(66g) The State of Development of Hydrogen and Oxygen Evolving Electrocatalysts for Solar-Fuels Generating Devices

Objective comparisons of electrocatalyst activity and stability using standard methods under identical conditions are necessary to evaluate the viability of existing electrocatalysts for integration into solar-fuels devices as well as to help inform the development of new catalytic systems.  In this paper, we start by describing a standard protocol that has been developed to serve as a primary screening tool for evaluating the activity, short-term (2-h) stability, and electrochemically-active surface area (ECSA) of 17 hydrogen evolution reaction (HER) electrocatalysts and 26 oxygen evolution reaction (OER) electrocatalysts under conditions relevant to an integrated solar-water splitting device in aqueous acidic or alkaline solution. Trends will be discussed among these high-performance materials, with a specific emphasis on drawing comparisons among geometric area activity versus turnover frequency. Opportunities and challenges will be described for catalyst development, followed by recent efforts to produce highly active and stable catalysts for these reactions. The paper will conclude with a discussion of efforts to integrate the latest catalysts onto semiconductor photoelectrodes to produce active and stable systems.