Experimental and Theoretical Studies on the Corrosion Inhibition of Carbon Steel by Two Indazole Derivatives in HCl Medium

Shenying Xu; Shengtao Zhang; Lei Guo; Li Feng; Bochuan Tan

doi:10.3390/ma12081339

Experimental and Theoretical Studies on the Corrosion Inhibition of Carbon Steel by Two Indazole Derivatives in HCl Medium

Materials (Basel). 2019 Apr 24;12(8):1339. doi: 10.3390/ma12081339.

Authors

Shenying Xu^{1

2}, Shengtao Zhang³, Lei Guo⁴, Li Feng⁵, Bochuan Tan⁶

Affiliations

¹ School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China. 20111802011@cqu.edu.cn.
² School of Chemistry and Chemical Engineering, Yibin University, Yibin 644000, China. 20111802011@cqu.edu.cn.
³ School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China. stzhang@cqu.edu.cn.
⁴ School of Material and Chemical Engineering, Tongren University, Tongren 554300, China. chygl@gztrc.edu.cn.
⁵ School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China. 20151802007@cqu.edu.cn.
⁶ School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China. 20161802006@cqu.edu.cn.

Abstract

In this work, two indazole derivatives, namely 5-aminoindazole (AIA) and 5-nitroindazole (NIA), were investigated as corrosion inhibitors for carbon steel in 1 M HCl solution by experimental and density functional theory (DFT) methods. The electrochemical results indicate that the inhibition ability follows the order of AIA > NIA, which is due to the stronger electron-donating effect of -NH₂ of the AIA group than the -NO₂ group of NIA. Besides, the frontier orbital theory shows that the AIA exhibits higher reaction activity than NIA, and a more negative adsorption energy for AIA was also obtained, which is consistent with the analysis of the electrochemical measurements. We draw the conclusion that the electron-donating effect makes it easier for AIA to donate electrons to iron atoms to form a stronger protective layer than NIA.

Keywords: DFT; carbon steel; corrosion inhibitor; electrochemistry; indazole derivatives.