Layered-double-hydroxide-containing composite material and method for producing same

A method for producing a layered-double-hydroxide-containing composite material, the method comprising:

• providing a porous substrate;
• soaking the porous substrate in an aqueous stock solution that contains magnesium ions (Mg2+) and aluminum ions (Al3+) in a total concentration of 0.20 to 0.40 mol/L and urea;
• and
• performing hydrothermal treatment of the porous substrate in the aqueous stock solution to form a layered-double-hydroxide-containing functional layer on and/or in the porous substrate, wherein the layered double hydroxide is an agglomeration of platy particles, and the platy particles are oriented in such a manner that the tabular faces of the platy particles are substantially perpendicular to or oblique to the surface of the porous substrate, and wherein the functional layer has a thickness of not more than 50 μm.