This section of the article provides detailed experimental data and analysis for benchmarking heterogeneous electrocatalysts used in the oxygen evolution reaction (OER). It includes X-ray photoelectron spectroscopy (XPS) spectra of various materials, such as bare glassy carbon, electrodeposited IrOx, CoOx, NiOx, NiCeOx, and others, to confirm their composition and surface properties. The specific capacitance values for different materials in alkaline and acidic solutions are discussed, with a focus on Ni-containing materials. The surface area of a Pt disk is determined through cyclic voltammograms and electrochemical impedance spectroscopy. Representative current and potential steps for NiOx are presented, along with activity and stability measurements for various catalysts. The stability of IrOx films prepared with different deposition solutions is also evaluated. The 2-electron reduction of O2 at a rotating Pt ring is analyzed, and the use of Tafel plots to compare electrocatalysts is discussed, highlighting the limitations and complexities involved. Finally, the challenges and considerations for studying electrocatalysis at intermediate pH are addressed, emphasizing the importance of buffer choice and its impact on catalytic activity.This section of the article provides detailed experimental data and analysis for benchmarking heterogeneous electrocatalysts used in the oxygen evolution reaction (OER). It includes X-ray photoelectron spectroscopy (XPS) spectra of various materials, such as bare glassy carbon, electrodeposited IrOx, CoOx, NiOx, NiCeOx, and others, to confirm their composition and surface properties. The specific capacitance values for different materials in alkaline and acidic solutions are discussed, with a focus on Ni-containing materials. The surface area of a Pt disk is determined through cyclic voltammograms and electrochemical impedance spectroscopy. Representative current and potential steps for NiOx are presented, along with activity and stability measurements for various catalysts. The stability of IrOx films prepared with different deposition solutions is also evaluated. The 2-electron reduction of O2 at a rotating Pt ring is analyzed, and the use of Tafel plots to compare electrocatalysts is discussed, highlighting the limitations and complexities involved. Finally, the challenges and considerations for studying electrocatalysis at intermediate pH are addressed, emphasizing the importance of buffer choice and its impact on catalytic activity.