An electrochemical cell 102 comprises an ion exchange membrane 10 having anion and cation exchange materials. The membrane 10 can have separate anion and cation exchange layers 12, 14 that define a heterogeneous water-splitting interface therebetween. In one version, the membrane 10 has a textured surface having a pattern of texture features 26 comprising spaced apart peaks 28 and valleys 30. The membranes 10 can also have an integral spacer 80. A cartridge 100 can be fabricated with a plurality of the membranes 10 for insertion in a housing 129 of the electrochemical cell 102. The housing 129 can also have a detachable lid 96 that fits on the cartridge 100. The electrochemical cell 102 can be part of an ion controlling apparatus 120.