梯度自掺杂纯相CuBi2O4光电极的可控构筑及其载流子迁移机制研究

CuBi2O4是一种新型的光电极材料，理论光电流密度高达19mA/cm2，而光电分离效率低是制约其发展的最关键因素。通过梯度自掺杂创建内建电场是促进其光电分离的有效途径，然而现有的梯度自掺杂技术依赖热扩散、可控性差、易出现相分离，严重制约了该技术的发展。此外，梯度自掺杂薄膜载流子迁移机制尚缺乏理论研究。本项目提出功率渐变磁控溅射法，拟通过分别控制Cu和Bi的溅射功率渐变，实现从薄膜底部至顶部Cu/Bi浓度梯度的可控调节，在抑制相分离的前提下，创建贯穿整个梯度自掺杂CuBi2O4光电极薄膜的内建电场；并在揭示梯度自掺杂对光电极薄膜内建电场及光电分离影响机制的基础上，建立梯度自掺杂光电极薄膜载流子传输及光电流计算数学模型。研究成果将为梯度自掺杂半导体薄膜的制备提供简单经济、容易调控的新方法，为梯度自掺杂光电极薄膜的定向优化提供理论指导，并促进其在光电催化领域的实际应用。

CuBi2O4 has emerged as a photoelectrode material due to its high theoretical photocurrent density of 19 mA/cm2. However, the photoelectrocatalytical property of CuBi2O4 is largely limited by its poor charge separation. Gradient self-doping is an elegant way to improve the charge separation in CuBi2O4. However, the current gradient self-doping technique, based on high temperature diffusion-assisted reaction, is severely hampered by the limited thermal diffusion coefficient, poor controllability, and phase segregation. Moreover, the charge transfer mechanism in gradient self-doped photoelectrode remains unclear and lacks theoretical research. In this proposal, a new strategy of using gradient sputtering power to realize gradient self-doping is proposed. The Cu/Bi change from the bottom to the top of the film can be created by separately varying the power supply of Cu and Bi. Electric field across the entire film will be created in the phase-pure gradient self-doped CuBi2O4. The effect of gradient self-doping on the built-in electric field and charge separation will be revealed, and correspondingly a new mathematical model about the carrier transfer in gradient self-doped photoelectrode will be developed. The research findings are expected to provide an economic and controllable approach to realize gradient self-doping, offer new insights into the mechanisms of charge transfer in gradient self-doped photoelectrode, and promote its practical application in photoelectrocatalysis.