Abstract
The surface wettability of plants exhibits many unique advantages, which enhances the environmental adaptability of plants. In view of the rapid development of responsive materials, smart surfaces have been explored extensively to regulate surface wettability through external stimuli. Herein, we summarized recent advancements in bioinspired surfaces with switchable wettability. Typical bioinspired surfaces with switchable wettability and their emerging applications have been reviewed. In the end, we have discussed the remaining challenges and provided perspective on future development.
Introduction
The surface wettability of plants exhibits unique advantages (Wu et al., 2009, 2010, 2011a,b; Jiang et al., 2011), which enhances the environmental adaptability and improves survival chances. (Zhang et al., 2012a, 2019b, 2020; Yong et al., 2017) For example, water droplets roll freely on the surface of lotus leaves, which shows self-cleaning characteristics (Figure 1a; Zhang et al., 2012c). Rose petals demonstrate water droplets pinning effect, which is helpful for keeping rose petals hydrated (Figure 1b; Zhang et al., 2012b) Water droplets on the surface of reed leaves prefer to flow along the direction of the parallel leaf veins (Figure 1c; Wang et al., 2015) This anisotropic rolling characteristic plays an important role in collecting dewdrops on the roots and improves the environmental adaptability in dry and hot climates (Jiang et al., 2016). Insects easily slide from the edge of pitcher plants to the inner bottom and provide nourishment for the pitcher plants (Figure 1d; Huang et al., 2017; Zhang et al., 2017). Similar to insects, water droplets are also easy to slide on the liquid-infused surface (Yong et al., 2018). In addition, there are plenty of stimulated-responsive creatures on our planet. For example, organisms show reversible deformable body postures under environment stimulate (Cui et al., 2019). Chameleon owns excellent camouflage capabilities (Jiang et al., 2019b). Venus Flytrap generates closure motions under external forces (Le et al., 2019). Pinecone opens in dry environment and closes in wet environment (Mulakkal et al., 2018). Currently, motivated by such examples with extreme wettability and stimulated-responsive creatures, bioinspired surfaces with switchable wettability have been proposed and prepared (Xin et al., 2018; Jiang et al., 2019a; Han et al., 2020; Li et al., 2020).
Figure 1
Smart surfaces have attracted considerable interests because the surface chemistry and surface roughness play an important role in controlling surface wettability (Fang et al., 2010; Xu et al., 2013; Huang et al., 2017; Wei et al., 2017). Nowadays, the rapid development of responsive materials has enabled surface chemistry and surface roughness change to switch surface wettability through external stimuli (Xin et al., 2016; Wu et al., 2017; You et al., 2018; Salter and Booth, 2019; Zhang et al., 2019c; Fu et al., 2020; Zou et al., 2020). Due to the reversible dynamic control capability, tremendous effects have been devoted to developing driving techniques (Yin et al., 2018; Liu et al., 2020; You et al., 2020) such as temperature, light, electric/magnetic fields, chemicals, and mechanical motion (Han et al., 2015a,b, 2016; Yong et al., 2015). Importantly, the stimulated-responsive bioinspired surface has great prospects in diverse applications, such as droplet manipulations, oil-water separation, cell culture, smart skin (Yang et al., 2018; Liu et al., 2019; Lu et al., 2019).
In this minireview, we focus on the recent advancements in bioinspired stimulated-responsive surfaces with switchable wettability. Typical examples, such as thermal/photothermal, electric, magnetic, mechanical motion and chemical response surfaces, have been summarized. Finally, the challenges and future perspective for smart surfaces with switchable wettability are also discussed.
Mechanism
Typically, surface chemistry and surface roughness play important roles in the surface wettability. According to the Cassie equation (Li et al., 2019; Zhang et al., 2019a; Namdari et al., 2020): cos θ* = fs cos θs - fa; fs + fa =1, θ* and θs are the apparent contact angle (CA) and intrinsic CA of the substrate. fs and fa are apparent area fractions of the substrate and air troughs. Therefore, the surface wettability becomes switchable when the surface chemistry and surface roughness change under different environment stimuli. For example, as shown in the Figure 1e, the surface is initially hydrophobic without stimuli because of the structured substrate. Under stimuli, the surface chemical composition changes, leading to the changing of θs. Therefore, the surface water CA changes. Similarly, as shown in the Figure 1f, the surface water CA changes when the apparent area fractions of the substrate and air troughs change (fs and fa) under environment stimuli. In addition, a combination change of surface chemistry and surface roughness can be used to design surfaces with switchable wettability (Figure 1g) because of the combination change of θs, fs, and fa.
Surfaces With Switchable Wettability
Thermal/Photothermal Response
Benefiting from temperature responsive shape memory polymer (SMP) materials, Cheng et al. have successfully developed thermal response surfaces that tune superhydrophobic characters between isotropic and anisotropic state (Cheng et al., 2018). The groove structure is prepared by heat-pressing a template on the micro/nanostructured pillars surface. The collapsed pillars would recover to the initial structure when the surrounding temperature is above the Tg. In particular, this thermal response surface shows outstanding rewritable capability. Besides, Geng et al. have made intensive efforts to develop a photothermal responsive tube based on PDMS/rGO-PNIPAm (Figure 1h; Geng et al., 2018). rGO converts light into heat. PNIPAm shows the reversible hydrophilic/hydrophobic switch. Therefore, the PDMS/rGO-PNIPAm tube can be used as an amazing sunlight-driven water transporter by gradient in the surface wettability.
Electric Response
In 2017, Wei et al. fabricated electric-responsive polypyrrole (Ppy) arrays (Wei et al., 2017). The Ppy array shows reversible morphological transition between hydrophobic nanotubes and hydrophilic nanotips. The morphological transition is because of the volume change of Ppy under different voltage. As a result, the water CAs of the Ppy array are 105 ± 15° under −0.8 V and 44 ± 10° under 0.5 V, respectively. Besides, Oh et al. demonstrated dielectric elastomer-actuated liquid-infused poroelastic film (Figure 1i; Oh et al., 2018) The elastomeric film contracts in the thickness direction and expands in-plane under voltage. Therefore, the liquid-infused poroelastic film can be used for droplet manipulations including droplet oscillation, jetting, mixing.
Magnetic Response
Magnetically transformable surface was constructed by conformally infusing a liquid lubricant into magnetically responsive hierarchical micropillars (Figure 1j; Huang et al., 2017) The surface shows superhydrophobic property when micropillars are perpendicular to the surface. Whereas, the surface shows slippery property when micropillars are parallel to the surface. This liquid-infused magnetism responsive surface shows adaptive liquid repellency. Besides, due to the switching wetting state, the magnetic response surface can be used for fog harvesting and liquid transport. Similarly, various magnetic response switching wetting surfaces have been successfully designed and fabricated based on PDMS@cobalt microparticles and PDMS@Fe3O4 (Cao et al., 2017; Li et al., 2018). Recently, Jiang et al. have developed magnetic response Janus microplates arrays (Jiang et al., 2019b). The microplates were prepared by casting a mixture of PDMS and magnetic particles into a polystyrene mold. Then, the one side of microplates was modified by superhydrophobic spray to obtain superhydrophobic property. Another side of microplates was scanned by femtosecond laser to expose the hydrophilic carbonyl irons particles.
Mechanical Motion
Wang et al. developed a superhydrophobic PDMS skin that switches between lotus leaf and rose petal modes (Wang et al., 2018b). The superhydrophobic PDMS skins with monolithic and hierarchical structures were fabricated by direct laser writing technique. The water droplet rolled off with a slight tilt under ε <50% (rolling state). Whereas, the water droplet firmly stuck on the surface under ε >70% (pinning state). This smart surface shows potential in droplet manipulations by movable joints. Similarly, this group developed pneumatic surfaces by embedding micro-air-sac network in an elastomer (Figure 1k; Wang et al., 2018a). The surface exposes one surface and hiding the other by deflation and inflation.
Chemical Response
Zhu et al. prepared polyphenylsulfone-pyridine (PPSU-Pyx)-based nanoporous membrane with switchable wettability in response to pH (Figure 1l; Zhu et al., 2017) Due to the conformational switch of pyridine pendants, the porous membrane shows reversibly switch wettability. The CAs of PPSU-Pyx are 63.3° in acid solution (pH = 3) and 106.5° in alkaline solution (pH = 11). Besides, Liu et al. developed chemical response structured copper surfaces by exchanging counterion from PFO− to Cl− (Liu et al., 2018). After the PFO− treatment, structured copper surfaces was filled with fluorine-containing groups, leading to hydrophobic characters. Whereas, the hydrophobic surface loses fluorine-containing groups after the Cl− treatment. As a result, the hydrophobic surface become hydrophilic.
Conclusion and Outlook
In this minireview, we have summarized the typical stimulated-responsive surfaces with switchable wettability including thermal/photothermal, electric, magnetic, mechanical motion and chemical response surfaces. Taking advantage of the stimulated-responsive characters, the smart surfaces can be used as droplet manipulators, fog collection, smart skin, stem cell differentiation, and others. The further trend of smart surfaces with switchable wettability may be developed from new driving mechanism, fabrication methods, and broaden the application areas. We believe that continued efforts to smart surfaces with switchable wettability would have potential applications in the fields of bionic manufacturing, electronic information, biomedicine, etc.
Statements
Author contributions
All authors listed have made a substantial, direct and intellectual contribution to the work, and approved it for publication.
Funding
This work was supported by the National Natural Science Foundation of China (NSFC) (Nos. 61590930, 61905087, 61805098, and 61827826) and Postdoctoral Science Foundation of China (2020M670850).
Conflict of interest
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
References
1
CaoM. Y.JinX.PengY.YuC. M.LiK.LiuK. S.et al. (2017). Unidirectional wetting properties on multi-bioinspired magnetocontrollable slippery microcilia. Adv. Mater. Weinheim.29:1606869. 10.1002/adma.201606869
2
ChengZ. J.ZhangD. J.LvT.LaiH.ZhangE. S.KangH. J.et al. (2018). Superhydrophobic shape memory polymer arrays with switchable isotropic/anisotropic wetting. Adv. Funct. Mater.28:1705002. 10.1002/adfm.201705002
3
CuiH. Q.ZhaoQ. L.WangY. L.DuX. M. (2019). Bioinspired actuators based on stimuli-responsive polymers. Chem. Asian J.14, 2369–2387. 10.1002/asia.201900292
4
FangH. H.YangJ.DingR.ChenQ. D.WangL.XiaH.et al. (2010). Polarization dependent two-photon properties in an organic crystal. Appl. Phys. Lett97:101101. 10.1063/1.3486683
5
FuX. Y.ChenZ. D.HanD. D.ZhangY. L.XiaH.SunH. B. (2020). Laser fabrication of graphene-based supercapacitors. Photonics Res.8, 577–588. 10.1364/PRJ.382401
6
GengH. Y.ZhouK.ZhouJ. J.MaH. Y.LvC. J.LiC.et al. (2018). Sunlight-driven water transport via a reconfigurable pump. Angew. Chem. Intern. Edition57, 15435–15440. 10.1002/anie.201808835
7
HanD. D.ZhangY. L.JiangH. B.XiaH.FengJ.ChenQ. D.et al. (2015a). Moisture-responsive graphene paper prepared by self-controlled photoreduction. Adv. Materials27, 332–338. 10.1002/adma.201403587
8
HanD. D.ZhangY. L.LiuY.LiuY. Q.JiangH. B.HanB.et al. (2015b). Bioinspired graphene actuators prepared by unilateral UV irradiation of graphene oxide papers. Adv. Funct. Mater25, 4548–4557. 10.1002/adfm.201501511
9
HanD. D.ZhangY. L.MaJ. N.LiuY. Q.HanB.SunH. B. (2016). Light-mediated manufacture and manipulation of actuators. Adv. Mater.28, 8328–8343. 10.1002/adma.201602211
10
HanD. D.ChenZ. D.LiJ. C.MaoJ. W.JiaoZ. Z.WangW.et al. (2020). Airflow enhanced solar evaporation based on Janus graphene membranes with stable interfacial floatability. ACS Appl. Mater. Interfaces.12, 25435–25443. 10.1021/acsami.0c05401
11
HuangY.StoginB. B.SunN.WangJ.YangS. K.WongT. S. (2017). A switchable cross-species liquid repellent surface. Adv. Mater.29:1604641. 10.1002/adma.201604641
12
JiangH. B.LiuY.LiuJ.LiS. Y.SongY. Y.HanD. D.et al. (2019a). Moisture-responsive graphene actuators prepared by two-beam laser interference of graphene oxide paper. Front. Chem.7:464. 10.3389/fchem.2019.00464
13
JiangH. B.LiuY. Q.ZhangY. L.LiuY.FuX. Y.HanD. D.et al. (2018). Reed leaf-inspired graphene films with anisotropic superhydrophobicity. ACS Appl. Mater. Interfaces10, 18416–18425. 10.1021/acsami.8b03738
14
JiangH. B.ZhangY. L.LiuY.FuX. Y.LiY. F.LiuY. Q.et al. (2016). Bioinspired few-layer graphene prepared by chemical vapor deposition on femtosecond laser-structured Cu foil. Laser Photon. Rev.10, 441–450. 10.1002/lpor.201500256
15
JiangS. J.HuY. L.WuH.ZhangY. C.ZhangY. Y.WangY. L.et al. (2019b). Multifunctional Janus microplates arrays actuated by magnetic fields for water/light switches and bio-inspired assimilatory coloration. Adv. Mater.31:1807507. 10.1002/adma.201807507
16
JiangY.WangH. Y.WangH.GaoB. R.HaoY. W.JinY.et al. (2011). Surface plasmon enhanced fluorescence of dye molecules on metal grating films. J. Phys. Chem. C115, 12636–12642. 10.1021/jp203530e
17
LeX. X.LuW.ZhangJ. W.ChenT. (2019). Recent progress in biomimetic anisotropic hydrogel actuators. Adv. Sci6:1801584. 10.1002/advs.201801584
18
LiD. K.HuangJ. X.HanG. C.GuoZ. G. (2018). A facile approach to achieve bioinspired PDMS@Fe3O4 fabric with switchable wettability for liquid transport and water collection. J. Mater. Chem. A6, 22741–22748. 10.1039/C8TA08993K
19
LiJ.LiJ. Q.SunJ.FengS. L.WangZ. K. (2019). Biological and engineered topological droplet rectifiers. Adv. Mater.31:1806501. 10.1002/adma.201806501
20
LiZ. Z.WangL.FanH.YuY. H.ChenQ. D.JuodkazisS.et al. (2020). O-FIB: far-field-induced near-field breakdown for direct nanowriting in an atmospheric environment. Light Sci. Applicat.9:41. 10.1038/s41377-020-0275-2
21
LiuY.GaoH. P.LiS. Y.HanZ. W.RenL. Q. (2018). Bioinspired platform with reversibly switchable wettability for transfer and storage of droplets. Chem. Eng. J.337, 697–708. 10.1016/j.cej.2017.12.139
22
LiuY. Q.ChenZ. D.MaoJ. W.HanD. D.SunX. Y. (2019). Laser fabrication of graphene-based electronic skin. Front. Chem.7:461. 10.3389/fchem.2019.00461
23
LiuY. Q.MaoJ. W.ChenZ. D.HanD. D.JiaoZ. Z.MaJ. N.et al. (2020). Three-dimensional micropatterning of graphene by femtosecond laser direct writing technology. Opt. Lett.45, 113–116. 10.1364/OL.45.000113
24
LuZ.HeF.HsiehC. Y.WuX.SongM.LiuX.et al. (2019). Magnetic hierarchical photocatalytic nanoreactors: toward highly selective Cd2+ removal with secondary pollution free tetracycline degradation. ACS Appl. Nano Mater.2, 1664–1674. 10.1021/acsanm.9b00113
25
MulakkalM. C.TraskR. S.TingV. P.SeddonA. M. (2018). Responsive cellulose-hydrogel composite ink for 4D printing. Mater. Des.160, 108–118. 10.1016/j.matdes.2018.09.009
26
NamdariN.MohammadianB.JafariP.MohammadiR.SojoudiH.GhasemiH.et al. (2020). Advanced functional surfaces through controlled damage and instabilities. Mat. Horizons7, 366–396. 10.1039/C9MH01516G
27
OhI.KeplingerC.CuiJ. X.ChenJ. H.WhitesidesG. M.AizenbergJ.et al. (2018). Dynamically actuated liquid-infused poroelastic film with precise control over droplet dynamics. Adv. Funct. Mater28:1802632. 10.1002/adfm.201802632
28
SalterP. S.BoothM. J. (2019). Adaptive optics in laser processing. Light-Sci. Appl.8:110. 10.1038/s41377-019-0215-1
29
WangJ. N.LiuY. Q.ZhangY. L.FengJ.SunH. B. (2018a). Pneumatic smart surfaces with rapidly switchable dominant and latent superhydrophobicity. NPG Asia Mater.10:e470. 10.1038/am.2017.218
30
WangJ. N.LiuY. Q.ZhangY. L.FengJ.WangH.YuY. H.et al. (2018b). Wearable superhydrophobic elastomer skin with switchable wettability. Adv. Funct. Mater.28:1800625. 10.1002/adfm.201800625
31
WangJ. N.ZhangY. L.LiuY.ZhengW. H.LeeL. P.SunH. B. (2015). Recent developments in superhydrophobic graphene and graphene-related materials: from preparation to potential applications. Nanoscale7, 7101–7114. 10.1039/C5NR00719D
32
WeiY.MoX. J.ZhangP. C.LiY. Y.LiaoJ. W.LiY. J.et al. (2017). Directing stem cell differentiation via electrochemical reversible switching between nanotubes and nanotips of polypyrrole array. ACS Nano11, 5915–5924. 10.1021/acsnano.7b01661
33
WuD.ChenQ. D.NiuL. G.WangJ. N.WangJ.WangR.et al. (2009). Femtosecond laser rapid prototyping of nanoshells and suspending components towards microfluidic devices. Lab. Chip.9, 2391–2394. 10.1039/b902159k
34
WuD.WangJ. N.WuS. Z.ChenQ. D.ZhaoS. A.ZhangH.et al. (2011a). Three-level biomimetic rice-leaf surfaces with controllable anisotropic sliding. Adv. Funct. Mater21, 2927–2932. 10.1002/adfm.201002733
35
WuD.WuS. Z.ChenQ. D.ZhaoS.ZhangH.JiaoJ.et al. (2011b). Facile creation of hierarchical PDMS microstructures with extreme underwater superoleophobicity for anti-oil application in microfluidic channels. Lab Chip11, 3873–3879. 10.1039/c1lc20226j
36
WuD.WuS. Z.NiuL. G.ChenQ. D.WangR.SongJ. F.et al. (2010). High numerical aperture microlens arrays of close packing. Appl. Phys. Lett.97:031109. 10.1063/1.3464979
37
WuJ.WangH.SuZ.ZhangM.HuX.WangY.et al. (2017). Highly flexible and sensitive wearable e-skin based on graphite nanoplatelet and polyurethane nanocomposite films in mass industry production available. ACS Appl. Mater. Interf.9, 38745–38754. 10.1021/acsami.7b10316
38
XinW.ChenX. D.LiuZ. B.JiangW. S.GaoX. G.JiangX. Q.et al. (2016). Photovoltage enhancement in twisted-bilayer graphene using surface plasmon resonance. Adv. Opt. Mater.4, 1703–1710. 10.1002/adom.201600278
39
XinW.LiX. K.HeX. L.SuB. W.JiangX. Q.HuangK. X.et al. (2018). Black-phosphorus-based orientation-induced diodes. Adv. Mater.30:1704653. 10.1002/adma.201704653
40
XuB. B.ZhangY. L.XiaH.DongW. F.DingH.SunH. B. (2013). Fabrication and multifunction integration of microfluidic chips by femtosecond laser direct writing. Lab. Chip.13, 1677–1690. 10.1039/c3lc50160d
41
YangS.YinK.ChuD. K.HeJ.DuanJ. A. (2018). Femtosecond laser structuring of Janus foam: Water spontaneous antigravity unidirectional penetration and pumping. Appl. Phys. Lett113:203701. 10.1063/1.5061723
42
YinK.YangS.DongX. R.ChuD. K.DuanJ. A.HeJ. (2018). Ultrafast achievement of a superhydrophilic/hydrophobic Janus foam by femtosecond laser ablation for directional water transport and efficient fog harvesting. ACS Appl. Mater. Interfaces10, 31433–31440. 10.1021/acsami.8b11894
43
YongJ. L.ChenF.YangQ.FarooqU.HouX. (2015). Photoinduced switchable underwater superoleophobicity–superoleophilicity on laser modified titanium surfaces. J. Mater. Chem. A3, 10703–10709. 10.1039/C5TA01782C
44
YongJ. L.ChenF.YangQ.HuoJ. L.HouX. (2017). Superoleophobic surfaces. Chem. Soc. Rev.46, 4168–4217. 10.1039/C6CS00751A
45
YongJ. L.HuoJ. L.YangQ.ChenF.FangY.WuX. J.et al. (2018). Femtosecond laser direct writing of porous network microstructures for fabricating super-slippery surfaces with excellent liquid repellence and anti-cell proliferation. Adv. Mater. Interfaces5:1701479. 10.1002/admi.201701479
46
YouR.HanD. D.LiuF. M.ZhangY. L.LuG. Y. (2018). Fabrication of flexible room-temperature NO2 sensors by direct laser writing of In2O3 and graphene oxide composites. Sensors Actuators B Chem.277, 114–120. 10.1016/j.snb.2018.07.179
47
YouR.LiuY. Q.HaoY. L.HanD. D.ZhangY. L.YouZ. (2020). Laser fabrication of graphene-based flexible electronics. Adv. Mater.32:1901981. 10.1002/adma.201901981
48
ZhangP. C.ZhaoC. Q.ZhaoT. Y.LiuM. J.JiangL. (2019a). Recent advances in bioinspired gel surfaces with superwettability and special sdhesion. Adv. Sci.6:1900996. 10.1002/advs.201900996
49
ZhangP. F.ZhangL. W.ChenH. W.DongZ. C.ZhangD. Y. (2017). Surfaces inspired by the nepenthes peristome for unidirectional liquid transport. Adv. Mater.29:995. 10.1002/adma.201702995
50
ZhangX. L.SongJ. F.LiX. B.FengJ.SunH. B. (2012a). Optical tamm states enhanced broad-band absorption of organic solar cells. Appl. Phys. Lett101:243901. 10.1063/1.4770316
51
ZhangY. L.ChenQ. D.JinZ.KimE.SunH. B. (2012b). Biomimetic graphene films and their properties. Nanoscale4, 4858–4869. 10.1039/c2nr30813d
52
ZhangY. L.LiuY. Q.HanD. D.MaJ. N.WangD.LiX. B.et al. (2019b). Quantum-confined-superfluidics-enabled moisture actuation based on unilaterally structured graphene oxide papers. Adv. Mater.31:1901585. 10.1002/adma.201901585
53
ZhangY. L.MaJ. N.LiuS.HanD. D.LiuY. Q.ChenZ. D.et al. (2020). A “Yin” - “Yang” complementarity strategy for design and fabrication of dual-responsive bimorph actuators. Nano Energy68:104302. 10.1016/j.nanoen.2019.104302
54
ZhangY. L.XiaH.KimE.SunH. B. (2012c). Recent developments in superhydrophobic surfaces with unique structural and functional properties. Soft Matter.8, 11217–11231. 10.1039/c2sm26517f
55
ZhangY. Y.JiaoY. L.ChenC.ZhuS. W.LiC. Z.LiJ. W.et al. (2019c). Reversible tuning between isotropic and anisotropic sliding by one-direction mechanical stretching on microgrooved slippery surfaces. Langmuir35, 10625–10630. 10.1021/acs.langmuir.9b01035
56
ZhuX. B.ZhouY. H.HaoJ. R.BaoB.BianX. J.JiangX. Y.et al. (2017). A charge-density-tunable three/two-dimensional polymer/graphene oxide heterogeneous nanoporous membrane for ion transport. ACS Nano11, 10816–10824. 10.1021/acsnano.7b03576
57
ZouT. T.ZhaoB.XinW.WangY.WangB.ZhengX.et al. (2020). High-speed femtosecond laser plasmonic lithography and reduction of graphene oxide for anisotropic photoresponse. Light Sci. Appl.9:69. 10.1038/s41377-020-0311-2
Summary
Keywords
bioinspired surfaces, smart surfaces, switchable wettability, fabrication, applications
Citation
Han D-D, Cai Q, Chen Z-D, Li J-C, Mao J-W, Lv P and Gao B-R (2020) Bioinspired Surfaces With Switchable Wettability. Front. Chem. 8:692. doi: 10.3389/fchem.2020.00692
Received
25 May 2020
Accepted
03 July 2020
Published
12 August 2020
Volume
8 - 2020
Edited by
Jiale Yong, Xi'an Jiaotong University, China
Reviewed by
Moyuan Cao, Tianjin University, China; Dong Wu, University of Science and Technology of China, China
Updates
Copyright
© 2020 Han, Cai, Chen, Li, Mao, Lv and Gao.
This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Bing-Rong Gao brgao@jlu.edu.cn
This article was submitted to Physical Chemistry and Chemical Physics, a section of the journal Frontiers in Chemistry
†These authors have contributed equally to this work
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