Strong activation effect on a Ru-Co-C thin film catalyst for the hydrolysis of sodium borohydride

Abstract

In this work, we prepared a series of Ni foam supported Ru-Co, Ru-Co-B and Ru-Co-C catalysts in the form of columnar thin films by magnetron sputtering for the hydrolysis of sodium borohydride. We studied the activity and durability upon cycling. We found a strong activation effect for the Ru-Co-C sample which was the highest ever reported. This catalyst reached in the second cycle an activity 5 times higher than the initial (maximum activity 9310 ml.min−1.gCoRu−1 at 25 °C). Catalytic studies and characterization of the fresh and used samples permitted to attribute the strong activation effect to the following factors: (i) small column width and amorphous character (ii) the presence of Ru and (iii) dry state before each cycle. The presence of boron in the initial composition is detrimental to the durability. Our studies point out to the idea that after the first cycle the activity is controlled by surface Ru, which is the most active of the two metals. Apart from the activation effect, we found that catalysts deactivated in further cycles. We ascribed this effect to the loss of cobalt in the form of hydroxides, showing that deactivation was controlled by the chemistry of Co, the major surface metal component of the alloy. Alloying with Ru is beneficial for the activity but not for the durability, and this should be improved.

Synchronous Growth of Porous MgO and Half-Embedded Nano-Ru on a Mg Plate: A Monolithic Catalyst for Fast Hydrogen Production

“…Over the past years, intensive efforts were continued to tune the catalyst performances by strategies such as alloying, shape control, and support adjustment. , Also, metal catalysts based on earth-abundant elements have been investigated to develop economical catalysts. A comparative study showed that Co is more active than Fe, Ni, and Cu .…”

Hydrogen generation from a sodium borohydride–nickel core@shell structure under hydrolytic conditions

“…At the lab scale, the catalyst is generally introduced into the ask containing the NaBH 4 fuel. 5,15 At the demonstrator scale, the aqueous solution is stored in a tank and pumped into a catalytic reactor when H 2 is needed. [8][9][10][11]16 Considering this design, two important comments should be made.…”