Edge activation of an inert polymeric carbon nitride matrix with boosted absorption kinetics and near-infrared response for efficient photocatalytic CO2 reduction

2020 ◽  
Vol 8 (23) ◽  
pp. 11761-11772 ◽  
Author(s):  
Qiong Liu ◽  
Zhongxin Chen ◽  
Weijian Tao ◽  
Haiming Zhu ◽  
Linxin Zhong ◽  
...  
Keyword(s):  
Activation Energy ◽  
Energy Barrier ◽  
Carbon Nitride ◽  
Near Infrared ◽  
Co2 Reduction ◽  
Absorption Capacity ◽  
Absorption Kinetics ◽  
Activation Energy Barrier ◽  
Polymeric Carbon

The edge-activation of the polymeric carbon nitride matrix by hydroxyethyl groups results in enhanced CO2 absorption capacity and decrease in the CO2 activation energy barrier.

scholarly journals The Activating Effect of Strong Acid for Pd-Catalyzed Directed C–H Activation by Concerted Metalation-Deprotonation Mechanism

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 4083
Author(s):  
Heming Jiang ◽  
Tian-Yu Sun
Keyword(s):  
Activation Energy ◽  
Dft Calculations ◽  
Energy Barrier ◽  
Computational Study ◽  
Strong Acid ◽  
Activation Energy Barrier ◽  
Pd Catalysts ◽  
Acid Ligand ◽  
Strong Acids

A computational study on the origin of the activating effect for Pd-catalyzed directed C–H activation by the concerted metalation-deprotonation (CMD) mechanism is conducted. DFT calculations indicate that strong acids can make Pd catalysts coordinate with directing groups (DGs) of the substrates more strongly and lower the C–H activation energy barrier. For the CMD mechanism, the electrophilicity of the Pd center and the basicity of the corresponding acid ligand for deprotonating the C–H bond are vital to the overall C–H activation energy barrier. Furthermore, this rule might disclose the role of some additives for C–H activation.

The molten helix: low activation energy barrier for helix-helix transitions

Peptides ◽  
1994 ◽  
pp. 896-898
Author(s):  
G. R. Marshall ◽  
M. L. Smythe ◽  
S. E. Huston ◽  
R. D. Bindal
Keyword(s):  
Activation Energy ◽  
Energy Barrier ◽  
Activation Energy Barrier

scholarly journals Effect of Two-Step Austempering Process on Transformation Kinetics of Nanostructured Bainitic Steel

Materials ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 166 ◽  
Author(s):  
Chunhe Chu ◽  
Yuman Qin ◽  
Xuemei Li ◽  
Zhinan Yang ◽  
Fucheng Zhang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Energy Barrier ◽  
Bainitic Ferrite ◽  
Transformation Process ◽  
Transformation Rate ◽  
Bainitic Steel ◽  
Transformation Kinetics ◽  
Activation Energy Barrier ◽  
Quenching Process ◽  
Kinetics Of

The two-step austempering process has been reported to be an effective method to accelerate the bainitic transformation process by introducing martensite (Q-M-B). However, in this study, it was found that the Q-M-B process reduced the incubation time, but the transformation duration remained nearly unchanged. The notably reduced activation energy barrier for nucleation of bainitic ferrite on the preformed martensite should be responsible for the reduced duration time of the Q-M-B process. A process that both of the two steps were above, Ms (Q-B-B), has been demonstrated to increase transformation rate and improve the amount of bainitic ferrite, which probably results from the additional hysteresis free energy provided by the first quenching process.

Sulfur doped Li1.3Al0.3Ti1.7(PO4)3 solid electrolytes with enhanced ionic conductivity and a reduced activation energy barrier

2020 ◽  
Vol 22 (30) ◽  
pp. 17221-17228
Author(s):  
Abdulkadir Kızılaslan ◽  
Mine Kırkbınar ◽  
Tugrul Cetinkaya ◽  
Hatem Akbulut
Keyword(s):  
Activation Energy ◽  
Ionic Conductivity ◽  
Energy Barrier ◽  
Solid Electrolytes ◽  
Activation Energy Barrier ◽  
Conductivity Enhancement

The mechanism of the ionic conductivity enhancement in sulfur-doped Li1.3Al0.3Ti1.7(PO4)3 (LATP) solid electrolytes.

scholarly journals Interplay between spin crossover and proton migration along short strong hydrogen bonds

2021 ◽  
Author(s):  
Verónica Jornet-Mollá ◽  
Carlos Giménez-Saiz ◽  
Laura Cañadillas-Delgado ◽  
Dmitry S. Yufit ◽  
Judith A. K. Howard ◽  
...  
Keyword(s):  
Activation Energy ◽  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Low Temperatures ◽  
Energy Barrier ◽  
Spin Crossover ◽  
Strong Hydrogen Bond ◽  
Activation Energy Barrier ◽  
Proton Migration

A proton migration across a short strong hydrogen bond can be triggered by spin crossover of a remote Fe2+ cation, with the onset of a photoinduced activation energy barrier for proton motion at low temperatures.

scholarly journals Measuring the activation energy barrier for the nucleation of single nanosized vapor bubbles

2019 ◽  
Vol 116 (26) ◽  
pp. 12678-12683 ◽  
Author(s):  
Jing Chen ◽  
Kai Zhou ◽  
Yongjie Wang ◽  
Jia Gao ◽  
Tinglian Yuan ◽  
...  
Keyword(s):  
Activation Energy ◽  
Rate Constant ◽  
Nucleation Rate ◽  
Energy Barrier ◽  
Bubble Nucleation ◽  
Vapor Bubbles ◽  
Activation Energy Barrier ◽  
Facet Structure ◽  
Optical Images ◽  
Local Activation Energy

Heterogeneous bubble nucleation is one of the most fundamental interfacial processes that has received broad interest from diverse fields of physics and chemistry. While most studies focused on large microbubbles, here we employed a surface plasmon resonance microscopy to measure the nucleation rate constant and activation energy barrier of single nanosized embryo vapor bubbles upon heating a flat gold film with a focused laser beam. Image analysis allowed for simultaneously determining the local temperature and local nucleation rate constant from the same batch of optical images. By analyzing the dependence of nucleation rate constant on temperature, we were able to calculate the local activation energy barrier within a submicrometer spot. Scanning the substrate further led to a nucleation rate map with a spatial resolution of 100 nm, which revealed no correlation with the local roughness. These results indicate that facet structure and surface chemistry, rather than geometrical roughness, regulated the activation energy barrier for heterogeneous nucleation of embryo nanobubbles.

scholarly journals Tailoring the Grain Boundary Chemistry of Polymeric Carbon Nitride for Enhanced Solar Hydrogen Production and CO2 Reduction

2019 ◽  
Vol 131 (11) ◽  
pp. 3471-3475 ◽  
Author(s):  
Guigang Zhang ◽  
Guosheng Li ◽  
Tobias Heil ◽  
Spiros Zafeiratos ◽  
Feili Lai ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Grain Boundary ◽  
Carbon Nitride ◽  
Co2 Reduction ◽  
Solar Hydrogen ◽  
Solar Hydrogen Production ◽  
Boundary Chemistry ◽  
Polymeric Carbon

scholarly journals Conjugated Electron Donor–Acceptor Hybrid Polymeric Carbon Nitride as a Photocatalyst for CO2 Reduction

Molecules ◽  
2019 ◽  
Vol 24 (9) ◽  
pp. 1779 ◽  
Author(s):  
Asif Hayat ◽  
Mati Ur Rahman ◽  
Iltaf Khan ◽  
Javid Khan ◽  
Muhammad Sohail ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Molecular Orbital ◽  
Density Functional ◽  
Carbon Nitride ◽  
Co2 Reduction ◽  
Characterization Methods ◽  
Base Functions ◽  
Activity Performance ◽  
Donor Acceptor ◽  
Polymeric Carbon

This work incorporates a variety of conjugated donor-acceptor (DA) co-monomers such as 2,6-diaminopurine (DP) into the structure of a polymeric carbon nitride (PCN) backbone using a unique nanostructure co-polymerization strategy and examines its photocatalytic activity performance in the field of photocatalytic CO2 reduction to CO and H2 under visible light irradiation. The as-synthesized samples were successfully analyzed using different characterization methods to explain their electronic and optical properties, crystal phase, microstructure, and their morphology that influenced the performance due to the interactions between the PCN and the DPco-monomer. Based on the density functional theory (DFT) calculation result, pure PCN and CNU-DP15.0 trimers (interpreted as incorporation of the co-monomer at two different positions) were extensively evaluated and exhibited remarkable structural optimization without the inclusion of any symmetry constraints (the non-modified sample derived from urea, named as CNU), and their optical and electronic properties were also manipulated to control occupation of their respective highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO). Also, co-polymerization of the donor–acceptor 2,6-diamino-purine co-monomer with PCN influenced the chemical affinities, polarities, and acid–base functions of the PCN, remarkably enhancing the photocatalytic activity for the production of CO and H2 from CO2 by 15.02-fold compared than that of the parental CNU, while also improving the selectivity.

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