Physical Chemistry Chemical Physics

doi: 10.1039/d2cp90204dpmid: N/A

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doi: 10.1039/d2cp90205bpmid: N/A

A graphical abstract is available for this content

Li, Feng; Zhou, Ce; Klinkova, Anna

doi: 10.1039/d2cp02846hpmid: 36214354

The electrocatalytic performance of nanostructured heterogeneous electrocatalysts can be tailored by adjusting their geometries due to the morphologically dependent physicochemical effects, such as field-induced reagent concentration near high-curvature nanoscale features and the confinement of reaction intermediates in a nanocavity. However, the theoretical studies on these physicochemical effects in various nanoscale structures are considerably less common in comparison to the density functional theory calculations on the atomic structure design due to the absence of consistent simulation protocols in this area. This tutorial review presents the theory, models, and protocols for the simulation of the electrochemical properties of nanoelectrocatalysts with complex morphologies using the finite element method (FEM), including the local electric field (E-field) and the current density in the electrolyte adjacent to the electrode (Jelectrolyte) and in the electrode (Jelectrode). In the E-field simulation, we demonstrate the significant screening effect of the EDL on the E-field distribution as well as the influence of the relative permittivity of the electrolyte on the screening strength. In the Jelectrolyte simulation, we illustrate the impact of the electrode kinetics on the electron transfer, which can significantly affect the Jelectrolyte profile. In the Jelectrode simulation, we reveal that the Jelectrode crowding can occur in constricted areas of nanostructures, which would cause the structural transformation via electromigration. Finally, we discuss the applicability and limitations of the theoretical models discussed in this tutorial, suggesting the focus of future work to develop advanced multiscale modelling approaches. We hope this tutorial will assist electrochemists in navigating how to conduct accurate electrochemical physics effect simulations for analyzing the catalytic performance of nanoelectrocatalysts and thereby contribute to a wider adoption of FEM simulations in the rational design of advanced electrocatalysts.

Lee, Yong Jieh; Putri, Lutfi Kurnianditia; Ng, Boon-Junn; Tan, Lling-Lling; Wu, Ta Yeong; Chai, Siang-Piao

doi: 10.1039/d2cp03768hpmid: 36278396

Effective photocatalytic polyethylene degradation by TiO2 is hindered by the sluggish kinetics of alkyl hydroperoxide decomposition. Introduction of oxygen vacancies onto TiO2 destabilizes the hydroperoxide O–O bond due to mid-gap states and the elevated Fermi level. Downshift of the d-band center by oxygen vacancies also enhanced adsorbate–surface interactions and lowered the activation energy barrier from Gibbs calculations. Experimental evidence additionally substantiated enhanced polyethylene degradation on TiO2−x compared to TiO2.

Shin, Donghan; Jung, YounJoon

doi: 10.1039/d2cp03244apmid: 36155687

It is necessary to quantitatively determine substituent effects to accurately elucidate reaction mechanisms in the field of organic chemistry. This paper reports that the molecular electrostatic potential (MESP) can be used as a general and versatile measure for the substituent effects in various chemical reactions by performing extensive density functional theory (DFT) calculations for more than 400 molecules, followed by statistical analyses. We observed a robust and linear correlation between the electrostatic potential and the substituent parameters for various cases of reactive systems, regardless of the DFT functionals, basis sets, and solvation models used. In addition, we statistically analysed the normality of the residuals from the linear regression to demonstrate that strong linear relationships hold universally, which indicates that the electrostatic potential can serve as a physically meaningful quantity for the predictive estimation of substituent effects. In contrast, conventionally used methods based on the charge deviation in the aromatic carbons, as computed using various charge analysis methods, (e.g., Hirshfeld charge analysis) do not demonstrate the statistical normality. Furthermore, we illustrate that MESP can be extensively adopted to strengthen the validity of the linear free energy relationships (LFERs) under various chemical conditions. The results revealed that the MESP shift derived by a functional group on a mono-substituted benzene ring is a strong predictor for the substituent effects on the electronic behaviours in chemical reactions; thus, it can serve as an alternative to other empirical parameters such as the Hammett or Swain–Lupton parameters, or the charge shift.

Brumboiu, Iulia Emilia; Ericsson, Leif K.E.; Blazinic, Vanja; Hansson, Rickard; Opitz, Andreas; Brena, Barbara; Moons, Ellen

doi: 10.1039/d2cp03514fpmid: 36128981

This joint experimental–theoretical spectroscopy study of the fullerene derivative PC60BM ([6,6]-phenyl-C60-butyric acid methyl ester) aims to improve the understanding of the effect of photooxidation on its electronic structure. We have studied spin-coated thin films of PC60BM by X-ray Photoelectron Spectroscopy (XPS), Near-edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy, and Fourier Transform Infrared Spectroscopy (FTIR), before and after intentional exposure to simulated sunlight in air for different lengths of time. The π* resonance in the C1s NEXAFS spectrum was found to be a very sensitive probe for the early changes to the fullerene cage, while FTIR spectra, in combination with O1s NEXAFS spectra, enabled the identification of the oxidation products. The changes observed in the spectra obtained by these complementary methods were compared with the corresponding Density Functional Theory (DFT) calculated single-molecule spectra of a large set of in silico generated oxidation products of PC60BM where oxygen atoms were attached to the C60 cage. This comparison confirms that photooxidation of PC60BM disrupts the conjugation of the fullerene cage by a transition from sp2 to sp3-hybridized carbon and causes the formation of several oxidation products, earlier proposed for C60. The agreement between experimental and calculated IR spectra suggests moreover the presence of dicarbonyl and anhydride structures on the fullerene cage, in combination with cage opening at the adsorption site. By including PC60BM with physisorbed O2 molecules on the cage in our theoretical description in order to model oxygen diffused through the film, the experimental O1s XPS and O1s NEXAFS spectra could be reproduced.

Qiao, Shu-Xiang; Sui, Chang-Hao; Yang, Liu; Li, Ya-Ping; Sun, Yu-Xin; Zhang, Nai-Xin; Bai, Jia-Qi; Jiao, Na; Lu, Hong-Yan

doi: 10.1039/d2cp03155hpmid: 36222115

As an allotrope of graphene, T-graphene was predicted to be an intrinsic two-dimensional (2D) superconductor with a superconducting critical temperature (Tc) of about 20.8 K [Gu et al., Chin. Phys. Lett. 36, 097401 (2019)]. In this work, based on first-principles calculations, hole doping and biaxial tensile strain (BTS) are considered to modulate the electron–phonon coupling (EPC) and superconductivity of T-graphene. It is found that the EPC constant of T-graphene is 0.807 and the calculated critical temperature Tc is 28.2 K at a doping level of 0.5 hole per unit cell (3.31 × 1014 cm−2) and 12% BTS. Furthermore, when 0.8 hole per unit cell (5.43 × 1014 cm−2) doping and 10% BTS are applied, the EPC constant is 0.939, and the Tc can be boosted to 35.2 K, which is higher than those of the pristine T-graphene and many other 2D carbon-based superconductors.

Jóźwik, Przemysław; Cardoso, José P. S.; Carvalho, Diogo F.; Correia, Maria R. P.; Sequeira, Miguel C.; Magalhães, Sérgio; Faye, Djibril Nd.; Grygiel, Clara; Monnet, Isabelle; Bross, Adam S.; Wetzel, Christian; Alves, Eduardo; Lorenz, Katharina