Durability enhancement of a Pt/C electrocatalyst using silica-coated carbon nanofiber as a corrosion-resistant support

• Published in: International journal of hydrogen energy Vol. 44; no. 8; pp. 4177 - 4187
• Main Authors: Islam, Jahowa, Kim, Sang-Kyung, Lee, Eunjik, Park, Gu-Gon
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 08-02-2019
• Subjects: Carbon nanofiber; Durability; Pt/C catalyst; Silica coating; Silica precursor; Pt/C catalyst; Carbon nanofiber; Silica precursor; Durability; Silica coating
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2018.12.138

Electrochemical oxidation of a carbon support is one of the major challenges to making proton exchange membrane fuel cells (PEMFCs) durable. The aim of this study was to develop a durable carbon-based electrocatalyst support for use in PEMFCs. Platelet-type carbon nanofiber (PCNF) was coated in a uniform and discrete manner with silica by successive hydrolysis of two kinds of silica precursors, APTES and TEOS. The shape and thickness of the silica coating on carbon was controlled by adjusting the amount of APTES and TEOS. The platinum was mainly deposited on silica rather than carbon because the zeta potential of silica is more favorable to binding platinum precursor ions than that of PCNF. Accelerated degradation testing of the silica-coated catalysts (Pt/PCNFSiO2) and Pt/PCNF showed that Pt/PCNFSiO2 possess higher durability than Pt/PCNF under potential cycling. After 30,000 potential cycles ranging from 1.0 V to 1.5 V, the electrochemical surface area losses were 21%, 16%, and 11% and the half-wave potential (E1/2) degradation losses were 16 mV, 9 mV, and 8 mV for Pt/PCNF and Pt/PCNFSiO2 with two different amounts of silica wt%. Silica-coated carbon nanofibers are expected to be a suitable electrocatalyst support for PEMFCs.
•Carbon nanofiber (CNF) was coated in uniform and discrete manner with silica.•Thickness and shape of silica on carbon nanofiber (CNF) was controlled.•Platinum deposited more on silica than carbon when both silica and carbon were exposed.•Durability of Pt/CNF catalyst was improved under potential cycling by coating the CNF.