Ultrafast Growth of Large 2D Silver Nanosheets by Highly Ordered Biological Template at Air/Gel Interface

Abstract

However, dislocations, disinclinations, and symmetry-breaking instabilities can frequently prompt the formations of defects and grain boundaries in the synthesis processes [15,16] and crystal growth rate of the 2D nanostructure is very slow. [17,18] In nature system, organic-inorganic hybrid nanostructures with high-crystallinity and diverse morphologies can be constructed by biomineralization process. [19,20] This natural process can efficiently induce the molecular rearrangement for high complexity [21] and many functionalities. [22,23] Therefore, these unique biological phenomena have been applied in synthesis method to control the crystallinity and morphology of 2D nanostructures with superior material properties. Here, we show a solution-based ultrafast 2D growth method for large-scale and high-quality silver nanosheets on air/gel interface. The biological hydrogel polymer forms a multilayered structure by a solvent-induced phase separation process at air/gel interface with trapped silver (Ag) salts between the layers. [24] Furthermore, the trapped Ag salts between each biological hydrogel layers can efficiently reduce into large-scale 2D Ag nanosheets during the annealing process.The mixture of the Ag salts and hydrogel solution is a transparent, light yellow color at room temperature with reduced viscosity as compared with pure gelatin solution (Figure S1a, Supporting Information), while its nominal phase-change temperature is 154 °C based on the thermal gravimetric analysis (TGA) analysis results ( Figure S1b, Supporting Information). The viscosity of the hydrogel mixture decreases further at above 40 °C as the hydrogen bond in the triple-helix gelatin chain [25] degrades by the intercalation of Ag ions between various functional side chains (e.g., amine, carboxyl, hydroxyl, and thiolate groups). [26] Adding methyl alcohol and Ag salts in the solution can partially neutralize and condense the hydrogel polymer chains [24,27] to form large and continuous multilayer membranes via the salting-out effect ( Figure S2, Supporting Information). Conceptually, Ag ions are coordinated on the randomly coiled gelatin chains, which are rapidly accumulated under elevated temperature to form a multi layered structure (Figure 1a). [28] The neutralization and condensation process occurs, and the Ag ions are trapped between the layers of the hydrogel scaffold (Figure 1b). A reducing agent, dopamine, is used to promote the conversion of Ag ions to atoms while large, multilayered gelatin scaffolds constrain the crystallization process laterally to increase the The growth of large and high-quality 2D nanomaterials is challenging due to the formation of defects from dislocations, disinclinations, and symmetrybreaking instabilities. In this study it is demonstrated that biological template can be utilized to align the molecular orientation for large grain size in the synthesis of the high-quality 2D silver nanostructure. The solvent assisted multilayering phenomenon of hydrogel forms biological template at the air/ gel interface...

Infiltrated thin film structure with hydrogel-mediated precursor ink for durable SOFCs

“…On the other hand, the infused precursor solution with gelatin formed a continuous morphology on the porous SSC cathode backbone, instead of agglomerated particles. The non-agglomerated surface can be related to the crystal growth of metal oxide between the confined complex layers, which was reported in previous research 9 . Since the metallic ions were captured by the side chains of gelatin molecule, such as amide, hydroxyl, and carboxyl groups, the metallic ions can be partially condensed to form membranes by salting out effect during the evaporation process 21 .…”

“…Due to its superior properties, gelatin has been employed as a base material for bio-applications and binding material for the synthesis of inorganic compounds. Seong et al reported a dense 2-dimensional metal structure by applying self-layering and crystallization of metal-ion/gelatin complex 9 . In addition, Wang et al demonstrated a homogeneous polymer/metal complex system by applying calcined gelatin-based iron precursor solution to control the metal oxide/carbon hybrid structure 10 .…”

Hydrogel Film Assembly Process at Droplet Interface with Evaporation Temperature

“…[1][2][3][4] Due to their biocompatibility and functional side-chains, the hydrogelbased assembly process can be applied to various academic and industrial fields, such as crystal fabrication [5,6] and biomedical applications. [11] According to the mechanism, it was demonstrated that the biological template can be used for aligning the molecular orientation in the synthesis of the highquality nanostructure. Jang et al have reported the fabrication of layer-by-layer structured single crystalline nanomaterials within several minutes by gelatin.…”

Self‐Assembly of Large‐Area 2D Polycrystalline Transition Metal Carbides for Hydrogen Electrocatalysis

“…Dimensional reduction of 3D materials to 0D, 1D, or 2D nanostructures (thickness vs lateral size < 1%), has attracted interest for discovering intriguing new catalytic properties. Notably, including 2D nanostructures comprised of metals, transition metal dichalcogenides, transition metal oxides, and 2D transition metal carbides (TMCs) have been explored for enhanced catalytic performance, and advances in this area have led to reliable and cost‐effective fabrication methods ideal for base‐metal hydrogen evolution catalysts.…”

“…The process parameters (concentration, peptide selection, and temperature) can be carefully controlled to enable the preparation of hydrogel materials containing 0D particles, 1D tubes, or 2D lamellar products . These self‐assembling soft structures are amenable to subsequent transformation by thermal and chemical approaches . By selecting carbide‐forming metals, a nanostructured hydrogel can be prepared that is amenable for subsequent conversion into TMCs that retain their supramolecular dimensionality.…”