Unraveling the reinforced photoelectrocatalytic activity and stability via unique configuration of P3+-O-v-Ti3+ in TiO2-x nanotube array

Blue defective TiO2 is particularly attractive compared to TiO2 owing to its high electron conductivity and oxygen vacancies (O-v). However, it remains a challenge to overcome short-time deactivation in that active site of Ti3+ coordinated with high-electronegative oxygen atom usually aggravates the tendency to high valence state. Herein, we design a unique configuration of P3+-O-v-Ti3+ in TiO2-x nanotube array via utilizing PH3 to synchronize the reaction during the transformation from amorphous TiO2 to anatase detective TiO2 (TiO2-x). The performance results and DFT simulations reveal that the 3 s orbital (M shell) of P3+ in PT1 has a delocalized electron pair and significantly changes the valence electron configuration in 3d orbital of Ti3+ in the configuration P3+-O-v-Ti3+, thus regulating its electronic structure and forming a midgap state at the band gap. The unique structure of P3+-O-v-Ti3+ allows Ti3+ to exist in a more stable form via modulating electronic structure and constructing a new channel for electron transfer, resulting in a remarkable photoelectrocatalytic performance and an unprecedented stability with the lifetime of over 39632 h in 1 M NaClO4 electrolyte at 1 mA/cm(2). This work not only provides an efficient way to prepare the stable photoelectrodes but paves the way to identify the roles of phosphorus with different valence states in catalytic activity and stability.