XAFS study of an intermetallic TiFe0.95Zr0.03Mo0.02 system for CO2 conversion

An intermetallic TiFe0.95Zr0.03Mo0.02 system used for CO2 conversion was studied by XAFS spectroscopy. The initial samples prepared by the skull-furnace method were exposed to the below treatments: (1) H2 absorption (up to ∼1 mol of H2 per 1 mol of the initial sample); (2) H2 thermal desorption (up to ∼0.18 mol of H2 at 180 deg. C in inert argon atmosphere); (3) hydrogen titration by CO2 (at 350 deg. C for 4-6 h). For samples [TiFe0.95Zr0.03Mo0.02]H2x (x≤0.18), the position of Ti-K edge shifts of about ∼3 eV compared to that of the initial sample. From the XAFS studies of the modified [TiFe0.95Zr0.03Mo0.02] intermetallide, it is established that the interaction of dissolved hydrogen and titanium follows the donor-acceptor mechanism. Hydrogen atoms are located on the straight line connecting two titanium atoms. The one distance between a hydrogen atom and a titanium atom is less than 1.5 A. It is proposed that the effect of strong binding of hydrogen in the [TiFe0.95Zr0.03Mo0.02]H2x intermetallide at a molar concentration of absorbed hydrogen of 0.18 is associated with the formation of such binding