Precision Chemistry最新文献

Biomarkers, including proteins, nucleic acids, and metabolites, are the molecules that can provide insightful information about biological processes and pathological developments. Identification and quantification of biomarkers are highly beneficial for disease diagnosis, progression monitoring, and treatment supervision. However, disease development often involves the complex interplay of molecular networks that limits the utility of individual biomarkers in reaching reliable diagnostic and therapeutic decisions. Thus, recent developments of bioassays have turned the focus to analysis of a collection of biomarkers simultaneously, aiming to improve precision in diagnosis. To achieve the demanded throughput in multiplex detection while keeping the excellent analytical performance in speed, sensitivity, and selectivity, nanomaterials stand out to be the proper enabling tools, with their unique but highly diversified physical and chemical properties and the much advanced synthesis strategies. Herein, this review highlights the recent (2020-2024) developments in the nanomaterial-enabled, optical multiplex sensing techniques. Four key approaches to achieve multiplexity were discussed: spatial coding, signal coding, biocarriers, and data deconvolution using machine learning. We believe these advancements have driven forward the applications of multiplex detection in clinical settings by improving the throughput of biomarker analysis.

The reverse water–gas shift (RWGS) reaction is a key process for CO₂ conversion and sustainable fuel production, yet the nature of the active sites on Pt/TiO₂ cluster catalysts remains elusive. Using first-principles microkinetic simulations, we systematically investigated the catalytic behavior of Pt clusters on TiO₂ under operational reaction conditions. We studied three distinct catalytic sites─Pt cluster surfaces, oxygen vacancies (O_V) on TiO₂, and Pt–O_V–Ti interfaces─and revealed that the Pt–O_V–Ti interface exhibited the highest RWGS activity via a redox mechanism. This synergy enhances CO₂ activation and facilitates oxygen reduction more effectively than the isolated O_V on TiO₂, which show 4-fold lower activity. In contrast, CO-covered Pt clusters show minimal CO₂ activation but serve as H₂ dissociation sites, enabling hydrogen spillover to adjacent O_V on TiO₂, thereby sustaining the RWGS process. Kinetic analysis revealed OH reduction to H₂O as the rate-determining step on both interfacial Pt–O_V–Ti and at the O_V on the TiO_2–X support. These findings highlight the pivotal role of the Pt–O_V–Ti interface in driving the RWGS and offer a design strategy for optimizing high-temperature CO₂ hydrogenation catalysts by maximizing the number of interfacial active sites.

The emergence of In₂O₃ as an efficient catalyst for selective hydrogenation has attracted significant attention. However, the mechanism of hydrogen (H₂) dissociation on In₂O₃ remains experimentally elusive. In this work, we show that the interaction of H₂ with In₂O₃ is strongly influenced by the presence of oxygen vacancies. Using a combination of in situ near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS), ultraviolet photoelectron spectroscopy (UPS), infrared reflection absorption spectroscopy (IRRAS), and density functional theory (DFT) calculations, we systematically investigated the interaction of H₂ on well-defined oxidized In₂O₃(111) and partially reduced In₂O_3-x (111) surfaces. Our results reveal that H₂ dissociates and adsorbs as hydroxyl groups (OH), which are exclusively stabilized on the In₂O_3-x (111) surface. The adsorbed hydrogen species act as electron donors, contributing to interfacial electron accumulation near the surface and inducing downward band bending. DFT calculations further indicate that oxygen vacancies in In₂O_3-x (111) are critical for facilitating the heterolytic dissociation of H₂, leading to the stabilization of In-H and OH species. These findings provide valuable implications for the catalytic behavior of indium oxide in hydrogenation and hydrogen-involved redox reactions.

Tin(IV) oxide nanocrystals (SnO₂ NCs) have significant potential in various applications, with their performance closely related to their band gap. The band gap is influenced by the size and shape of the NCs, which can be precisely controlled by adjusting reaction conditions. In this study, we present deliberately designed synthesis protocols to produce high-quality SnO₂ NCs with tunable band gaps using different methods. Key factors affecting the synthesis include control of the oxidizing agent, reaction temperature, solvent selection, and reaction time optimization. The resulting NCs were characterized by using TEM, XRD, XPS, and optical spectroscopy. Notably, SnO₂ NCs synthesized by controlling the oxidizing agent (air injection) in a hot organic solution were smaller in size and exhibited abundant oxygen vacancies. In contrast, extending the reaction time or using ethanol as a solvent in hydrothermal systems facilitated larger spherical or rod-like SnO₂ NCs with fewer oxygen vacancies. Further analysis of the band gap and valence band maximum energy revealed that the abundant vacancies in SnO₂ NCs synthesized with the air-controlled hot organic solution method resulted in a narrower band gap and an upshifted valence band. These synthetic strategies illustrate the potential for deliberately designing SnO₂ NCs with optimized electronic structures for various applications.

Proton exchange membrane fuel cells (PEMFCs) have emerged as important zero-emission power sources due to their efficiency and eco-friendly characteristics. A critical feature required for their widespread adoption is the performance of low-temperature cold start. However, at subzero degrees Celsius, the freezing of the produced water can hinder or even lead to failure of the fuel cell start-up process. To successfully achieve a cold start under such conditions, the PEMFC must rapidly and reliably transition from a fully cooled state to a stable operating condition. Various improvements have been focused on the system engineering aspect to address this challenge, yet many of these methods come with their drawbacks. This paper reviews the recent progress of the PEMFC cold start from the perspective of key materials engineering. It provides a detailed summary of how the proton exchange membrane (PEM), catalyst layer, microporous layer (MPL), and gas diffusion layer (GDL) affect the cold-start performance. Further analysis reveals that the fundamental mechanisms of improving cold-start performance can be summarized into three aspects: increasing the ratio of water bound in the ionomer, hindering the transformation process from supercooled water to ice, improving the removal of supercooled water, or ensuring it is transported to the outside of the membrane electrode assembly (MEA) before it gets frozen. By precisely regulating these key components, it is possible to develop a simple and energy-efficient solution for improving the cold start performance of the PEMFC.

[This corrects the article DOI: 10.1021/prechem.4c00064.].

Twisted nanographenes (NGs) are currently attracting a lot of attention owing to their geometrical and electronic structures that differ substantively from conventional planar and nonplanar NGs, while the strategic synthesis of twisted NGs is still a topic of interest because the products are often interconvertible among unidirectionally, alternatively, or randomly twisted geometries and otherwise obtained as a mixture of them. Herein, we report the conformationally specific synthesis of twisted NGs where the geometry was reinforced by introducing 1,4-dioxane rings at a K-region of a central pyrene core that bears a large contortion. The 1,4-dioxane rings were generated by semi-deprotection, of tetraoxa[4.4.4]-propellanes in precursor molecules, which were confirmed to be engaged in forming C-C bonds via a Friedel-Crafts type mechanism. The large contortion within the pyrene core causes a narrowed HOMO-LUMO gap on account of unusual p _z -lobe overlap between +z and -z sides, giving rise to red emission with a high quantum yield of 94% as well as stable redox processes of 2e^- uptake/release.