Influence of the crystal structure of Ag2CO3 on the photocatalytic activity under visible light of Ag2CO3-Palygorskite nanocomposite material

[Display omitted] •Nanocomposite photocatalysts based on Ag2CO3 supported on palygorskite nanofibers.•Visible light activity of Ag2CO3-Palygorskite nanocomposite photocatalyst.•Synergetic effect of β- and m-Ag2CO3 phases supported on palygorskite photocatalyst.•Surface functionalization of natural clay for eco-friendly photocatalytic treatments.•m-Ag2CO3 is more efficient than β-Ag2CO3 as photocatalyst under visible light. In a companion paper, it has been demonstrated the remarkably beneficial effect of palygorskite clay (Pal) fibers as support material coupled to appropriate thermal treatments and aging under CO2 atmosphere in monitoring the phase composition of Ag2CO3-Pal composite. In this new nanocomposite material, the structure of the functional component Ag2CO3 can be controlled from 100% stable monoclinic (m) to 100% metastable hexagonal β through an adjusted mixture of m- and β-Ag2CO3. The present study deals with the assessment of the visible photocatalytic properties of these various nanocomposite materials towards the removal of Orange G dye from aqueous solutions. It was found that the Ag2CO3-Pal nanocomposite in which Ag2CO3 was single-phased and crystallized with the stable monoclinic structure was more active than the one crystallizing entirely with the metastable β-Ag2CO3 structure. Nevertheless, the composite material containing a mixture of both Ag2CO3 phases with a relative content of 32% of β- and 68% of m-phase was found to be the most photoactive compound of the series. This behavior reveals likely a synergetic effect between both phases in the photocatalytic degradation of the dye under visible light.