Flow cell designs for electrochemical production of hydrogen peroxide on-site (H2O2)

Abstract

The rise in publications over the past few years indicates a markedly rekindled interest in synthetic electrochemistry. By eliminating the harsh chemical oxidizing and reducing agents employed in conventional synthetic procedures, electrochemical synthesis offers a gentle, environmentally friendly, and atom-efficient path to fascinating and useful compounds. As a result, promoting a wider use of electrochemistry by synthetic chemists ought to be a top goal. The additional expertise and specialized equipment needed to use this technology still prevents its mainstream acceptance, despite the resurgence of interest in it. between discovered new electrochemistry in electrochemical half-cell and the development of flow electrochemical cell technology for chemical production, there is currently a knowledge gap. In my master thesis, I successfully developed and engineered two different electrochemical flow cells that each could synthesize hydrogen peroxide (H2O2) from partial reduction of oxygen. First design was able to produce H2O2 in alkaline media over synthesized carbon catalyst. The catalyst was tested in my self-designed flow cell, and it was confirmed its capability by showing a remarkable electrosynthesis of H2O2 with production rate of 7.820 mol gcat-1 h-1 at 0.35 VRHE and maintaining almost 100% faradaic efficiency at the cathode potential of 0.6 VRHE for 12 hours without any degradation. The second flow cell design was able to produce H2O2 in natural media using commercially available unmodified catalysts such as Carbon Black, Activated Carbon, and Ketjen Black. The Activated Carbon showed remarkable performance as preliminary results reaching 6700 ppm in 1 hour. The key feature of this design to not only produce H2O2 in neutral media but also produce pure H2O2 in DI water. Further work is being done on this part of the research. Finally, the partial ORR was coupled with furfural oxidation, thermodynamically favored, to produce valuable chemicals from both sides of the flow cell with slightly different design than the first one, which we adapted the from the second design and made a room for a reference electrode. The paired electrolyzer achieved total of ~200% at 0.6 VRHE and doubled the production but suffered from mass transfer limitation.