The Joint Center for Artificial Photosynthesis (JCAP) is DOE supported Solar Hub collocated at the California Institute of Technology and the Lawrence Berkeley National Laboratory. The aim of the JCAP is to undertake research aimed at the development of technology for the large-scale generation of hydrogen by the photo-electrochemical splitting of water with the option to use the hydrogen generated in this manner to produce liquid fuels. Work in our group has established that electrocatalysts based on Ni exhibit are among the most active catalysts based on earth abundant elements for the oxidation of water. For this reason, we have carried out extensive studies of the composition and structure of Ni-based catalysts on the oxygen evolution reaction (OER). Our work has shown that in alkaline electrolytes Ni is rapidly converted into a-Ni(OH)2 which with aging converts to �-Ni(OH)2. Electrochemical oxidation of aged films results in the formation of materials that have the apparent structure and composition best described as �-Ni(OH)(1-x)(OOH)x with x lying between 0.78 and 1.0. The OER activity is observed to increase with a decreases in the apparent oxidation state of Ni (i.e., with a decrease in the value of x). A similar trend has been observed when Fe is substituted into the lattice of NiOOH. The reason for the increase in OER activity with decreasing charge on the Ni cations is revealed by theoretical work showing that the strength of binding of all intermediate species involved in OER increases with decreasing Ni oxidation state and results in a shift in the difference between the binding energies of OH and OOH species that is favorable for a reduction in the OER overpotential.

Experimental and theoretical studies of the electrochemical oxidation of water on Ni-based catalysts

247th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.