Anti-Site Defects-Assisted Enhancement of Electrogenerated

Oct 26, 2018 - Anti-Site Defects-Assisted Enhancement of Electrogenerated Chemiluminescence from in Situ Mn2+-Doped Supertetrahedral Chalcogenide ...M...
0 downloads 0 Views 2MB Size
Download PDF
Research Article www.acsami.org

Cite This: ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX

Anti-Site Defects-Assisted Enhancement of Electrogenerated Chemiluminescence from in Situ Mn2+-Doped Supertetrahedral Chalcogenide Nanoclusters Feng Wang,†,‡,∥ Jian Lin,§,∥ Shansheng Yu,† Xiaoqiang Cui,*,† Asghar Ali,‡ Tao Wu,§ and Yang Liu*,‡

Downloaded via UNIV OF LOUISIANA AT LAFAYETTE on October 27, 2018 at 02:57:08 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.

†

Key Laboratory of Automobile Materials of MOE and Department of Materials Science, Jilin University, Changchun, China, 130012 ‡ Department of Chemistry, Key Lab of Bioorganic Phosphorus Chemistry and Chemical Biology of Ministry of Education, Beijing Key Laboratory for Microanalytical Methods and Instrumentation, Tsinghua University, Beijing, China, 100084 § College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, Jiangsu, China, 215123 S Supporting Information *

ABSTRACT: Understanding and revealing the connection between defects and dopant for improving electrogenerated chemiluminescence (ECL) efficiency remain a constant challenge. In this work, the in situ Mn 2+ -doped Mn1.36Zn5.64In28S56 supertetrahedral chalcogenide semiconductor nanoclusters (NCs) with an ECL efficiency as high as 27.1% was obtained, the corresponding ECL behaviors were investigated, and the vital role of more anti-site defects (ADs) introduced in situ on the ECL emission was elucidated. The ADs can not only give rise to the ECL emission peak at 494 nm but also assist transfer of electrons to induce and enhance the ECL emission at 627 nm from doped Mn2+ in the NCs. Furthermore, based on the fact that dissolved oxygen can enhance the ECL intensity, a highly sensitive ECL sensor for the determination of dissolved oxygen was developed. This insight into the fundamental interactions between Mn2+ dopants and defects in NC host may open new opportunities for the design of novel ECL materials to promote their application potential in electrochemical analysis and imaging. KEYWORDS: supertetrahedral chalcogenide, doping, defects, electrogenerated chemiluminescence, dissolved oxygen distribution of Mn2+ dopants in host materials while increasing the amounts of Mn2+. In view of these facts, creating highefficiency Mn2+-doped ECL materials continues to be challenging. Recently, the doping behavior from NCs-based metal chalcogenide (ISC-10-MInS, M = Cd or Zn), which is composed of coreless supertetrahedral NCs denoted as T5MInS with the formula of [M6In28S56], has attracted increasing attention because preciously doping in host materials can overcome interactions between dopants to induce ideal optical and optoelectronic performance.27 For instance, precise monoCu+- and Mn2+-doped supertetrahedral CdInS nanoclusters showed enhanced photoelectric response and unusual red shift in Mn2+ emission respectively.28,29 In our previous work, it was observed that both the “vacancy point defect” (VD) and antisite defects (ADs) in the nanoclusters can induce the ECL emissions, in addition, the Mn2+ introduced by the postdoping process can tune the ECL behaviors of the nanoclusters.30

1. INTRODUCTION During the past decades, the Mn2+-doped semiconductor nanocrystals have attracted significant attention because the purposefully doped Mn2+ can adjust the electronic structure of the host and generate desirable optical,1,2 electronic,3,4 and catalytic properties5−9 for achieving some intriguing applications in bioimaging,10−12 electronic device,13,14 and energy storage.15−17 The Mn2+-doping concentration and dopants’ position are generally accepted to have a significant effect on the physical and chemical properties of the host materials.18−21 The metal-doped semiconductors show unique electrogenerated chemiluminescence (ECL) features and have great potential in sensor devices and bioimaging applications.22−24 However, there are few reports about Mn2+-doped modulation of ECL behaviors of host materials, and the corresponding ECL efficiencies are lower in neutral aqueous medium. For instance, the Mn2+-doped polycrystalline ZnS electrode prepared by chemical vapor deposition and the Mn2+containing cluster [(tmeda)6 Zn8Mn6Se13Cl2] (tmeda = tetramethylethylenediamine) in persulfate solution all exhibited lower ECL efficiency of 0.3%,25,26 which may be the results of substantial challenge in achieving the highly uniform © XXXX American Chemical Society

Received: August 9, 2018 Accepted: October 16, 2018

A

DOI: 10.1021/acsami.8b13635 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX

Research Article

ACS Applied Materials & Interfaces Unfortunately, Mn2+-postdoped CdInS NCs exhibited quite a low ECL efficiency (0.0085%), which may be ascribed to the postdoping process. Because, during the postdoping process, the corrosion from organic solvents resulted in the damage of host structure and the slow dynamic of ion diffusion limited the doping level.28 Here, in situ Mn2+-doped ISC-10-ZnInS microcrystals composed of coreless supertetrahedral NCs denoted as T5ZnInS with different doping contents were purposely prepared for optimizing ECL efficiency. An ECL efficiency as high as 27.1% was obtained from in situ Mn2+-doped Mn1.36Zn5.64In28S56 NCs; meanwhile, the strong Mn···Mn interactions against the ECL emission was pointed out in combination with the calculated density of states (DOS) results by density functional theory (DFT). More importantly, the ECL behavior of in situ Mn2+-doped Mn1.36Zn5.64In28S56 NCs was investigated, and new insight by ADs-assisted enhancement of ECL emission from Mn2+ in NCs was proposed. Furthermore, based on the fact that dissolved oxygen can enhance the ECL intensity, a highly sensitive ECL sensor for dissolved oxygen determination was established.

at 600 V. The relative ECL efficiencies were obtained via the formula below (eq 1)32,33 t t jij ∫ I dt zyz jij ∫ I dt zyz jj 0 zz jj 0 zz zz /jj t zz ⌀x = ⌀stjj t jj z j z j ∫ i dt zz jj ∫ i dt zz 0 0 k {x k {st

ij b I dv yz ij b I dv yz jj ∫ zz jj ∫a zz zz /jj zz =⌀stjjjj a b z j z jj ∫ i dv zzz jjj ∫ b i dv zzz a a k {x k {st

(1)

Here, the ECL efficiency (5.0%) from the annihilation emission of [Ru(bpy)3]2+ in 0.1 M acetonitrile containing 1 mM (TBA)BF4 is used as ⌀st, the ECL intensity is taken as I, i is the current intensity, and x stands for the sample measured. All the averaged values of ECL efficiencies are acquired from five independent measurements. The ECL spectra were measured via capturing the ECL intensities at peak potential through band-pass filters with different wavelengths (440, 460, 490, 535, 555, 575, 600, 620, 640, 680, 705, and 745 nm). Then, the ECL spectrum was obtained via plotting the ECL intensities at the corresponding wavelengths. (Note: herein, the ECL intensities were corrected via multiplying the intensity correction factors. Correction factor = (FWHM × T%)555 nm/(FWHM × T %)x nm, in which FWHM and T% represent full width at halfmaximum and light transmittance, respectively, and x is the wavelength of filters). 2.6. Theoretical Calculation. All theoretical calculations were conducted using density functional theory (DFT) by Dmol3 code34,35 with a long-range dispersion correction by Grimme’s scheme.36 The double numerical polarized atomic orbital basis and the generalized gradient approximation (GGA) were adopted, in which GGA was parameterized with Perdew−Burke−Ernzerhof scheme.37 To reduce the computational cost, the core electrons are treated by DFT semicore pseudopots method.38 For geometrical relaxation, the energy convergence threshold was set as 10−5 Ha. An energy criterion of 10−6 Ha was used to determine whether the self-consistent field has converged. In all DOS plots, the Femi energy levels were located at 0 eV. 2.7. Detection of Dissolved Oxygen. The dissolved oxygen concentrations (0−20 mg/L) were adjusted via purging N2 or O2 into air-saturated aqueous solution controlled by LZB-3WB class rotor. The oxygen concentrations were calibrated via a commercial dissolved oxygen meter (CM-04-35). The ECL sensor of dissolved oxygen was performed by measuring the ECL intensity in a range of dissolved oxygen concentrations (0−20 mg/L).

2. EXPERIMENTAL SECTION 2.1. Materials. Zn(NO3)2·6H2O (AR, 99%), In powder (99.99%, 200 mesh), S powder (99.99% metals basis), Mn(Ac)2·4H2O (99.99% metal), Cd(NO3)2·4H2O (AR, 99%), piperidine (PR, 99%), 1,5diazabicyclo[4.3.0]non-5-ene (DBN, 98%), hydrogen peroxide (H2O2, 30%), NaH2PO4·2H2O (AR, 99%), and Na2HPO4·12H2O (AR, 99%) were purchased from Aladdin Industrial, Inc. KCl (AR, 99.5%) was purchased from Beijing Chemical Works. 2.2. Synthesis. The microcrystals of ISC-10-ZnInS, ISC-10CdInS, Mn2+-postdoped ISC-10-ZnInS and Mn2+-postdoped ISC-10CdInS were prepared following literature methods.29 In situ doped samples with different Mn2+ contents were prepared as follows: 120 mg S powder, 80 mg In powder, 37 mg Zn(NO3)2·6H2O, Mn(Ac)2· 4H2O (1, 3, 8, 9, and 10 mg, respectively), and 1 mL deionized H2O were mixed with 1.0 mL DBN and 1.2 mL PR in 25 mL Teflon cup via stirring for half an hour and then heated at 200 °C for 10 days via hydrothermal process. The products obtained were washed with ethanol three times. The ISC-10-MnInS microcrystals were prepared based on the literature methods as well.31 2.3. Characterization. The powder X-ray diffraction (XRD) results were acquired using a diffractometer (D2PHASER, Bruker, Germany) with Cu Kα radiation. Scanning electron micrographs (SEM) and energy-dispersive spectroscopy (EDS) were recorded on field emission scanning electron microscope (HITACHI S-4700). 2.4. Immobilization of ISC-10 Samples on Glassy Carbon Electrode (GCE). Two milligrams of the sample powder was dispersed in 1 mL water by ultrasonication for at least 1 h to gain 2 mg/mL aqueous suspension. The 3 mm diameter glassy carbon electrode was polished by alumina powder of 0.3 μm and then cleaned ultrasonically using ethanol and water respectively. After that, 10 μL solution was dropped on GCE. After being dried in dark ambient temperature, the GCE was used to measure the electrochemistry and ECL properties. 2.5. Test from Photoluminescence (PL), Electrochemical, and ECL. A fluorescence spectrophotometer (Edinburgh FLS-920) was used to test the PL spectra. The cyclic voltammetry (CV) and ECL data were measured using GCE as the working electrode, Ag/ AgCl/KCl as the reference electrode, and Pt wire as the counter electrode. The cyclic voltammetry was performed in 0.1 M phosphatebuffered solution (PBS) bubbled with N2 for 25 min at the scan rate of 100 mV/s in an electrochemical workstation (CHI-802B, CH Instruments, Chenhua Co., Shanghai, China). The ECL was performed at the scan rate of 100 mV/s via MPI-B ECL detection system, where the voltage from photomultiplier tube (PMT) was set

3. RESULTS AND DISCUSSION The in situ Mn2+ -doped ISC-10-ZnInS samples were successfully prepared by using Zn2+ salt and Mn2+ salt as precursors. The as-prepared sample presented XRD patterns similar to the simulated one of ISC-10-CdInS (Cd6In28S56) as shown in Figure S1A, indicating that T5 NC structure and the similar stacking mode were reserved.28 In addition, an octahedron morphology was seen in the SEM image (Figure S1B), which was similar to that of the ISC-10-CdInS crystal. In addition, the component distributions of the elements such as S, Zn, Mn, and In were same both on the surface and inside of the crystal (Figure S1C). For the in situ Mn doping NCs, the doped Mn can occupy the vacancy defect site in the crystal and can also replace the sites of Zn in the crystal. As a result, the stoichiometric number of Mn doped in the NCs can be written as MnxZnyIn28S56 (x ≤ 1, y = 6; x ≥ 1, y = 7 − x), where “x ≤ 1” means that the vacancy sites are partially or totally occupied by Mn and then the stoichiometric number of Zn is 6. However, x ≥ 1 means that some Zn sites are occupied by Mn in the cluster. Thus, the stoichiometric number of Zn should be 7 − x. The actual x values were determined by energyB

DOI: 10.1021/acsami.8b13635 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX

Research Article

ACS Applied Materials & Interfaces dispersive spectrometry (EDS), and the specific calculation method and results are described in Table S1. In consequence, the electrochemical and ECL behaviors were investigated using Mn2+-doped ISC-10-ZnInS composed of Mn1.36Zn5.64In28S56 as a model, as shown in Figure 1. Figure

Figure 2. ECL−potential curves of in situ Mn2+-doped ISC-10-ZnInS samples with different Mn2+-doping concentrations ((a) Zn6In28S56, (b) Mn0.16Zn6In28S56, (c) Mn0.43Zn6In28S56, (d) Mn1.29Zn5.71In28S56, (e) Mn1.36Zn5.64In28S56, (f) Mn2.11Zn4.89In28S56) modified GCE in 0.1 M PBS with 0.1 M KCl in air. The inset represents the corresponding ECL efficiencies.

ion doped NC, based on the lowest-energy principle, Mn2+ ion at the vacancy site in T5 NC (assigned as Mn@Zn6In28S56) is the optimized atomic configuration, as shown in the inset of Figure S2. The corresponding DOS plots are shown in Figure S2. The extra electronic energy level within the band gap is introduced for Mn@Zn6In28S56. The extra energy level introduced by Mn dopant is discrete in the band gap, being closer to the Fermi level, because Mn2+ at the vacancy site in T5 NCs can be a single isolated dopant. As for doping with two Mn2+ ions, there are two possible atomic configurations: one is the NC with one Zn2+ ion occupied at the core site and two Mn2+ situated symmetrically at the tetrahedral faces from NC via replacing Zn2+ (Zn@Mn2Zn4In28S56), and another one is the NC with one Mn2+ ion located at the core site and one other Mn2+ ion at the tetrahedral faces instead of the Zn2+ ion (Mn@MnZn5In28S56). Their atomic configurations and corresponding DOS plots are displayed in Figure S3. For Zn@ Mn2Zn4In28S56NCs, two symmetrically distributed Mn2+ ions at the faces are not adjacent, resulting in two isolated dopants. For this special case, the isolated dopants will enhance the intensity of extra d states peak in the band gap, and the peak position does not change, as shown in Figure S3A. On the other hand, as for Mn@MnZn5In28S56 NCs, the Mn···Mn interaction from adjacent Mn dopants in NCs will induce their d states hybridization, leading to the broadening of d state in the band gap. As a result, the position of Mn2+ dopants plays a significant role in modulating the energy level of NCs. When three Mn2+ ions are doped into the T5 NCs, whereas increasing the number of Mn2+ ions to three, based on the lowest-energy principle, there are four possible atomic configurations with one Mn2+ at the core site and other two Mn2+ on the tetrahedral faces instead of Zn2+, as shown in the inset of Figure S4. Figure S4 shows that the intermediate energy levels within the band gap are further broaden at the DOS spectra for all situations due to stronger d states hybridization, which should be ascribed to the presence of Mn2+ cluster in the T5 NC. Combined with the ECL intensity of NCs with different Mn2+ doping level (Figure 2), it can be seen that the Mn···Mn interaction in the Mn2+ pair or cluster introduced at a higher doped level is adverse to the production of ECL. To further manifest this point of view, ISC-10-MnInS was also synthesized, in which divalent Zn2+ ions were

Figure 1. Cyclic voltammetry curve (A) in 0.1 M PBS with 0.1 M KCl bubbled with N2 for 25 min and ECL−potential curve (B) in 0.1 M PBS with 0.1 M KCl in air of in situ Mn2+-doped Mn1.36Zn5.64In28S56 NCs modified GCE. The PMT was biased at 750 V.

1A shows the CV curve of the Mn1.36Zn5.64In28S56. A reduction peak with −2.111 V half-wave potential (assigned as R1) was observed. Meanwhile, a sharp ECL emission (assigned as E1) can be observed at a lower cathode potential in the ECL− potential curve, as shown in Figure 1B, which indicates that in situ Mn2+-doped NCs can generate cathode ECL emission in 0.1 M PBS in air. For in situ doping process, the greatest merit lies in that the doping level of metal elements can be readily tuned. Therefore, we purposely prepared a series of doped ZnInS samples with different contents of Mn2+ dopants. Figure 2 shows their ECL−potential curves, and the inset of Figure 2 displays the corresponding ECL efficiencies of the samples. The ECL intensity increased when x was increased from 0 to 1.36, but it was decreased when x was increased from 1.36 to 2.11; an ECL efficiency as high as 27.1% was obtained from Mn1.36Zn5.64In28S56 NCs. The facts indicated that the ECL efficiency was enhanced 90 times after the Mn2+ doping compared to that (0.3%) of undoped Zn6In28S56 NCs and higher than those of the reported Mn2+-doped semiconductor materials in an aqueous solution.25,39 To rationally explain the ECL efficiency of the in situ Mn-doped MnxZnyIn28S56 with different concentrations of Mn2+ dopants, the optimized atomic configurations of single T5 NC in ISC-10 crystals with different numbers of Mn atom dopant were constructed, and DFT calculations were employed. As a heteroatom, Mn2+ ion with half-occupied 3d orbitals shows considerable variability in comparison with Zn2+ ion. For the single Mn2+ C

DOI: 10.1021/acsami.8b13635 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX

Research Article

ACS Applied Materials & Interfaces completely replaced with Mn2+ ions. As shown in Figure S5, the XRD pattern is in accordance with that of ISC-10-CdInS except for a little shift toward larger angles, which should be the result of the size shrink of the Mn7In18S56 NC. It was observed that no ECL emission appeared during the potential scanning from 0 to −2 V (Figure S6), and the stronger Mn··· Mn interactions can also be read out from the DOS results calculated based on the optimal atomic configuration of the Mn7In18S56 NC (Figure S7). These facts demonstrate that the high dispersion of Mn2+ with a high doping level overcoming the Mn···Mn interactions is vital to obtain a highly efficient ECL emission. To reveal the ECL radiation paths from E1 mentioned above from the in situ Mn2+-doped MnxZnyIn28S56, the electrochemistry and ECL behaviors of Zn6In28S56 and in situ Mn2+doped Mn1.36Zn5.64In28S56 NCs were investigated. One reduction peak of −2.110 V in the cathodic region was observed in the CV curve of Figure S8A. The ECL emissions were produced in the cathodic and anodic regions, respectively, as shown in Figure S8B. Figure S8C shows that the emission peak of PL and ECL at −1.50 V were located at 485 and 587 nm, respectively. These electrochemical and ECL behaviors of Zn6In28S56 NCs are similar to those of Cd6In28S56 NCs with similar vacancy structure reported previously.30 Therefore, the reduction peak may come from electron injection into the conduction band (CB), and the ECL emission peak of 585 nm at −1.50 V comes from the recombination of the electron at the ADs-induced trap state below the CB and the hole at the VDs-induced trap state above the valence band.30 The R1 mentioned above at −2.111 V, is similar to that of Zn6In28S56 NCs, which indicates that R1 reduction peak from in situ Mn2+-doped Mn1.36Zn5.64In28S56 NCs may also originate from the electron injection into the CB of NCs. Figure 3A shows the PL spectrum at the excitation wavelength of 400 nm (curve a) and the ECL spectrum (curve b) at −1.50 V of the in situ Mn2+-doped Mn1.36Zn5.64In28S56 NCs. After the Mn2+ doping, the ECL emission at 587 nm is suppressed, and two ECL emission peaks centered at 494 nm (P1) and 627 nm (P2) are observed at the same potential of −1.50 V. Considering the wavelength interval of ca. 20 nm for the band-pass filters (Figure S9), the P1 peak is actually close to the PL emission peak of the Zn6In28S56 sample at 485 nm (Figure S8C), which is ascribed to the radiation recombination of the electron−hole pairs at the ADs-induced trap states.31 Thus, the P1 peak should be attributed to the charge carrier recombination at the ADs-induced trap states (Scheme 1). The P2 peak at 627 nm from in situ Mn 2 + -doped Mn1.36Zn5.64In28S56 NCs is close to the PL peak of 632 nm, which indicates that the P2 ECL emission comes from the radiation recombination of the charge carriers from the Mn2+induced trap states. These facts demonstrated that in situ Mn2+ doping can not only induce more ADs to generate ECL emission at 494 nm but also occupy the VD to suppress the intrinsic ECL emission at 587 nm and produce a red-shifted ECL emission at 627 nm at the cathodic region in the Mn1.36Zn5.64In28S56 NCs. However, as for the ECL emission from the Mn1.36Zn5.64In28S56 NCs, as shown in Figure 3B, both the starting potential and the peak potential are consistent with those of the ECL emissions from the Zn6In28S56 NCs, indicating that the P2 should be ascribed to the injection of electrons into the ADs-induced trap state rather than the direct electron injection from electrode into Mn2+ ions in the NCs

Figure 3. (A) PL spectrum (a) at the excitation wavelength of 400 nm and the ECL spectrum (b) at −1.5 V of in situ Mn2+-doped Mn1.36Zn5.64In28S56 NCs. (B) The normalized ECL−potential curves of Zn6In28S56 NCs (a) and in situ Mn2+-doped Mn1.36Zn5.64In28S56 NCs (b) modified GCE in 0.1 M PBS with 0.1 M KCl in air.

reported previously.39 Thus, the ECL emission mechanism from Mn1.36Zn5.64In28S56 NCs can be proposed as follows O2 + 2H 2O + 2e− → H 2O2 + 2OH−

(2)

H 2O2 + e− → OH− + •OH

(3)

NC + •OH → (NC)+• + OH−

(4)

Mn 2 + + •OH → Mn 3 + + OH−

(5)

NC + e− → (NC)−•

(6)

(NC)−• + NC+• → (NC)*

(7)

(NC)* → NC + hv (494 nm)

(8)

and NC−• + Mn 3 + → (Mn 2 +)* + NC

(9)

(Mn 2 +)* → Mn 2 + + hv (627 nm)

(10)

During the negative potential scanning, dissolved oxygen is reduced to form H2O2 (eq 2). Then, H2O2 is reduced to produce oxidizing co-reactant (•OH) (eq 3), which can be supported by the enhancement of H2O2 on the ECL intensity (Figure S10). The produced •OH introduces holes into the ADs-induced trap state to generate (NC)+• species (eq 4). With further scanning to a more negative potential, the formed (NC)+• species can recombine with (NC)−• produced via trapping electron from cathode (eq 6) to lead to the formation of an (NC)* excited state (eq 7). Finally, the P1 peak of 494 nm is acquired via the excited (NC)* relaxation to the ground state (eq 8). On the other hand, the •OH radical can also oxidize Mn2+ to form Mn3+, as shown in eq 5. Meanwhile, the electron on the ADs-induced trap state in (NC)−• can rapidly D

DOI: 10.1021/acsami.8b13635 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX

Research Article

ACS Applied Materials & Interfaces Scheme 1. Proposed ECL Radiation Paths in the In Situ Mn2+-Doped MnxZnyIn28S56

transfer to Mn3+ and generate (Mn2+)* (eq 9). The ECL emission at 627 nm from P2 is obtained via relaxation from the excited state to the ground state (eq 10). In addition, as for the in situ Mn2+-doped Mn1.01Cd5.99In28S56 NCs, two obvious ECL peaks centered at 495 and 643 nm are observed at −1.410 V, which are similar to those of Cd6In26S56 NCs, as shown in Figure S11B. The facts indicate that the ECL reaction mechanism and the radiation paths proposed may be applicable for the in situ Mn2+-doped T5 chalcogenide nanocluster with a vacancy site. In addition, as for the Mn2+-postdoped T5-ZnInS (Mn@ Zn6In28S56), the ECL intensity obtained (Figure S12A) is lower than that (Figure 2-d) from in situ Mn2+-doped Mn1.29Zn5.71In28S56 NCs, and only an ECL peak of 620 nm is seen in the ECL spectrum (Figure S12B), suggesting that postdoping process cannot create more ADs for the assisted enhancement of the ECL emission from Mn2+ in NCs, except occupying the core site of NCs. In addition, compared to the ECL emission intensities of Cd6In28S56 NCs (Figure S11A-a) and Mn2+-postdoped Mn@Cd6In28S56 NCs (Figure S11A-b), in situ Mn2+-doped Mn1.01Cd5.99In28S56 NCs (Figure S11A-c) also have a higher active ECL emission. These facts demonstrate that the new insight into the ADs-assisted enhancement of ECL emission from Mn2+ doped in NCs is feasible for the in situ Mn 2+ -doped supertetrahedral chalcogenide NCs. Based on the fact of the dissolved oxygen-assisted ECL emission of Mn1.36Zn5.64In28S56 NCs, an ECL sensor for dissolved oxygen determination was built. This sensor is simple, fast, and label-free. Figure S13 shows the effect of scan rates on ECL intensity. The highest ECL intensity is achieved at the scan rate of 500 mV/s. Thus, 500 mV/s was selected in the dissolved oxygen determination. The ECL intensity is proportional to the concentration of dissolved oxygen in the range from 0.68 to 19.6 mg/L, as shown in Figure 4. The linear relationship can be represented as I = 658.892CO2 (mg/L) + 325.378 with the correlation coefficient of R2 = 0.991, where I represents the ECL intensity and CO2 is the concentration of the dissolved oxygen. The detection limit was calculated to be 0.64 mg/L according to the equation of CLOD = 3SB/m, where CLOD is the limit of detection, SB is the standard deviation obtained in the blank solution from which no response signal was obtained, and m is the slope of the calibration curve and is compared to that reported for the detection of dissolved

Figure 4. Calibration curve of the ECL sensor for dissolved oxygen detection based on in situ Mn2+-doped Mn1.36Zn5.64In28S56 NCs modified GCE. Scan rate was 500 mV/s.

oxygen.40,41 This result indicates that the in situ Mn2+-doped supertetrahedral chalcogenide NCs can have great promise in the applications of biosmall molecular sensor or imaging.

4. CONCLUSIONS In conclusion, the ECL behaviors of in situ Mn2+-doped supertetrahedral chalcogenide NCs were studied and a high ECL efficiency of 27.1% from Mn1.36Zn5.64In28S56 NCs was obtained. The possible ECL emission mechanisms from Mn1.36Zn5.64In28S56 NCs was proposed. In situ Mn2+ doping can introduce more VDs to induce an ECL emission at 494 nm. More importantly, the ADs introduced can also assist in the transfer of electrons to generate a higher active ECL emission at 627 nm from Mn2+ in NCs. Additionally, a highsensitivity ECL sensor for detecting the dissolved oxygen with a simple, fast, and label-free method was achieved. This new enhanced mechanisms provide a potential means for enhancing the ECL properties of Mn2+ in metal chalcogenide-based NCs, thus promoting their sensing and bioimaging applications.

■

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acsami.8b13635. PXRD, SEM, EDS, other electrochemistry data and simulation results, etc. (PDF) E

DOI: 10.1021/acsami.8b13635 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX

Research Article

ACS Applied Materials & Interfaces

■

(9) Gao, J.; Tay, Q.; Li, P. Z.; Xiong, W. W.; Zhao, Y.; Chen, Z.; Zhang, Q. Surfactant-Thermal Method to Synthesize a Novel TwoDimensional Oxochalcogenide. Chem. - Asian J. 2014, 9, 131−134. (10) Norris, D. J.; Efros, A. L.; Erwin, S. C. Doped Nanocrystals. Science 2008, 319, 1776−1779. (11) Dou, Y. K.; Chen, Y.; He, X. W.; Li, W. Y.; Li, Y. H.; Zhang, Y. K. Synthesis of Water-Dispersible Mn2+ Functionalized Silicon Nanoparticles under Room Temperature and Atmospheric Pressure for Fluorescence and Magnetic Resonance Dual-Modality Imaging. Anal. Chem. 2017, 89, 11286−11292. (12) Wu, P.; Yan, X. P. Doped Quantum Dots for Chemo/ Biosensing and Bioimaging. Chem. Soc. Rev. 2013, 42, 5489−5521. (13) Panda, S. K.; Hickey, S. G.; Demir, H. V.; Eychmüller, A. Bright White-Light Emitting Manganese and Copper Co-Doped ZnSe Quantum Dots. Angew. Chem., Int. Ed. 2011, 123, 4524−4528. (14) Yuan, X.; Ji, S.; De Siena, M. C.; Fei, L.; Zhao, Z.; Wang, Y.; Li, H.; Zhao, J.; Gamelin, D. R. Photoluminescence Temperature Dependence, Dynamics, and Quantum Efficiencies in Mn2+-Doped CsPbCl3 Perovskite Nanocrystals with Varied Dopant Concentration. Chem. Mater. 2017, 29, 8003−8011. (15) Erwin, S. C.; Zu, L.; Haftel, M. I.; Efros, A. L.; Kennedy, T. A.; Norris, D. J. Doping Semiconductor Nanocrystals. Nature 2005, 436, 91−94. (16) Zhang, L.; Ji, X.; Ren, X.; Ma, Y.; Shi, X.; Tian, Z.; Asiri, A. M.; Chen, L.; Tang, B.; Sun, X. P. Electrochemical Ammonia Synthesis via Nitrogen Reduction Reaction on MoS2 Catalyst: Theoretical and Experimental Studies. Adv. Mater. 2018, 30, No. e1800191. (17) Jalalah, M.; Ko, Y. H.; Harraz, F. A.; Al Assiri, M.; Park, J. G. Enhanced efficiency and Current Density of Solar Cells via EnergyDown-Shift Having Energy-Tuning-Effect of Highly UV-LightHarvesting Mn2+-Doped Quantum Dots. Nano Energy 2017, 33, 257−265. (18) Li, Z. J.; Hofman, E.; Blaker, A.; Davis, A. H.; Dzikovski, B.; Ma, D. K.; Zheng, W. Interface Engineering of Mn-Doped ZnSeBased Core/Shell Nanowires for Tunable Host-Dopant Coupling. ACS Nano 2017, 11, 12591−12600. (19) Zhu, J.; Yang, X.; Zhu, Y.; Wang, Y.; Cai, J.; Shen, J.; Sun, L.; Li, C. Room-Temperature Synthesis of Mn-Doped Cesium Lead Halide Quantum Dots with High Mn Substitution Ratio. J. Phys. Chem. Lett. 2017, 8, 4167−4171. (20) Wang, Z. Q.; Ren, X.; Wang, L.; Cui, G. W.; Wang, H. J.; Sun, X. P. Hierarchical CoTe2−MnTe2 Hybrid Nanowire Array Enables High Activity for Oxygen Evolution Reaction. Chem. Commun. 2018, 54, 10993−10996. (21) Wu, P.; Zhang, J.; Wang, S.; Zhu, A.; Hou, X. Sensing During In Situ Growth of Mn-Doped ZnS QDs: A Phosphorescent Sensor for Detection of H2S in Biological Samples. Chem. - Eur. J. 2014, 20, 952−956. (22) Shan, Y.; Xu, J. J.; Chen, H. Y. Distance-Dependent Quenching and Enhancing of Electrochemiluminescence from a CdS:Mn Nanocrystal Film by Au Nanoparticles for Highly Sensitive Detection of DNA. Chem. Commun. 2009, 45, 905−907. (23) Shan, Y.; Xu, J. J.; Chen, H. Y. Opto-Magnetic Interaction Between Electrochemiluminescent CdS: Mn Film and Fe3O 4 Nanoparticles and Its Application to Immunosensing. Chem. Commun. 2010, 46, 4187−4189. (24) Wu, P.; Hou, X.; Xu, J. J.; Chen, H. Y. Electrochemically Generated versus Photoexcited Luminescence from Semiconductor Nanomaterials: Bridging the Valley between Two Worlds. Chem. Rev. 2014, 114, 11027−11059. (25) Ouyang, J.; Fan, F. R. F.; Bard, A. J. Semiconductor Electrodes, 62. Photoluminescence and Electroluminescence from ManganeseDoped ZnS and CVD ZnS Electrodes. J. Electrochem. Soc. 1989, 136, 1033−1039. (26) Hesari, M.; Turnbull, J.; Khadka, C. B.; Weigend, F.; Corrigan, J. F.; Ding, Z. Enhancing Electrochemiluminescence of Chalcogenide Clusters by Means of Mn Replacement. Electrochim. Acta 2016, 210, 79−86.

AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected] (X.C.). *E-mail: [email protected] (Y.L.). ORCID

Jian Lin: 0000-0001-5186-0746 Shansheng Yu: 0000-0001-9493-6341 Xiaoqiang Cui: 0000-0002-5858-6257 Tao Wu: 0000-0003-4443-1227 Yang Liu: 0000-0003-0042-5183 Author Contributions ∥

F.W. and J.L. contributed equally to this work.

Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS This work was financially supported via National Key Research and Development Program of China (Nos 2016YFA0203101, 2016YFA0200400), National Natural Science Foundation of China (Nos 21874080, 21622506, 51571100, 21375073, 21621003, and 21671142), Beijing Municipal Science and Technology Commission (Z171100001117135), Jiangsu Province Natural Science Fund for Distinguished Young Scholars (BK20160006), and Program for JLU Science and Technology Innovative Research Team (JLUSTIRT, 2017TD-09). We thank the High Performance Computing Center of Jilin University for allocation of computing resources.

■

REFERENCES

(1) Pradhan, N.; Peng, X. Efficient and Color-Tunable Mn-Doped ZnSe Nanocrystal Emitters: Control of Optical Performance via Greener Synthetic Chemistry. J. Am. Chem. Soc. 2007, 129, 3339− 3347. (2) Liu, W.; Lin, Q.; Li, H.; Wu, K.; Robel, I.; Pietryga, J. M.; Klimov, V. I. Mn2+-Doped Lead Halide Perovskite Nanocrystals with Dual-Color Emission Controlled by Halide Content. J. Am. Chem. Soc. 2016, 138, 14954−14961. (3) Fainblat, R.; Barrows, C. J.; Hopmann, E.; Siebeneicher, S.; Vlaskin, V. A.; Gamelin, D. R.; Bacher, G. Giant Excitonic Exchange Splittings at Zero Field in Single Colloidal CdSe Quantum Dots Doped with Individual Mn2+ Impurities. Nano Lett. 2016, 16, 6371− 6377. (4) Beaulac, R.; Archer, P. I.; Ochsenbein, S. T.; Gamelin, D. R. Mn2+-Doped CdSe Quantum Dots: New Inorganic Materials for SpinElectronics and Spin-Photonics. Adv. Funct. Mater. 2008, 18, 3873− 3891. (5) Devi, L. G.; Kottam, N.; Murthy, B. N.; Kumar, S. G. Enhanced Photocatalytic Activity of Transition Metal Ions Mn2+, Ni2+ and Zn2+ Doped Polycrystalline Titania for the Degradation of Aniline Blue under UV/Solar Light. J. Mol. Catal. A: Chem. 2010, 328, 44−52. (6) Devi, L. G.; Kumar, S. G.; Murthy, B. N.; Kottam, N. Influence of Mn2+ and Mo6+ Dopants on the Phase Transformations of TiO2 Lattice and Its Photo Catalytic Activity under Solar Illumination. Catal. Commun. 2009, 10, 794−798. (7) Liu, Y.; Kanhere, P. D.; Ling Wong, C.; Tian, Y.; Feng, Y.; Boey, F.; Wu, T.; Chen, H.; White, T. J.; Chen, Z.; Zhang, Q. HydrazineHydrothermal Method to Synthesize Three-Dimensional Chalcogenide Framework for Photocatalytic Hydrogen Generation. J. Solid State Chem. 2010, 183, 2644−2649. (8) Zhao, J. X.; Li, X. H.; Cui, G. W.; Sun, X. P. Highly-Active Oxygen Evolution Electrocatalyzed by a Fe-Doped NiCr2O4 Nanoparticles Film. Chem. Commun. 2018, 54, 5462−5465. F

DOI: 10.1021/acsami.8b13635 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX

Research Article

ACS Applied Materials & Interfaces (27) Nie, L.; Zhang, Q. Recent Progress in Crystalline Metal Chalcogenides as Efficient Photocatalysts for Organic Pollutant Degradation. Inorg. Chem. Front. 2017, 4, 1953−1962. (28) Wu, T.; Zhang, Q.; Hou, Y.; Wang, L.; Mao, C.; Zheng, S. T.; Bu, X.; Feng, P. Monocopper Doping in Cd-In-S Supertetrahedral Nanocluster via Two-Step Strategy and Enhanced Photoelectric Response. J. Am. Chem. Soc. 2013, 135, 10250−10253. (29) Lin, J.; Zhang, Q.; Wang, L.; Liu, X.; Yan, W.; Wu, T.; Bu, X.; Feng, P. Atomically Precise Doping of Monomanganese Ion into Coreless Supertetrahedral Chalcogenide Nanocluster Inducing Unusual Red Shift in Mn2+ Emission. J. Am. Chem. Soc. 2014, 136, 4769−4779. (30) Wang, F.; Lin, J.; Zhao, T.; Hu, D.; Wu, T.; Liu, Y. Intrinsic “Vacancy Point Defect” Induced Electrochemiluminescence from Coreless Supertetrahedral Chalcogenide Nanocluster. J. Am. Chem. Soc. 2016, 138, 7718−7724. (31) Lin, J.; Hu, D. D.; Zhang, Q.; Li, D. S.; Wu, T.; Bu, X.; Feng, P. Improving Photoluminescence Emission Efficiency of NanoclusterBased Materials by In Situ Doping Synthetic Strategy. J. Phys. Chem. C 2016, 120, 29390−29396. (32) Richter, M. M.; Debad, J. D.; Striplin, D. R.; Crosby, G. A.; Bard, A. J. Electrogenerated Chemiluminescence. 59. Rhenium Complexes. Anal. Chem. 1996, 68, 4370−4376. (33) O’Reilly, E. J.; Keyes, T. E.; Forster, R. J.; Dennany, L. Insights into Electrochemiluminescent Enhancement through Electrode Surface Modification. Analyst 2013, 138, 677−682. (34) Delley, B. An All-Electron Numerical Method for Solving the Local Density Functional for Polyatomic Molecules. J. Chem. Phys. 1990, 92, 508−517. (35) Delley, B. From Molecules to Solids with the DMol 3 Approach. J. Chem. Phys. 2000, 113, 7756−7764. (36) Grimme, S. Semiempirical GGA -Type Density Functional Constructed with A Long-Range Dispersion Correction. J. Comput. Chem. 2006, 27, 1787−1799. (37) Perdew, J. P.; Burke, K.; Ernzerhof, M. Generalized Gradient Approximation Made Simple. Phys. Rev. Lett. 1996, 77, 3865−3868. (38) Delley, B. Hardness Conserving Semilocal Pseudopotentials. Phys. Rev. B 2002, 66, No. 155125. (39) Wang, X. F.; Xu, J. J.; Chen, H. Y. A New Electrochemiluminescence Emission of Mn2+-Doped ZnS Nanocrystals in Aqueous Solution. J. Phys. Chem. C 2008, 112, 17581−17585. (40) Bellani, S.; Ghadirzadeh, A.; Meda, L.; Savoini, A.; Tacca, A.; Marra, G.; Meira, R.; Morgado, J.; Fonzo, F. D.; Antognazza, M. R. Hybrid Organic/Inorganic Nanostructures for Highly Sensitive Photoelectrochemical Detection of Dissolved Oxygen in Aqueous Media. Adv. Funct. Mater. 2015, 25, 4531−4538. (41) Zheng, R. J.; Fang, Y. M.; Qin, S. F.; Song, J.; Wu, A. H.; Sun, J. J. A Dissolved Oxygen Sensor Based on Hot Electron Induced Cathodic Electrochemiluminescence at A Disposable CdS Modified Screen-Printed Carbon Electrode. Sens. Actuators, B 2011, 157, 488− 493.

G

DOI: 10.1021/acsami.8b13635 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX