Origin of Electrocatalytic Activity in Amorphous Nickel-Metalloid Electrodeposits


Sarac B., Karazehir T., Micusik M., Halkali C., Gutnik D., Omastova M., ...More

ACS APPLIED MATERIALS & INTERFACES, vol.13, no.20, pp.23689-23701, 2021 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 13 Issue: 20
  • Publication Date: 2021
  • Doi Number: 10.1021/acsami.1c03007
  • Title of Journal : ACS APPLIED MATERIALS & INTERFACES
  • Page Numbers: pp.23689-23701

Abstract

In transition metal-based alloys, the nonlinearity of the current at large cathodic potentials reduces the credibility of the linear Tafel slopes for the evaluation of electrocatalytic hydrogen activity. High-precision nonlinear fitting at low current densities describing the kinetics of electrochemical reactions due to charge transfer can overcome this challenge. To show its effectiveness, we introduce a glassy alloy with a highly asymmetric energy barrier: amorphous NiP electrocoatings (with different C and O inclusions) via changing the applied DC and pulsed current and NaH2PO2 content. The highest hydrogen evolution reaction (HER) activity with the lowest cathodic transfer coefficient alpha = 0.130 with high J(0) = -1.07 mA cm(-2) and the largest surface areas without any porosity are observed for the pulsed current deposition. The calculated alpha has a direct relation with morphology, composition, chemical state and coating thickness defined by the electrodeposition conditions. Here, a general evaluation criterion with practicality in assessment and high accuracy for electrocatalytic reactions applicable to different metallic alloy systems is presented.