Challenges in scaling up H2O2 electrosynthesis: Addressing Joule heating effects

The scaling up of hydrogen peroxide (H2O2) electrosynthesis remains challenging in achieving economically compelling energy efficiency (>0.1 kg kWh(-1)) at industrially relevant generation rates (>= 100 mA cm(-2)). This study reveals that Joule heating significantly hinders the optimization of energy efficiency in the electrosynthesis process. The increase in current density is accompanied by the amplification of Joule heating, resulting in increased cell voltage and reduced H2O2 selectivity, thereby contributing to a decrease in energy efficiency. Temperature control experiments show that H2O2 selectivity attenuation induced by Joule heating can be suppressed when electrolyte temperature is kept below 35 degrees C. H2O2 selectivity reaches about 90% at a current density of 300 mA cm(-2) even with commercial catalysts. Instead, cell voltage drop due to Joule heating is almost inevitable, primarily originating from polarization resistance, which cannot be effectively reduced. By optimizing electrode distance and electrolyte conductivity to mitigate polarization resistance, the possibility of eliminating the Joule heating effect for successful scale up of the H2O2 electrosynthesis process at industrially relevant generation rates is discuss.