Quantitative study of the kinetics of hydrogen evolution reaction on aluminum surface and the influence of chloride ion

• Published in: International journal of hydrogen energy 2021-11, Vol.46 (80), p.39665-39674
• Main Authors: Zhang, Qin-Hao, Li, Xin-Ran, Liu, Pan, Meng, Xian-Ze, Wu, Lian-Kui, Luo, Zhuang-Zhu, Cao, Fa-He
• Format: Article
• Language: English
• Subjects: Aluminum; Chloride effect; Hydrogen generation; Kinetic parameters; SECM
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2021.09.189

The behaviors and kinetics of hydrogen evolution reaction (HER) on pure aluminum with passive film in the presence and absence of chloride ion are quantitatively investigated by using the tip generation/substrate collection mode of scanning electrochemical microscopy (SECM) with dual Al/Pt ultramicroelectrode (UME) as tip electrode and Pt UME as substrate electrode. The standard rate constants k0 and transfer coefficients αH of HER in ClO4−- and Cl−-containing solution are 6.9 × 10−7 cm/s and 0.22, 7.1 × 10−6 cm/s and 0.19, respectively. Results show that the kinetic of HER is slow and the destruction of Cl− on passive film can significantly promote the HER on Al surface. Moreover, these αH far less than commonly used 0.5 in corrosion research, can explain the great difference between theoretical Tafel slopes and experimental results. Besides, the existence of current plateau in Al electrode explains the large difference in corrosion potential during parallel testing. The Al tip and Pt substrate current were recorded by scanning the tip potential from −0.967 V to the positive direction until current suddenly drops in 5 mM HCl +0.1 M NaCl solution (graph on the left). Schematic diagram of distance determination by Fc/Fc+ between Pt tip and Pt substrate electrode in 1 mM FcMeOH +0.1 M KNO3 solution (dotted line), and the quantitative detection of HER generated on Al surface in deaerated acid solution after moving Al tip above the Pt substrate (solid line), as shown in the middle graph. The Al tip current, hydrogen evolution reaction current and Al oxidation current were recorded in the potential from −0.967 V to 1.333 V in 5 mM HClO4 + 0.1 M NaClO4 (graph on the right). [Display omitted] •The kinetics of HER on Al surface was studied by the modified TG/SC mode of SECM.•Kinetic parameters k0 and transfer coefficients αH of HER are obtained.•HER rate in Cl− ion solution is significantly higher than that in ClO4− ion solution.•αH far from 0.5 explains the difference of theoretical βc and experimental results.•The current platform can explain the large difference of Ecorr during parallel testing.