (OER) catalyst electrode using low cost and earth abundant material, stainless steel (SS). Since surface modification of SS is facile in conjunction with the segregation phenomena of added elements from the iron matrix by thermal or electrochemical treatments we applied two ways to synthesize active OER catalyst electrodes. First, Ni-rich cratered structures were spontaneously formed on the SS surface by harsh electro-oxidation. The chemical composition changes of Fe and Ni on the catalyst surface dramatically was found to enhance water oxidation activity showing an overpotential value of 504 mV at 10 mA/cm2 in a CO2-saturated bicarbonate electrolyte. Active SS surface was also synthesized by a sulfide precursor layer formation by sulfurization followed by its removal by an electro-oxidation process. Interestingly, a newly exposed catalytic layer after eliminating the Fe-S overlayer has a nanoporous structure with changed elemental composition, resulting in a significant improvement in OER performance with an overpotential value of 265 mV at current density of 10 mA/cm2 in alkaline electrolyte condition. The details of the synthetic method and characterization of OER catalyst electrodes will be discussed in the presentation.