Materials libraries synthesized by nanolithography are a transformative approach to combinatorial chemistry capable of quickly accessing millions of unique nanomaterials with complex element control that can be mined for new knowledge. This proposal will expand the compatible nanomaterials made using nanolithography and interface the libraries with molecular cocatalysts and surface ligands. Such modifiers can tailor catalyst electronics, local environments, and tandem reactivity, but the limited speed of conventional testing has impeded progress in understanding this molecular control of materials. Using uHTE, we can study massive amounts of cocatalysts/modifiers and their combinations, unveiling valuable lessons for hybrid catalyst design, particularly for identifying motifs with enhanced redox performance. To screen libraries, we will develop sensors and molecular probes for chemoselective and spatiotemporal detection of product formation or materials restructuring. Molecular probes, microelectrode sensors, and scanning electrochemical techniques with micron resolution will discover unique catalysts worthy of in-depth analysis. Further acceleration of screening can be achieved with automation and machine learning. These generalizable uHTE methods will let us study underexplored reactions primed for electrification including hydroformylation, or reduction of phosphate, iron oxide, sulfur dioxide, or carbon monoxide. uHTE will also streamline testing of new approaches to redox catalysis in our other projects.