The construction of a heterostructured RGO/g-C₃N₄/LaCO₃OH composite with enhanced visible light photocatalytic activity for MO degradation

Abstract

The construction of a heterojunction and the introduction of a cocatalyst can both promote the transfer of photogenerated electrons, which are effective strategies to enhance photocatalytic efficiency. In this paper, a ternary RGO/g-C₃N₄/LaCO₃OH composite was synthesized by constructing a g-C₃N₄/LaCO₃OH heterojunction and introducing a non-noble metal cocatalyst RGO through hydrothermal reactions. TEM, XRD, XPS, UV-vis diffuse reflectance spectroscopy, photo-electrochemistry and PL tests were carried out to characterize the structures, morphologies and carrier separation efficiencies of products. Benefiting from the boosted visible light absorption capability, reduced charge transfer resistance and facilitated photogenerated carrier separation, the visible light photocatalytic activity of the ternary RGO/g-C₃N₄/LaCO₃OH composite was effectively improved, resulting in a much increased MO (methyl orange) degradation rate of 0.0326 min⁻¹ compared with LaCO₃OH (0.0003 min⁻¹) and g-C₃N₄ (0.0083 min⁻¹). Moreover, by combining the results of the active species trapping experiment with the bandgap structure of each component, the mechanism of the MO photodegradation process was proposed.

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1. Introduction

Environmental pollution is one of the main challenges for the rapid development of a green economy.¹ Photocatalysis based on semiconductors is considered as a promising technology with wide application prospects to address environmental problems.² However the development of photocatalysts with low cost, high stability and efficiency remains a challenge.³ Though rare earth-based materials including YVO₄,⁴ CeO₂ (ref. 5) and LaCO₃OH⁶ have attracted wide attention in photocatalysis, their application is still limited because of their large bandgaps, leading to a poor ability in visible light absorption.⁷ The construction of heterojunctions,^8,9 the introduction of cocatalysts¹⁰ and elemental doping¹¹ are effective strategies to decrease the bandgaps of rare earth photocatalysts and hence improve the utilization efficiency of visible light and accelerate the kinetics of photocatalytic process.

LaCO₃OH is a rare earth hydroxyl carbonate with an excellent luminescence property, showing a great potential in photocatalytic pollutants degradation and H₂ evolution.^12,13 LaCO₃OH has a relatively broad bandgap of 4.0 eV, which could inhibit the recombination of photogenerated carriers.¹⁴ On the other side, as a result of the broad bandgap, it can only absorb ultraviolet light in photocatalytic reactions. Based on recent research, the visible light absorption capability of LaCO₃OH can be boosted by constructing heterojunction.¹⁵ Under visible light irradiation, pure LaCO₃OH showed a negligible photocatalytic activity, while heterostructured g-C₃N₄/LaCO₃OH synthesized through a one-step hydrothermal reaction exhibited a substantially enhanced NO removal ratio of 30.3% after 30 min.¹⁶ g-C₃N₄, a kind of semiconductor photocatalyst, has drawn wide attention in vast fields because of its visible light response and layered structure, which can provide rich surface chemistry and shorten the electron transfer pathways.¹⁷ While there are only few reports about g-C₃N₄/LaCO₃OH heterojunction as the catalyst for the photodegradation of organic dyes at present. Wang et al.¹³ synthesized a g-C₃N₄/LaCO₃OH heterostructure for photocatalytic NO removal, which showed an improved NO removal ratio of 30.3% compared with pristine g-C₃N₄ (19.3%) after 30 min visible light irradiation. Similar composite also shown considerable improvement in N₂ photofixation (8.2 mM g⁻¹ h⁻¹) compared to g-C₃N₄ (2.1 mM g⁻¹ h⁻¹).¹⁸ While there is still no report about the application of g-C₃N₄/LaCO₃OH heterojunction in the photodegradation of dyes. The introduction of cocatalyst such as noble metal (Pt¹⁹ and Ag²⁰), non-noble metal (Ni²¹) and non-metal material such as graphene oxide (GO) can restrain the recombination of photogenerated carriers and enhance visible light absorption capacity.²² Among all these cocatalysts, GO has fascinating properties including good conductivity, high carrier mobility and large exposed specific surface, which can provide abundant active sites for the photocatalytic process.²³ Therefore, for the first time, we proposed to introduce reduced graphene oxide (RGO) into g-C₃N₄/LaCO₃OH heterojunction and result in a heterostructured ternary composite for photocatalytic degradation of the organic dye. Benefitting from the extended light absorption in visible light region along with accelerated separation kinetics of charge carriers, the constructed RGO/g-C₃N₄/LaCO₃OH composite can serve as the catalyst for the photodegradation of methyl orange (MO) under visible light irradiation with a superior performance than each component.

Herein, ternary composite RGO/g-C₃N₄/LaCO₃OH heterojunction was synthesized through hydrothermal reactions and its photocatalytic activity was evaluated by using it as the catalyst in the degradation of MO under visible light irradiation. The photocatalysis mechanism was investigated and the migration pathway of photogenerated carriers was proposed. This work is excepted to provide a novel strategy to enhance the photocatalytic activity of rare-earth based semiconductors with broad bandgaps for the photodegradation of organic dyes.

2. Experimental section

2.1 Materials

Analytical grade chemicals were used directly in the experiments. Graphite powder, K₂S₂O₈, H₂SO₄, HCl, KMnO₄ and BaCl₂ were purchased from Sinopharm, China. Urea, La(NO₃)₃·6H₂O and MO were provided by Aladdin, China.

g-C₃N₄ was synthesized through the method in the literature.²⁴ 10.0 g urea was calcined at 250 °C for 1 h, then 350 °C for 2 h and 550 °C for another 2 h in a tube furnace. The obtained pale yellow powder was washed with distilled water then dried at 60 °C for 12 h.

X wt% g-C₃N₄/LaCO₃OH (X represents the mass ratio of g-C₃N₄, X = 15.0, 25.0, 35.0) was synthesized through a hydrothermal reaction. For 15.0 wt% g-C₃N₄/LaCO₃OH, 50.0 mg g-C₃N₄ and 671.6 mg La(NO₃)₃·6H₂O were dispersed in 35 mL distilled water and stirred for 3 h. After adjusting pH to 8.0–8.5 using 0.1 M NaOH aqueous solution, the obtained suspension was transferred to 100 mL autoclave and heated at 160 °C for 6 h. After washed with distilled water for 3 times, the product was dried at 60 °C for 12 h. Pure LaCO₃OH was also produced via a reported method for comparison.¹⁴

RGO/g-C₃N₄/LaCO₃OH was obtained through a hydrothermal reaction using g-C₃N₄/LaCO₃OH and GO as raw materials, as shown in Scheme 1, and the latter was produced by the Hummers' method.¹⁰ For Y wt% RGO/g-C₃N₄/LaCO₃OH (Y represents the mass ratio of RGO, X = 0.6, 0.8, 1.0), 50.0 mg 25.0 wt% g-C₃N₄/LaCO₃OH was dispersed in 35.0 mL distilled water, in which 400.0 μL GO suspension (1.0 mg mL⁻¹) was added. The obtained mixture was heated at 160 °C for 6 h in an autoclave, and the product was washed and dried in the same way as the synthesis of g-C₃N₄/LaCO₃OH sample.

Scheme 1 The schematic fabrication process of RGO/g-C₃N₄/LaCO₃OH composite.

2.2 Characterization

An X-ray diffractometer (XRD, Bruker D8 Advance) with Cu Kα radiation was used to characterize the products' structures. X-ray photoelectron spectroscopy (XPS) was performed on Thermal ESCALAB 250Xi. The morphologies, microstructures, elemental mappings and the corresponding energy-dispersive X-ray spectroscopy (EDS) of the products were recorded by transmission electron microscopy (TEM, JEOL JEM 2010 EX). UV-vis diffuse reflectance spectra were tested on a Shimadzu UV-2500 spectrophotometer using BaSO₄ as the reference. Photoluminescence spectra (PL) were characterized by a F4500 Hitachi spectrophotometer with an excitation wavelength of 330 nm. The photoelectrochemical performance and electrochemical impedance spectroscopy (EIS) of the products were performed on a CHI 660E workstation using a three electrode system in 0.2 M Na₂SO₄ aqueous solution. The counter electrode was Pt wire and the reference electrode was saturated calomel electrode. For the working electrode, 10 mg product was dispersed in 1.0 mL ethanol and the suspension was dropped on fluorine-doped tin oxide (FTO) glass.

2.3 Photocatalytic tests

Photocatalytic performances of the obtained products were evaluated through the degradation of MO under visible light irradiation (λ > 420 nm), which was provided by a Xe lamp with a filter. The photograph of the lamp and the transmission spectrum of the filtered light were shown in Fig. S1.† 10 mg sample and 20 mL MO solution (10 mg L⁻¹) was added in to a quartz reactor, whose temperature was maintained at 30 °C. After stirring in darkness for 1 h to establish the adsorption–desorption equilibrium, the suspension was exposed in visible light. The concentrations of MO under different irritation times were then calculated based on the intensities of the peak at 465 nm in UV-vis spectra.

3. Results and discussion

As shown in Scheme 1, ternary RGO/g-C₃N₄/LaCO₃OH heterojunction was synthesized through a two-step hydrothermal process. It can be observed in Fig. 1A that the synthesized g-C₃N₄ composes of 2D nanosheets with smooth and uniform surface. g-C₃N₄/LaCO₃OH heterojunction was fabricated by the in situ growth of LaCO₃OH on the surface of g-C₃N₄ via the hydrothermal reaction. In this process, g-C₃N₄ served as a self-sacrificial agent to produce CO₃²⁻ and OH⁻ due to the weaker binding energy of C chain. Then La³⁺ ions adsorbed on g-C₃N₄ reacted with the generated CO₃²⁻ and OH⁻ to produced LaCO₃OH, resulting in the in situ construction of g-C₃N₄/LaCO₃OH heterojunction.^13,18 The TEM image (Fig. 1B) shows that LaCO₃OH nanoparticles with diameters of 20–50 nm are evenly dispersed on g-C₃N₄. Then RGO was further introduced as the cocatalyst to obtain ternary RGO/g-C₃N₄/LaCO₃OH (Fig. 1C). In the high-resolution TEM image, the heterostructure interface between the (3 0 0) plane of LaCO₃OH and (0 0 2) plane of g-C₃N₄ can be clearly observed (Fig. 1D), suggesting the construction of g-C₃N₄/LaCO₃OH heterojunction. The scanning TEM image, corresponding elemental mappings and EDS spectrum (Fig. 1E–G) verify that RGO/g-C₃N₄/LaCO₃OH are composed of La, C, O and N element, and La mainly distributed in the nanoparticles, which is consistent with the TEM results. The XRD patterns of LaCO₃OH, g-C₃N₄, g-C₃N₄/LaCO₃OH and RGO/g-C₃N₄/LaCO₃OH are shown in Fig. 1H. For the synthesized LaCO₃OH, its XRD pattern agrees well with hexagonal LaCO₃OH (JCPDS No. 49-0981).¹⁴ In the XRD pattern of g-C₃N₄, two typical peaks at 13.20° and 27.54° are corresponding to the (1 0 0) and (0 0 2) plane, respectively.¹⁶ The typical peaks of both LaCO₃OH and g-C₃N₄ can be observed in the g-C₃N₄/LaCO₃OH and RGO/g-C₃N₄/LaCO₃OH composite with good crystallinities, indicating that the crystal structures of these two components were maintained during the hydrothermal processes. With the introduction of RGO, the (0 0 2) peak of g-C₃N₄ broaden because of the interlayer stacking between 2D RGO and g-C₃N₄ sheets.²⁵ All the above results clarified that ternary RGO/g-C₃N₄/LaCO₃OH heterojunction was successfully constructed.

Fig. 1 TEM images of (A) g-C₃N₄, (B) g-C₃N₄/LaCO₃OH and (C) RGO/g-C₃N₄/LaCO₃OH; a high-resolution TEM image (D), a scanning TEM image (E), the corresponding elemental mappings (F) and the EDS spectrum (G) of RGO/g-C₃N₄/LaCO₃OH; (H) XRD patterns of LaCO₃OH, g-C₃N₄, g-C₃N₄/LaCO₃OH and RGO/g-C₃N₄/LaCO₃OH.

XPS spectra are used to further study the constitution and surface chemical states of the products. In the survey spectrum of RGO/g-C₃N₄/LaCO₃OH (Fig. 2A), La, C, O and N elements can be identified, which is in accordance with the results of EDS. As shown in Fig. 2B, the spectrum of La 3d can be divided into two pairs of peaks. Peaks at 851.9 and 835.1 eV can be assigned to La 3d_3/2 and 3d_5/2 of La³⁺, respectively, and peaks at 855.5 and 838.5 eV are two corresponding shakeup satellite peaks.¹⁴ C 1s spectrum of RGO/g-C₃N₄/LaCO₃OH can be fitted into five peaks considering three different sources (Fig. 2C). Peaks at 286.4, 285.1 and 286.4 eV can be indexed to O–C–O, C–OH and C–C in RGO, respectively. Peaks at 289.2 and 288.3 eV stem from CO₃²⁻ in LaCO₃OH and N–C=N in g-C₃N₄, respectively. Compared with g-C₃N₄, the binding energy of N–C=N in RGO/g-C₃N₄/LaCO₃OH increased by 0.3 eV because of the electron transfer at the interfaces of the composite.⁶ For N 1s spectrum, peaks at 400.8, 399.4 and 398.5 eV are attributed to C–N–H (or C–NH₂), N–C and N=C–N in g-C₃N₄, respectively (Fig. 2D).¹⁷ The groups such as –OH and –NH₂ can provide abundant active sites for the photodegradation of MO.

Fig. 2 XPS spectra of RGO/g-C₃N₄/LaCO₃OH: (A) the survey spectrum compared with g-C₃N₄ and LaCO₃OH; (B) La 3d spectrum compared with LaCO₃OH; (C) C 1s spectrum and (D) N 1s spectrum compared with g-C₃N₄.

UV-vis spectra of LaCO₃OH and g-C₃N₄ were measured to evaluate their band gap structures (Fig. 3A). The light absorption edge of g-C₃N₄ is 460 nm, indicating its small bandgap and good response to the visible light. While LaCO₃OH exhibits a light absorption edge of 300 nm, demonstrating its large bandgap along with poor visible light absorption capability. For g-C₃N₄/LaCO₃OH and RGO/g-C₃N₄/LaCO₃OH, light absorption edges are located at 475 and 500 nm respectively, indicating the improved visible light absorption capability benefiting from the construction of heterojunction and the introduction of cocatalyst RGO. The band gaps E_g (eV) of LaCO₃OH and g-C₃N₄ can be calculated based on the Kubelka–Munk function:

αħv = A(ħv − E_g)^n/2 (1)

where A, v, ħ and α are constant, light frequency, Plank's constant and the absorption coefficient, respectively. For semiconductors such as g-C₃N₄ and LaCO₃OH, n = 4.²⁴ The calculated E_g for LaCO₃OH and g-C₃N₄ are 2.75 and 4.02 eV, respectively (Fig. 3B). According to the results of XPS spectra, the valence band (VB) potentials (E_VB) of LaCO₃OH and g-C₃N₄ can also be calculated. As shown in Fig. 3C and D, the results are 3.55 and 1.58 eV, respectively. The conduction band (CB) potentials (E_CB) can be calculated by the equation:

E_CB = E_CB − E_g (2)

The calculated E_CB of LaCO₃OH and g-C₃N₄ are 0.47 and −1.17 eV, respectively.

Fig. 3 (A) The UV-vis spectra of LaCO₃OH, g-C₃N₄, g-C₃N₄/LaCO₃OH and RGO/g-C₃N₄/LaCO₃OH; (B) the bandgap energy diagram and the valence band (XPS) spectra of the (C) LaCO₃OH and (D) g-C₃N₄.

The photocatalytic performance of the obtained heterostructured products were assessed by the photodegradation of MO under the visible light irradiation. After 50 min, the degradation of MO without catalysts is negligible, as shown in Fig. 4A. For pure LaCO₃OH, the photodegradation activity is low with a MO removal ratio of only 6.8% after 50 min because of its poor visible light absorption capability, which is proved by its UV-vis spectrum. Constructing g-C₃N₄/LaCO₃OH heterojunction can significantly improve the MO removal ratio. Among the composites with different mass ratios of g-C₃N₄, 25% g-C₃N₄/LaCO₃OH exhibited the highest activity with a calculated photodegradation rate constant of 0.0150 min⁻¹ (Fig. 4B), which is 50.0 and 1.8 times higher than LaCO₃OH and g-C₃N₄ respectively. Such results confirmed that the construction of heterojunction could be conducive to the improvement of photocatalytic activity compared with each component.

Fig. 4 (A) The activities of the MO photodegradation using RGO, g-C₃N₄, LaCO₃OH and g-C₃N₄/LaCO₃OH with different ratios of g-C₃N₄ as catalysts during 50 min and (B) the corresponding photodegradation rate constants; (C) the activities of the MO photodegradation using RGO and RGO/g-C₃N₄/LaCO₃OH with different ratios of RGO as catalysts during 50 min and (D) the corresponding photodegradation rate constants; (E) the cyclic tests and (F) activities of the MO photodegradation in the presence of three scavengers of 0.8% RGO/g-C₃N₄/LaCO₃OH.

Whereas, though the MO removal ratio has been effectively improved, the photodegradation of MO only 51.2%. To further improve the activity of the photocatalyst and shorten the reaction time, RGO was introduced into the composite as the cocatalyst. Photocatalytic performances of ternary RGO/g-C₃N₄/LaCO₃OH composite with different mass ratios of RGO is shown in Fig. 4C. Though RGO itself shows no activity in the photodegradation of MO as expected, the introduction of RGO into 25% g-C₃N₄/LaCO₃OH can still further enhance its photocatalytic performance. When the reaction time decreased to 50 min, the MO removal ratio of 0.8% RGO/g-C₃N₄/LaCO₃OH can be remarkably improved to 84.5%, which is the highest among ternary composites with different mass ratios, and is much improved compared with 25% g-C₃N₄/LaCO₃OH (51.2%). The corresponding photodegradation rate constant of 0.8% RGO/g-C₃N₄/LaCO₃OH is 0.0326 min⁻¹, which is 2.17 times higher than that of 25% g-C₃N₄/LaCO₃OH (Fig. 4D). Such improvement arises from the introduction of cocatalyst RGO, which can serve as the transfer medium for the photogenerated carriers, thus can accelerate their transfer kinetics and restrain their recombination, leading to an increased rate of photocatalytic reaction.

The high stability of ternary RGO/g-C₃N₄/LaCO₃OH composite was clarified by the cycling test carried out using 0.8% RGO/g-C₃N₄/LaCO₃OH as the catalyst. As shown in Fig. 4E, the rate constant remains basically stable during 20 cycles. The slight decrease was generated by the sample loss during the washing and drying process after each cycle. TEM images shows that after the long-time cycling, there is no obvious change in the microstructure of the RGO/g-C₃N₄/LaCO₃OH composite, confirming its high structural stability (Fig. S2†). Moreover, the active species trapping experiment was taken to analyze the active species during the photocatalytic degradation process (Fig. 4F). There is no significant change on MO removal ratio with the existence of t-BuOH, demonstrating that ˙OH radical does not involved in the photodegradation reaction. While with the addition of 1,4-benzoquinone (BQ) and Na₂EDTA, the MO removal ratio declined from 84.5% to 45.6% and 52.9% respectively, indicating that both active species ˙O₂⁻ and h⁺ play a critical role in the photodegradation process. The above characterizations show that compared with single components, RGO/g-C₃N₄/LaCO₃OH exhibits an enhanced photocatalytic activity for MO degradation, which is owing to the construction of heterojunction and the introduction of cocatalyst RGO.

More photoelectrochemical characterizations including EIS tests, transient photocurrent responses and PL spectroscopy were performed to study the separation efficiency of photogenerated charge carriers. The Nyquist plots (Fig. 5A) demonstrates that 0.8% RGO/g-C₃N₄/LaCO₃OH has the smallest semicircle radius in the high-frequency region compared with that of g-C₃N₄/LaCO₃OH, g-C₃N₄ and LaCO₃OH, indicating its lowest charge transfer resistance benefited from the construction of the heterojunction and the introduction of RGO, leading to the highest separation efficiency of photogenerated electron–hole pairs.²⁶ Transient photocurrent curves during five on/off cycles are shown in Fig. 5B. 0.8% RGO/g-C₃N₄/LaCO₃OH generates a stable and highest photocurrent of 1.52 μA cm⁻², which is 1.78 and 4 times higher compared with 25% g-C₃N₄/LaCO₃OH (0.85 μA cm⁻²) and g-C₃N₄ (0.38 μA cm⁻²), indicating the heterostructured ternary composite can effectively accelerate the charge transfer process. In PL spectra, the lower PL intensity means the lower recombination rate and longer lifetime of the photogenerated carriers.²⁷ As shown in Fig. 5C, compared with g-C₃N₄ and 25% g-C₃N₄/LaCO₃OH, the PL intensity of 0.8% RGO/g-C₃N₄/LaCO₃OH is much lower, confirming that cocatalyst RGO plays an important role in the restriction of photogenerated carriers' recombination. Overall, the synergistic effect of heterostructure and cocatalyst RGO endows RGO/g-C₃N₄/LaCO₃OH composite an improved photocatalytic activity by reducing the charge transfer resistance, facilitating the separation of charge carries and lowering their recombination rate.

Fig. 5 (A) The Nyquist plots of RGO, g-C₃N₄, LaCO₃OH and RGO/g-C₃N₄/LaCO₃OH in the frequency range from 10⁶ Hz to 0.1 Hz; (B) transient photocurrent responses and (C) the PL spectra.

According to above characterizations, the mechanism of the MO photodegradation process using RGO/g-C₃N₄/LaCO₃OH composite as the catalyst was proposed, as shown in Fig. 6. With the irradiation of visible light, g-C₃N₄ with a smaller bandgap of 2.75 eV can be excited and produce photogenerated electrons and holes, while LaCO₃OH does not response to visible light due to its large bandgap (4.02 eV). The electrons generated on the VB of g-C₃N₄ (1.58 eV) can be excited and separate with holes, then transfer to the CB of g-C₃N₄ (−1.17 eV). As g-C₃N₄ has a more negative CB compared with LaCO₃OH (−0.47 eV), the photogenerated electrons will transfer to the CB of LaCO₃OH driven by the interfacial electric field force, thus the recombination of photogenerated electrons and holes can be retarded. The introduction of RGO as cocatalyst can not only enhance the light absorption efficiency but also provide abundant active sites for the photocatalytic reaction because of the enlarged surface area and facilitated charge transfer kinetics of RGO. The main reactions in the photodegradation process of MO are as follows:

g-C₃N₄ + ħv → g-C₃N₄ (h⁺) + LaCO₃OH/g-C₃N₄ (e⁻)

LaCO₃OH/g-C₃N₄ (e⁻) + ħv → 2D-RGO (e⁻)

LaCO₃OH/g-C₃N₄ (e⁻) + 2D-RGO (e⁻) + O₂ → (˙O₂⁻)

(˙O₂⁻) + MO → CO₂ + H₂O

g-C₃N₄ (h⁺) + MO → CO₂ + H₂O

Fig. 6 The schematic of the proposed mechanism of RGO/g-C₃N₄/LaCO₃OH composites for MO photodegradation under visible light irradiation.

During this process, N=N bond of MO was broken under the attack of generated radicals, and aromatic hydrocarbons such as 4-amino-N,N-dimethylaniline and 4-diazenyl-N,N-dimethyl benzenamine were produced. Then the aromatic rings were continuously opened under the attack of reactive oxygen species and converted into carbon dioxide and water eventually.^28–30

4. Conclusion

In summary, ternary RGO/g-C₃N₄/LaCO₃OH composite was constructed by coupling RGO with heterostructured g-C₃N₄/LaCO₃OH through a hydrothermal reaction, and serve as an effective catalyst for the photodegradation of MO under visible light. Compared with pure g-C₃N₄, the MO photodegradation rate can be increased from 0.0083 min⁻¹ to 0.0150 min⁻¹ by constructing g-C₃N₄/LaCO₃OH heterojunction, and further boosted to 0.0326 min⁻¹ by introducing RGO as the cocatalyst, which is 3.93 times higher than pure g-C₃N₄. Such significant improvement is owing to the improved photocatalytic activities stemmed from the combination of g-C₃N₄/LaCO₃OH heterostructure with RGO, which can accelerate the transfer and restrict the recombination of the photogenerated carriers, and prolong their lifetime. This study realized the utilization of LaCO₃OH with a broad bandgap in the visible light region as a promising photocatalyst for the MO degradation, and also proposed a novel strategy for the further development of photocatalyst based on semiconductors with wide bandgaps.

Conflicts of interest

There are no conflicts to declare.

Acknowledgements

This research was supported by LiaoNing Revitalization Talents Program (XLYC2007166), Joint Funds for Innovation Capability Improvement of Natural Science Foundation of Liaoning Province (2021-NLTS-12-08), Science and Technology Innovation Foundation of Dalian (2022RQ047), Doctoral Startup Foundation of Dalian University (No. 1201012), the Key Task and Local Project in Science & Technology of SYUCT (LDB2019004).

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Footnote

† Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d3ra02415f

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