Wei Yu

A novel, ultra low-cost surface enhanced Raman spectroscopy (SERS) substrate has been developed by modifying the surface chemistry of cellulose paper and patterning nanoparticle arrays, all with a consumer inkjet printer. Micro/nanofabrication of SERS substrates for on-chip chemical and biomolecular analysis has been under intense investigation. However, the high cost of producing these substrates and the limited shelf life severely limit their use, especially for routine laboratory analysis and

We demonstrate a paper-based surface swab and lateral-flow dipstick that includes an inkjet-printed surface-enhanced Raman spectroscopy (SERS) substrate for analyte detection. Due to capillary-action wicking of cellulose, the paper dipstick enables extremely simple and pump-free loading of liquid samples into the detection device, and in addition provides inherent analyte concentration within the detection volume. Furthermore, the flexible nature of the paper-based SERS device also enables it to

We demonstrate an extremely simple and practical surface enhanced Raman spectroscopy (SERS) technique for trace chemical detection. Filter membranes first trap silver nanoparticles to form a SERS-active substrate and then concentrate analytes from a mL-scale sample into a μL-scale detection volume. We demonstrate a significant improvement in detection limit as compared to colloidal SERS for the pesticide malathion and the food contaminant melamine. The measured SERS intensity exhibits low variat

In principle, surface enhanced Raman spectroscopy (SERS) is thought to provide unique identification of a target analyte, even in complex samples or in the presence of multiple analytes. In practice, however, this is not always true for real-world samples due to various forms of interference. In this report, we build upon our previous work on inkjet-printed SERS substrates by using paper and polymer membranes to integrate sample cleanup and analyte separation with SERS detection. Inkjet-printed

The safety issue caused by the dendrite growth is not only a key research problem in lithium-ion batteries but also a critical concern in alkali metal (i.e., Li, Na, and K)-oxygen batteries where a solid metal is usually used as the anode. Herein, we demonstrate the first dendrite-free K-O₂ battery at ambient temperature based on a liquid Na-K alloy anode. The unique liquid-liquid connection between the liquid alloy and the electrolyte in our alloy anode-based battery provides a homog

The rational design of a stable and catalytic carbon cathode is crucial for the development of rechargeable lithium-oxygen (LiO₂ ) batteries. An edge-site-free and topological-defect-rich graphene-based material is proposed as a pure carbon cathode that drastically improves LiO₂ battery performance, even in the absence of extra catalysts and mediators. The proposed graphene-based material is synthesized using the advanced template technique coupled with high-temperature a

Abstract Although lithium–oxygen batteries have attracted attention due to their extremely high energy densities, rational design, and critical evaluation of high‐energy‐density cathode for practical Li–O 2 batteries is still urgently needed. Herein, the multiscale, angstrom‐to‐millimeter, precisely controllable synthesis of binder‐free cathodes with minimally stacked graphene free from edge sites is demonstrated. The proposed Li–O 2 battery, based on a hierarchically porous cathode with a pract

The formation of the insulated film-like discharge products (Li₂O₂) on the surface of the carbon cathode gradually hinders the oxygen reduction reaction (ORR) process, which usually leads to the premature death of the Li-O₂ battery. In this work, by introducing the molecular sieve powder into the ether electrolyte, the Li-O₂ battery exhibits a largely improved discharge capacity (63 times) compared with the one in the absence of this inorganic oxide ad