The electrochemical coreduction of carbon dioxide (CO 2 ) and nitrogenous species (such as NO 3 − , NO 2 − , N 2 , and NO) for urea synthesis under ambient conditions provides a promising solution to realize carbon/nitrogen neutrality and mitigate environmental pollution. Although an increasing number of studies have made some breakthroughs in electrochemical urea synthesis, the unsatisfactory Faradaic efficiency, low urea yield rate, and ambiguous C−N coupling reaction mechanisms remain the major obstacles to its large-scale applications. In this review, we present the recent progress on electrochemical urea synthesis based on CO 2 and nitrogenous species in aqueous solutions under ambient conditions, providing useful guidance and discussion on the rational design of metal nanocatalyst, the understanding of the C−N coupling reaction mechanism, and existing challenges and prospects for electrochemical urea synthesis. We hope that this review can stimulate more insights and inspiration toward the development of electrocatalytic urea synthesis technology.

Plasmonic sensors are promising for ultrasensitive chemical and biological analysis. Gold nanoplates (Au NPLs) show unique geometrical structures with high ratios of surface to bulk atoms, which display fascinating plasmonic properties but require optimization. This study presented a systematic investigation of the influence of different parameters (shape, aspect ratio, and resonance mode) on localized surface plasmon resonance properties, refractive index (RI, n) sensitivities, and surface-enhanced Raman scattering (SERS) enhancement ability of different types of Au NPLs through finite-difference time-domain (FDTD) simulations. As a proof of concept, triangular, circular, and hexagonal Au NPLs with varying aspect ratios were fabricated via a three-step seed-mediated growth method by the experiment. Both FDTDsimulated and measured experimental results confirm that the RI sensitivities increase with the aspect ratio. Furthermore, choosing a lower order resonance mode of Au NPLs benefits higher RI sensitivities. The SERS enhancement abilities of Au NPLs also predicted to be highly dependent on the shape and aspect ratio. The triangular Au NPLs showed the highest SERS enhancement ability, while it drastically decreased for circular Au NPLs after the rounding process. The SERS enhancement ability gradually became more intense as the hexagonal Au NPLs overgrown on circular Au NPLs with increasing volumes of HAuCl 4 solution. The results are expected to help develop effective biosensors.

DNA structure functionalized MOFs for construction of a ratiometric SERS biosensor to sensitively detect ATP.

The self-assembly of gold nanoparticles (Au NPs) on a liquid phase interface is often employed as a surface-enhanced Raman scattering (SERS) platform with advantages of simple preparation, high reproducibility, and a defectfree character, but they are limited to only detect a target with Raman signals. To overcome this problem, microRNA 155 without a Raman signal can be detected by a liquid phase interfacial ratiometric SERS platform. Compared with the typical solid phase SERS platform, we propose a distinctive strategy not only owning the advantages of the liquid phase interfacial platform but also breaking the limitation of recent liquid−liquid interfacial SERS analysis. This platform presents a fabulous sensitivity with a limit of detection (LOD) of 1.10 aM for microRNA 155. By simply altering the duplex-specific nuclease (DSN) enzyme amplification, our strategy can realize detection of a variety of microRNAs, paving the way to practical applications of a liquid phase SERS platform.

Au nanoparticles (Au NPs) can be self-assembled in a bottom-up orderly manner at the oil–water interface, which is widely used as SERS platforms, but the stability of the Au NP interface needs to be improved due to shaking or shifting and the Brownian motion. The DNA structure with unique sequence specificity, excellent programmability, and flexible end-group modification capability owns good potential to precisely control the plasmonic structure’s distance. In this study, a large area of the SERS substrate is obtained from the DNA structure-stabilized self-assembled ordered Au NPs on the cyclohexane–water interface. Combining with the exonuclease III (exo III)-assisted DNA recycling amplification strategy, we construct a liquid-phase SERS biosensor for efficient detection of microRNA 155 (miRNA 155). Compared with the traditional randomly assembled Au NPs on the two-phase interface, the SERS signal is significantly enhanced and more stable. The detection limit of the SERS biosensor for miRNA 155 reached 1.45 fmol/L, which has a very wide linear range (100 fmol/L–5 nmol/L). This work gives an efficient approach to stabilize the self-assembly Au NPs on the liquid–liquid interface, which can broaden the application of SERS analysis.