Potential of Plasmon-Activated Water as a Comprehensive Active Green Energy Resource

Liquid water is the most commonly used environmental-friendly solvent and reactant in chemical reactions and physical processes. Conventionally, it is considered as a passive reactant. In this work, we investigate the potential of plasmon-activated water (PAW) with intrinsically reduced hydrogen-bonded structures compared to normal deionized (DI) water to serve as an active green energy resource. The efficiency of the electrochemical oxidation of water performed on a platinum electrode to form hydrogen peroxide is significantly enhanced in PAW compared to that in DI water. In addition, the limiting current density of the oxygen reduction reaction on a platinum/carbon-coated disk electrode is also enhanced when using PAW (in 0.9 wt % NaCl or in 0.1 M KOH). Moreover, the cell capacitance with semitransparent platinum-coated fluorine-doped SnO₂ electrodes is significantly increased from ca. 2 × 10^-9 to 6.1 × 10^-7 F when decreasing the applied frequency from 10 to 0.1 Hz in a cell containing PAW instead of DI water (without the supporting electrolyte). More interestingly, compared to that in DI water, the efficiencies of the hydrogen evolution reaction in an acid solution (0.05 M H₂SO₄) and the oxygen evolution reaction in an alkaline solution (0.1 M KOH) performed with PAW in situ increase by about 20% with nanoscale-granulated gold electrodes under resonant illumination. These increases are more significant in neutral solutions for hydrogen evolution reactions and oxygen evolution reactions.