Dissolution of Na2CaV4O12 in aqueous solution: From layer-by-layer exfoliation to dissociative reconstruction of V4O12 clusters

Layered Na 2 CaV 4 O 12 is a highly promising electrode material and a key intermediate in the hydrometallurgical extraction of vanadium from raw materials; however, the mechanism of its dissolution in water remains unclear. A combined experimental and density functional theory (DFT) study was conducted to elucidate the dissolution process at the atomic scale. Experimental results show that Na 2 CaV 4 O 12 completely dissociates in neutral water, releasing Na + and vanadate species into solution, while Ca 2+ reprecipitates as CaV 2 O 6 upon reaching supersaturation. DFT simulations reveal that the dissolution proceeds spontaneously via a layer-by-layer exfoliation mechanism on the dominant (001) surface. Water adsorption sequentially weakens Na-O bonds (E ads = −0.628 eV), leading to the release of Na + , promotes Ca 2+ detachment through a hydrogen-bonding network (E ads = −0.873 eV), and finally triggers dissociative chemisorption on the exposed cyclic V 4 O 12 clusters (E ads = −2.501 eV), cleaving them into chain-like VO 3 - units. This work provides fundamental insights for the design of stable vanadium-based materials and the optimization of hydrometallurgical processes.