Facile Carbon Embedding in TiO ₂ Nanotube Arrays for Enhanced Cathodic Luminol Electrochemiluminescence and Choline Detection

A sensitive electrochemiluminescence (ECL) platform for choline detection was developed based on carbon‐embedded TiO ₂ nanotube arrays (C/TiNTs) under mild alkaline conditions. The electrode was prepared by two‐step anodization followed by argon annealing, during which residual electrolyte species confined in the nanotube channels were directly converted into an inner carbon‐containing layer. This facile strategy introduces a conductive carbon layer into TiO ₂ nanochannels without additional coating procedures. As a result, the cathodic luminol ECL of C/TiNTs was markedly enhanced relative to bare TiO ₂ nanotube arrays, owing to improved interfacial charge transport and more efficient use of reactive intermediates within the confined nanotube channels. The enhanced ECL response was further used to construct a choline sensor, enabling highly sensitive choline detection over a linear range of 5.0 × 10 ⁻⁸ to 2.0 × 10 ⁻⁴ mol L ⁻¹ with a detection limit of 2.0 × 10 ⁻⁸ mol L ⁻¹ . These results demonstrate that this facile electrolyte‐derived carbon‐embedding strategy can be extended to the construction of other biosensors based on enhanced nanochannel ECL interfaces.