【Device Papers】Engineering Charge Separation in α-Ga₂O₃ Nanorod Arrays for Photoelectrochemical UV Detection

      Researchers from the Nanjing University of Posts and Telecommunications have published a dissertation titled "Engineering Charge Separation in α-Ga₂O₃ Nanorod Arrays for Photoelectrochemical UV Detection" in ACS Applied Nano Materials.

Abstract

      Oxygen vacancy (O_V) states are the most prevalent chemical defects in metal oxides without extrinsic dopants, which govern the regime of photoelectrochemical (PEC) kinetics. So far, although tremendous strategies are developed to overcome the negative effects from O_V, the threshold at which O_V plays a positive role has not been specifically studied. Furthermore, the kinetics of stoichiometry changes as well as their effects on the charge transport aroused from manipulating O_V distribution are still in confusion. Here, taking α-Ga₂O₃ nanorod arrays as the model, we show the evolution mechanism about the changes in O_V distribution during vacancy engineering. Since the O diffusion flow into bulk is regulated by the surface O_V-assisted migration mechanism, the surface O_V concentration decreased first and recovered slightly after a period of time. This is deviated from the common sense that the longtime O₂ annealing should bring about monotonical O_V decrease at the surface. After PEC characterization and theory calculation, the results show that O_V plays to the score in the PEC process, depending on its own spatial distribution. The optimized engineering strategy of O_V spatial distribution is proposed to establish the efficient carrier separation nanoarchitectures for high-performance UV photodetection. This work provides an insight for clarifying fundamental rules for defect engineering in the PEC field.

DOI：

https://doi.org/10.1016/j.jmat.2024.06.006