The efficient electrochemical conversion of H₂O to ½ O₂ and H₂ is crucial for the development of overall water-splitting technologies. However, an important challenge in the implementation of new integrated solar-water splitting devices is the discovery of efficient electrocatalysts for the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER), the two component reactions of water splitting (Scheme 5.1). In order to address this challenge, electrocatalysis researchers have reported thousands of materials for the OER and the HER that differ in their compositions, structures, morphologies, and preparations. Standardization in the evaluation and reporting of the performance of these materials as water-splitting catalysts is necessary to assess the utility of these catalysts for integration into solar fuels devices.