New solar energy-storage resource of plasmon-activated water solution with higher chemical potential

Abstract

Nowadays, solar energy is the most environmentally friendly energy source to drive many chemical reactions and physical processes. However, the corresponding fabrication procedures for obtaining excellent energy-storage devices are relatively complicated and expensive. In this work, we report an innovative strategy on plasmon-activated water (PAW) serving as energy-storage medium from solar energy. The lifetime of the created energetic PAW solution from hot electron transfer (HET) on Au nanoparticles (AuNPs) illuminated with sunshine can last for 2 days, making the energy-storage system is practically available. Encouragingly, the energy-conversion efficiency from the solar energy in the PAW solution is ca. 6.7%. Compared to conventional deionized (DI) water solution, the prepared metastable PAW solution exhibited distinctly higher chemical potential at room temperature. It demonstrates abilities in faster evaporation and enhancing chemical reactions, including hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Our proposed strategy on the simple and cheap energy-storage system based on prepared PAW utilizing solar energy is the first time shown in the literature.

Figure 1

Reaction glass cell for creating plasmon-activated water (PAW) solutions under solar irradiation and corresponding evaporation rates of PAW-based solutions (0.1 M KCl) after exposure to sunlight for 3 h. Deionized (DI) water-based solutions (0.1 M KCl) are demonstrated for reference. (a) Gold nanoparticle (AuNP)-coated ceramic rods in glass sample vials with 0.1 M KCl-containing DI water solutions under solar irradiation: 1, AuNP-coated ceramic rods; 2, 0.1 M KCl-containing DI water; 3, sunshine. (b) Evaporation rates in 30 min of the as-prepared and aged (2 days) PAW-based, DI water-based, and blank experiment-based solutions (0.1 M KCl); the blank solution was obtained by using experimental conditions similar to those for preparing the PAW solution in situ but using blank ceramic rods with no AuNP coating. (c) Schematic descriptions of the energy-progress of the process curve of PAW solutions in energy transfer for the dissolution and evaporation processes.

Figure 2

Specific heat (compared to the 0.1 M KCl deionized (DI) water solution) of plasmon-activated water (PAW)-based solutions (0.1 M KCl) after exposure to solar irradiation for 3 h. (a) Rates of rising temperatures measured in the as-prepared PAW-based and DI water-based solutions (0.1 M KCl) with the same masses under a constant applied power. (b) The temperature-heating time dependence between room temperature and 40 °C of the as-prepared PAW-based and DI water-based solutions. (c) The temperature-heating time dependence between room temperature and 40 °C of aged (for 2 days) PAW-based and DI water-based solutions. The blank solution was obtained using experimental conditions similar to those for preparing the PAW solution in situ but using blank ceramic rods without an AuNP coating.

Figure 3

NMR-T₁ represents the time required for the longitudinal component of magnetization to recover to its equilibrium value after applying a perturbing pulse sequence. Spectra represent spectral signals as a function of the repetition time for (a) the deionized (DI) water solution (0.1 M KCl, as-prepared), (b) the plasmon-activated water (PAW) solution ex situ (0.1 M KCl, as-prepared), (c) the PAW solution in situ (0.1 M KCl, as-prepared), (d) the DI water solution (0.1 M KCl, aged for 2 days), (e) the PAW solution ex situ (0.1 M KCl, aged for 2 days), and (f) the PAW solution in situ (0.1 M KCl, aged for 2 days).

Figure 4

Linear sweep voltammetry (LSV) recorded on a planar Pt electrode for the oxygen evolution reaction (OER) in plasmon-activated water (PAW)-based and deionized (DI) water-based solutions. (a) LSV at scan rates of 0.05 V s^–1 in the PAW solution in situ, the PAW solution ex situ, and the DI water solution (all containing 0.1 M KCl). (b) OER currents at 1.5 V vs. Ag/AgCl in the PAW solution in situ, the PAW solution ex situ, and the DI water solution (all containing 0.1 M KCl) for 0, 1, 2, and 3 days after their preparation. (c) LSV at scan rates of 0.05 V s^–1 of the PAW solution in situ, the PAW solution ex situ, and the DI water solution (all containing 0.1 M NaOH). (d) OER currents at 1.5 V vs. Ag/AgCl in the PAW solution in situ, the PAW solution ex situ, and the DI water solution (all containing 0.1 M NaOH) for 0, 1, 2, and 3 days after their preparation.

Figure 5

Linear sweep voltammetry (LSV) recorded on a planar Pt electrode for the hydrogen evolution reaction (HER) in plasmon-activated water (PAW)-based and deionized (DI) water-based solutions (0.1 M KCl). (a) LSV at scan rates of 0.05 V s^–1 in the PAW solution in situ, the PAW solution ex situ, and the DI water solution. (b) HER currents of at − 1.4 V vs. Ag/AgCl in the PAW solution in situ, the PAW solution ex situ, and the DI water solution for 0, 1, 2, and 3 days after their preparation.

Figure 6

Cyclic voltammogram (CV) recordings on the same planar Au electrode showing the 5th (at the beginning) and the 25th (at the end) scans with oxidation–reduction cycle (ORC) treatments at 0.5 V s^–1 to roughen the Au electrodes in plasmon-activated water (PAW)-based and deionized (DI) water-based solutions (0.1 M KCl). (a) The 5th scans in the as-prepared solutions; (b) the 25th scans in the as-prepared solutions; (c) the 5th scans in the solutions aged for 2 days; and (d) the 25th scans in solutions aged for 2 days.

Figure 7

Cyclic voltammogram (CV) recordings on the same planar Au electrode showing the 3rd scans of the oxidation–reduction cycle (ORC) at 0.5 V s^–1 in plasmon-activated water (PAW)-based and deionized (DI) water-based solutions (50 mM K₃Fe(CN)₆). (a) For the as-prepared solutions and (b) for solutions aged for 2 days.

Figure 8

Cyclic voltammogram (CV) recordings of the same planar Au electrode showing the 5th (at the beginning) and the 25th (at the end) scans of the oxidation–reduction cycle (ORC) treatments at 0.5 V s^–1 for roughening the Au electrode in deionized (DI) water-based solutions (0.1 M KCl) under different degrees of illumination from indoor fluorescent lamps. (a) The 5th scans in a completely dark condition, with full fluorescent lamps, and in the shadow of fluorescent lamps. (b) The 25th scans in a completely dark condition, with full fluorescent lamps, and in the shadow of fluorescent lamps.