A Microbial-Mineralization-Inspired Approach for Systematic Syntheses of Copper Oxides with Controlled Morphologies in an Aqueous Solution at Room Temperature

Abstract

A microbial-mineralization-inspired approach directed the selective syntheses of copper oxides and related compounds from divalent copper ions in an aqueous solution at room temperature. The systematic syntheses were achieved by three routes; direct, transient-intermediate, and precursor-transformation routes. Inspired by microbial mineralization processes, the oxidation states, crystal phases, and morphologies of copper oxides and related compounds were controlled by the tuning of synthetic conditions. The present approaches facilitated the formation of spherical CuO and Cu2O crystals with hierarchical structures and high specific surface area. The resultant CuO hierarchical spheres showed improved properties as a catalyst for decomposition of an organic molecule in the presence of hydrogen peroxide.

Thin Films that Consist of CuO Mesocrystal Nanosheets: An Application of Microbial‐Mineralization‐Inspired Approaches to Thin‐Film Formation

“…In route A 2 , the use of poorly soluble starting materials facilitated the formation of Cu 2 O and Cu 2 (OH) 3 Cl thin films. [13] A glass substrate was immersed at a specified concentration of hydrazine monohydrate (N 2 H 4 ·H 2 O) in aqueous solution that contained spherical CuO powder for 10 min. In routes A 2 and A 3 , the use of a poorly soluble copper source and a base facilitated the formation of Cu 2 O and Cu 2 (OH) 3 Cl thin films, respectively.…”

“…Spherical CuO crystals with a high specific surface area were used as the copper source for the preparation of Cu 2 O thin films (Figure 4 a, b and the Supporting Information, Figure S3). [13] A glass substrate was immersed at a specified concentration of hydrazine monohydrate (N 2 H 4 ·H 2 O) in aqueous solution that contained spherical CuO powder for 10 min. Polyhedrons of Cu 2 O of less than 500 nm in size were formed over the whole of the glass substrate (Figure 4 b).…”

“…Herein, we have studied the thin-film coating of copper oxides and a related compound through synthetic processes that were inspired by microbial mineralization under mild conditions ( Figure 1). [11][12][13] Iron, manganese, and copper oxides with controlled oxidation states, crystal phases, and morphologies have been synthesized through direct and intermediate routes. [2d] In direct routes, manganese and iron oxides are synthesized directly from metal sources that are dissolved in aqueous media, whereas, in intermediate routes, the metal oxides are synthesized through the formation of intermediate compounds.…”

“…[4][5][6][7][8][9][10] We have reported microbial-mineralization-inspired approaches for the syntheses of transitionmetal oxides with controlled oxidation states, crystal phases, and morphologies. [11][12][13] Iron, manganese, and copper oxides with controlled oxidation states, crystal phases, and morphologies have been synthesized through direct and intermediate routes. Although precipitates of these transitionmetal oxides have been obtained by using these approaches, thin-film coatings were not fully studied in our previous works.…”