Table 5.

Summary of microwave hydrothermal synthesis of ZnO without any additional heat treatment. SSA: specific surface area.

Substrates	Conditions during Preparation	Properties	Ref.
Zn(NO3)2·6H2O (0.1, 0.5 and 2 M), NaOH, H2O	pH: 8–12; T: 100–190 °C; P: 1–13 bar, duration: 2 min–2 h; microwave reactor	SSA: 4.7–18.1 m2/g; particles, submicrometre grains and star-like morphology	[506]
Zn(NO3)2·6H2O (0.1 M), NaOH (2 M), H2O	P: 9–39 bar, duration: 3–7 min; power: 70–100%; microwave reactor (750 W)	heterogeneous nano- and microstructures; particles size: 10–300 nm	[507]
ZnCl2·2H2O (0.1 M), KOH or urea, H2O	pH: 12; P: 10–40 bar; duration: 3–15 min; microwave reactor	SSA: 8.6–102.2 m2/g; particles size: 37–114 nm, flower-like morphology	[508]
Zn(NO3)2·6H2O (0.005 M), hexamethylenetetramine (C6H12N4) (0.005 M), H2O	T: 90 °C; duration: 2 min; microwave reactor	ZnO rods (e.g., bipods, tripods, tetrapods and multipods); diameter: 160–220 nm; length: 1.25–1.3 µm	[509]
Zn(NO3)2·6H2O (0.13 M), NaOH (1.3 M), 1-n-butyl-3-methyl imidazolium tetrafluoroborate, H2O	T: 90–125 °C; duration: 2–10 min; microwave reactor	morphology: flower-like + needle-like, from 60 to 450 nm and lengths up to several micrometres	[510]
Zn(CH3COO)2·2H2O, N,N dimethylformamide, H2O	duration: 23 min; power: 50%; microwave oven	spherical particles ~160 nm and nanoplatelets and nanorods ~2 nm in diameter and ~80 nm in length	[511]
ZnO was dissolved in NH4(OH) and Zn2+ 0.08 M, H2O, NH4(OH) (0.5, 1, 5, 10 and 14.8 M) was obtained	T: 90–150 °C; P: 0.7–4.8 bar; power: 1000 W; microwave reactor	flower-like agglomeration	[512]
Zn(NO3)2·6H2O (0.005 M), hexamethylenetetramine (C6H12N4) (0.010 M), NaOH (3 M)	pH: 9 and 13; T: 96 °C; duration: 60 min;	flower-like ZnO microstructures (2–3 µm) of hexagonal prisms (length: 1–2 μm, diameter: 50–130 nm) with planar and hexagonal pyramid tips (length: 1.5 μm, diameter: 300 nm)	[513]
Zn(NO3)2·6H2O (0.43 M), NaOH (0.43 M), H2O, NaCl, wet mechanical mixtures obtained	T: 75–135 °C; power: 650 W; microwave oven	SSA: 9–13 m2/g; microtubes	[514]
Zn(NO3)2·6H2O (0.05 M), urea (0.05 M), H2O	duration: 40 min; power: 180 W; microwave oven	nanotubes have regular polyhedral shapes, hollow cores with diameters of 100–200 nm, lengths of 1–3 mm and wall thicknesses of 10–40 nm.	[515]
Zn(NO3)2·6H2O (0.43 M), NaOH (0.43 M), H2O	duration: 15 min; T: 75–170 °C; power: 40–450 W; Teflon cell in microwave oven; pulsed mode	SSA: 9–19 m2/g, crystallite size: 30–45 nm	[516]
Zn(CH3COO)2·2H2O and hydrazine (N2H4·H2O) in a molar ratio of 1:4 in H2O	duration: 10 min; power: 150 W; microwave oven	nanorods; diameter about 25–75 nm and length in the range of 500–1500 nm	[517]
Zn(NO3)2·6H2O, NaOH, H2O	duration: 20 min; T: 100–180 °C; power: 0–1000 W; microwave reactor	nanorods; nanowires; nanothruster vanes; nanodandelions; nanospindles	[518]
Zn(NO3)2·6H2O (1.6 M), NaOH (3.2 M), H2O	pH: 8.3; duration: 1–5 min; microwave oven	nanorods (diameter: 100–200 nm) and flower structures	[519]
Zn(NO3)2·6H2O, NaOH (different concentrations), H2O	duration: 1 h; T: 110 °C; microwave oven	submicron starshaped structures, chrysanthemum flower structures, nanoflakes	[520]
Zn(NO3)2·6H2O, pyridine (C5H5N), aniline (C6H5NH2) and triethanolamine (TEA, C6H15NO3) (different concentrations), H2O	duration: 10 min; T: 90 °C; microwave reactor	various morphologies: linear linked needles, regularly hexagonal cross section of a needle, hollow structures, hexagonal nanorings, hexagonal columns, nanosheets	[521]
Zn(CH3COO)2·2H2O, NaOH, 1-ethyl-3- methylimidazolium bis(trifluoromethylsulfonyl)imid, H2O	duration: 2–7 min; T: power: 255 W; microwave oven (850 W)	nanoparticles, length less than 100 nm	[522]
Zn(NO3)2·6H2O (0.025 M); hexamethylenetetramine (C6H12N4) (0.025 M), H2O	duration: 1–30 min; T: 100–180 °C; power: 120–700 W; microwave oven	nanowires	[523]
Zn(NO3)2·6H2O, NaOH (5 M) nasturtium officinale leaf extract, H2O	pH: 10; duration: 10 min; microwave oven (1000 W)	heterogeneous aggregates of NPs	[524]
Zn(NO3)2·6H2O (0.025 M), Zn(CH3COO)2·2H2O, NH4(OH) (0.16 M), H2O, ethylenediamine (EDA, C2H8N2), hexamethylenetetramine (C6H12N4), triethyl citrate (C12H20O7), tripotassium citrate monohydrate (C₆H₅K₃O₇·H₂O)	duration: 15 min; T: 90 °C; microwave reactor	nanorods, nanoneedles, nanocandles, nanodisks and nanonuts	[525]
Zn(NO3)2·6H2O, hexamethylenetetramine (HMTA), polyvinylpyrrolidone (PVP), H2O	duration: 60 min; T: 100 °C; power: 300 W; microwave reactor	nanostars, average size: ≈625 nm, crystallite size ≈550 nm, SSA = 20.6 m2/g	[526]
Zn(CH3COO)2·2H2O (different concentrations), NH4(OH), H2O	duration: 85 s; T: 90 °C; power: 800 W; microwave oven	flower-like shapes with diameter of 3 to 5 µm, flowers with rod-like nanostructures, spherical particles in 2–4 µm diameter; 2–3 µm structured balls with occasional large 10 µm lumps	[527]
Zn(CH3COO)2·2H2O, NH4(OH) (different concentrations), H2O	pH: 7.0–11.1; duration: 2 h; T: 150 °C; microwave reactor	hexagonally shaped prismatic (width ≈ 1 μm, length ≈ 5 μm); flower-like structures formed by a micron sized crystals; heterogeneous particles (size from ~50 nm to 300 nm)	[528]
Zn(CH3COO)2·2H2O, NaOH, (o- and m- and p)-nitrobenzoic acid, H2O	duration: 10 min; microwave reactor	flower-like products consist of sword-like ZnO nanorods, which were 60–100 nm in width and several micrometres in length.	[529]
ZnCl2·2H2O, NaOH, H2O, bis(dodecyldimethyl ammonium bromide) (C26H56BrN)	duration: 5–10 h; T: 100–140 °C; power: 300–400 W; microwave reactor	flower-like with mean r 0.5–1.5 µm, sphere-like with mean diameter of 0.5 µm	[530]
ZnCl2·2H2O, NaOH, H2O, cetyltrimethylammonium bromide (CTAB, C19H42BrN), Pluronic F127	duration: 5 min; power: 130 W; microwave oven	SSA: 15.5–24.8 m2/g, diameter: 58–93 nm, heterogeneous shape	[531]
Zn(CH3COO)2·2H2O, Na(OH) (different concentrations), H2O	duration: 5 min; power: 450 W; microwave oven	nanoplates flowers	[532]
Zn(CH3COO)2·2H2O, NaOH, H2O, polyethylene glycol, ethanol	duration: 30 min; T: 140 °C; power: 700 W; microwave reactor (multimode)	nanorods, flowers	[533]
Zn(CH3COO)2·2H2O (0.5 M), KOH (2 M), H2O	pH: 8; T: 120 and 140 °C; duration: 8 min; microwave oven (800 W)	multiwires with a flower-like shape of 50–400 nm in width and length	[534]
Zn(CH3COO)2·2H2O (0.1 M), Zn(NO3)2·6H2O (0.1 M), NH4OH, polyvinilpirrolidone, hydrazine hydrate solution (N2H4 in H2O), H2O	pH: 7.5–8; duration: 5–10 min; microwave oven (1000 W)	spherical nanoparticles, stars, flowers	[535]
Zn(NO3)2·6H2O, NaOH, gum arabic (stabilising agent), NaOH, H2O	pH: 10; duration: 5 min; power: 450 W	stars (diameter: 1020 nm), spherical particles (diameter: 240 nm)	[536]
Zn(NO3)2·6H2O, NaOH, gum arabic (stabilising agent), NaOH, H2O	pH: 10; duration: 2–10 min; power: 350 W	aggregates of NPs (20–40 nm), size of aggregates: 150–200 nm	[537]
Zn(NO3)2·6H2O (0.1 M), NH4(OH), hydrazine hydrate (N2H4·H2O), H2O	pH: 8; duration: 10 min; microwave oven	flower morphology consists of sharp nanorods which look like petals	[538]
Zn(NO3)2·6H2O (0.005 M), KOH (4 M), H2O	pH: 12; T: 120 °C; duration: 4 h; microwave oven	nanowires with diameter of 80 nm and lengths of up to 10 µm.	[539]
Zn(NO3)2·6H2O (0.01 M), urea (0.1 M), H2O	T: 120 °C; duration: 10–24 min; power: 150 W; microwave oven	javelins, length: 14–17 µm, width: 0.9–1.4 µm	[540]
Zn(CH3COO)2·2H2O, KOH	duration: 20 min; power: 180 W; microwave oven	flowerlike structures composed of hexagonal ZnO spear-shaped nanorods with diameters and lengths of 50 nm and 2–4 μm,	[541]
ZnCl2·2H2O (different concentrations), NH4(OH), H2O	duration: 10–40 min; power: 10–50%; microwave oven (800 W)	nanorods	[542]
ZnCl2·2H2O, arginine (C6H14N4O2), H2O	T: 120–180 °C; duration: 3–10 min; microwave reactor	rods and flowers	[543]
Zn(CH3COO)2·2H2O (different concentrations), NaOH, H2O	pH: 12; T: 120–140 °C; duration: 15–60 min; power: 0–100%; microwave oven (900 W)	nanosheets	[544]
Zn(CH3COO)2·2H2O, NH4(OH), H2O	pH: 9; duration: 90 sec; microwave oven (900 W)	narcissus-like nanostructures with crystallite sizes of 10–15 nm and average diameter of 1–2.5 µm	[545]
Zn(CH3COO)2·2H2O, NaHCO3, H2O	duration: 15 min; power: 200 W; microwave oven	amorphous material	[546]
Zn(CH3COO)2·2H2O (0.0026 M), NaOH (1 M), H2O, cetyltrimethylammonium bromide (CTAB, C19H42BrN)	T: 130 °C; duration: 30–180 min; Teflon autoclave in microwave oven (800 W)	nanowires and microwires of about 50–400 nm in width and several micrometres in length	[547]
Zn(NO3)2·6H2O (different concentrations), hexamethylenetetramine (C6H12N4), H2O	duration: 2–3 min; power: 600–900 W; Teflon bottle in microwave oven (1000 W)	nanorods diameters from 117 to 156 nm	[548,549]
Zn(NO3)2·6H2O (different concentrations), NaOH, H2O	pH: 7–13.1; duration: 20; power: 180 W; microwave oven	nanoparticles in clusters, nanoplates in flower-like clusters, and spear-shaped particles in flower-like clusters	[550]
ZnCl2·2H2O (0.066 M), NaOH (1.75 M), H2O	pH: 13.75; duration: 5 min; power: 150–1000 W; microwave oven (1000 W)	nanoparticles, nanoneedles, nanosheets (leaf-like)	[551]
Zn(CH3COO)2·2H2O (0.1 M), NaOH (4 M), CH3(CH2)11OSO3Na (0.1 M), C12H25C6H4SO3Na (0.025 M), H2O	T: 75–130 °C; duration: 1–5 h; power: 400 and 700 W; microwave reactor	SSA: 33.1–419.7 m2/g; square shaped sheets	[552]
Zn(NO3)2·6H2O, hexamethylenetetramine (C6H12N4)	duration: 30–45 sec; power: 700 W, microwave oven	multiple linked rods such as bipods, tripods (T- shaped), tetrapods (+ and X-shaped), tassel brush and flower shaped and individual rods	[553]
Zn(CH3COO)2·2H2O (different concentrations), triethanolamine (TEA, C6H15NO3), H2O	T: 80–100 °C; duration: 10–30 min; microwave reactor (1000 W)	pompon-like spheres, peach nut-like spheres, misshapen spheres	[554]
Zn(CH3COO)2·2H2O, NaOH, bis(triaminomethyl) carbonate (C3H12N6O3), H2O	pH: 12; duration: 2 min; power: 600 W; microwave oven	flower-like structure (2 µm) composed of petals with average size of about 600–700 nm in length, 300–400 nm in width, and 50–70 nm in tip	[555]
Zn(NO3)2·6H2O, NaOH, H2O	duration: 15–50 min; power: 120–420 W; microwave reactor (700 W)	nanostructures consisted of flower-like, sword-like, needle-like and rods-like structures	[556]
Zn(CH3COO)2·2H2O (different concentrations), NH4(OH), H2O	pH: 10.2; duration: 50–70 s; microwave oven (800 W)	rod-arrays film on glass	[557]
Zn(NO3)2·6H2O, polyvinyl pyrrolidone, NH4(OH), H2O	pH: 10.2; duration: 10 min; microwave oven (1000 W)	star-shaped nanostructures	[558]
Zn(NO3)2·6H2O (0.06 M), NaOH (0.06 M), polyethylene glycols (PEG)-2000, H2O	T: 180 °C; duration: 10, 20, 30, 60 min; microwave reactor	hierarchical structured nanorods	[559]
ZnSO4·7H2O (0.1 M), NaOH (0.4 M)	duration: 2 min; microwave oven	nanoparticles (10–15 nm)	[560]
Zn(CH3COO)2·2H2O, NaOH, 1-butyl-3-ethyl imidazolium tetrafluoroborate (C8H15BF4N2), H2O	T: 120–140 °C; duration: 5 min; microwave reactor (800 W)	calthrop-like framework	[561]
Zn(NO3)2·6H2O (0.03 M), NaOH (0.06 M), H2O, polyethylene glycol (PEG) 2000, H2O	T: 180 °C; duration: 30 min; microwave reactor	rods with the diameter of 300 nm and length of 1 µm	[562]
Zn(NO3)2·6H2O, Zn(C5H7O2)2·xH2O, urea, C2H4(OH)2 (different concentrations), H2O	T: 150 °C; duration: 1–30 min; microwave reactor	microrods with width of 200–300 nm and length of up to 4 µm	[563]
Zn(NO3)2·6H2O, dodecylamine (C12H27N), H2O	T: 80–130 °C; duration: 1–50 min; power: 150 W; microwave oven	hexagonal quasi-hourglasses (tripods, tetrapods, pentapods, multipods)	[564]
Zn(CH3COO)2·2H2O, triethanolamine (TEA, C6H15NO3), NH4(OH), H2O	pH: 6-12; T: 80–160 °C; duration: 10–60 min; power: 150 W; microwave reactor	spherical nanoparticles 60–90 nm, rugby-like nanostructures with diameter of 450 nm and length of about 700 nm	[565]
Zn(CH3COO)2·2H2O, triethanolamine (TEA, C6H15NO3, (different concentrations), NaOH (different concentrations), H2O	pH: 9.0–12; duration: 90 s; power: 900 W; microwave oven	nanospheres with the crystallite size of 57 nm; raspberry-like nanostructures with the crystallite size of 62 nm; hollow nanospheres with the crystallite size of 78 nm; nanoparticles with the crystallite size of 24 nm	[566]
Zn(NO3)2·6H2O (0.1 M), C6H12N4 (0.1 M)	T: 90 °C; duration: 2 h; microwave oven	nanorods on the surface of GaN 80–170 nm, nanorods on the surface of glass 40–100 nm	[567,568,569]
Zn(NO3)2·6H2O, C6H12N4	duration: 5 h; microwave oven	nanorods on the surface of glass, average width of nanorod: 20–1000 nm, average length of nanorod: 150–5000 nm	[570]
Zn(CH3COO)2·2H2O, KOH,	T: 90 °C; duration: 10–30 min; microwave oven	micro-tube structure 200–400 nm in diameter, flower-like structure composed of spear-shaped nanorods with diameters and lengths of 70 nm and 1–5 μm,	[571]
Zn(CH3COO)2·2H2O (different concentrations), NaOH, C2H5OH	pH: 10; T: 100 °C duration: 45–60 min; power: 800 W; microwave reactor	plates (SSA: 10.7 m2/g), rounded plates (SSA: 9.18 m2/g), brush-like (SSA: 9.5 m2/g), flower-like (SSA: 8.5 m2/g)	[572]
Zn(CH3COO)2·2H2O, NH4(OH), H2O	pH: 8; duration: 180 s; microwave oven (900 W)	SSA: 22.9 m2/g; uniform flower-like nanostructures composed of petals attached in the centre with lengths in the range of 700–950 nm and a width in the range of 130–230 nm; each single petal is composed of nanoparticles with lengths of 45–95 nm	[573]
Zn(CH3COO)2·2H2O, NH4(OH), C25N3H30Cl, Polyethylene glycol (PEG) 400, C19H42BrN, H2O	duration: 10 min; microwave reactor	rod-like nanostructures, star-like nanostructures	[574]
ZnSO4·7H2O, NaOH, H2O	pH: 9; duration: 5–25 min; microwave reactor	sheet nanostructures	[575]
Zn(NO3)2·6H2O (0.1 M), NH4(OH), H2O, cetyltrimethylammonium bromide (CTAB, C19H42BrN)	pH: 7; T: 150 °C; duration: 1 h; microwave reactor	nanorods, length: 1–2 μm and width: 100–150 nm	[576]
Zn(CH3COO)2·2H2O, NH4(OH), H2O	duration: 8 min; power: 900 W; microwave oven	nanoparticles (15 nm) which were self-assembled to form a sheet-like structure	[577]
Zn(NO3)2·6H2O, NaOH, polyvinyl alcohol, H2O	duration: 10 min; power: 700 W; microwave oven	nanoparticles (40 nm)	[578]
Zn(NO3)2·6H2O (0.005 M), Zn(CH3COO)2·2H2O (0.005 M), ZnSO4·7H2O (0.005 M), KOH (2 M), H2O	pH: 12; T: 130 °C; duration: 1 h; microwave reactor (800 W)	flower-like structures, plates	[579]
ZnCl2·2H2O (0.5 M), urea, H2O	duration: 5 min; power: 800 W microwave reactor	sponge-like nanostructure	[580]
Zn(CH3COO)2·2H2O, Zn(NO3)2·6H2O, ZnCl2·2H2O, NaOH, KOH, NH4(OH), sodium di-2-ethylhexyl-sulfosuccinate (C20H36Na2O7S), H2O	T: 80–140 °C; duration: 5–20 min; power: 300–1200 W; microwave reactor	hexagonal rods (3–4 μm long and 1 μm wide), hexagonal prismatic, bihexagonal rod-like structure (6 μm long and 2 μm wide), hexagonal prismatic particles (60–80 nm in diameter and length between 90 and 110 nm)	[581]
ZnCl2·2H2O, NH4(OH), H2O	T: 80–140 °C; duration: 20 min; power: 240 W; microwave oven	flower-shaped ZnO microcrystals (about 5 μm)	[582]
Zn(NO3)2·6H2O, hexamethylenetetramine (C6H12N4), H2O	T: 170 °C; duration: 2–20 min; microwave reactor	irregular sheet-like structures and rods, tripods	[583]
Zn(NO3)2·6H2O, hexamethylenetetramine (C6H12N4), H2O	T: 90 °C; duration: 3 h; microwave reactor	nanorods on paper	[584]
Zn(NO3)2·6H2O (0.1 M), NH4(OH), albumen, H2O	pH: 8; duration: 5 min; microwave oven	sheet-like and spherical-like nanostructures (13–50 nm), nanowhiskers and nanorods (10–57 nm)	[585]
Zn(NO3)2·6H2O (0.03 M), hexamethylenetetramine (C6H12N4), H2O	duration: 2–30 min; power: 10–100%; microwave oven (1100 W)	nanostructured-films (networked-nanoflakes morphology)	[586,587]
Zn(CH3COO)2·2H2O, NaOH, glutamic tetrofluoroborate (different concentrations), H2O	T: 80 °C; duration: 10 min; power: 1000 W; microwave reactor	clew-like hierarchical nanosheet spheres, nanoneedle-like structures	[588]
Zn(NO3)2·6H2O (different concentrations), hexamethylenetetramine (C6H12N4), H2O	duration: 5–20 s; power: 180-1100 W; microwave oven	growth of nanorods, diameters: 50–80 nm	[589,590,591]
Zn(NO3)2·6H2O (0.03 M), hexamethylenetetramine (C6H12N4), H2O	duration: 30 min; power: 110 W; modified microwave oven (1100 W)	porous nanostructures grown on Al-Si substrate (Al layer thickness form 0 to 150 nm); Al-free Si substrate: nanorods were formed (length: 350 nm, diameter: 50 nm); Al on Si substrate: nanoflake (height ~380 nm ) with pores sizes ranging from 50 nm to several hundreds of nanometres.	[592]
Zn(NO3)2·6H2O (different concentrations), hexamethylenetetramine (C6H12N4, different concentrations), H2O	T: 80 °C; duration: 10 min; power: 30–50%; microwave oven	ZnO nanoarray (rod-like structures) on glass, size control achieved by regulating the parameters	[473]
Zn(NO3)2·6H2O (different concentrations), NH4(OH), H2O	duration: 8 min; power: 800 W; microwave oven	flower-like and rod-like structures	[593]
Zn(CH3COO)2·2H2O (0.45 M), NaOH (8 M), Triton X-100	duration: 1–6 min; power: 100–600 W; microwave oven	rods (400–800 nm), flower structures	[594]
Zn(CH3COO)2·2H2O, KOH, H2O	duration: 3 min; power: 800 W; microwave oven	hexagonal nanorods (length from ~1.5 μm to 3 μm and in diameter from ~30 nm to 80 nm)	[595]
Zn-dust, HNO3, NaOH, polyethylene glycol (PEG, MW 2000), H2O	duration: 10–20 min; microwave oven	SSA: 14.4-21.8 m2/g; particles with irregular shape (plate and rod-like particles), crystallite size: 34–42 nm	[596]
Zn(CH3COO)2·2H2O, NaOH, cetyltrimethylammonium bromide (CTAB, C19H42BrN, different concentrations), H2O	T: 130°; duration: 15–60 min; microwave oven	wire-like architecture with a width in the range of 60–80 nm, flower-like microstructures composed of nanorods, rod has a width of 300–400 nm and a length of 3–4 µm	[597]
Zn(CH3COO)2·2H2O, Zn(NO3)2·6H2O, NaOH, NH4(OH), di-2-ethylhexyl sodium sulfosuccinate (C20H36Na2O7S), H2O	T: 80–140 °C; duration: 5–20 min; power: 300–1200 W; microwave reactor	cauliflower-like structures, hexagonal prismatic type particles (200–300 nm)	[598]
Zn(CH3COO)2·2H2O, Zn(NO3)2·6H2O, NH4(OH), hydrazine hydrate (N2H4·H2O), H2O	pH: 11.5; duration: 10–25 min; power: 510–680 W; microwave oven	nanoparticles, nanorods, flowers	[599]
Zn(CH3COO)2·2H2O, NaOH, H2O	T: 140 °C; duration: 45 min; power: 400 W; microwave reactor (1600 W)	nanorods, diameter ranging from 60 to 80 nm with average length of about 250 nm	[600]
Zn(CH3COO)2·2H2O (0.005 M), NaOH (0.025 M), H2O	duration: 6 min; power: 400–600 W; microwave oven	mixture of nanorods and nanoplates	[601]
Zn(CH3COO)2·2H2O (0.18 M), NaOH (different concentrations), H2O	pH: 7–9.5; T: 50 °C; duration: 3 min; microwave reactor (600 W)	nanorods (width: 80–300 nm, height: 150–1000 nm) grown on Si, GaAs and GaN substrate	[602]
Zn(CH3COO)2·2H2O (0.18 M), NaOH (different concentrations), H2O	pH: 6.75–7.75; T: 50 °C; duration: 2 min; microwave reactor (600 W)	rods (width: 0.5–2.5, height: 1.5–2.2 µm) grown on GaN substrate	[603]
Zn(CH3COO)2·2H2O, NH4(OH), H2O	pH: 10.1–10.9; T: 90 °C; duration: 20 min; power: 100 W; microwave oven	nanorods grown on Si substrate	[604]
Zn(NO3)2·6H2O, hexamethylenetetramine (C6H12N4 ), H2O	T: 90 °C; duration: 2 h (switched on and off automatically); microwave oven	nanorods grown on Si substrate (thickness: ~1 µm)	[605]
Zn(NO3)2·6H2O, hexamethylenetetramine (C6H12N4), H2O	duration: 10–30 min; power: 120 W; microwave oven	rods, bipods (length: 0.46–1 µm, width: 0.1–0.13 µm)	[606]
Zn(NO3)2·6H2O, hexamethylenetetramine (C6H12N4), H2O, oxalic acid dihydrate (C2H2O4·2H2O)	P: 20.68 bar; duration: 15 min; microwave reactor (300 W)	nanorods or flower grown on paper	[607]
Zn(NO3)2·6H2O, hexamethylene tetramine (C6H12N4), H2O	T: 80 °C; duration: 5–20 min; power: 100–1600 W; microwave reactor (1600 W)	nanorods grown on glass substrate	[608]
Zn(NO3)2·6H2O, hexamethylene tetramine (C6H12N4, different concentrations), H2O	duration: 10 min; power: 240 W; microwave oven	nanorods (diameter: 89–216 nm) grown on glass substrate	[609]
Zn(NO3)2·6H2O, NH4(OH), H2O	pH: 10.0–12.0; T: 90–120 °C; duration: 1 h min; microwave reactor	nanorods grown on glass substrate, control of size of diameter of rods within the size range between circa 125 and 770 nm	[610]
Zn(CH3COO)2·2H2O (different concentrations), hexamethylenetetramine (C6H12N4), H2O	T: 60–110 °C; duration: 5–40 min; microwave reactor	nanorods (diameter from ~30 to ~300 nm, length from ~60 nm to ~520 nm) grown on Si substrate	[611]
Zn(CH3COO)2·2H2O, NH4(OH), NaOH, CH3COOH, H2O	pH: 9.8 or 10.8; duration: five steps (each step included 30 s of irradiation and 10 s off); microwave oven	dandelion-like nanostructures (needles: 50–200 nm, height ~2 µm) or a flower-like microstructures grown on activated carbon cloth	[612]
Zn(CH3COO)2·2H2O, NH4(OH), palmitic acid (CH3(CH2)14COOH), H2O	pH: 4–5; duration: 10–30 min; microwave oven	rod shaped structures	[613]
ZnSO4·7H2O, NH4(OH), H2O	pH: 10; duration: 2 min; power: 600 W; microwave oven	nanoparticles (~50 nm)	[614]
Zn(NO3)2·6H2O, potassium sodium citrate, NaOH, H2O	T: 90 °C; duration: 2 min; power: 600 W; microwave oven (650 W) with a refluxing apparatus	sphere-like particles (~2.32 μm)	[615]
tris(ethylenediamine)zinc nitrate ([Zn(en)3](NO3)2), NaOH, H2O	pH: 7–12; T: 180 °C; duration: 20 min; power: 400 W; microwave reactor (1600 W)	nanorods, diameter: from 40 nm (pH 12) to 600 nm (pH 7)	[616]
Zn(NO3)2·6H2O, hexamethylenetetramine (C6H12N4), H2O	T: 100 °C; duration: 60 min; power: 100 W; microwave reactor	nanorods (180–350 nm) grown on glass	[617]
Zn(NO3)2·6H2O, hexamethylenetetramine (C6H12N4), polyethylenimine, NH4OH, H2O	T: power on and off in order to control the solution temperature; duration: 6–10 × (30–60 s “on” and 5 min “off”); microwave oven (350 W)	nanorods (180–350 nm) grown on glass	[618]
Zn(CH3COO)2·2H2O, NH4(OH), carbon fibre, H2O	duration: 3 × (30 s irradiation and 30 s stop); microwave oven (1120 W)	rods (diameter: 0.3–0.5 µm, length: 1.0–1.5 µm) grown on carbon fibre	[619]
Zn(NO3)2·6H2O, NaOH, NH4(OH), polyethylene glycol (PEG, MW 400), H2O	T: 100 °C, duration: 5 min; microwave oven (800 W)	quasi-spherical shape and dimensions of less than 5 μm, flower-like structures (>5 μm),	[620]
Zn(NO3)2·6H2O, C6H12N4, polyethylenimine, NH4(OH), H2O	duration: 5–15 min; microwave oven (800 W)	nanoflowers and nanowalls grown on P–Si	[621]
Zn(CH3COO)2·2H2O, NaOH, 1-hexyl-2-ethyl-3-methylimidazoliumtetrafluoroborate (C6H11BF4N2), H2O	duration: 2–9 min; power: 30%; microwave oven	flakes-shaped particles, flower-like shaped particles	[622]
Zn(NO3)2·6H2O, NaOH, plant extract, H2O	pH: 10; duration: 15 min; microwave oven	nanoparticles	[623]
Zn(NO3)2·6H2O, (C6H12N4)2, H2O	T: 70–130 °C; duration: 10 min; microwave reactor	nanorods on paper, length 120–480 nm, thickness 55–75 nm	[624]
Zn(NO3)2·6H2O, triethanolamine (TEA, C6H15NO3), H2O	duration: 10 min; power: 640 W; microwave oven	nanoparticles	[625]
Zn(CH3COO)2·2H2O, KOH, triethanolamine (TEA, C6H15NO3), 1,2,4,5-benzenetetracarboxylic acid, H2O	pH: 8–12; T: 150 °C; duration: 30 min; power: 800 W; microwave reactor	dumbbell-like structures, football-like structures, hexagonal bi-pyramidal structures, SSA: 7–24 m2/g; size 50 nm–10 μm	[626]
Zn(CH3COO)2·2H2O, NaOH, H2O	pH: 8–10; duration: 6 min; microwave oven (700 W)	sheet-like structures and uniform microstructures	[627]
Zn(CH3COO)2·2H2O, Tris (hydroxymethyl) aminomethane (C4H11NO3), H2O	duration: 3 min; microwave oven (300 W)	spherical nanoparticles	[628]
Zn(CH3COO)2·2H2O, KOH, benzene-1,2-dicarboxylic acid, benzene-1,3-dicarboxylic acid, benzene-1,4-dicarboxylic acid, H2O	pH: 7–12; T: 150 °C; duration: 30 min; power: 800 W; microwave reactor	rod-like structures, needle-like structures, platelet-like structures, hexagonal columnar shape of the particles, rice-grain shape structures	[629]
Zn(CH3COO)2·2H2O (0.1 M), NaOH (0.1 M), {4-[(E)-2-(furan-2-yl)ethenyl]pyridin-1-ium-1-yl} acetate (1 wt% and 3 wt%), CH3OH, H2O	duration: 20 min; microwave oven	heterogeneous shape of nanoparticles, size: 200–800 nm, average crystallite size: 21–23 nm	[630]
Zn(NO3)2·6H2O, hexamethylenetetramine (C6H12N4), NH4(OH), H2O	pH, 6.8–13, duration: 10–15 min; pulsed microwave heating in microwave oven (850 W)	rod, flower, star, tetrapod	[631]
Zn(NO3)2·6H2O (different concentrations), hexamethylenetetramine (C6H12N4), H2O	T: 105 °C; duration: 10–30 min; microwave oven (850 W)	growth of nanorods on P-type silicon wafer, diameters: from 26–32 nm to 35–40 nm, lengths: from 330 nm–607 nm	[632]
Zn(NO3)2·6H2O, hexamethylenetetramine (C6H12N4), H2O	duration: 20 min; power: 750 W; microwave oven	growth of nanorods on silicon substrate, diameters ~80 nm, lengths ~500 nm	[633]
Zn(NO3)2·6H2O, coffee powder extract, H2O	duration: 5 min; power: 540 W; microwave oven	spherical nanoparticles (80–120 nm)	[634]
Zn(NO3)2·6H2O, tomato extract, H2O	duration: 5 min; power: 180–540 W; microwave oven	spherical nanoparticles (40–100 nm)	[635]
Zn(NO3)2·6H2O, tea leaf extract, H2O	duration: 7 min; power: 540 W; microwave oven	spherical nanoparticles (26 nm)	[636]
Zn(CH3COO)2·2H2O, Longan fruits extract, H2O	duration: 1 min on & 1 min off irradiation cycle (1–30 cycles); power: 450–800 W; microwave oven	SSA: 35 m2/g, diameter: 10–100 nm, heterogeneous shape	[637]
Zn(CH3COO)2·2H2O (0.22 M), carbinol, H2O	duration: 5–15 min; power: 900 W; microwave oven	spherical nanoparticles, diameters: 30 nm–50 nm; hexagonal facetted nanostructures, average size: 400–450 nm	[638]
Zn(NO3)2·6H2O, NH4(OH) (28%), H2O	pH: 12; duration: 5–25 min; power: 180–540 W; microwave oven (1200 W)	spherical and flower-like particles on paper; non-uniform size	[639]
ZnO powder, hydrogen peroxide (H2O2, 30%)	P: 30 bar; duration: 15 min; power: 1200 W; microwave oven (1200 W)	rod-like nanostructures, average size: 36 nm	[640]