祝贺硕士生赵宇枭的研究工作《Dual effects of ultrasound on fabrication of anodic aluminum oxide》发表于Ultrasonics Sonochemistry!

Abstract

Ultrasound has been proven to enhance the mass transfer process and impact the fabrication of anodic aluminum oxide (AAO). However, the different effects of ultrasound propagating in different media make the specific target and process of ultrasound in AAO remain unclear, and the effects of ultrasound on AAO reported in previous studies are contradictory. These uncertainties have greatly limited the application of ultrasonic-assisted anodization (UAA) in practice. In this study, the bubble desorption and mass transfer enhancement effects were decoupled based on an anodizing system with focused ultrasound, such that the dual effects of ultrasound on different targets were distinguished. The results showed that ultrasound has the dual effects on AAO fabrication. Specifically, ultrasound focused on the anode has a nanopore-expansion effect on AAO, leading to a 12.24 % improvement in fabrication efficiency. This was attributed to the promotion of interfacial ion migration through ultrasonic-induced high-frequency vibrational bubble desorption. However, AAO nanopores were observed to shrink when ultrasound was focused on the electrolyte, accompanied by a 25.85 % reduction in fabrication efficiency. The effects of ultrasound on mass transfer through jet cavitation appeared to be the reason for this phenomenon. This study resolved the paradoxical phenomena of UAA in previous studies and is expected to guide AAO application in electrochemistry and surface treatments.

超声在不同介质中传播的不同效果使得超声在AAO中的具体靶点和过程尚不清楚，并且先前研究中报道的超声对AAO的影响是矛盾的。这些不确定性极大地限制了超声波辅助阳极氧化（UAA）在实践中的应用。在本研究中，基于聚焦超声阳极氧化系统，将气泡解吸和传质增强效应解耦，从而区分了超声对不同目标的双重影响。结果表明，超声对AAO的制备具有双重影响。具体而言，聚焦在阳极上的超声波对AAO具有纳米孔膨胀效应，导致制造效率提高12.24%。这归因于通过超声诱导的高频振动气泡解吸促进界面离子迁移。然而，当超声波聚焦在电解质上时，观察到AAO纳米孔收缩，同时制造效率降低25.85%。超声波对射流空化传质的影响似乎是造成这种现象的原因。这项研究解决了以往研究中UAA的悖论现象，有望指导AAO在电化学和表面处理中的应用。

《超声波声化学》(Ultrasonics Sonochemistry)是一本以化学-化学综合综合研究为特色的国际期刊。该刊2021年影响因子为9.336。

文章链接：https://www.sciencedirect.com/science/article/pii/S1350417723001438