Impact of Different Electrolytes on Photocatalytic Water Splitting

Abstract

Despite extensive research in photocatalytic water splitting, electrolyte usage varies greatly across different photocells. Photocatalytic water splitting continues to be performed in a wide range of electrolytes, from very acidic to very basic, with incomplete understanding of how the electrolyte composition affects performance. This study provides guidelines for electrolyte selection in water splitting applications. To determine properties that comprise an ideal electrolyte for photocatalytic electrolysis, the effects of several parameters were studied: pH, dissolved oxygen, conductivity, and composition. The photoactive anode was a nanostructured thin TinormalO2 film synthesized by a flame aerosol process. The photocatalytic conversion efficiency increased with both pH and conductivity, but changes in dissolved oxygen levels had no discernible effect. The electrolyte composition was adjusted using selected salts and bases. Although the effect of the cation was negligible, anions were found to reduce efficiencies if their oxidation potential makes them thermodynamically favored over water molecules for oxidation. The results of these studies were applied in an analysis of the prospects for splitting seawater to produce hydrogen.

The Influence of the Structural and Morphological Properties of WO3 Thin Films Obtained by PLD on the Photoelectrochemical Water-Splitting Reaction Efficiency

“…29 mA/cm 2 at 1.6 V vs. RHE (1.35 V vs. Ag/AgCl) for the sample prepared with laser irradiating at 355 nm. These results are contradictory to other studies on different oxides (TiO 2 [50], ZnO [51], BiVO 4 [52]), where the photoelectrochemical performance increases with the pH value. Despite high instability of WO 3 in alkaline media [53], our WO 3 thin films show an excellent photoelectrochemical response, with no noticeable leakage currents or short circuits in the measured potential range.…”

Design Guidelines for High‐Performance Particle‐Based Photoanodes for Water Splitting: Lanthanum Titanium Oxynitride as a Model

“…It is known that a higher pH value is more favorable for photoelectrochemical oxidation of water. Firstly, there will be a higher electrical conductivity of the electrolyte, which reduces ohmic losses, and secondly, the surface of the semiconductor will be completely covered by adsorbed hydroxide ions, which trap holes more efficiently than adsorbed water . Nevertheless, these experiments suggest that the hole accumulation at the SS‐LTON/CoO x is greatly reduced in comparison to the bare electrode.…”

Cascade synthesis and optoelectronic applications of intermediate bandgap Cu3VSe4 nanosheets

“…At low pH, namely using acid KCl aqueous solution as the electrolyte, the proposed H + reduction reaction at cathode (Cu 3 VSe 4 NSs-FTO thin film) is , which consumes hydrogen ions; whereas, at high pH (pH = 10), the reaction at cathode consumes water rather than H + , being 48 , 49 . The consumption of water takes place via an extra water dissociation , thus, the process of photocatalytic reduction is naturally slowed at higher pHs 50 , in turn, the larger amount of H + present at acid pH facilitates the H 2 production. Besides, at pH of 4, the surface of Cu 3 VSe 4 NSs-FTO thin film is positively charged by adsorbing H + , facilitating the reduction reaction, whereas, at higher pH (pH of 7 and 10) the electrode/electrolyte interface is neutral or negatively charged, which eliminates the electrostatic interaction, or even creates a strong electrostatic repulsion towards Cl − that results in a lower hole capture rate and in a low production of hydrogen 51 .…”