Activity

ConspectusElectrochemiluminescence (ECL) is a light-emitting process which combines the intriguing merits of both electrochemical and chemiluminescent methods. It is an extensively used method especially in clinical analysis and biological research due to its high sensitivity, wide dynamic range, and good reliability. ECL devices are critical for the development and applications of ECL. Much effort has been expended to improve the sensitivity, portability, affordability, and throughput of new ECL devices, which allow ECL to adapt broad usage scenarios.In this Account, we summarize our efforts on the recent development of ECL devices including new electrodes, ECL devices based on a wireless power transfer (WPT) technique, and novel bipolar electrochemistry. As the essential components in the ECL devices, electrodes play an important role in ECL detection. We have significantly improved the sensitivity of luminol ECL detection of H2O2 by using a stainless steel electrode. By using semiconductor materials (e.g.,ughput analysis, drug screening, biological study, and mechanism investigation.A new red-light-emitting fluorescent probe (R)-5 was synthesized. In the presence of Zn2+, this compound was found to exhibit good enantioselective fluorescence enhancement at λ = 655 nm when treated with a variety of amino acids in aqueous solution. This probe in combination with a green-light-emitting probe (S)-4 that has enantioselective fluorescence enhancement at λ = 505 nm has formed a pseudoenantiomeric sensor pair because of their opposite enantioselectivities. This sensor pair can simultaneously detect both enantiomers of a chiral amino acid at two very different wavelengths (Δ = 150 nm). It was used to visually and semiquantitatively determine the enantiomeric compositions of amino acids. For example, when a 11 mixture of (R)-5 and (S)-4 was treated with Zn(OAc)2 and histidine samples of 0-100% [d-His], the color of the mixtures changed from green to yellow, orange, and red under a UV lamp (365 nm), which allowed a quick quantification of [d-His]%. This is the first example of using fluorescence to visually quantify the enantiomeric composition of chiral compounds.The theoretical prediction of the catalytic activity is very beneficial for the design of highly efficient catalysts. At present, most theoretical descriptors focus on estimating the catalytic activity and understanding the enhancement mechanism of catalysts, while it is also quite important to find a factor to correlate the descriptors with preparation methods. In this work, a correlation factor, the d electron density of transition metal ions, was developed to correlate the d band center values of transition metal ions with the preparation methods of amorphization and Al introduction. According to the results of theoretical simulations, the correlation factor not only exhibited favorable linear relationships with the theoretical overpotentials of (CoFeAlx)3O4 and (CoFeAlx)3O4 + (CoFeAlx)OOH systems but also correlated with two preparation methods by altering the volume of systems. Based on theoretical guidance, the electrocatalytic activities of the prepared (CoFeAlx)3O4 specimens were gradually improved by the preparation methods of amorphization and Al introduction, and the Am-CoFeAl-2-10h specimen exhibited a low kinetic barrier of 268 mV, fast charge transfer rate, and stable electrocatalytic activity. This strategy could be applied to design highly efficient catalysts by adjusting the correlation factor of the active site with suitable preparation methods.Fe2O3-based catalysts have promising potential in the selective catalytic reduction (SCR) of NO with NH3 with the advantages of environmental friendliness, excellent medium-high SCR activity, good N2 selectivity, and high SO2 tolerance. However, the NH3-SCR mechanism over Fe2O3-based catalysts remains highly uncertain and controversial due to the complex nature of the SCR reaction. Herein, the NH3-SCR reaction pathways over the α-Fe2O3(012) surface are elucidated at the atomic level by density functional theory calculations and experimental measurements. We demonstrate that, different from the NH3 activation mechanism in numerous SCR catalytic systems, the reaction tends to follow the NO activation mechanism, in which NO activated at Fe sites reacts with NH3 to form a NH2NO intermediate and further decomposes into N2 and H2O, in synchronization with the formation of a surface OH group. Subsequently, the catalyst is regenerated by an O2-assisted surface-dehydrogenation process. The activation of NO as well as the formation of the NH2NO intermediate is the rate-determining step of the complete SCR cycle. This study enhances the atomic-level understanding toward the NH3-SCR reaction and provides insights for the development of Fe2O3-based SCR catalysts.The pH-dependence of enzyme fold stability and catalytic activity is a fundamentally dynamic, structural property which is difficult to study. The challenges and expense of investigating dynamic, atomic scale behavior experimentally means that computational methods, particularly constant pH molecular dynamics (CpHMD), are well situated tools for this. However, these methods often struggle with affordable sampling of sufficiently long time scales while also obtaining accurate pKa prediction and verifying the structures they generate. We introduce Titr-DMD, an affordable CpHMD method that combines the quasi-all-atom coarse-grained discrete molecular dynamics (DMD) method for conformational sampling with Propka for pKa prediction, to circumvent these issues. The combination enables rapid sampling on limited computational resources, while simulations are still performed on the atomic scale. this website We benchmark the method on a set of proteins with experimentally attested pKa and on the pH triggered conformational change in a staphylococcal nuclease mutant, a rare experimental study of such behavior. Our results show Titr-DMD to be an effective and inexpensive method to study pH-coupled protein dynamics.The electrochemical nitrogen reduction reaction (NRR) is regarded as a sustainable method for N2 fixation. N2 adsorption and N≡N cleavage are the main challenges for the NRR. Herein, we propose a potential approach to enhance N2 activation via introducing oxygen vacancies (OVs) into nanoporous NiO/MoO3. Nanoporous NiO/MoO3 with OVs (np-OVs-NiO/MoO3) is prepared by a two-step process of dealloying and solid-state reaction. np-OVs-NiO/MoO3 exhibits a high NH3 yield of 35.4 μg h-1 mgcat-1 and a Faradaic efficiency (FE) of 10.3% in 0.1 M PBS solution. The introduction of OVs enhances the conductivity, N2 adsorption, and catalytic performance of np-NiO/MoO3. The dual-metal sites with OVs have a unique electronic structure in favor of the “π back-donation” behavior, which decreases the energy barrier of protonation steps and improves the whole NRR process. This approach provides new insight into the design of composite transition metal oxides with OVs for the NRR catalyst under ambient conditions.