Table 1:

Synthesis of ZnO materials using microfluidic reactors.

Microreactor type	Particle type	Particle size	Particle shape	Reaction condition	Key precursors	Reference (By year)
T-shaped mixer	ZnO	9 nm	Near-sphere	673 K; 30 MPa	ZnSO4+KOH	200446
T-shaped mixer	ZnO	~3 μm	Flower	90 °C	Zn(OAc)2+NaOH	200847
Microchamber	ZnO	100 nm×(0.5–3 μm)	Wire	90 °C; 0.72–2.88 mL/h	Zn(NO3)2+HMT	200948
Microchamber	ZnO	(80–100 nm)×(70–860 nm)	Wire	90 °C	Zn(NO3)2+HMT	200949
Y-shaped mixer	ZnO	(50–100 nm)×1.5 μm	Wire	60–150 °C; 10–25 μL/min	Zn(OAc)2+NaOH; Zn(NO3)2+HMT	201050
Coflowing reactor	ZnO	~4 nm	Sphere	250 °C; 25 MPa	Zn(acac)2+TOP/OL/OA	201151
T-junction	ZnO	~0.4–4 μm	Sphere; cylinder; star; flower	90–150 °C; 250–3000 μL/min	Zn(OAc)2+NaOH	201152
Straight microchannel	ZnO	(50–100 nm)×(5–6 μm)	Wire	90–95 °C; 0.5–1 μL/min	Zn(NO3)2+HMT+PEI	201153
Microdot array; Micropost array	ZnO	(100–200 nm)×(2–3 μm)	Wire	95 °C	Zn(NO3)2+HMT+PEI	201254
T-shaped mixer	ZnO	~5 nm-1 μm	Sphere; tactoid	70 °C; 6.8–28.1 mL/min	Zn(NO3)2+NaOH	201355
Membrane dispersion reactor	ZnO	7–26 nm	Near-sphere	R.T.; 10–50 mL/min	ZnSO4+NH4HCO3	201356
Straight microchannel	ZnO	~80 nm×4 μm	Wire	85–90 °C	DMF	201357
Straight microchannel	ZnO	Up to 11.2 μm in length	Wire	85 °C; 0.55–0.91 mL/min	Zn(NO3)2+Hexamine	201358
T-shaped mixer	ZnO:Na	3–4 μm	Flower	80 °C; 6.5 mL/min	Zn(NO3)2+NaOH	201359
Microchamber	ZnO	(100–200 nm)×20 μm	Wire	95 °C	Zn(NO3)2+HMT+PEI	201360
Microchamber	ZnO	(50–200 nm)×(1–1.5 μm)	Wire	385 K	Zn(NO3)2+HMT	201461
Y-junction	ZnO	10–20 nm	Near-sphere	40–70 °C; 1–7 mL/min	Zn(NO3)2/ZnSO4/ ZnCl2+NaOH	201462
T-shaped mixer	ZnO	~3–5 μm	Flower; wire	70 °C; 6.8–28.1 mL/min	Zn(OAc)2+NaOH	201463
T-shaped mixer; winding channel	ZnO	3–5 nm	Sphere	60 °C; 0.855–1.645 μL/min	Zn(OAc)2+NaOH	201464
Straight microchannel	ZnO	50 nm×3 μm	Wire	95 °C; 1–1000 mm/s	Zn(NO3)2+HMT+PEI	201565
Microchamber	ZnO:Al	(70–140 nm)×(3.9–4.7 μm)	Flake	80 °C; 2 mL/h	Zn(NO3)2+Al(NO3)3+NH4Cl	201566
Y-shaped mixer	ZnO	(100–150 nm)×(1–2 μm)	Wire	60–150 °C; 10–25 μL/min	Zn(OAc)2+NaOH+Zn(NO3)2+HMT	201667
T-shaped mixer	ZnO	(50–500 nm)×(0.24–16.6 μm)	Wire	70–80 °C; 6.8–28.1 mL/min	Zn(OAc)2+NaOH	201668
T-shaped mixer; cross-type mixer	ZnO-Ag	500 nm	Hedgehog	100 °C; 1 mL/min	Zn(NO3)2+NaOH+AgNO3+NaBH4	201669
Y-shaped mixer	ZnO	2–3 nm	Sphere	180 W ultrasonic power; 20–60 °C	Zn(OAc)2+LiOH	201670
Straight microchannel	ZnO	~100 nm×(1–2 μm)	Sharp end; wire; hexahedral-puncheon	750 μL/h; 60 °C	ZnSO4+NH4Cl	201671
Microchamber	ZnO	(100–300 nm)×(1–3 μm)	Wire	90 °C	Zn(NO3)2+HMT	201672
Straight microchannel	ZnO/Zn(OH)F	~40 μm in length	Wire	90 °C; 25 μL/min	Zn(NO3)2+NH4F+HMT	201673
Cellulose hydrogel	ZnO	~5 μm	Flower	40–500 °C	Zn(OAc)2+NaOH	201774
Y-shaped mixer	ZnO	10–600 nm	Sphere; sheet; spindle	60 °C; 500 μL/min	Zn(NO3)2+NaOH	201775
Straight microchannel	ZnO	~1–4 μm in length	Wire	50–60 °C	ZnSO4+NH4Cl	201776
Flow-focusing with expansion channel	ZnO	145 nm	Rod	100–150 °C	Zn(acac)2+Benzyl alcohol	201877
Straight microchannel	ZnO	160 nm×8.7 μm	Wire	90 °C; 10 μL/min	Zn(NO3)2+HMT+PEI	201878
Microchamber	ZnO	~1 μm in length	Wire	95 °C	Zn(NO3)2+HMT	201879
Y-shaped mixer	ZnO-PAA	~100 nm×500 nm	Wire	90 °C; 25 μL/min	Zn(NO3)2+NH4OH	201880
Three-channel mixer	ZnO-CuO	~7 nm (crystallite size)	Irregular	70–80 °C; 0.3–0.54 mL/min	Zn(NO3)2+Cu(NO3)2+Na2CO3	201981
Spiral microchannel	ZnO	~100 nm-2 μm	Sphere; ellipsoid; rod; cube; urchin; platelet	r.t.−80 °C; 2.5–500 μL/min	Zn(NO3)2+NaOH	201982

Abbreviations: DMF: Dimethyl formamide; HMT: Hexamethylenetetramine; OA: Oleic acid; OL: Oleylamine; PAA: Poly(acrylic acid); PEI: Polyethylenimine; R.T.: Room temperature; TOP: Trioctylphosphine.