Surface-enhanced Raman scattering (SERS) has powerful capabilities in the field of environmental analysis and biological diagnostics because of its instinctive properties of high sensitivity and label-free detection. However, the fabrication of SERS substrate requires complicated processes and expensive equipment. This paper proposes a simple method approach to synthesize a 3D SERS substrate via electroless galvanic replacement reaction inside a microfluidic channel. Copper microparticles are assembled in a microfluidic channel, and silver nitrate solution is pumped into the channel to in situ produce the silver nanoparticles (Ag NPs) on the surface of copper microparticles. Because the copper particles occupy the channel by stack, the 3D Cu@AgNP SERS substrate can be obtained. The probing molecule (methylene blue) was utilized to investigate with the limit of detection (1×10−7 M). The biological molecules (urea and melamine) have been used to demonstrate its benefits in medical applications, and cancer cell detection has been implemented to demonstrate its benefits in cell biology. In addition, the device can filter and wash cells, forming a simple and fast filter. Our work on this simple fabrication method of active SERS substrate has great value for medical and biological applications.
Here, we report on using dark-field microscopy (DFM) as a simple and low-cost imaging platform to visually resolve the kinetics of single cuprous oxide (Cu2O) microparticles for NO2 removal in a real-time manner. Unexpectedly, we find that the redox reaction between Cu2O microparticles and NO2 is oscillating with the reaction time. Specifically, the oscillatory behavior of single Cu2O microparticles for NO2 reduction shows a large particle-to-particle variability, which is also dependent upon the NO2 pressure and Cu2O facets. A combined DFM imaging, spectroscopic, scanning electron microscopy, and density functional theory study uncovers that Cu2O is gradually transformed to copper nitrate hydroxide [Cu2(NO3)(OH)3], and this oscillatory reaction is attributed to the cyclic formation and structural collapse of Cu2(NO3)(OH)3. The present findings open an alternative avenue for probing structure–performance relationships, which are anticipated to benefit the creation of functional materials for air purification.
Mingming Yi,Wenhui Zhu,Ping Wu,Yiou Qiu,Guoliao Sun,Liancheng Wang
Copper-based conductive inks have been extensively researched due to their low sintering temperature and high anti-oxidation properties for various electrical devices. However, the unstable oxidation properties of copper (Cu) limit its practical application. The existing anti-oxidation methods adopted in copper sintering often reduce copper strength and reliability. Therefore, the study presents a novel copper composite ink comprising copper precursors, copper microparticles, organic protective agents, and antioxidants. The sintering process is simple, requiring only 20 min at
$300~^{\circ }$
C in nitrogen without any additional pressure. As a result, sintered copper with an oxidation rate of only 3.21 wt% was successfully obtained using the mixed ink of copper particles and precursors. The porosity of the sintered copper is 10.69%, which is a 71.77% reduction compared to the copper sintered by using pure copper precursor ink, due to the synergistic effect. Furthermore, the study discusses and analyzes the lattice growth mechanism and synergy mechanism of copper particles and their precursors during copper sintering.
危险品化学品经营许可证（带存储）