Theoretical Study of Atomic Layer Deposition Reaction Mechanism and Kinetics for Aluminum Oxide Formation at Graphene Nanoribbon Open Edges

The atomic layer deposition (ALD) reaction of Al2O3 at graphene nanoribbon open edges has been studied theoretically by ab initio density functional theory and transition state rate theory. The structures of reactants, adsorption complexes, products, and transition states of the model reactions were optimized at the B3LYP/6-311G(d,p) level of theory. The potential energy profiles have revealed the mechanisms of the chemical adsorption and the dissociation reactions. The potential barriers of the adsorption reactions for the zigzag edge (eq ) and armchair edge (eq ) are predicted to be 1.5 and 6.5 kcal/mol, respectively, while in the following steps the adsorption process is a barrierless reaction and the dissociation process undertakes the release of CH4 via a tight transition state. The reaction rates for all five solid−gas interface reaction steps have been calculated in the temperature range 300−1000 K and the pressure range 0.1 Torr−10 atm. The result shows that the adsorption rate of the zigzag edge with H2O is much faster than that of the armchair edge with H2O. Theoretical prediction for reaction temperature and pressure is in good agreement with the experimental conditions. This work outlines a way by ALD to selectively decorate and passivate the zigzag and armchair edges of graphene nanoribbons, which have significantly different electrical and magnetic properties

Theoretical Study on the Oxidation Mechanism and Dynamics of the Zigzag Graphene Nanoribbon Edge by Oxygen and Ozone

Graphene nanoribbons (GNRs), as an emerging class of material, hold great potential for the future high speed and low power electronic and spintronic devices. The fabrication of GNRs is of the utmost interest in terms of graphene based device research. Chemical narrowing of GNRs by oxidation is a promising technique in producing nanoribbons of desired widths. In this article, we hope to elucidate the etching mechanism of zigzag GNR (ZGNR) edge by oxidation through theoretical investigations. The oxidation mechanisms and dynamics of the ZGNR edge by O₂ and O₃ are fully revealed by density functional theory and statistical theory. The relationship between the reaction time and pressure as well as temperature is estimated dynamically. These theoretical results successfully interpret the recent experimental results and can be further used to predict the appropriate oxidation conditions for the precision etching of ZGNRs

Stability test of variables.

This table reports the result of stability test according to the Fisher-ADF test.</p

<i>spriv</i>’s instrumental variable regression.

This table reports the results of 2SLS regressions analyzing the impact of private capital holding (spriv) on stability of CCBs and the moderating effect of government’s financial awareness. The dependent variables of Columns 1- 6 are spriv, spriv × Finawa, Ln_Z, ROA, CAR and σ(ROA) respectively. Variables are defined in Table 1. The sample period is from 2007 to 2017. In parentheses are t-statistics. ***, **, * indicate statistical significance at the 1%, 5%, and 10% level, respectively.</p

Private ownership shares (<i>spriv</i>), government’s financial awareness of and stability of CCBs.

This table reports the results of dynamic panel system GMM regressions analyzing the impact of private ownership shares (spriv) on stability of CCBs and the moderating effect of government’s financial awareness. The dependent variables of Columns 1- 4 are Ln_Z, ROA, CAR and σ(ROA) respectively. Variables are defined in Table 1. The sample period is from 2007 to 2017. In parentheses are t-statistics. ***, **, * indicate statistical significance at the 1%, 5%, and 10% level, respectively.</p

Descriptive statistics.

This table reports the descriptive statistics for the main variables. The sample period is from 2007 to 2017.</p

<i>Priv</i>’s instrumental variable regression.

This table reports the results of 2SLS regressions analyzing the impact of private capital holding (Priv) on stability of CCBs and the moderating effect of government’s financial awareness. The dependent variables of Columns 1- 6 are Priv, Priv × Finawa, Ln_Z, ROA, CAR and σ(ROA) respectively. Variables are defined in Table 1. The sample period is from 2007 to 2017. In parentheses are t-statistics. ***, **, * indicate statistical significance at the 1%, 5%, and 10% level, respectively.</p

Private capital relative holding (<i>Privl</i>), government’s financial awareness of and stability of CCBs.

This table reports the results of dynamic panel system GMM regressions analyzing the impact of private capital relative holding (Privl) on stability of CCBs and the moderating effect of government’s financial awareness. The dependent variables of Columns 1- 4 are Ln_Z, ROA, CAR and σ(ROA) respectively. Variables are defined in Table 1. The sample period is from 2007 to 2017. In parentheses are t-statistics. ***, **, * indicate statistical significance at the 1%, 5%, and 10% level, respectively.</p

<i>ROA</i> in different years.

Based on the panel data of 123 city commercial banks in China from 2007 to 2017, we use the dynamic panel system GMM estimation method to empirically test the impact of private capital holdings on the stability of city commercial banks. The results show that private capital holding improves the operating performance of city commercial banks, reduces the volatility of return on total assets, and is conducive to the stability of city commercial banks. Furthermore, the lack of financial awareness of local governments has led to the negative impact of private capital, that is, the stability of the banks has declined.</div

<i>Ln</i>_<i>Z</i> in different years.

Based on the panel data of 123 city commercial banks in China from 2007 to 2017, we use the dynamic panel system GMM estimation method to empirically test the impact of private capital holdings on the stability of city commercial banks. The results show that private capital holding improves the operating performance of city commercial banks, reduces the volatility of return on total assets, and is conducive to the stability of city commercial banks. Furthermore, the lack of financial awareness of local governments has led to the negative impact of private capital, that is, the stability of the banks has declined.</div