Unraveling the atomic-scale mechanism of interfacial alkali ion close packing in nano glassy fibers driven by CO2-mediated attraction

Abstract

The poor alkali resistance of nano-glassy fiber (NGF) hinders its application in aggressive alkaline environments like cement and alkaline wastewater. This study introduced a potential strategy to enhance the alkali resistance of NGF based on the distinct atomic-scale interactions between CO₂ molecules and NGF ions at high temperatures. The short-range structure in the NGF-CO₂ system was elucidated through the pair distribution functions and coordination numbers of ion–oxygen pairs and second-nearest-neighbor ion–ion pairs. High-mobility Na ions were observed to exhibit a strong interaction with CO₂, penetrating through the melt skeleton and accumulating at the interface. The enrichment of Na ions as network modifiers enhanced the alkali resistance of NGF, with the maximum thickness of the enrichment layer reaching ∼5 Å at 1173 K. These findings present a straightforward production approach for alkali-resistant NGF, not requiring additional costly materials or processes.