The Fischer–Tropsch reaction converts synthesis gas (CO + H₂) into hydrocarbons and water on a solid catalyst by repeated C–C coupling of C1 surface intermediates. Low-temperature Fischer–Tropsch (LTFT) synthesis is the regime, typically near 200–250 °C on cobalt or iron catalysts, that favors long-chain n-alkanes and waxes over the lighter, more olefinic slate of high-temperature Fischer–Tropsch operation. ε-Iron carbide is an active iron phase for this low-temperature conversion of syngas to hydrocarbons ^[1]. Product selectivity within the LTFT window can be shifted from paraffins toward α-olefins by modifying the catalyst environment without leaving the low-temperature manifold ^[2]. Plasma-synthesized nanocatalysts for CO hydrogenation under LTFT conditions instantiate the same C1 polymerization on a nanostructured metal surface ^[3]. The concept is bounded as catalytic CO hydrogenation with C–C chain growth at the lower-temperature FT branch; it is not methanol synthesis, not the methanol-to-olefins reaction, and not high-temperature FT, whose operating temperature, catalyst formulation, and carbon-number distribution differ.