Untangling the Cobalt Promotion Role for Ruthenium in Sodium Borohydride Dehydrogenation With Multiwalled Carbon Nanotube-Supported Binary Ruthenium Cobalt Catalyst

Abstract

In the present study, multiwalled carbon nanotube-supported Ru (Ru/MWCNT) and RuCo (RuCo/MWCNT) nanocatalysts with 3 wt% Ru loading were synthesized via sodium borohydride (SBH) reduction method for the dehydrogenation of SBH (R-SBH)(.) These nanocatalysts were characterized with XRD, XPS, SEM-EDX, and TEM. Ru/MWCNT and Ru:Co/MWCNT catalysts with varying Ru:Co atomic ratios were prepared successfully, and electronic state of Ru:Co altered compared to Ru. R-SBH activities of these Ru/MWCNT and RuCo/MWCNT were examined in alkaline environment. RuCo/MWCNT at 80:20 atomic ratio exhibits superior H-2 evolution. Further experiments were performed with RuCo/MWCNT at 80:20 atomic ratio to determine how NaOH concentration (C-NaOH), reaction temperature (T-rxn), SBH concentration (C-SBH), and amount of nanocatalyst (M-c) affect R-SBH activities. Activation energy (Ea) was calculated using the Arrhenius equation. RuCo/MWCNT at 80:20 atomic ratio exhibits superior H-2 evolution activities compared to the literature values. Initial rate (IR) for this nanocatalyst was found as 123.9385 mL H-2 g(cat)(-1) min(-1). As a result of these kinetic calculations, the Ea of the nanocatalysts was calculated as 35.978 kJ/mol. The degree of reaction (n) was found to be 0.53 by trial and error. RuCo/MWCNT at 80:20 atomic ratio is a promising nanocatalyst for R-SBH.