Exploring Multidimensional Chemical Spaces: Instrumentation and Chemical Systems for the Parallelization of Hydrogen Evolving Photocatalytic Reactions

Photocatalytic hydrogen (H2) evolution, particularly though water reduction, presents an enticing alternative to current fossil fuel intensive methods of hydrogen production. While this field has been active for decades and advances have been made, it has been limited to serial experimentation due to the solar-mimicking lamps used and data collection techniques. With the democratization of machine and instrument design through the ever-decreasing prices of computers and sensing equipment, paired with the availability of high-power light emitting diodes (LEDs) as viable replacement light sources, reactor design has seen significant changes in recent years. After the advent of the first LED-illuminated parallel reactors for gas evolving photocatalytic reactions, a host of research groups around the world have matched the design and used their own creative means of studying H2 evolving reactions in parallel. Here we report select cases of research utilizing parallelized reactors for light-driven H2 evolution, highlighting the benefits of parallel and high-throughput experimentation. Lastly, changes to reactor design and sensing methodology, specifically how colorimetric measurement enabled the development of a 108-well parallelized reactor, are described, and these state-of-the-art reactors are compared to alternative, nonparallelized approaches using serial, robotic automation.