fig4

Figure 4. Investigation of the solubility-induced concentration gradients. (A) High-resolution XPS Fe 2p spectrum of the PSD-10 electrolyte; (B) Time-resolved in situ Raman spectra at the cold side of the PSD-10 electrolyte under a ΔT; (C) Optical images of precipitation in DMSO/H₂O/K₃Fe(CN)₆/K₄Fe(CN)₆ solution and solids of K₃Fe(CN)₆, and K₄Fe(CN)₆·3H₂O (photographed by the authors); (D) XRD patterns and (E) Raman spectra of the precipitate and supernatant in the DMSO/H₂O/K₃Fe(CN)₆/K₄Fe(CN)₆ solution; (F) UV-vis absorption spectra of redox species with varying DMSO volume fractions and (G) temperature-dependent UV-vis spectra of redox species in DMSO/H₂O solutions; (H) Morphological characterization of the PSD-10 electrolyte (SEM image); (I) Raman spectra of P(AAm-AMPS) and PSD-10 electrolytes. XPS: X-ray photoelectron spectroscopy; DMSO: dimethyl sulfoxide; XRD: X-ray diffraction; UV-vis: ultraviolet-visible; SEM: scanning electron microscopy; AAm: acrylamide; AMPS: 2-acrylamido-2-methylpropanesulfonic acid.