Zn Precursor Research Articles

Exploration of the Different Dimensions of Wurtzite ZnO Structure Nanomaterials as Gas Sensors at Room Temperature.

In this work, we report on the synthesis of four morphologies of ZnO, namely, nanoparticles, nanorods, nanosheets, and nanoflowers, from a single precursor Zn(CH3COO)2·2H2O under different reaction conditions. The synthesised nanostructured materials were characterised using powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopy, UV-Vis, XPS analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and nitrogen sorption at 77 K. The XRD, FTIR, and Raman analyses did not reveal any significant differences among the nanostructures, but differences in the electronic properties were noted among the different morphologies. The TEM and SEM analyses confirmed the four different morphologies of the ZnO nanostructures. The textural characteristics revealed that the specific surface areas were different, being 1.3, 6.7, 12.7, and 26.8 m2/g for the nanoflowers, nanoparticles, nanorods, and nanosheets, respectively. The ZnO nanostructures were then mixed with carbon nanoparticles (CNPs) and cellulose acetate (CA) to make nanocomposites that were then used as sensing materials in solid-state sensors to detect methanol, ethanol, and isopropanol vapour at room temperature. The sensors' responses were recorded in relative resistance. When detecting methanol, 6 out of 12 sensors were responsive, and the most sensitive sensor was the composite with a mass ratio of 1:1:1 of ZnO nanorods:CNPs:CA with a sensitivity of 0.7740 Ω ppm-1. Regarding the detection of ethanol vapour, 9 of the 12 sensors were responsive, and the 3:1:1 mass ratio with ZnO nanoparticles was the most sensitive at 4.3204 Ω ppm-1. Meanwhile, with isopropanol, 5 out of the 12 sensors were active and, with a sensitivity of 3.4539 Ω ppm-1, the ZnO nanoparticles in a 3:1:1 mass ratio were the most sensitive. Overall, the response of the sensors depended on the morphology of the nanostructured ZnO materials, the mass ratio of the sensing materials in the composites, and the type of analyte. The sensing mechanism was governed by the surface reaction on the sensing materials rather than pores hindering the analyte molecules from reaching the active site, since the pore size is larger than the kinetic diameter of the analyte molecules. Generally, the sensors responded well to the ethanol analyte, rather than methanol and isopropanol. This is due to ethanol molecules displaying a more enhanced electron-donating ability.

Optimization of ZnO Nanoparticles’ Synthesis via Precipitation Method Applying Taguchi Robust Design

Zinc oxide (ZnO) possesses exceptional potential to be utilized in water and wastewater treatment applications, either as a photocatalyst or in membrane incorporation. In the present study, ZnO nanoparticles were synthesized using the precipitation method. The Taguchi approach with the L32b orthogonal array was utilized in order to optimize the experimental conditions for the synthesis of the nanoparticles and to ensure that relatively smaller-sized particles were obtained. The design was characterized by ten factors, where nine of them possessed four levels, while one had two levels. This study’s design factors were the type of Zn precursor, the concentration of the Zn precursor, the type of precipitating agent, the precipitation agent’s concentration, the type of utilized solvent, the pH value of the solvent, the temperature used during the synthetic procedure, the calcination temperature, the time of stirring during synthesis, as well as the stirring speed. The influences of those factors on the selected response parameters (the average crystallite size, degree of crystallinity, energy band gap (Eg), and photodegradation constant (k)) were then evaluated. XRD analysis and the calculated Eg values indicated that the hexagonal wurtzite structure was the only crystalline phase present in the produced samples. The photocatalytic efficiency of all ZnO nanoparticles was examined in the degradation of rhodamine B under UV light irradiation. The optimal conditions were achieved using zinc acetate dihydrate as the Zn precursor at a concentration equal to 0.3 M, sodium hydroxide as the precipitating agent (1.5 M), methanol as the solvent (the pH value of the solvent was equal to 13), a temperature during the synthetic procedure of 70 °C, 600 °C as calcination temperature, a 90 min stirring time, and 700 rpm as the stirring speed. The optimized ZnO sample was synthesized based on the aforementioned conditions and thoroughly characterized. The acquired results confirmed the prediction of the Taguchi approach, and the most enhanced k-value was observed.

Conformal Coverage of ZnO Nanowire Arrays by ZnMnO3 : Room-temperature Photodeposition from Aqueous Solution.

Compositionally and structurally complex semiconductor oxide nanostructures gain importance in many energy-related applications. Simple and robust synthesis routes ideally complying with the principles of modern green chemistry are therefore urgently needed. Here we report on the one-step, room-temperature synthesis of a crystalline-amorphous biphasic ternary metal oxide at the ZnO surface using aqueous precursor solutions. More specifically, conformal and porous ZnMnO3 shells are photodeposited from KMnO4 solution onto immobilized ZnO nanowires acting not only as the substrate but also as the Zn precursor. This water-based, low temperature process yields ZnMnO3 /ZnO composite electrodes featuring in 1 M Na2 SO4 aqueous solution capacitance values of 80-160 F g-1 (as referred to the total mass of the porous film i. e. the electroactive ZnMnO3 phase and the ZnO nanowire array). Our results highlight the suitability of photodeposition as a simple and green route towards complex functional materials.

A facile synthesis of highly efficient and widely emission tunable quintuple CuZnGaSSe quantum dots

Due to their unique optical properties, I-III-VI alloyed quantum dots (QDs) have attracted significant attention. By cationic alloying and composition adjusting, quaternary and quintuple alloyed QDs could be synthesized and the optical properties could be further investigated by adjusting the synthesis parameters. In this study, we synthesized CuZnGaSSe (CZGSSe) QDs using a one-pot method and the photoluminescence quantum yield (PL QY) could reach 72.2%. The effects of the capping ligands, the halogen ions in Zn precursors and the reaction temperatures were explored and the growth mechanism of the CZGSSe QDs was discussed. Finally, by adjusting the S/Se ratio and Cu/Ga ratio, the prepared QDs exhibited tunable emission wavelengths ranging from 469 nm to 599 nm. This study is of significance for researching the growth sequence and guiding the synthesis of efficient quintuple QDs.

Optically Transparent TiO2 and ZnO Photocatalytic Thin Films via Salicylate-Based Sol Formulations

Sol compositions for transparent TiO2 and ZnO photocatalytic thin film deposition are of interest for the wet-chemical fabrication of self-cleaning coatings. The choice of stabilizing agent is crucial for the sol film-forming properties, with acetylacetone and monoethanolamine conventionally employed for TiO2 and ZnO deposition sols, respectively. Salicylic acid (SA), capable of chelating both Ti(IV) and Zn(II) precursors, remains underexplored. This study presents novel SA-based sol formulations for the deposition of both TiO2 and ZnO films, based on titanium tetraisopropoxide (TTIP) and zinc acetate dihydrate (ZAD) precursors, in a fixed 1:3 (TTIP:SA) and 1:2 (ZAD:SA) ratio, and isopropanol solvent, varied across the 1:10 to 1:20 precursor-to-solvent ratio range. Fourier-Transform Infrared Spectroscopy analysis and Density Functional Theory computations confirmed the formation of H2Ti[SA]3 and Zn[SA]2·2H2O complexes. Scanning Electron Microscopy, X-ray diffraction, and Ultraviolet-Visible spectroscopy were employed to study the structural and optical properties of the dip-coated films, revealing dense TiO2 (86–205 nm) and ZnO (35–90 nm) layers of thickness proportional to the salicylate concentration and transmittance in the 70–90% range. Liquid-phase Methylene blue (MB) photooxidation experiments revealed that all films exhibit photocatalytic activity, with ZnO films being superior to TiO2, with 2.288 vs. 0.366 nm h−1 cm−2 MB removal rates.

The activity of Zn precursors determines the cation exchange reaction kinetics with Ag2S: Zn-doped Ag2S or Ag2S@ZnS QDs

The activity of Zn precursors determines the cation exchange reaction kinetics with Ag2S: Zn-doped Ag2S or Ag2S@ZnS QDs

Analysis of dominant and intense XRD peak of (111) plane of ZnS nanocrystals for microstructural study through single line Voigt method: Calculated low dislocation density value emphasizes larger stacking of (111) plane

In this work, a wet chemical synthesis method has been used for the preparation of ZnS nanocrystals using the precursor Zn(NO3)2 (Zinc Nitrate) and Na2S (Sodium sulfide), where 3-Mercaptopropionic acid has been used as a capping agent. Morphological characterization of the prepared ZnS nanocrystals has been performed through HR-TEM and FE-SEM analysis and the average particle size has been obtained as approximately 26 nm. The HR-TEM image also suggests the formation of smooth crystalline ZnS nanoparticles with dominance of the (111) plane. The XRD pattern firmly indicates dominance of (111) crystalline planes over the other planes. For this, different microstructural properties of prepared ZnS nanoparticles have been studied considering only the dominant (111) diffraction peak using single line Voigt method. Finally, the average particle size calculated from morphological analysis has been compared with the crystallite size calculated by XRD analysis through the Single line Voigt method. Calculated dislocation density value indicates presence of less defects states in the sample and confirms the growth of ZnS nanoparticles in a particular direction of (111) plane with pure crystalline nature.

Rational design of AgGaS/ZnS/ZnS quantum dots with a near-unity photoluminescence quantum yield via double shelling scheme

In this study, a two-step method was used to synthesize highly luminescent AgGaS/ZnS/ZnS quantum dots (QDs). In the first step, an inner ZnS shell was formed via a one-pot method, which resulted in a smaller lattice mismatch between the AgGaS core and the outer ZnS shell, thereby facilitating the formation of a thick outer shell. After the two-step shelling process, the synthesized AgGaS/ZnS/ZnS QDs showed an excellent photoluminescence quantum yield (PLQY) of 96.4% with a peak wavelength of 508 nm, representing the highest PLQY reported thus far for AgGaS QDs. Furthermore, the effect of halogen ions in Zn precursors on the shelling process was investigated. It was proposed that the capacity of halogen ions to coordinate with the QDs influenced the balance between Zn cation diffusion and ZnS shelling reaction. Specifically, the ZnS shelling reaction was dominant when ZnCl2 was employed, while Zn cation diffusion was the dominant process under the I−-rich environment. This work provides insights into the interfacial restructuring during the ZnS shelling and offers a clear map for the tailored synthesis of core/shell QDs.

Supercritical hydrothermal synthesis of nano-ZnO: Effects of key parameters and reaction mechanism

In this paper, ZnO particles with the particle size as low as 23 nm were successfully prepared by supercritical hydrothermal synthesis technique. The particle size of nano-ZnO decreased with the increase of temperature and pressure. Nano-ZnO particles in ZnSO4 system were spherical with smaller particle size. The discrepancy in nano-ZnO produced by different precursor of Zn(NO3)2, Zn(CH3COO)2 or ZnSO4 is attributed to the anion effects and supersaturation. The particles in the KOH system (29 nm) were smaller than those in the NaOH system (44 nm). For precursor concentration, intermediate Zn(OH)2 was generated at lower concentration, while Zn4SO4(OH)6·4H2O was produced at higher concentration. For alkali concentration, as the gradual increase of KOH concentration, Zn(OH)2 began to decrease and gradually transformed into Zn(OH)3– and [Zn(OH)4]2−. When the KOH concentration reached a certain value, [Zn(OH)4]2− occupied the dominance in the mixed solution.

High yielded Co–C derived from polyester-Cobalt carbothermal reduction for efficient activation of peroxymonosulfate to degrade levofloxacin

A kind of high yield and recyclable Cobalt–Carbon composite (Zn1Co5/PnC) was prepared by carbothermal reduction process, in which the cobalt acetate and zinc acetate were considered as Zn and Co precursors, and the polyester waste was evolved as the carbon precursor. The morphology, structure and composition of the composite were characterized using scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Results showed that evaporation of zinc contributed to the formation of porous carbon structure, and the Co nanoparticles were wrapped and protected by the porous carbon matrix. The Zn1Co5/PnC activated peroxymonosulfate (PMS) system (Zn1Co5/PnC/PMS) was constructed to degrade the levofloxacin (LEV). The activity and mechanism of LEV degradation was understood. The LEV degradation efficiency was high to 96.60% within 90 min in the presence of Zn1Co5/P4C. Moreover, the Zn1Co5/P4C still maintained favorable PMS activation performance after five-cycle runs. The results show that the Zn1Co5/P4C played positive role in activating the PMS, it may be due to the facts that the polyester derived carbon could supported the Co while the evaporated Zn could increase the surface area of Zn1Co5/P4C, leading to the increased activity. The possible degradation pathways were proposed by identifying the intermediate products through liquid chromatography-mass spectrometry analysis. This study put forward a promising method to use polyester waste to synthesize high yield cobalt-carbon composite for degrading the antibiotic in wastewater.

RGO-Modified ZnWO4/WO3 Nanocomposite for Detection of NH3

The composite of ZnWO4/12WO3-0.5 wt % rGO was successfully synthesized for the first time by one-step precursor calcination of equimolar W and Zn precursors, followed by loading rGO prepared by hydrazine reduction. The structure, composition, and morphology of the as-synthesized composite were characterized by various spectral analyses. Compared with reported metal-oxide-based NH3 sensors, our sensor can detect low concentrations of NH3, and the method used herein is simple, low-cost, and effective. The composite-based sensor exhibits the highest response of 10.1–20 ppm NH3, which is 3.98 times that of WO3, and has better selectivity and stability at an operating temperature of 140 °C. The improvement is attributed to the synergistic effect of p–n heterojunction formation and rGO decoration; the former creates an additional depletion layer to expand the resistance change in air and gas, while the latter provides more surface active sites to increase gas adsorption and accelerates the electron transfer for enhancing gas-sensing performance. The work has reference value to develop novel metal-oxide-based NH3 sensors.

Influence of the precursor composition on the resulting absorber properties and defect concentration in Cu2ZnSnSe4 absorbers

In this paper the influence of composition variations during the growth of Cu2ZnSnSe4 (CZTSe) layers on defect concentrations and final absorber properties is analyzed. The samples are prepared from sputtered metallic and alloyed Zn/Cu–Sn/(Sn)/Zn precursors. The variation of sputtered Sn content facilitates different forms for the embedded Sn (Cu3Sn, Cu6Sn5, elemental Sn). The predominating formation reaction during the subsequent annealing is tuned by the ratio of the alloys and the overall chemical composition in the precursor. During the high temperature stage of CZTSe formation the layer undergoes an in-process composition shift (Sn content variation), after which the final absorber composition is reached. As all absorbers are reaching a comparable end composition, in this paper the influence of the different precursor compositions and corresponding reaction pathways on the resulting defects and optoelectronic properties of the absorbers are addressed. Spectroscopic investigations were used to extract the defect configuration of the absorbers. The results are complemented with device performance measurements. Preferable precursor compositions leading to lower defect concentration and improved photoluminescence quantum-yield is identified. The obtained Urbach energy and VOC deficit are among the most promising results measured in our laboratories.

Construction of a thermally stable ZIF-8 membrane embedded inside a porous support for H2/CO2 separation: Close interlocking between membrane grains and porous support grains

Zeolitic imidazolate framework-8 (ZIF-8) membranes have emerged as promising wall candidates for use in membrane reactors. These membranes can improve the water gas shift (WGS) reaction performance because of their exceptional thermal stability and marked H2/CO2 sieving ability. Here, we propose a modified counter diffusion scheme to form an unprecedented, thermally stable ZIF-8 membrane: Pre-deposition of a zinc precursor (zinc acetate dihydrate) and subsequent solvothermal reaction with a methanolic solution of the ligand (2-methylimidazole). It appears that the pre-deposition and drying of the Zn precursor on and inside a porous support were key to retarding the diffusion of the Zn source, thus leading to the primary contact between the Zn source and ligand molecules within the porous support. As a result, it is likely that a continuous ZIF-8 layer was formed on the top surface and, more preferentially, at the interface with the grains of the porous support, reaching an infiltration depth of approximately 80 μm. Accordingly, this allowed for the effective blocking of the support pores by ZIF-8 grains, as well as their high dispersion. Notably, the resulting ZIF-8 membrane exhibited a maximum H2/CO2 separation factor of ca. 8.7 at a WGS reaction temperature of 300 °C. Unlike the conventional membrane architecture, ZIF-8 grains were densely embedded inside the porous support, thus reducing the risk of mechanical damage. Furthermore, the unique membrane structure was desirable for securing superior thermal stability for reliable and sustainable H2/CO2 separation at 300 °C for up to 72 h.

Coordinatively Cross-Linked Binders for Silicon-Based Electrodes for Li-Ion Batteries: Beneficial Impact on Mechanical Properties and Electrochemical Performance.

A simple and versatile preparation of Zn(II)-poly(carboxylates) reticulated binders by the addition of Zn(II) precursors (ZnSO4, ZnO, or Zn(NO3)2) into a preoptimized poly(carboxylic acids) binder solution is proposed. These binders lead systematically to a significantly improved electrochemical performance when used for the formulation of silicon-based negative electrodes. The formation of carboxylate-Zn(II) coordination bonds formation is investigated by rheology and FTIR and NMR spectroscopies. Mechanical characterizations reveal that the coordinated binder offers a better electrode coating cohesion and adhesion to the current collector, as well as higher hardness and elastic modulus, which are even preserved in the presence of a carbonate solvent (i.e., in battery operation conditions). Ultimately, as shown from operando dilatometry experiments, the electrode expansion during lithiation is reduced, mitigating electrode mechanical failure. Such coordinatively reticulated electrodes outperform their uncoordinated counterparts with an improved capacity retention of over 30% after 60 cycles.

Synthesis of single‐crystalline InP tetrapod nanocrystals via addition of ZnCl2

AbstractRecently, single‐crystalline indium phosphide (InP) tetrapods, which allow an exciton to act in a true tetrapodal geometry, were successfully synthesized and proved as a useful platform to study multiple exciton behaviors. We used ZnCl2 precursor, a commonly used additive in the synthesis of aminophosphine‐based InP nanocrystals to enhance the optical performance, and successfully synthesized InP tetrapods (InP‐ZnCl2) with the narrower arm length distribution. Interestingly, no distinct enhancement in photoluminescence was observed while the arm length of the InP tetrapod was suppressed with the addition of ZnCl2. Further shell growth on InP‐ZnCl2 successfully preserved tetrapodal geometry in InP‐ZnCl2/ZnSe and showed higher photoluminescence than that of tetrapodal InP/ZnSe. The crystal structure of InP‐ZnCl2 was also retained even along with various Zn feed ratios as observed in x‐ray diffraction (XRD) patterns and showed no peak shift as Zn only passivates the surface of InP tetrapods. These results provide a platform to study the role of Zn precursor.

A reactivity-controlled epitaxial growth strategy for synthesizing large nanocrystals

Large ZnSe nanocrystals are expected to be promising blue-light emitters with an emission peak of 455–475 nm, which is important for the construction of display apparatus. The final size of ZnSe nanocrystals via one-step injection can be varied by the reactivity of the Zn and Se precursors; however, it has a limit of <5 nm. To describe the key factors in determining the final size of ZnSe nanocrystals, we proposed a nuclei number-considered LaMer model based on the Maxwell–Boltzmann distribution of crystal embryos. As a result, a general strategy of reactivity-controlled epitaxial growth was developed to synthesize large ZnSe nanocrystals through sequential injection of high-reactivity and low-reactivity Zn and Se precursors. The resultant ZnSe nanocrystals achieved pure blue emission between 455 and 470 nm. We further fabricated stable, large ZnSe/ZnS core–shell nanocrystals with photoluminescence quantum yields up to approximately 60%. Moreover, the reactivity-controlled epitaxial growth strategy is versatile and could be used to synthesize large ZnSe, CdSe and PbSe nanocrystals with average sizes up to 35 nm, 76 nm and 87 nm, respectively. The control of quantum-confined and classical effects in these large semiconductor nanocrystals will open up new directions for fundamental research and application exploration. Synthesizing Se-based nanocrystals with large diameters remains challenging. Here, a reactivity-controlled epitaxial growth strategy was demonstrated to synthesize nanocrystals of ZnSe, CdSe and PbSe with average diameters of 35 nm, 76 nm and 87 nm, respectively. The large ZnSe nanocrystals emitted pure blue light, which is important for display technology.

Narrow‐Band Blue‐Emitting Indium Phosphide Quantum Dots Induced by Highly Active Zn Precursor

AbstractColloidal indium phosphide quantum dots (In(Zn)P/ZnS QDs) show potential for application in the field of light emitting diodes (LED) and Mini/Micro‐LEDs displays due to their tunable emission and low toxicity. However, the performance of blue‐emitting indium phosphide QDs is still lagging behind that of red and green. Herein, a facile method to overcome this difficulty is proposed. The highly active Zn(ClO4)2 precursor is injected into the reaction mixture during the nucleation process to enhance zinc incorporation, which generates the In(Zn)P alloy QDs with enlarged bandgap. At the same time, the increase of zinc content can inhibit excessive growth of In(Zn)P QDs, and significantly improve its size distribution. The monodisperse In(Zn)P/ZnS QDs exhibit excellent blue emission (466 nm) and have the narrowest full width at half maxima (41 nm) of blue emission In(Zn)P QDs ever reported. This work provides a feasible and effective strategy for obtaining narrow‐band blue‐emitting In(Zn)P/ZnS QDs.

Aerosol-assisted synthesis of mesoporous Cu/ZnO-ZrO2 catalyst with highly selective photothermal CO2 reduction to methanol.

This study uses a facile aerosol-assisted method to synthesize mesoporous Cu/ZnO-ZrO2 catalysts, with superior thermal and photothermal performance for CO2 reduction to methanol. The process is based on forming an aerosol from Zn and Zr precursors and a surfactant solution. Then, fast drying of the droplets was used to obtain the ZnO-ZrO2 support with uniform nanoparticles and 6 nm calibrated mesopores. After impregnation with Cu species, the Cu/ZnO-ZrO2 catalyst exhibited high activity for the targeted reaction, as shown by the high TOFCu values and superior methanol yields and selectivity. Extensive characterization, such as BET, TEM, and photocurrents, confirms the abundant mesopores and relatively high surface area of the ZnO-ZrO2 support synthesized by the aerosol-assisted surfactant method, thus promoting Cu dispersion as well as enhancing the localized surface plasmon resonance (LPSR) effect to generate efficient currents and change the chemical state of Cu by in situ oxidation and reduction to promote a hydrogen overflow effect under visible light irradiation. Therefore, the simple and scalable aerosol-assisted process presented in this study provides new insight into the fabrication of composite mesoporous oxide as a promising photothermal catalyst.

NO2 Gas Sensing Properties of Ag-Functionalized Porous ZnO Sheets

Herein, we report a simple and scalable synthesis route to prepare Ag-functionalized porous ZnO sheets and their enhanced NO2 gas sensing properties. Porous ZnO sheets functionalized with well-dispersed submicron Ag particles were prepared by using a hydrothermal method-based one-pot synthesis route from Zn and Ag precursors. NO2 gas sensing performance (response, selectivity, response time, and recovery time) was optimized at 200°C in the gas sensor fabricated with 3 at% Ag-functionalized porous ZnO sheets. We demonstrated a response ([Formula: see text]/[Formula: see text]) of 17.18 to 10 ppm NO2 gas and also obtained a high response of 14.05 even at 60% relative humidity due to the synergetic effect of improved NO2 gas adsorption in the presence of Ag particles and increased resistance by the formation of Schottky barrier at Ag-ZnO heterojunctions.

Luminescent AgGaSe2/ZnSe nanocrystals: rapid synthesis, color tunability, aqueous phase transfer, and bio-labeling application.

The unique optoelectronic properties of I-III-VI2 nanocrystals (NCs) have attracted extensive attention. Herein, element Se in oleylamine reduced by alkythiol, which has been demonstrated to generate highly reactive alkylammonium selenide, was selected as the Se precursor by us to successfully synthesize high-quality tetragonal AgGaSe2 NCs via a facile colloidal method in just 2 minutes. Further, the photoluminescence (PL) properties of the as-synthesized AgGaSe2 NCs were systematically optimized through utilizing one Zn precursor to integrate shell coating and anionic/cationic alloying strategies into our reactive system, resulting in not only the obvious improvement of PL intensity but also tunable PL color from blue to red. Furthermore, the ligand exchange approach was adopted for the aqueous phase transfer of the oleophilic AgGaSe2/ZnSe NCs. Our data suggest that either metalated mercaptopropionic acid (Zn-MPA) short- or 11-mercaptoundecanoic acid long-chain ligand exchanged NCs all could maintain the original high crystallinity, present good water solubility, and retain up to nearly 95% and 70% of the initial PL intensity, respectively. Benefiting from the low cytotoxicity, the water-soluble AgGaSe2/ZnSe NCs can be applied as a fluorescent probe in cell imaging and signal labels for the fluoroimmunoassay of prostate-specific antigen, implying their potential in biological application.