Investigation of the Kinetics and Mass Transport Aspects of Hydrogen Evolution during Electroless Deposition of Nickel–Phosphorus. Issue 7 (1st January 2017)

• Record Type: Journal Article
• Authors: Liu, Xinyu; Richtering, Werner; Akolkar, Rohan
• Is Part Of: Journal of the Electrochemical Society. Volume 164:Issue 7(2017)
• Page Start: D498
• Page End: D504
• Publication Date: 2017-01-01
• Subjects: electroless Ni-P deposition -- hydrogen evolution -- sodium hypophosphite; Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/2.1521707jes
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : Electroless deposition of nickel-phosphorus (Ni–P) alloy, facilitated by the use of sodium hypophosphite as reducing agent, is important to many industrial applications. During electroless Ni–P deposition, hydrogen gas evolves as a by-product. In this paper, we first analyze the source of hydrogen evolution. Specifically, we demonstrate that hydrogen gas evolves primarily due to chemical hydroxylation of hypophosphite anions catalyzed by the Ni surface and not due to electrochemical water splitting. Then, using careful volumetric measurements of the rate of hydrogen evolution on a rotating disc electrode, the effects of pH, hypophosphite concentration and hydrodynamics on the hypophosphite hydroxylation reaction are investigated. A mathematical rate expression is formulated, which incorporates the relevant kinetic and mass transport parameters affecting the hypophosphite hydroxylation reaction. Comparison of the model with experimental hydrogen evolution rate measurements allows precise determination of the rate constant and reaction orders. The approach presented herein has broad applicability to the study of gas evolution kinetics in chemical systems where access to the reaction rate is not available through amperommetry.