Engineering Exciton–Phonon Interactions for Suppressing Nonradiative Energy Loss in Energy-Transfer-Initiated Photocatalysis

Introduction

Over the past decades, low-dimensional semiconductors have been emerging as competitive candidates for photocatalytic solar energy conversion.^1–5 Compared with their bulk counterparts, low-dimensional semiconductors tend to possess promoted excitonic effects owing to their reduced dielectric screening. Accordingly, excitons serving as primary photoinduced species dominate photoexcitation properties of these low-dimensional systems, while exciton-involved energy transfer opens up an alternative pathway for realizing versatile photocatalytic solar energy conversion.^6–10 In this case, effective exciton accumulation is an essential precondition for gaining advanced energy-transfer-initiated photocatalysis. However, the general robust nonradiative decay of excitons in low-dimensional semiconductors undoubtedly sets limitations to exciton accumulation and hence to energy-transfer-initiated photocatalysis. Therefore, searching effective strategies for suppressing nonradiative decay of excitons in low-dimensional semiconductors is crucial to the relevant photocatalytic solar energy conversion.

Due to structural confinements, phonon-mediated scatterings leading to rapid energy exchange between electronic and vibrational subsystems tend to be quite strong in low-dimensional systems.^11–15 These scatterings serve as major factors in determining nonradiative decay of excitons in low-dimensional systems. For instance, inelastic exciton–phonon scattering leads to direct energy dissipation via vibrational relaxation, where high-frequency phonon-mediated interactions lead to faster nonradiative decay of excitons compared with low-frequency phonon-mediated ones; in contrast, elastic exciton–phonon interactions dominate the coherent superposition of exciton states, where the loss of quantum coherence (also known as excitonic dephasing) arising from promoted elastic couplings restrain the nonradiative decay rate.¹⁴ Moreover, different types (i.e., acoustic and optical) of phonons further complicate the handling of these effects.¹⁵ In this regard, suppressing nonradiative decay of excitons by engineering the strength and type of exciton–phonon interactions in low-dimensional semiconductor-based photocatalysts would be promising and meaningful for gaining optimized energy-transfer-initiated catalytic behaviors.

To date, several strategies, such as strain engineering, thickness control, and core–shell design, have been proposed to regulate exciton–phonon interactions in low-dimensional systems.^16–22 For instance, exciton–phonon interaction in transition metal dichalcogenide monolayers can be effectively regulated by external strain, giving rise to prominent modifications in excitonic properties like energy profile and decay rate^16,17; exciton–phonon interaction in organic–inorganic hybrid perovskites is closely associated with the thicknesses of organic/inorganic layers, which can impact exciton dynamics and hence optoelectronic performance of these systems^19,20; as for hybrid systems, shell thickness impacted exciton–phonon interaction in CdSe-CdS core–shell structures, and accordingly, the exciton dynamics and hence the photoluminescence quantum yield can be controlled by varying shell thickness.^21,22 However, in terms of photocatalysis, the feasibilities of these strategies remain in doubt, and these strategies tend to give rise to some additional, undesirable effects on electronic and surface properties. Here, we deduce that large-size vacancy clusters bringing about ample lattice displacements or even structural distortions would be suitable to tune exciton–phonon coupling in low-dimensional semiconductors. We focused our attention on bismuth oxybromide (BiOBr), whose low electronic dimensionality arising from confined layered structure endows the system with extraordinarily strong excitonic effects,^23,24 and the alternating heterogeneous slabs are anticipated to impact the coupling between electronic and lattice subsystems. Herein, by taking BiOBr as a typical example, we highlight that large-size Bi–Br vacancy clusters can effectively suppress nonradiative decay of excitons involved therein. According to spectroscopic analyses and an ab initio nonadiabatic molecular dynamics method based on GW plus real-time propagation of the Bethe–Salpeter equation (GW + rtBSE-NAMD),²⁵ we elucidated that vacancy clusters can significantly promote exciton–low-frequency phonon coupling and reduce exciton–high-frequency optical phonon coupling. Such modifications control the nonradiative decay channel, thereby giving rise to prolonged exciton lifetimes and enhanced exciton accumulation. Consequently, the defective sample with Bi–Br vacancy clusters (denoted BiOBr-V) exhibits prominent performance in energy-transfer-initiated photocatalysis. This work establishes a brand-new perspective on the regulation of excitonic processes in semiconductor-based photocatalysts via phonon engineering and calls for reevaluation of the potential influence of traditional optimization strategies (like defect engineering) on exciton–phonon interaction in low-dimensional semiconductor-based photocatalysts.

Experimental Methods

Preparation of BiOBr and BiOBr-V samples

BiOBr sample was prepared through a hydrothermal method. In a typical procedure, the stoichiometric precursors (bismuth nitrate pentahydrate, 2 mmol; potassium bromide, 2 mmol) were added into 30 mL of distilled water. After being stirred for 1 h, the above mixture was transferred into an autoclave with Teflon inner lining (50 mL) and heated in an oven at 160 °C for 24 h. After a natural cooling process, the precipitate in the lining was washed with distilled water and ethanol, followed by a drying treatment under ambient conditions. The obtained powders were denoted BiOBr. The defective BiOBr-V was synthesized by annealing the above BiOBr powders in molten alkali-bromide salts. In detail, the mixture of BiOBr (200 mg), potassium bromide (5.5 g), and lithium bromide (4.5 g) were fully ground in an agate mortar using a pestle. The mixture was then transferred into a quartz boat, followed by an annealing treatment (450 °C) under high-purity O₂ atmosphere for 12 h. After being cooled, the obtained solid block was dissolved with distilled water, and the precipitate was washed with distilled water and ethanol several times, followed by a drying treatment under ambient conditions. The obtained powders were denoted BiOBr-V.

Detecting photocatalytic single oxygen generation

9,10-Diphenylanthracene (DPA) was employed as a molecular probe for detecting photocatalytic singlet oxygen (¹O₂) generation in the systems. In a typical procedure, a certain amount of catalyst (i.e., 20 mg of BiOBr/BiOBr-V, 0.1 mg of 1- pyrenecarboxylic acid, or their mixture) was added into 50 mL of DPA solution (acetonitrile, 0.06 mM) in a quartz vial equipped with a balloon (to prevent the volatilization of acetonitrile). The mixture was stirred in the dark (30 min) for ensuring adsorption–desorption equilibrium, and then was illuminated by using a visible-light source (xenon lamp, Au-Light CEL-HXF300, equipped with a 420 nm cut-off filter). The DPA consumption was evaluated by monitoring the absorbance evolution of the solution. For atmosphere-dependent tests, the reaction vessel was filled with certain gas (O₂ or N₂) before illumination. For the scavenger-control test, 5 mg of sodium azide (NaN₃) was added into the mixture before illumination. Electron spin resonance (ESR)-trapping tests for detecting reactive oxygen species generation were performed according to our previous report,²⁴ using 2,2,6,6-tetramethylpiperidine (TEMP) as the trapping agent. Blank control groups were also performed, according to the above general procedures in the absence of any photocatalyst (i.e., BiOBr and BiOBr-V) or co-catalyst [i.e., 1-pyrenecarboxylic acid (PCA)], to exclude the interference of photoinstability or impurity of DPA and TEMP.

Photocatalytic aerobic oxidation of secondary amines

In a typical reaction, 0.25 mmol of amine, 0.4 μmol of PCA, and 5 mg of BiOBr/BiOBr-V were added into 5 mL of acetonitrile in a 20 mL quartz vial equipped with a balloon. A xenon lamp (CEL-HXF300, Au-Light) equipped with a 420 nm cut-off filter was employed as the light source. The performance was evaluated by nuclear magnetic resonance spectroscopy, using 1,1,2,2-tetrachloroethane as the internal standard. For the scavenger-control tests, 10 mg of NaN₃ was added into the mixture before illumination.

Results and Discussion

Structural characterizations of the samples

The defective sample (denoted BiOBr-V) was prepared by annealing pristine BiOBr in molten eutectic mixtures (see details in the Supporting Information), during which the release of molecular BiBr₃ led to the formation of large-size Bi–Br vacancy clusters. The X-ray diffraction (XRD; Figure 1a) patterns of BiOBr and BiOBr-V match well the reported data (JCPDS card No. 73-2061). The X-ray photoelectron spectra (XPS; Supporting Information Figure S1) verify the components of the samples to be Bi, O, and Br. Note that quantitative analysis of sample composition was challenging due to the complicated surface structures like surface atom deficiency, dangling bond (e.g., hydrogen bond and hydroxyl group), and water adsorption. The scanning electron microscopy (SEM; Supporting Information Figures S2a and S2b) images confirmed the similar, plate-like morphology of both the samples. In the BiOBr-V sample, some small dots, which are broken fragments generated during the annealing procedure, attached on the nanoplates were observed ( Supporting Information Figure S2c). The similar morphology was also evidenced by their approximate specific surface areas, while the promoted proportion of nanometer-scale pores would be associated with the presence of vacancy clusters in BiOBr-V ( Supporting Information Figure S3). X-ray absorption spectroscopy (XAS; Figure 1b) was employed to identify the orbital hybridizations in the two samples: the peaks (centered at ∼527.0 and 529.2 eV) originating from O 2p and Bi 6p hybridization exhibited near-identical intensity ratios, which suggests the similar valence states in the two cases; however, BiOBr-V exhibited remarkable spectral broadening (inset of Figure 1b) compared with BiOBr, which would be related to thermal vibrations and static disorder induced by the defective structures.^26,27 In addition, ambient-atmosphere ESR measurements confirmed the presence of oxygen vacancy in both samples ( Supporting Information Figure S4).

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The Raman spectra for investigating the vibrational scenarios are displayed in Figure 1c. As for BiOBr, typical vibrational bands peaking at ∼91, 111, and 160 cm⁻¹ were assigned to E_g, A_1g internal stretching, and A_1g external stretching modes, respectively.²⁸ However, quite different vibrational scenarios were found in the BiOBr-V sample: the band centered at 111 cm⁻¹ remained unchanged, whereas the other two bands exhibited obvious redshifts and greater intensities. Since the major contributor to the 111 cm⁻¹ band is the Bi–O bond and the major contributors of the other two bands are the Bi–Br and Br–Br bonds,²⁸ the distinct vibrational scenario in BiOBr-V most likely originated from structural modifications related to Bi and Br atoms. The high-angle annular dark-field scanning transmission electron microscopy (HAADF–STEM) was used to gather direct evidences of defective structures in BiOBr-V. As displayed in Figure 1d, the atomic structure image of BiOBr-V presents a distance of ∼0.28 nm that corresponds to the atomic arrangements of plates with (001) exposed facets. Compared with the uniformly distributed bright spots in BiOBr ( Supporting Information Figure S5), the deficient sites and heterogeneous contrasts (marked by green and red dashed circles in Figure 1d, respectively) in BiOBr-V directly verify the presence of Bi–Br vacancy clusters. In detail, the deficient sites (marked by green dashed circle) suggests the concurrent absences of Bi and Br atoms along the [001] axis; the heterogeneous contrasts (marked by red dashed circle) suggest the inhomogeneous distribution of adjacent Bi and Br atoms (detailed discussions are provided in Supporting Information Note 1 and Figure S6). The above results confirmed that BiOBr plates containing rich Bi–Br vacancy clusters were successfully prepared.

Nonadiabatic molecular dynamics simulations

In view of the unique structural and vibrational scenarios arising from Bi–Br vacancy clusters, we carried out first-principle calculations to gain theoretical insights of the impacts of Bi–Br vacancy clusters on exciton dynamics. The ground-state calculations suggest that the two systems possess similar electronic structures, and the Bi–Br vacancy clusters do not introduce deep-level trap states (see details in Supporting Information Note 2 and Figures S7 and S8). These features enabled us to exclude the potential effects of defect-state-induced nonradiative recombination of excitons. With regard to the impacts of exciton–phonon interactions, we further interrogated exciton dynamics of the pristine and defective systems at a finite temperature by using the GW + rtBSE-NAMD method (see details in Supporting Information Note 3 and Figure S9). We plotted the time evolutions of the lowest exciton state’s energies and exciton binding energies in the two systems at 300 K (Figure 2a). Because of the comparable exciton energies and exciton binding energies, we confirmed that Bi–Br vacancy clusters do not impact the intrinsically strong excitonic effects in the BiOBr structure. The calculated exciton energies are larger than the values estimated by photoluminescence measurements in our previous reports,^23,24 which might be associated with the different dielectric environments. Additionally, the lowest-energy exciton states exhibit notable time-dependent energy fluctuations, which reveal remarkable exciton–phonon interactions in both the pristine and defective systems.

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To further understand the exciton–phonon interactions, we carried out Fourier transform analyses of the relevant exciton-energy fluctuations (Figure 2b). The Fourier transform of the pristine BiOBr case displays a dominant peak centered at ∼117 cm^–1, which was assigned to the A_1g internal stretching mode. Moreover, there is another prominent, high-frequency phonon mode peak around ∼800 cm⁻¹, which might be associated with the superposition of E_g internal shear and B_1g internal stretching modes.²⁸ As for the defective system, a quite different scenario was observed: the highest peak was still located at ∼117 cm⁻¹, whereas there was no obvious peak around ∼800 cm⁻¹; furthermore, two distinct peaks centered at ∼67 and 433 cm⁻¹ emerged, which correspond to two different E_g modes that were mainly related to the shear vibrations of intralayer oxygen atoms and interlayer bismuth atoms, respectively. Clearly, Bi–Br vacancy clusters notably modulated the couplings between excitons and phonons, promoting exciton–low-frequency phonon coupling but suppressing exciton–high-frequency phonon coupling. With respect to exciton dynamics, the vanishing of exciton–high-frequency phonon coupling would effectively slow down exciton depopulation.^29,30 Time-dependent exciton energy changes deduced from the population of certain excitons are provided in Figures 2c and 2d. The average exciton lifetimes were calculated to be ∼249 and 415 ps for the pristine and defective systems, respectively, which is consistent with the averaged non-adiabatic coupling relationships in Supporting Information Figure S10. Based on the GW + rtBSE-NAMD simulations, we deduced that prolonged exciton lifetime and enhance exciton accumulation arising from the promoted exciton–low-frequency optical phonon coupling and suppressed exciton–high-frequency optical phonon coupling could be expected in the defective BiOBr-V system.

Photoluminescence properties of the samples

Photoluminescence measurements were performed to gain experimental insights into the impacts of Bi–Br vacancy clusters on exciton–phonon coupling and hence on exciton dynamics. Excitation wavelength in all the photoluminescence measurements was set at 350 nm, based on the UV–vis spectra ( Supporting Information Figure S11). Figure 3a displays the steady-state fluorescence spectra at 10 K. The pristine BiOBr sample exhibited a prominent sub-band emission peaking at ∼480 nm, which is in accordance with the excitonic emission of BiOBr system.^23,24 The weak shoulder observed at ∼565 nm was associated with the slight oxygen vacancies in the sample. In comparison, the defective BiOBr-V sample exhibited a high-intensity, broad emission centered at ∼492 nm. Notably, the ∼12 nm redshift (i.e., 480 vs 492 nm) was ascribed to the distinct variation tendencies (in both energy level and proportion) of various emissions; details are provided in Supporting Information Note 4 and Figure S12. The broadening spectral profile could be related to the promoted exciton–phonon coupling in the defective sample.^31,32 In addition, the potential impacts of broken fragments generated during the annealing procedure on the excited-state properties of BiOBr-V sample were excluded (see details in Supporting Information Note 5 and Figure S13).

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The remarkable changes in exciton–phonon coupling induced by Bi–Br vacancy clusters were also evidenced by temperature-dependent photoluminescence tests (from 10 to 100 K, with a temperature interval of 10 K). As for the pristine BiOBr case ( Supporting Information Figure S14), the intensity of the 480 nm excitonic emission dramatically decreased with increasing temperature, which resulted in a high proportion of oxygen-vacancy-related emission (i.e., 565 nm emission) under high-temperature conditions. We attributed remarkable suppression of the 480 nm excitonic emission to the promoted phonon-mediated nonradiative decay of excitons under a high temperature. In comparison, the emission peak of BiOBr-V (Figure 3b) exhibited a notable redshift with increasing temperature, which suggests the different exciton–phonon coupling scenarios in the system.^33–35 To get a quantitative assessment on the strengths of exciton–phonon coupling in the two samples, we plotted the peak energy shifts of short-lived excitonic emission extracted from the whole spectral profiles for both BiOBr and BiOBr-V (Figure 3c and Supporting Information Note 4 and Figure S12). A semi-empirical function was employed to fit the temperature-dependent peak shifts

where E (E₀) is the emission peak energy at temperature T (0 K), α_e–p is linked to the strength of exciton–phonon coupling, and θ is the effective phonon energy on temperature scale, respectively.³⁵ Compared with BiOBr, BiOBr-V possessed a 6.3-fold enhancement (i.e., 57.8 vs 9.2 meV) in parameter α_e–p, verifying the remarkably promoted exciton–phonon coupling strength in the defective system. However, a counterintuitive feature is that the temperature-dependent decreasing rate of emission intensity of BiOBr-V was much slower than that of BiOBr since promoted exciton–phonon couplings usually lead to faster decays in other systems.^36,37 Moreover, time-resolved photoluminescence tests also gave counterintuitive results. Time-resolved fluorescence spectra monitoring at 470 nm (corresponding to the short-lived excitonic emission peak; Figure 3d) verified that BiOBr-V possessed a slower excitonic radiative decay than BiOBr. Time-dependent phosphorescence measurements also confirmed the slower lifetime of long-lived excitonic emission in BiOBr-V ( Supporting Information Figure S12). Combined with the theoretical simulations, the counterintuitive features are understood as follow: Bi–Br vacancy clusters boost the couplings between excitons and low-frequency optical phonons and suppress the couplings between excitons and high-frequency optical phonons; the former may be responsible for the broadening and temperature-dependent peak shift of excitonic emission, while the latter is responsible for the changes in intensity and lifetimes of excitonic emissions. The above results confirmed that that Bi–Br vacancy clusters effectively modify the exciton–phonon couplings and thus the exciton dynamics in the system.

Photocatalytic performance evaluation

On the grounds of the optimized exciton dynamics, the defective BiOBr-V sample was expected to be beneficial to trigger energy-transfer-involved photocatalysis. To verify this, we evaluated the performances of photocatalytic PCA (an effective ¹O₂ photosensitizer) activation of both samples. Due to the large S₀–S₁ energy gap, PCA possesses faint absorption and hence poor reactivity in the visible light region (Figure 4a). However, the transfer of long-lived excitons from semiconductors to ground-state PCA molecules enables visible-light-driven generation of triplet PCA.⁶ Therefore, we expect considerable visible-light driven photocatalytic ¹O₂ generation in the BiOBr-V/PCA system. Here, we used DPA to probe ¹O₂ generation in the presence of different catalysts, which were assessed by monitoring the absorbance evolution of DPA solution. Figure 4b displays the absorbance evolutions of DPA solution in the presence of BiOBr/PCA and BiOBr-V/PCA. Obviously, BiOBr-V/PCA exhibited much higher reactivity in ¹O₂ generation than BiOBr/PCA. Note that ¹O₂ generation was also detected for bare BiOBr and BiOBr-V (i.e., in the absence of PCA; Figure 4c), whereas the mismatched energy levels between excitonic states of the semiconductor systems and excited states of molecular oxygen were responsible for the suboptimal yields. Control tests under N₂ and O₂ atmospheres (inset of Figure 4c) confirmed that the reactive species for DPA consumption were derived from molecular oxygen. The addition of NaN₃ (a scavenger of ¹O₂) can effectively suppress DPA consumption, confirming the ¹O₂ generation in the BiOBr-V/PCA system. Moreover, ESR measurements also confirmed the relevant ¹O₂ generation, using TEMP as the spin label agent. As displayed in Figure 4d, both the BiOBr/PCA and BiOBr-V/PCA cases exhibit typical hyperfine structures corresponding to 2,2,6,6-tetramethylpiperidine-N-oxyl, whereas the higher intensity clearly verifies the enhanced ¹O₂ generation in BiOBr-V/PCA case. The above results validated the excellent energy-transfer-initiated photocatalytic performance of the defective BiOBr-V sample, which echoes the positive role of Bi–Br vacancy clusters in suppressing nonradiative decay of excitons involved therein.

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The considerable ¹O₂ generation undergoing exciton-involved energy transfer route greatly promises the defective sample great potential in selective aerobic oxidation. To this end, we carried out selective amine oxidation reactions to assess such potentials. As an important reaction, the aerobic oxidation of amines into corresponding imines has been widely investigated because of its great significance in obtaining bioactive organic nitrogen compounds.^38,39 Benefiting from its suitable oxidizing ability and unique electronic configuration, ¹O₂ is a facile oxidizing agent for this conversion. Here, we selected a series of secondary amines as the substrates to evaluate the scope of the photocatalytic reaction of the two samples, where the yields obtained under optimized conditions are listed in Table 1. As one of the most typical secondary amines, dibenzylamine was first used to distinguish the differences between the two samples. In the presence of O₂ atmosphere (entry 1), both pristine BiOBr and defective BiOBr-V converted the dibenzylamine to N-benzylidenebenzylamine, while the latter improved the yield, corresponding to the increasing exciton accumulation related to the promoted exciton–phonon coupling. The mere BiOBr and BiOBr-V sample (without PCA) exhibited relatively low yields ( Supporting Information Figure S15), which is related to suboptimal ¹O₂ generation as a consequence of the mismatched energy levels between their excitonic states and the excited states of molecular oxygen. Note that ¹O₂ generation via energy transfer between triplet PCA (rather than long-lived excitonic states in BiOBr or BiOBr-V) and ground-state ³O₂ is directly responsible for the oxidation of amines into the corresponding imines. That is to say, PCA acts as a molecular co-catalyst in our system, and accordingly, not only exciton dynamics in BiOBr-V but also energy transfer between BiOBr-V and PCA impacted the final photocatalytic performance. Control tests under inert atmosphere (that is, N₂ atmosphere; entry 2) confirmed that the functional species for photocatalytic imine generation derived from the activation of molecular oxygen, in view of the markedly reduced yields for both samples. The addition of ¹O₂-scavenger (NaN₃; entry 3) sharply suppressed the oxidation process, which provided conclusive evidence of the ¹O₂-dominated aerobic oxidation in this photocatalytic scenario. Bis-(4-methoxybenzyl)-amine (entry 4), a symmetric dibenzylamine derivative, was used to explore the exciton-dominated photocatalytic behaviors, where a better yield was obtained in the defective sample. Moreover, BiOBr-V also exhibited better performance in the selective oxidation of asymmetric amines (entries 5–7), which would be quite meaningful for extending the scope of this photocatalytic application. Tetrahydroisoquinoline (entry 8) was used to estimate the conversion of heterocyclic amines, where the defective sample gave rise to a higher yield of 3,4-dihydroisoquinoline. In addition, the impacts of Bi-Br vacancy-cluster concentration on exciton–phonon interaction and photocatalytic activity were also interrogated, which further confirmed the positive role of exciton–phonon engineering in promoting energy-transfer-mediated photocatalysis in the BiOBr system (see details in Supporting Information Note 6 and Figure S16). All these cases demonstrate the great potential of BiOBr-V/PCA system in the regioselective oxidation of secondary amines into corresponding imines.

Conclusion

We have demonstrated for the first time that phonon engineering is feasible in suppressing nonradiative decay of excitons and hence facilitating energy-transfer-initiated photocatalysis of low-dimensional semiconductors. By taking BiOBr as a prototype, we highlighted that large-size Bi–Br vacancy clusters effectively tune exciton–phonon interactions that are closely associated with exciton nonradiative decays in the system. With the combination of spectroscopic analyses and theoretical simulations, we identified the crucial role of Bi–Br vacancy clusters in boosting exciton–low-frequency optical phonon coupling and suppressing exciton–high-frequency optical phonon coupling. Such modifications can effectively reduce exciton depopulation undergoing nonradiative decay pathways, thereby giving rise to prolonged exciton lifetime and promoted exciton accumulation in the defective BiOBr-V sample. Benefiting from these features, the defective BiOBr-V sample exhibits desirable performance in energy-transfer-initiated photocatalytic activation of small molecules. This work provides a comprehensive understanding of excitonic aspects in low-dimensional photocatalysts, and proposes an intriguing phonon-engineering-based strategy for gaining efficient energy-transfer-initiated photocatalysis.

Supporting Information

Supporting Information is available and includes additional experimental details, structural characterizations, theoretical calculations, spectroscopic data, photocatalytic tests, and the corresponding discussions.

Conflict of Interest

There is no conflict of interest to report.

Funding Information

This work was supported by the National Key R&D Program of China (no. 2019YFA0210004), the Strategic Priority Research Program of Chinese Academy of Sciences (no. XDB36000000), the National Natural Science Foundation of China (nos. 21922509, 21905262, 21890754, T2122004, 92163105 12074266, 11620101003, 11974322, U2032212, and U2032160), the Anhui Provincial Natural Science Foundation (no. 2108085J07), the University Synergy Innovation Program of Anhui Province (nos. GXXT-2020-005 and GXXT-2021-020), and the Science and Technology Project of Shenzhen (grant no. 20200802180159001).