The present teachings are directed toward an electrocatalytic cell including a barrier, having at least a first side and a second side opposite the first side, comprising a material permeable to oxygen ions and impermeable to at least C0
2 , CO, H,
2 H
2 0 and hydrocarbons, an electrical power supply in communication with the barrier, a catalyst adjacent the first side of the barrier, a supply of feedstock components in communication with the first side of the barrier, a supply of a carrier gas component in communication with the second side of the barrier; wherein the feedstock components contact the catalyst and react to form hydrocarbon- containing components and oxygen-containing components, and the electrical power supply biases the barrier to thereby conduct oxygen ions from the first side to the second side. Also presented are a device and methods for producing carbon nanotubes.