A Nanojunction Polymer Photoelectrode for Efficient Charge Transport and Separation

A novel nanojunction archiecture of metal-free photoanode, composed of B-doped carbon nitride nanolayer and bulk carbon nitride has been fabricated by a one-step construction approach. This type of nanojunction overcomes a few intrinsic drawbacks of carbon nitride film, e.g. severe bulk charge recombination and slow charge transfer. For the optium sample, the top layer of the nanojunction has a depth of ca. 100 nm and the bottom layer is ca. 900 nm. The nanojunction photoanode results into a 10 fold higher photocurrent than bulk graphitic carbon nitride and an extremely high incident photon-to-current efficiency (IPCE) of ca. 10% at 400 nm, which to the best of our knowledge is the highest for G-CN based polymer photoanodes in the absence of any sacrificial reagents. The EIS, MS and IMPS spectroscopies all prove such enhancement is mainly due to more than 10 times faster charge seperation rate and nearly 3 times higher conductivity due to the nanojunction architcutre.