Intermetallic catalyst for making hydrogen from methanol

Abstract

The outdoor application of antireflective (AR) films requires not only high transmittance but also such mechanical properties as good abrasion-resistance, certain humidity resistance to resist the damage of the harsh environment. In the study, AR films with excellent performance were prepared by the dip-coating process in which aqueous colloidal silica (ACS) was used as the silica source and orthophosphoric acid as adhesion promoting agent. In the process of heat treatment of the films, the orthophosphoric acid in silica sols firstly transformed into the chain of metaphosphoric acid by the polycondensation reactions and then reacted with surface Si–OH groups from colloidal silica particles and the substrate, resulting in the formation of the numerous Si–O–P cross-linkings and 3SiO2·2P2O5 phase. Because colloidal silica particles were coated with 3SiO2·2P2O5 phase and linked by strong Si–O–P chemical bonds, abrasion-resistant property of films was markedly boosted. When the weight ratio of H3PO4 to silica sols was 2.71%, the pencil hardness grade of corresponding film had reached 6 H. Meanwhile, the average transmittance of the film in the visible spectrum was 97.9% and the weighted average transmittance (WAT) in the full spectrum range was as high as 97.2%, while that of the bare glass substrate was merely 89.6%. Moreover, the average transmittance still remained at around 97.9% after having been soaked in tap water for 30 days.