ZnO Nanowires by Chemical Bath Deposition: A Review on Nucleation, Growth, and Green Chemistry

As a sustainable direct wide bandgap semiconductor, ZnO nanowires have received an increasing interest in the past three decades to act as potential building blocks in a large number of functional devices. The chemical bath deposition (CBD) of ZnO nanowires, as a hydrothermal growth operating at low temperature and roughly ambient pressure, can easily be implemented and scaled up for industrial purposes, attracting most of the recent attention in the community. However, despite its relative simplicity, a thorough understanding of the different physicochemical processes at work has emerged as highly critical to ensure ZnO nanowires of high quality. The present review reports a detailed analysis of the most recent and well-established state-of-the-art and scientific challenges of the CBD of ZnO nanowires, including the nucleation and growth processes at work using diverse seed layers, chemicals, and reactors, via the spontaneous and selective area growth approaches. The description of the elongation process of ZnO nanowires through its theoretical modeling is also discussed in detail. Eventually, a special emphasis is placed on the compatibility of the CBD of ZnO nanowires with green chemistry in order to identify its assets and the different opportunities for improvement.