Accelerated Discovery of Electrocatalysts for Electrochemical Ammonia Synthesis

Ammonia synthesis via the direct nitrogen reduction reaction mechanism has the potential to be more flexible in production level and scale of operation and may enable cost reductions compared to alternative technologies for green NH3 synthesis. For the research field to advance to higher Technology Readiness Levels selective electrocatalysts that promote the reaction over the competing hydrogen evolution reaction are needed. The aim of this work was to build tools that enable the development of selective electrocatalysts for NRR with high NH3 production rate. We have identified two limitations in the workflow which is typically used to test promising materials for NRR activity, that hindered the development of selective electrocatalysts thus far: 1) NRR activity measurements are found to be unreliable due to NH3 contaminations and 2) the experimental throughput of the workflow is too slow to enable rapid progress, due to single catalyst studies that require elaborate ammonia detection and calibration methods. In Chapter 2 and 3 we systematically analyzed the steps involved in an NRR activity measurement to develop alternative methods that overcome these limitations. For even more effective NRR catalyst development, we explored in Chapters 4 and 5 how to accelerate the experimental workflow even further by enabling combinatorial catalyst screenings and by carrying out experiments under thermodynamically more favourable conditions for NRR, respectively.....