Due to the energy crisis, the development of high-performance photoelectrocatalysts is becoming a hot research area in recent years. Among the materials studied, BiFeO3 (BFO) exhibits excellent photoelectrocatalytic performance due to its moderate bandgap and unique band structure. In this paper, both pure BFO and La-doped BFO were synthesized by solgel method. The average size of the BFO nanoparticles was tuned from 65 to 440 nm. For the La-doped BFO, the average size of the nanoparticles was reduced from 95 to 40 nm with the increase in doping level from 0 to 30%. Next, the photoelectrocatalytic performance of the pure BFO nanoparticles were enhanced with the reduction in nanoparticle size, which was possibly caused by increased surface-to-volume ratio. For the increase in doping of La, the corresponding photoelectrocatalytic performance was first enhanced and then degraded. To understand the obtained results, a mechanism was proposed, which can be attributed to the competition between geometric size effects and surface effects. Our findings provided a controlled way to tune the photoelectrocatalytic performance of BFO system, which is crucial for practical applications.

中文翻译：

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纯和掺杂 La 的 BiFeO3 纳米粒子的尺寸效应增强了光电催化性能

由于能源危机，高性能光电催化剂的开发成为近年来的热门研究领域。在研究的材料中，BiFeO3（BFO）由于其中等带隙和独特的能带结构而表现出优异的光电催化性能。本文采用溶胶凝胶法合成了纯 BFO 和掺 La 的 BFO。BFO 纳米粒子的平均尺寸从 65 到 440 nm 调整。对于 La 掺杂的 BFO，随着掺杂水平从 0% 增加到 30%，纳米颗粒的平均尺寸从 95 nm 减小到 40 nm。接下来，纯 BFO 纳米粒子的光电催化性能随着纳米粒子尺寸的减小而增强，这可能是由于表面积与体积比的增加所致。为了增加 La 的掺杂，相应的光电催化性能先增强后降低。为了理解所获得的结果，提出了一种机制，该机制可归因于几何尺寸效应和表面效应之间的竞争。我们的发现为调节 BFO 系统的光电催化性能提供了一种可控的方法，这对实际应用至关重要。