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Terminal Groups-Dependent Near-Field Enhancement Effect of Ti3C2Tx Nanosheets
Nanoscale Research Letters volume 16, Article number: 60 (2021)
Both multilayered (ML) and few-layered (FL) Ti3C2Tx nanosheets have been prepared through a typical etching and delaminating procedure. Various characterizations confirm that the dominant terminal groups on ML-Ti3C2Tx and FL-Ti3C2Tx are different, which have been assigned to O-related and hydroxyl groups, respectively. Such deviation of the dominant terminals results in the different physical and chemical performance and eventually makes the nanosheets have different potential applications. In particular, before coupling to Ag nanoparticles, ML-Ti3C2Tx can present stronger near-field enhancement effect; however, Ag/FL-Ti3C2Tx hybrid structure can confine stronger near-field due to the electron injection, which can be offered by the terminated hydroxyl groups.
Ti3C2Tx, a typical two-dimensional layered transition metal carbide with a graphene-like structure, has attracted great attention due to its wide potential applications in fields of catalysis, energy, and medicine thanks to its unique properties, especially large specific surface area and so on [1,2,3,4,5,6]. It has been demonstrated that the physical and chemical performance of Ti3C2Tx could be determined by its terminal groups, referred as Tx in the formula (usually are –F, –O and/or –OH), which can be adjusted by choosing different preparation procedures [7, 8]. For example, some experimental results indicate that the hydrophilic hydrophobic equilibrium of Ti3C2Tx can be modulated by interacting some agent groups with –O terminal groups on Ti3C2Tx , and the Pb adsorption capacity can be improved by connecting with hydroxyl groups on Ti3C2Tx . In the meantime, some theoretical works have determined that the attached methoxy groups could improve the stability of Ti2C and Ti3C2 , and O-related terminal groups could enhance the lithium ion storage capacity of various nanosheets . Apart from the multifarious applications by taking advantage of the unique layered structure with certain terminal groups, it is found that Ti3C2Tx can present plasmonic performance as well, and the resonance wavelength can be tuned by the terminals and/or thickness , indicating that Ti3C2Tx could confine electromagnetic field under excitation and eventually can be employed as broadband perfect absorbers [14, 15], Terahertz shielding devices , and photonic and/or molecular detectors or sensors [17,18,19]. However, most of previous works either concerned the etching condition dependent terminal groups  or focused on the overall plasmonic performance . Therefore, it is interesting to systematically study the relationship between the terminal groups of Ti3C2Tx with different layers and their near-field enhancement effect, since such effect has been widely employed in many optical related fields, such as surface-enhanced Raman scattering detection, due to the strong confined electromagnetic field [22,23,24].
In this work, in order to simplify the terminal options and avoid using hazardous HF, the mixed etching agent of LiF and HCl has been used to minimize the fluorine terminals (–F) in the etching process . Furthermore, the procedure of sonication in water has been carried out to delaminate the multilayered Ti3C2Tx (ML-Ti3C2Tx) into few-layered Ti3C2Tx (FL-Ti3C2Tx) without introducing any other reagents. As a result, the obtained Ti3C2Tx with different layers in this work will be mainly terminated by either O- or OH-related groups, which make ML-Ti3C2Tx or FL-Ti3C2Tx nanosheets reveal different physical and chemical properties and eventually present different near-filed enhancement performance. In addition, the hybrid structures composed of Ti3C2Tx and Ag nanoparticles have been prepared and the corresponding coupling effects have been explored as well. Such exploration regarding terminal dependent plasmonic performance of these Ti3C2Tx with different layers and configurations could help people to select suitable Ti3C2Tx-based materials in some specific optical fields.
Preparation of Ti3C2Tx Nanosheets
ML-Ti3C2Tx was prepared by following a modified previously reported method . The typical etching process started with the preparation of LiF solution by dissolving 1 g of LiF in 20 mL of dilute HCl solution (6 M) with stirring. Subsequently, 1 g of Ti3AlC2 powder was slowly added into the above solution, and the etching process was kept at 70 °C for 45 h under stirring. The wet sediment was then washed several times with deionized water until the pH of the suspension liquid was bigger than 6. Afterward, the suspension was collected and named as ML-Ti3C2Tx. To obtain FL-Ti3C2Tx, ML-Ti3C2Tx was further delaminated by sonication for 2 h in Ar atmosphere and followed by centrifugation at 3500 rpm for 1 h.
Preparation of Ag/Ti3C2Tx Nanocomposites
The synthesis of the hybrid materials was started with the preparation of the mixed solution of AgNO3 (12.5 mL, 2 mmol/L) and NaC6H5O7 (12.5 mL, 4 mmol/L) at room temperature. After rapidly adding PVP solution (25 mL, 0.1 g/mL), Ti3C2Tx solution (5 mL, 0.05 mg/mL) was then slowly added into the mixed solution with stirring for 10 min at room temperature. Subsequently, the above-mixed solution was heated up to 70 °C to react for 45 h. After centrifuging, the products were kept in water and named as Ag/ML-Ti3C2Tx and Ag/FL-Ti3C2Tx, respectively, according to the type of Ti3C2Tx used in the procedure.
A field emission scanning electron microscope (Carl ZEISS Sigma) and two transmission electron microscopes (JEM-2100F and JEM-1400Flash) have been employed to determine the morphologies of the samples. The X-ray diffraction (XRD) patterns in the range of 2θ = 5°–80° with a step of 0.02° were recorded on a powder diffractometer (X'Pert PRO MPD). Zeta potentials and surface states of ML-Ti3C2Tx and FL-Ti3C2Tx were measured by a Malvern Zetasizer (Nano-ZS90) and an X-ray photoelectron spectroscopy (XPS, ESCALAB 250Xi), respectively. The absorption and Raman performance of samples were recorded by a UV–Vis spectrophotometer (CARY 5000) and a Raman spectroscopy (LabRAM HR Evolution), respectively. The excitation wavelength of Raman detection was 532 nm, and the laser powers for usual Raman measurements and surface enhanced Raman scattering (SERS) characterizations were 12.5 mW and 0.05 mW, respectively.
Results and Discussion
Both morphologies of ML-Ti3C2Tx and FL-Ti3C2Tx are shown in Fig. 1a, b and c, d, respectively. It can be seen that FL-Ti3C2Tx looks more transparent, indicating that its layer number is much less than ML-Ti3C2Tx. Figure 1e shows the XRD patterns of all samples. Ti3AlC2 and ML-Ti3C2Tx show their typical phase features, which agree well with some previous reports [26,27,28]. It can be readily observed that the intense (002) peak of ML-Ti3C2Tx shifts to the lower angle comparing with that of Ti3AlC2, implying the removal of Al atoms from the MAX phase and the expanding along the c axis. Compared with the diffraction peaks of ML-Ti3C2Tx, both broadened (002) peak and disappeared (004) and (008) peaks of FL-Ti3C2Tx determined the successful preparation of the few-layered sample . Moreover, the (002) peak of FL-Ti3C2Tx locates at a little higher angle than that of ML-Ti3C2Tx, indicating that ML-Ti3C2Tx and FL-Ti3C2Tx should be terminated with different groups, which can be attributed to -O and -OH, respectively, since the as-prepared Ti3C2Tx (ML-Ti3C2Tx) will not be mainly terminated with -F without HF as etching agent and the corresponding c parameters attracted from the XRD patterns agree well with what previous works reported [25, 30].
Figure 2a shows Raman spectra of ML-Ti3C2Tx and FL-Ti3C2Tx. As it can be seen that the Raman signals in the range of 200–800 cm−1 for both samples are quite similar. Among them, the peak at 717 cm−1 is due to the A1g symmetrical out-of-plane vibration of Ti and C atoms, while the peaks at 244, 366 and 570 cm−1 are arising from the in-plane (shear) modes of Ti, C and surface terminal groups, respectively [31, 32]. As for the Raman signals ranging from 800 to 1800 cm−1, comparing with ML-Ti3C2Tx, FL-Ti3C2Tx not only shows stronger Raman signal at 1580 cm−1 (G band), but also presents two emerging Raman bands at 1000–1200 cm−1 and 1300 cm−1 (D band). Herein, the appearance of D band indicates that some Ti atoms have been peeled away and more C atoms are exposed to the surroundings . Therefore, the integrated Raman intensity of FL-Ti3C2Tx in this range is slightly larger than that of ML-Ti3C2Tx, implying that FL-Ti3C2Tx adsorbs more terminal groups. Zeta potentials of ML-Ti3C2Tx and FL-Ti3C2Tx are −4.38 and −26.9 mV, respectively, as shown in Additional file 1: Fig. S1, which further confirm that FL-Ti3C2Tx are terminated by more groups with negative charges.
The UV–Vis spectra shown in Fig. 2b reveal that both FL-Ti3C2Tx and ML-Ti3C2Tx present two dominant absorption bands. In the UV region (225–325 nm), FL-Ti3C2Tx displays relatively stronger absorption band which corresponds to the band gap transition , implying that there are more -OH groups have been terminated on FL-Ti3C2Tx . On the other hand, the comparison between the long wavelength absorption bands (600-1000 nm) of both samples shows that the relative intensity of FL-Ti3C2Tx in this range is obviously lower than that of ML-Ti3C2Tx, indicating that ML-Ti3C2Tx are mainly terminated by –O . FL-Ti3C2Tx can be well dispersed in the aqueous solution since the terminated –OH groups shows hydrophilicity and electrostatic repulsion between sheets [31, 36]. As for ML-Ti3C2Tx with more –O terminals, it can only form a suspension in the beginning and will deposit subsequently as shown in Additional file 1: Fig. S2a.
In order to shed more light on the surface groups terminated on ML-Ti3C2Tx and FL-Ti3C2Tx, XPS spectra of both samples were collected and are shown in Fig. 3. All corresponding detailed information regarding the surface states are summarized in Additional file 1: Table S1. The fraction of Ti-C in FL-Ti3C2Tx (9.80%) is lower than that in ML-Ti3C2Tx (17.31%), while the ratio of C–C in FL-Ti3C2Tx (44.62%) is higher. Such surface states changing evidences the loss of Ti atoms and the more exposed C atoms on the surface of FL-Ti3C2Tx, which agrees with the emerging D band in its Raman spectrum shown in Fig. 2a. The increased C-Ti-Tx ratio in FL-Ti3C2Tx (21.27%) indicates that there should be more active terminal groups adsorbed on its surface than ML-Ti3C2Tx, which agrees with the Zeta potential results shown in Additional file 1: Fig. S1. Apart from the quantity of the terminal groups, the analysis of XPS results also reveals that FL-Ti3C2Tx and ML-Ti3C2Tx have been terminated by different dominant functional groups, which also has been suggested by the (002) diffraction peaks shown in Fig. 1e. Regarding O 1 s spectra of these two samples, it can be clearly seen that more O-related states have been found on the surface of ML-Ti3C2Tx, and some of them are adsorbed oxygen molecules, which can dissociate to form Ti3C2Ox and therefore will repel O2 in air to prevent further oxidation of ML-Ti3C2Tx . As a result, ML-Ti3C2Tx seems present a better oxidation resistance with a lower TiO2 ratio (13.98%) than FL-Ti3C2Tx (19.60%).
Based on the observations and analyses of Figs. 1, 2 and 3, it can be concluded that although both ML-Ti3C2Tx and FL-Ti3C2Tx are terminated by some functional groups with negative charge, the amount and dominant type of the groups are quite different. On one hand, the quantity of terminal groups on FL-Ti3C2Tx is larger than that of ML-Ti3C2Tx. On the other hand, the dominant terminal structure on ML-Ti3C2Tx is Ti3C2O2, which makes ML-Ti3C2Tx to be more stable in the air , while for FL-Ti3C2Tx, it is mainly terminated by Ti3C2(OH)2, which helps FL-Ti3C2Tx to be well-dispersed in aqueous solutions .
Ti3C2Tx with functional terminal groups could reveal good adsorption performance and therefore could act as a surface-enhanced Raman scattering (SERS) substrate to improve the Raman activity of positively charged probe molecules [3, 39, 40]. Comparing with ML-Ti3C2Tx, FL-Ti3C2Tx should present better adsorption ability since it has been determined that it is terminated with more negative charges. Such better adsorption performance has been demonstrated by the optical photographs of the mixed solution with R6G and FL-Ti3C2Tx as shown in Additional file 1: Fig. S2b. However, Fig. 4a reveals that the ML-Ti3C2Tx substrate obviously performs better SERS activity than FL-Ti3C2Tx one. Considering ML-Ti3C2Tx with –O terminal presents stronger absorption band centered at around 800 nm, which can be assigned to the surface plasmon resonant absorption [3, 15, 39, 41], it therefore can be concluded that ML-Ti3C2Tx with stronger SERS activity should result from the stronger near-field effect induced by the relatively stronger surface plasmon resonance as shown in Fig. 2b.
In order to further explore the relationship between the terminal groups and the near-filed effect of Ti3C2Tx nanosheets, the hybrid structures composed of Ti3C2Tx nanosheets, including few layered and multilayered, and Ag nanoparticles (NPs) have been synthesized, which are accordingly labeled as Ag/FL-Ti3C2Tx and Ag/ML-Ti3C2Tx, respectively. The morphologies of both hybrid samples are shown in Additional file 1: Fig. S3. The insets indicate the corresponding size distributions of Ag NPs loading on ML-Ti3C2Tx (5–40 nm) is larger than that on FL-Ti3C2Tx (2–20 nm). Intuitively, it might be concluded that Ag/ML-Ti3C2Tx could perform better SERS activity than Ag/FL-Ti3C2Tx since both larger Ag NPs and relative stronger surface plasmon resonance of ML-Ti3C2Tx are beneficial to confine stronger near-field. However, the SERS spectra shown in Fig. 4b reveal a counterintuitive result. It is clear that the enhancement effect offered by Ag/FL-Ti3C2Tx is nearly 3 times of that by Ag/ML-Ti3C2Tx, implying that the coupling between Ag NPs and FL-Ti3C2Tx should play an important role during the detection process. As confirmed above that FL-Ti3C2Tx has been mainly terminated by -OH groups with lots of surface electrons, which will result in the formation of Ti3C2(OH)2 structure with a work function of 1.6–2.8 eV [42, 43]. As shown in Fig. 4c, the abundant surface electrons will therefore transfer from FL-Ti3C2Tx to Ag NPs with a work function of 4.7 eV . With the extra injection of hot electrons from FL-Ti3C2Tx, Ag NPs with smaller size could present stronger resonance under the excitation and eventually perform better SERS activity due to the coupling induced stronger electromagnetic effect. It is worth noting that the work function of Ti3C2O2 structure formed on the surface of ML-Ti3C2Tx is around 6.0 eV , which will result in electron transfer from Ag NPs surface to ML-Ti3C2Tx nanosheets and therefore will weaken the near-field enhanced effect supported by the Ag NPs. On the other hand, not like FL-Ti3C2Tx with -OH terminals, ML-Ti3C2Tx with -O terminals cannot offer sufficient electrons under excitation . It is therefore reasonable that the SERS activity of Ag/ML-Ti3C2Tx is worse than that of Ag/ FL-Ti3C2Tx.
In summary, ML-Ti3C2Tx and FL-Ti3C2Tx terminated with different dominant functional groups have been successfully prepared. It has been demonstrated that ML-Ti3C2Tx is more stable in the air due to the surface structure of Ti3C2O2 and show stronger SERS activity than FL-Ti3C2Tx because it can reveal stronger near-field effect. However, FL-Ti3C2Tx terminated by Ti3C2(OH)2 can be well dispersed in aqueous solution and will show better SERS performance after coupling to the Ag NPs due to the sufficient electron injection. Such research regarding the terminal groups-dependent near-field enhancement performance will help people to expand the potential applications of Ti3C2Tx in the optical related fields.
Availability of data and materials
The raw dataset obtained analyzed during the experimental work is avaiable from the corresponding author on reasonable request.
- ML-Ti3C2Tx :
- FL-Ti3C2Tx :
Few layered Ti3C2Tx
Surface enhanced Raman scattering
Hong Ng VM, Huang H, Zhou K, Lee PS, Que W, Xu JZ, Kong LB (2017) Recent progress in layered transition metal carbides and/or nitrides (MXenes) and their composites: synthesis and applications. J Mater Chem A 5:3039–3068
Cheng L, Li X, Zhang H, Xiang Q (2019) Two-dimensional transition metal MXene-based photocatalysts for solar fuel generation. J Phys Chem Lett 10:3488–3494
Xiong D, Li X, Bai Z, Lu S (2018) Recent advances in layered Ti3C2Tx MXene for electrochemical energy storage. Small 14:1703419
Yang J, Bao W, Jaumaux P, Zhang S, Wang C, Wang G (2019) MXene-based composites: synthesis and applications in rechargeable batteries and supercapacitors. Adv Mater Interfaces 6:1802004
Jiang X, Kuklin AV, Baev A, Ge Y, Ågren H, Zhang H, Prasad PN (2020) Two-dimensional MXenes: from morphological to optical, electric, and magnetic properties and applications. Phys Rep 848:1–58
Huang K, Li Z, Lin J, Han G, Huang P (2018) Two-dimensional transition metal carbides and nitrides (MXenes) for biomedical applications. Chem Soc Rev 47:5109–5124
Li T, Yao L, Liu Q, Gu J, Luo R, Li J, Yan X, Wang W, Liu P, Chen B et al (2018) Fluorine-free synthesis of high purity Ti3C2Tx (T= –OH, –O) via alkali treatment. Angew Chem Int Ed 57:6115–6119
Li M, Lu J, Luo K, Li Y, Chang K, Chen K, Zhou J, Rosen J, Hultman L, Eklund P et al (2019) Element replacement approach by reaction with Lewis acidic molten salts to synthesize nanolaminated MAX phases and MXenes. J Am Chem Soc 141:4730–4737
Bian R, Lin R, Wang G, Lu G, Zhi W, Xiang S, Wang T, Clegg PS, Cai D, Huang W (2018) 3D assembly of Ti3C2-MXene directed by water/oil interfaces. Nanoscale 10:3621–3625
Peng Q, Guo J, Zhang Q, Xiang J, Liu B, Zhou A, Liu R, Tian Y (2014) Unique lead adsorption behavior of activated hydroxyl group in two-dimensional titanium carbide. J Am Chem Soc 136:4113–4116
Enyashin AN, Ivanovskii AL (2013) Structural and electronic properties and stability of MXenes Ti2C and Ti3C2 functionalized by methoxy groups. J Phys Chem C 117:13637–13643
Xie Y, Naguib M, Mochalin VN, Barsoum MW, Gogotsi Y, Yu X, Nam K-W, Yang X-Q, Kolesnikov AI, Kent PRC (2014) Role of surface structure on Li-ion energy storage capacity of two dimensional transition-metal carbides. J Am Chem Soc 136:6385–6394
Mauchamp V, Bugnet M, Bellido EP, Botton GA, Moreau P, Magne D, Naguib M, Cabioc’h T, Barsoum MW (2014) Enhanced and tunable surface plasmons in two-dimensional Ti3C2 stacks: electronic structure versus boundary effects. Phys. Rev. B 89: 235428
Jhon YI, Jhon YM, Lee JH (2020) Broadband ultrafast photonics of two-dimensional transition metal carbides (MXenes). Nano Futures 4:032003
Chaudhuri K, Alhabeb M, Wang Z, Shalaev VM, Gogotsi Y, Boltasseva A (2018) Highly broadband absorber using plasmonic titanium carbide (MXene). ACS Photonics 5:1115–1122
Choi G, Shahzad F, Bahk Y-M, Jhon YM, Park H, Alhabeb M, Anasori B, Kim D-S, Koo CM, Gogotsi Y et al (2018) Enhanced Terahertz shielding of MXenes with nano-metamaterials. Adv Opt Mater 6:1701076
Velusamy DB, El‐Demellawi JK, El‐Zohry AM, Giugni A, Lopatin S, Hedhili MN, Mansour AE, Fabrizio ED, Mohammed OF, Alshareef HN (2019) MXenes for plasmonic photodetection. Adv Mater 31:1807658
Peng Y, Cai P, Yang L, Liu Y, Zhu L, Zhang Q, Liu J, Huang Z, Yang Y (2020) Theoretical and experimental studies of Ti3C2 MXene for surface-enhanced Raman spectroscopy-based sensing. ACS Omega 5:26486–26496
Yu M, Liu S, Su D, Jiang S, Zhang G, Qin Y, Li M-Y (2019) Controllable MXene nano-sheet/Au nanostructure architectures for the ultra-sensitive molecule Raman detection. Nanoscale 11:22230–22236
Benchakar M, Loupias L, Garnero C, Bilyk T, Morais C, Canaff C, Guignard N, Morisset S, Pazniak H, Hurand S et al (2020) One MAX phase, different MXenes: a guideline to understand the crucial role of etching conditions on Ti3C2Tx surface chemistry. Appl Surf Sci 530:147209
Ding S-Y, You E-M, Tian Z-Q, Moskovits M (2017) Electromagnetic theories of surface-enhanced Raman spectroscopy. Chem Soc Rev 46:4042–4076
Hantanasirisakul K, Gogotsi Y (2018) Electronic and optical properties of 2D transition metal carbides and nitrides (MXenes). Adv Mater 30:1804779
Fan X, Ding Y, Liu Y, Liang J, Chen Y (2019) Plasmonic Ti3C2Tx MXene enables highly efficient photothermal conversion for healable and transparent wearable device. ACS Nano 13:8124–8134
Peng Y, Lin C, Long L, Masaki T, Tang M, Yang L, Liu J, Huang Z, Li Z, Luo X et al (2021) Charge-transfer resonance and electromagnetic enhancement synergistically enabling MXenes with excellent SERS sensitivity for SARS-CoV-2 S protein detection. Nano-Micro Lett 13:52
Hope MA, Forse AC, Griffith KJ, Lukatskaya MR, Ghidiu M, Gogotsi Y, Grey CP (2016) NMR reveals the surface functionalisation of Ti3C2 MXene. Phys Chem Chem Phys 18:5099–5102
Ghidiu M, Lukatskaya MR, Zhao M-Q, Gogotsi Y, Barsoum MW (2014) Conductive two-dimensional titanium carbide ‘clay’ with high volumetric capacitance. Nature 516:78–81
Peng C, Wang C-A, Song Y, Huang Y (2006) A novel simple method to stably synthesize Ti3AlC2 powder with high purity. Mater Sci Eng A 428:54–58
Mashtalir O, Naguib M, Mochalin VN, Dall’Agnese Y, Heon M, Barsoum MW, Gogotsi Y (2013) Intercalation and delamination of layered carbides and carbonitrides. Nat Commum 4:1–7
Xuan J, Wang Z, Chen Y, Liang D, Cheng L, Yang X, Liu Z, Ma R, Sasaki T, Geng F (2016) Organic-base-driven intercalation and delamination for the production of functionalized titanium carbide nanosheets with superior photothermal therapeutic performance. Angew Chem Int Ed 55:14569–14574
Naguib M, Kurtoglu M, Presser V, Lu J, Niu J, Heon M, Hultman L, Gogotsi Y, Barsoum MW (2011) Two-dimensional nanocrystals produced by exfoliation of Ti3AlC2. Adv Mater 23:4248–4253
Yan J, Ren CE, Maleski K, Hatter CB, Anasori B, Urbankowski P, Sarycheva A, Gogotsi Y (2017) Flexible MXene/graphene films for ultrafast supercapacitors with outstanding volumetric capacitance. Adv Funct Mater 27:1701264
Hu T, Wang J, Zhang H, Li Z, Hu M, Wang X (2015) Vibrational properties of Ti3C2 and Ti3C2T2 (T = O, F, OH) monosheets by first-principles calculations: a comparative study. Phys Chem Chem Phys 17:9997–10003
Tong Y, He M, Zhou Y, Zhong X, Fan L, Huang T, Liao Q, Wang Y (2018) Electromagnetic wave absorption properties in the centimetre-band of Ti3C2Tx MXenes with diverse etching time. J Mater Sci-Mater El 29:8078–8088
Satheeshkumar E, Makaryan T, Melikyan A, Minassian H, Gogotsi Y, Yoshimura M (2016) One-step solution processing of Ag, Au and Pd@MXene hybrids for SERS. Sci Rep 6:32049
Berdiyorov GR (2016) Optical properties of functionalized Ti3C2T2 (T = F, O, OH) MXene: first-principles calculations. AIP Adv 6:055105
Lukatskaya MR, Mashtalir O, Ren CE, Dall’Agnese Y, Rozier P, Taberna PL, Naguib M, Simon P, Barsoum MW, Gogotsi Y (2013) Cation intercalation and high volumetric capacitance of two-dimensional titanium carbide. Science 341:1502–1505
Gan L-Y, Huang D, Schwingenschlögl U (2013) Oxygen adsorption and dissociation during the oxidation of monolayer Ti2C. J Mater Chem A 1:13672–13678
Fu ZH, Zhang QF, Legut D, Si C, Germann TC, Lookman T, Du SY, Francisco JS, Zhang RF (2016) Stabilization and strengthening effects of functional groups in two-dimensional titanium carbide. Phys Rev B 94:104103
Sarycheva A, Makaryan T, Maleski K, Satheeshkumar E, Melikyan A, Minassian H, Yoshimura M, Gogotsi Y (2017) Two-dimensional titanium carbide (MXene) as surface-enhanced Raman scattering substrate. J Phys Chem C 121:19983–19988
Guo J, Peng Q, Fu H, Zou G, Zhang Q (2015) Heavy-metal adsorption behavior of two-dimensional alkalization intercalated MXene by first-principles calculations. J Phys Chem C 119:20923–20930
Lin H, Wang X, Yu L, Chen Y, Shi J (2017) Two-dimensional ultrathin MXene ceramic nanosheets for photothermal conversion. Nano Lett 17:384–391
Khazaei M, Ranjbar A, Ghorbani-Asl M, Arai M, Sasaki T, Liang Y, Yunoki S (2016) Nearly free electron states in MXenes. Phys Rev B 93:205125
Chertopalov S, Mochalin VN (2018) Environment-sensitive photoresponse of spontaneously partially oxidized Ti3C2 MXene thin films. ACS Nano 12:6109–6116
Lu Y-W, Hu Y, Huang C, Cheng S, Xu C-X, Luo P-F, Cheng J-G, Jang Y (2016) Enhanced plasmon radiative intensity from Ag nanoparticles coupled to a graphene sheet. Appl Phys Lett 108:153113
This work was financially supported by the National Natural Science Foundation of China (61675061 and 11774077), the Fundamental Research Funds for the Central Universities (PA2019GDQT0013), and the Provincial Innovation and Entrepreneurship Training Program for College Students (S201910359033).
This work is supported by the National Natural Science Foundation of China (61675061 and 11774077), the Fundamental Research Funds for the Central Universities (PA2019GDQT0013), and the Provincial Innovation and Entrepreneurship Training Program for College Students (S201910359033).
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Figure S1. Zeta potentials of ML-Ti3C2Tx and FL-Ti3C2Tx. Figure S2. (a) Optical photographs of ML-Ti3C2Tx and FL-Ti3C2Tx. (b) Optical photographs of ML-Ti3C2Tx and FL-Ti3C2Tx soaking in R6G solutions. Figure S3. TEM images of (a) Ag/ML-Ti3C2Tx and (b) Ag/FL-Ti3C2Tx. The insets are the size distributions of Ag NPs in the corresponding samples. Table S1. Surface states and corresponding relative contents extracted from the XPS Ti 2p, C 1s and O 1s spectra of ML-Ti3C2Tx and FL-Ti3C2Tx.
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Yang, YY., Zhou, WT., Song, WL. et al. Terminal Groups-Dependent Near-Field Enhancement Effect of Ti3C2Tx Nanosheets. Nanoscale Res Lett 16, 60 (2021). https://doi.org/10.1186/s11671-021-03510-5
- Multilayered Ti3C2Tx
- Few-layered Ti3C2Tx
- Terminal group
- Near-field enhancement