An in-situ transient photo-induced voltage method to understand the PEC efficiency of C, N co-doped TiO2 photoanode

Photoelectrocatalysis (PEC) is one of the most important green energy conversion technologies. During the development of PEC, the Jabs, eta sep and eta inj are challenges that hinder the performance enhancement of different kinds of photoanodes in PEC systems. As a stable, cheap and non-toxic PEC material, TiO2 is also limited by the above challenges. Here, a series of C, N co-doped TiO2 photoanodes were synthesized by hydrothermal method combined with a simple one-step thermal diffusion treatment. Under AM 1.5 G light intensity, the PEC perfor-mance of TCN-1.5 is 4.06 mA cm-2 at 1.23 V vs RHE in 1.0 M NaOH, which is ca. 2.08 times as high as the photocurrent density of the pristine TiO2. Especially, an in-situ transient photoinduced voltage (TPV) method was developed to measure the changes on efficiencies mentioned above: Jabs, eta sep and eta inj are improved by about 9.8 %, 24.9 % and 48.3 %, respectively, and their product is equal to the increase of photocurrent density. This work analyzes the improvement of efficiencies in the PEC process through in-situ characterization and opens up a new way for PEC material design and fabrication.