Ligand-Exchange-Mediated Fabrication of Gold Aerogels Containing Different Au(I) Content with Peroxidase-like Behavior

Abstract

Noble-metal aerogels are emerging functional porous materials that have been applied in diverse fields. Among them, gold (Au) aerogels have displayed grand potentials in a wide range of catalytic processes. However, current fabrication methods fall short in obtaining Au gels with small ligament sizes and controlled surface valence states, which hinder the study of the underlying catalytic mechanisms. Here, a new approach of producing Au aerogels is reported. Via a two-phase ligand exchange, the long-chain ligands (oleylamine) of the as-prepared Au nanoparticles were replaced by short sulfide ions and subsequently self-assembled into three-dimensional gels. As a result, Au aerogels with small ligament sizes (ca. 3–4 nm) and tunable surface valence states are acquired. Taking the application for peroxidase mimics as an example, by correlating the surface valence with the catalytic properties, Au­(I) is found to be the active site for H2O2 and substrate-binding site for 3,3′,5,5′-tetramethylbenzidine, paving a new avenue for on-target devising Au-based catalysts.

A Review on Metal- and Metal Oxide-Based Nanozymes: Properties, Mechanisms, and Applications

“…With tuning copper states from Cu 0 to Cu 2+ , Xi et al found that the multi-enzyme-like activities (POD, CAT and SOD) of copper/carbon nanozymes were closely related to the Cu state [ 232 ]. Fan et al realized surface valence state control on Au-based nanozymes for the first time [ 233 ]. In their system, the catalytic efficiency for substrate oxidation (TMB and H 2 O 2 ) decreased with the reduced ratio of Au(I) complex in Au Aerogels.…”

Ag@CuO@Cu(OH)2: A Synergistic Catalyst for H2O2 Detection with Peroxidase‐Mimic Activity without Interference of O2

“…This corresponds to metallic Ag 0 that generate AgNPs [28] . The HR‐XPS spectrum of Cu2p of Ag@CuO@Cu(OH) 2 was well fit two major peaks at 934.9 and 955.0 eV ascribed with Cu 2p 3/2 and Cu2p 1/2 that confirms octahedral Cu 2+ existed in Ag@CuO@Cu(OH) 2 [29] . The peroxidase‐like activity of Ag@CuO@Cu(OH) 2 has been analysed by oxidation ability of TMB and catalytic mechanism was described in Figure 2d.…”

Preparation and Electrocatalysis Application of Pure Metallic Aerogel: A Review

“…However, the replaced S 2− can promote the generation of Au-S-Au bonds, connecting the nearby gold nanoparticles. Through further atom diffusion, nanoparticles grow anisotropically and form a three-dimensional network structure [88]. In fact, ionic surfactants on the colloids can also be replaced by the nonionic oligomer surfactants for gelation by heating [89].…”