Nano-to-macroporous TiO 2 (anatase) by cold sintering process

Cold Sintering Process (CSP) was applied on commercial nanopowders to produce nanostructured TiO 2 anatase with nano-to-macro porosity. Nanoporous TiO 2 based materials were obtained by applying CSP at 150 °C and pressures up to 500 MPa on three TiO 2 nanopowders with different specific surface area (s.s.a. = 50, 90 and 370 m 2 /g), using water as transient aqueous environment. Although TiO 2 is insoluble in water, a density of 68% and s.s.a. = 117 m 2 /g were achieved from the powder with the highest specific surface area. A post annealing process at 500 °C increased the density up to 73% with a s.s.a. = 59 m 2 /g, and the crystallites dimensions passed from 110 Å in the powder to 130 Å in CSP material and 172 Å after post annealing. Finally, macroporosity was produced by using thermoplastic polymer beads as sacrificial templates within TiO 2 nanopowder during CSP, followed by a debonding at 500 °C.