P-048

Reinis Drunka

reinis.drunka@rtu.lv

Mairis Iesalnieks, Mārtiņš Vanags, Andris Šutka

Institute of Physics and Materials Science, Riga Technical University, Latvia

Electrochemical Behavior of WO3 QDs Modified Carbon Electrodes in Acid Medium for Decoupled Water Electrolysis

Hydrogen is considered one of the most promising energy carriers for the future, with various production methods being actively explored to ensure sustainable energy systems. Among these, green hydrogen produced via water electrolysis is regarded as a highly efficient and environmentally friendly option, due to its low greenhouse gas emissions. However, optimizing electrolysis technology for both cost and efficiency remains a major challenge in the field.

This study investigates the electrochemical performance of WO3 quantum dots (QDs) integrated onto activated carbon for use in water electrolysis. The focus is on the application of these electrodes in decoupled water electrolysis, a process that separates hydrogen and oxygen evolution reactions (HER and OER) by utilizing redox mediators. This approach removes the need for membranes and enables lower power densities during operation, making it a promising technology for hydrogen production.

In this research, WO3 QDs were synthesized and applied to activated carbon surfaces, and the resulting electrodes were subjected to different heating treatments—air, nitrogen, and vacuum atmospheres. The electrochemical properties of the electrodes were evaluated using cyclic voltammetry (CV) and chronopotentiometry (CP) to assess hydrogen and oxygen production efficiencies, as well as overall cycle performance.

The findings reveal the significant effect that heating conditions have on the electrochemical behavior of the electrodes. Electrodes treated in a nitrogen atmosphere showed the highest capacitance and better intercalation properties, indicating improved electrochemical performance compared to those calcinated in air or vacuum. However, the nitrogen-treated electrodes demonstrated reduced efficiency in both hydrogen and oxygen evolution reactions. On the other hand, the electrodes calcinated in air showed a decline in their intercalation capacity, which negatively impacted their overall performance.

In terms of efficiency, the nitrogen-treated electrode exhibited higher hydrogen evolution performance, but its overall electrolysis efficiency was lower than that of the unheated electrode. The as prepared electrode had the best overall cycle efficiency, suggesting that while the nitrogen and vacuum treatments improved certain properties, they did not result in better overall performance in electrolysis.

This study highlights the importance of optimizing electrode preparation methods for water electrolysis. The WO3 QDs modified carbon electrode, calcinated in nitrogen, showed the best capacitance, but there was a trade-off in reaction efficiency, particularly for the OER. These results provide useful insights for improving electrode materials and optimizing hydrogen production processes, to enhance both performance and cost-effectiveness in future electrolysis technologies.