Ru/Ir nanojunctions supported on CNTs as active and ultrastable catalysts for CO preferential oxidation toward hydrogen purification

Abstract

Hydrogen purification is animportanttechnological step for proton exchange membrane fuel cells (PEMFCs), which can promote the service life of batteries. The preferential oxidation of CO (PROX) in hydrogen is a promising solution for hydrogen purification to avoid poisoning of catalysts by the trace amount of CO present in thehydrogen-richfeedgas. Herein, we demonstrate an interface engineering strategy to prepare Ru/Ir-CNTs nanojunctionswith remarkablecatalyticactivity for CO oxidation. The as-prepared catalyst shows thetotal COconversionin awidetemperaturerange of 50-200℃ under a high feeding gas flow velocity of 72000 mL g-1h−1 and remains stable after 48 h of continuous working. The catalyst also exhibits 100 % CO conversion in temperature from 80 to 100℃ under a much higher feeding gas flow velocity of 108000 mL g-1h−1. Moreover, the CO conversion remains 100 % after intermittent performance testing over a one-week time period. Theoretical calculations reveal that the interface of Ru/Ir can weaken the adsorption of *CO2, thus greatly increasing the temperature range of the complete transformation of CO. Compared to oxide supports, CNTs are more difficult to combine with CO2, which makes the catalyst completely convert CO for a long time within the operating temperature range.