Structure/Composition/Phase Regulations of Dealloying-Derived Nanoporous Metals and Their Solar Steam Generation...

Structural regulation is of primary importance in structure-property/application studies of dealloyed nanoporous metals. Three aspects are mainly considered to affect the microstructure of nanoporous metals: design of precursor alloy, choosing of dealloying parameter, and annealing treatment. Herein, through the combination of the above three strategies, the regulation of structure, composition and phase in nanoporous metals are simultaneously achieved. With a dilute Cu₉₉Ag_0.75Au_0.25 as the precursor, three kinds of nanoporous films are fabricated, including bi-phase nanoporous Cu-Ag-Au (B-NP-CuAgAu), hierarchically nanoporous Au (H-NPG) and single-phase homogeneously nanoporous Au (S-NPG). In situ X-ray diffraction and ex situ characterizations are utilized to reveal the structure/composition/phase evolutions during dealloying of Cu₉₉Ag_0.75Au_0.25, as well as the macroscopic changes of the dealloyed samples. Notably, the ultrafine ligaments/channels of B-NP-CuAgAu and the two-level nanoporous structure of H-NPG endow them with good broadband light absorption and excellent hydrophilicity, which contribute to their outstanding solar steam generation (SSG) performances. Specially, the B-NP-CuAgAu film shows a more efficient SSG performance with water evaporation rate of 1.49 kg m^-2 h^-1 and photothermal efficiency of 93.6% at 1 kW m^-2, and good seawater desalination ability.