Hierarchical Nanoporous Copper Fabricated by One‐Step Dealloying Toward Ultrasensitive Surface‐Enhanced Raman Sensing

Abstract

Geometry‐tunable substrates with abundant plasmon resonant structure are ideal to proffer high surface‐enhanced Raman scattering (SERS) activity for trace sensing including pollutants and toxics, whereas great challenge remains in creating high‐density “hotspots” in these structures for further improving Raman signals and detection sensitivity. Herein, one‐step dealloying strategy is proposed to fabricate free‐standing copper membranes with hierarchical porous architecture where a high density of inherent “hotspots” is built in the vicinity of secondary pores in 3D ligaments. The hierarchical nanoporous copper shows excellent SERS activity with an average enhancement factor of 6.4 × 109, originating from strong electromagnetic coupling effects induced by its highly dense “hotspots” and highly accessible surface. Moreover, the proposed one‐step dealloying strategy of dual‐phase binary alloys propounds an inexpensive yet effective route to construct ultrasensitive SERS substrate for trace detection and molecular diagnosis.

Copper‐Based Plasmonic Catalysis: Recent Advances and Future Perspectives

“…Reproduced with permission. [ 121 ] Copyright 2018, Wiley‐VCH. I) TEM images of spherical twinned, triangular, hexagonal, polycrystalline aggregate, fivefold‐symmetric, and bipyramidal Cu NPs.…”

“…Owing to the abundant high‐index facets, large specific surface areas, and high density of atomic kinks and steps, porous Cu has been widely used in catalysis, batteries, SERS, etc. [ 121,129–131 ] At present, porous Cu with adjustable pore sizes are facilely synthesized by dealloying method, thermal decomposition method, and wet chemical method. The pore size of porous Cu is continuously adjusted from tens to hundreds of nanometers, and even reaches to the micron level.…”

“…The pore size of porous Cu is continuously adjusted from tens to hundreds of nanometers, and even reaches to the micron level. [ 121,129–131 ] For example, Pan et al. fabricated freestanding Cu membranes with hierarchical architecture by etching Mg 72 Cu 28 dual‐phase binary alloy with HCl solution.…”

“…fabricated freestanding Cu membranes with hierarchical architecture by etching Mg 72 Cu 28 dual‐phase binary alloy with HCl solution. [ 121 ] The hierarchical architecture is composed of large porosity channels sized in 50–100 nm with plentiful smaller pores less than 20 nm on channel walls, which is able to be further adjusted by varying solvent concentrations and dealloying time (Figure 3H). Moreover, the porous Cu membranes are expected to provide ultrasensitive SERS detection via the stronger electromagnetic field attributed to the coupling effect of LSPR and abundant hot spots.…”

High‐entropy alloys and compounds for electrocatalytic energy conversion applications

“…Besides the conventional synthetic strategies mentioned above, a continuation of the three‐principal‐methods family has been growing rapidly. For examples, dealloying method is applied to prepare nanoporous HEMs 77 . Solvothermal method is proposed for the synthesis of HEMs in a nonaqueous solvent at temperature above the boiling point and pressure above 1 bar 78 .…”