Carbon nanotubes (CNTs) are anticipated to be the successor of silicon in next-generation integrated circuits. However, one great challenge to the practical application of this concept is the need to grow horizontal semiconducting CNT arrays with very high purity. Here we show that this roadblock can be eliminated by switching the direction of an applied electric field during synthesis. This electro-renucleation approach twists the chirality of the CNTs to produce nearly defect-free s-CNTs horizontally aligned on the substrate with less than 0.1% residual metallic CNT. In principle, this residual percentage can be further reduced to less than 1 ppm simply by tuning the CNTs’ diameters to around 1.3 nm. Electro-renucleation thus offers a potential pathway to practical applications of CNT electronics and opens up a new avenue for large-scale selective synthesis of semiconducting CNTs and other nanomaterials.

碳纳米管（CNT）有望成为下一代集成电路中硅的继任者。然而，对该概念的实际应用面临的一大挑战是需要生长具有非常高纯度的水平半导体CNT阵列。在这里，我们表明可以通过在合成过程中切换施加电场的方向来消除此障碍。这种电脱核方法扭曲了CNT的手性，从而产生了几乎无缺陷的s-CNT，该s-CNT在基板上水平排列，残留金属CNT的含量少于0.1％。原则上，仅通过将CNT的直径调整到1.3 nm左右，即可将残留百分比进一步降低至小于1 ppm。