Tailoring zinc oxide nanowire architectures collectively by catalytic vapor-liquid-solid growth, catalyst-free vapor-solid growth, and low-temperature hydrothermal growth

Economic Friendly ZnO-Based UV Sensors Using Hydrothermal Growth: A Review

“… One dimensional (1D) ZnO nanostructures are structures with at least one dimension smaller than 100 nm. They include nanowires [ 17 , 29 , 32 , 44 , 48 , 57 , 66 , 77 , 80 , 81 , 82 ], nanotubes [ 17 , 33 , 83 ], nanorods [ 15 , 22 , 26 , 72 , 75 , 77 , 80 , 84 , 85 , 86 ], nanoneedles [ 87 ] and nanofibers [ 78 , 88 , 89 ]. Two dimensional (2D) ZnO nanostructures are structures in which electrons can move freely only on a non-nano scale of two dimensions, such as nanobelts [ 17 , 18 , 42 , 77 , 87 ], thin films [ 71 , 90 , 91 ] and nanosheets [ 46 , 80 , 88 , 92 , 93 ].…”

“…One dimensional (1D) ZnO nanostructures are structures with at least one dimension smaller than 100 nm. They include nanowires [ 17 , 29 , 32 , 44 , 48 , 57 , 66 , 77 , 80 , 81 , 82 ], nanotubes [ 17 , 33 , 83 ], nanorods [ 15 , 22 , 26 , 72 , 75 , 77 , 80 , 84 , 85 , 86 ], nanoneedles [ 87 ] and nanofibers [ 78 , 88 , 89 ].…”

“…Wet chemical synthesis is carried out at low temperatures (˂200 °C) either in aqueous solution, organic solution or a mixture of both. It includes hydrothermal [ 23 , 32 , 33 , 41 , 43 , 44 , 45 , 46 , 47 , 48 ], sol-gel [ 19 , 49 , 50 , 51 ], solvothermal [ 52 ], ultrasonic irradiation growth in solution [ 41 ] and spray pyrolysis [ 28 , 53 ]. Solid-state synthesis includes microwave irradiation [ 41 , 42 ] and carbothermal reduction [ 13 , 42 ].…”

“…Vapor-phase synthesis is generally carried out at high temperatures (from 500 to 2000 °C). Vapor-solid growth [ 48 ], vapor-liquid-solid growth (VLS) [ 18 , 48 , 54 ], chemical vapor deposition (CVD) [ 17 , 18 , 20 , 55 , 56 , 57 ], metalorganic vapor-phase epitaxy (MOVPE) [ 17 , 58 ], atomic layer deposition (ALD) [ 13 ] and sputtering [ 19 , 59 , 60 ] are examples of vapor-phase synthesis. Figure 1 shows the different synthesis methods of ZnO nanostructures.…”

“…In contrast, wet chemical methods favor distinct advantages such as large-scale applications, the possibility of substrate selection (organic or inorganic substrate), high yield, ease of control over morphology, uniform morphology, homogeneous size and localized growth [ 44 , 61 , 62 , 63 ]. Among various wet chemical methods, the hydrothermal process is regarded as one of the most attractive methods for ZnO fabrication as it is facile to set up and is controllable, cost-effective, relatively low temperature and an environment benign process [ 39 , 48 , 64 , 65 ]. Many different approaches such as resistive nano heater [ 24 , 66 , 67 ], bulk heating [ 61 , 68 ], microcontact printing [ 17 , 63 , 69 , 70 , 71 ], inkjet printing [ 17 , 57 , 62 , 72 , 73 ] and laser-induced heating [ 44 , 46 , 61 , 68 , 74 , 75 ] have been developed via the hydrothermal method.…”