Chemical Capture of Phosphine by a Sol−Gel-Derived Cu/TiO2 Adsorbent − Interaction Mechanisms

Abstract

In this study, a novel sol−gel-derived Cu/TiO2 adsorbent has been demonstrated to exhibit exceptional capacities of 40.62, 49.52, and 108.48 mg PH3/g Cu/TiO2 for the oxidative capture of phosphine (PH3) in N2, air, and humidified air, respectively. We have proposed the oxidative mechanisms for PH3 on the Cu/TiO2 sample on the basis of elemental, chemical state, functional group, and microstructural analysis. Moreover, the influence of O2 and water vapor on the capture capacity is discussed. The transformation of PH3 followed the sequence of PH2 → H2P−OH → HP(OH)2 → P(OH)3 → HO−P═O → H3PO4. At the same time, the CuO/Cu(OH)2 moieties in the TiO2 lattice were reduced to Cu0. The H2P−OH and HO−P═O are the two stable intermediates, and they occupied the active species to inhibit further chemisorption. Direct oxidation of PH3 or the intermediates with adsorbed O2 was not efficient. However, the Cu/TiO2 sample catalyzed their interactions via reduction and then oxidation of the Cu2+ ions. Water vapor acts as a c...