Spatial separation of dual-cocatalysts on one-dimensional semiconductors for photocatalytic hydrogen production

Article abstract of DOI:10.1039/c9ta03090e

Light-driven hydrogen production using semiconductor photocatalysts has gained much interest owing to their ability to store sunlight in the form of portable chemical fuel. The spatial separation of dual-cocatalysts onto different surfaces has been considered as a useful strategy for fabricating dynamic particulate photocatalysts to hinder charge recombination and reverse reactions. Herein, using one-dimensional (1D) semiconductors, CdSe nanorods as an example, we experimentally demonstrated that photogenerated electrons and holes can be effectively separated along different directions of a 1D semiconductor. Following this phenomenon, the reduction cocatalyst Pt and oxidation cocatalyst PdS were spatially deposited on different sites via an in situ photodeposition process, which drastically enhanced the photocatalytic activity for hydrogen production to more than 20 times, thus exhibiting an extremely high apparent quantum efficiency (AQE) of ～45% at 420 nm. Further studies using photoluminescence spectroscopy indicated that the spatially separated dual-cocatalysts efficiently captured the photogenerated electrons and holes migrating to the surface, which greatly decreased the recombination of charge carriers and consequently led to superior photocatalytic performances. Our work provides an effective strategy for the rational construction of highly efficient photocatalyst systems based on (quasi) 1D semiconductors for artificial solar energy conversion.

Full text of DOI:10.1039/c9ta03090e

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Spatial separation of dual-cocatalysts on one-
dimensional semiconductors for photocatalytic
hydrogen production†
Cite this: DOI: 10.1039/c9ta03090e
Khakemin Khan,‡ab Xiaoping Tao,‡a Yue Zhao,ab Bin Zeng,ab Ming Shi,ab Na Ta,a
Received 22nd March 2019
Accepted 7th May 2019
a
a
Jianming Li,c Xu Jin,c Rengui Li
and Can Li
*
*
DOI: 10.1039/c9ta03090e
rsc.li/materials-a
Light-driven hydrogen production using semiconductor photo- environmentally friendly and renewable H2 fuels has received
catalysts has gained much interest owing to their ability to store considerable attention in the past few decades.1 Photocatalytic
sunlight in the form of portable chemical fuel. The spatial separation of water splitting offers a clean, sustainable and cost-effective
dual-cocatalysts onto different surfaces has been considered as pathway for hydrogen fuel production and is being considered
a useful strategy for fabricating dynamic particulate photocatalysts to as the “holy grail” of chemical science.2–5 In a typical photo-
hinder charge recombination and reverse reactions. Herein, using one- catalytic process, photocatalysts absorb incident light to
dimensional (1D) semiconductors, CdSe nanorods as an example, we generate electrons and holes, which are separated and trans-
experimentally demonstrated that photogenerated electrons and ferred to the surface for redox reactions.6 The recombination of
holes can be effectively separated along different directions of a 1D photogenerated charges and the inhibition of reverse reaction
semiconductor. Following this phenomenon, the reduction cocatalyst are challenging issues in photocatalysis.7 Dual cocatalysts, i.e.
Pt and oxidation cocatalyst PdS were spatially deposited on different reductive and oxidative cocatalysts, can improve the spatial
sites via an in situ photodeposition process, which drastically enhanced charge separation efficiency through quick trapping of photo-
the photocatalytic activity for hydrogen production to more than 20 generated holes by oxidative cocatalysts and withdrawing of
times, thus exhibiting an extremely high apparent quantum efficiency electrons by reductive cocatalysts.8–13 The rational construction
(AQE) of ꢀ45% at 420 nm. Further studies using photoluminescence of dual-cocatalysts on different sites so that the reduction and
spectroscopy indicated that the spatially separated dual-cocatalysts oxidation reactions can be separated in space, which has proven
efficiently captured the photogenerated electrons and holes to be crucial in inhibiting the charge recombination and reverse
migrating to the surface, which greatly decreased the recombination of reaction, leads to a remarkable enhancement in the photo-
charge carriers and consequently led to superior photocatalytic catalytic activities.11,14–16 One dimensional (1D) nanostructures
performances. Our work provides an effective strategy for the rational have drawn considerable attention owing to their intrinsic
construction of highly efficient photocatalyst systems based on (quasi) optical, structural, and electronic properties.17–21 Generally, a 1D
1D semiconductors for artificial solar energy conversion.
nanostructure is constructed with a high aspect ratio with at
least one of the dimensions as 1–100 nm, irrespective of whether
it is rod-, wire-, belt- or tube-shaped.22–24 A 1D nanostructure
provides a unique transit for charge transport along the long axis
of the 1D structure and decouples the direction of charge carrier
collection, which is favourable for the separation of electron–
hole pairs. Moreover, the tips of nanorods are usually correlated
with specic exposed facets of a single crystal,25–27 which helps in
selectively loading reduction cocatalysts (such as platinum and
gold)28–31 at the tip and oxidation cocatalysts such as CoO at the
lateral facets. Light-driven H2 production by using semi-
conductor nanocrystal heterostructures has gained much
interest owing to the ability to rationally improve their activity by
tailoring their composition, morphology, and size.10,29,30,32,33
However, there are few reports focusing on the spatial separation
of different cocatalysts on well-dened 1D nanostructured
semiconductors for photocatalytic water splitting.
1 Introduction
With the constant depletion of fossil fuels and their impact on
the environment, the conversion of solar energy into
aState Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese
Academy of Sciences, Dalian National Laboratory for Clean Energy, The Collaborative
Innovation Center of Chemistry for Energy Materials (iChem-2011), Zhongshan Road
457, Dalian, 116023, China. E-mail: canli@dicp.ac.cn; rgli@dicp.ac.cn
bUniversity of Chinese Academy of Sciences, Beijing, 100049, China
cResearch Institute of Petroleum Exploration & Development (RIPED), PetroChina, No.
20 Xueyuan Road, Haidian District, Beijing, 100083, P. R. China
† Electronic supplementary information (ESI) available. See DOI:
10.1039/c9ta03090e
‡ There authors contribute equally to this work.
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Herein, aiming for the rational designing of dual-cocatalysts intriguing the interests of elds including microelectronics and
on 1D nanostructure semiconductors, visible-light-responsive optics.35–37 Serving as a prototype material, CdSe nanorods were
CdSe nanorods were chosen as examples. Using an in situ synthesized using a hot-injection method similar to the re-
photo-reduction and photo-oxidation deposition as the probe ported process with an inconsequential modication.38 The
reaction, we demonstrated that photogenerated electrons and crystallinity of CdSe nanorods was conrmed from the X-ray
holes of CdSe nanorods were separated both parallelly and diffraction pattern, which showed well-aligned and strong
perpendicularly to the nanorod under visible-light irradiation. diffraction peaks indexed to the wurtzite structure (Fig. S1†),
The selective deposition of Pt and PdS nanoparticles, which act and its light absorption range reached more than ꢀ650 nm
as reduction and oxidation cocatalysts, respectively, was (Fig. S2†).
successfully fabricated at different positions of CdSe nanorods.
As shown in Fig. 2a and S3,† the as-prepared CdSe nanorods
Surprisingly, the spatially separated dual-cocatalyst (Pt and PdS) displayed a well-dened rod-like morphology with lengths of
system showed a remarkable enhancement in photocatalytic ꢀ2–3 mm and diameters of ꢀ15–20 nm. To identify the photo-
hydrogen production under visible light, which is more than 20 generated charge distribution on CdSe nanorods, in situ photo-
times higher than that of bare nanorods and exhibited an reduction and photo-oxidation depositions were introduced as
extremely high apparent quantum efficiency (AQE) of ꢀ45% at probing reactions to determine the transmittance of photo-
420 nm. Characterizations using photoluminescence spectros- generated electrons and holes. In our experiment, we chose the
copy indicate that the spatially separated dual-cocatalysts effi- photo-reduction deposition of Pt and photo-oxidation deposi-
ciently captured photogenerated charge carriers, which greatly tion of CoOx nanoparticles as probe reactions. As shown in
inhibited charge recombination and consequently led to supe- Fig. 2b and c, we found that almost all the Pt nanoparticles with
rior photocatalytic performances.
sizes of ꢀ2–6 nm were selectively deposited on the tip of CdSe
nanorods using H2PtCl6 as the precursor, indicating that the
photogenerated electrons were transmitted along the nanorod
and moved to the tip of the CdSe nanorods. Furthermore, aer
the photo-oxidation deposition of CoOx using Co(NO3)2 as the
precursor in the presence of NaIO3 as the sacricial reagent, we
found that most of the CoOx nanoparticles attached themselves
to the lateral surface of nanorods, revealing the fact that pho-
togenerated holes of CdSe were separated perpendicular to the
rod, which is complementary from the sites for the photo-
reduction deposition of Pt nanoparticles (Fig. 2d and e). Such
differentiated deposition sites for Pt and CoOx were further
conrmed by simultaneously depositing both Pt and CoOx on
CdSe nanorods (Fig. 2f). The chemical states of the deposited Pt
and CoOx were characterized by X-ray photoelectron spectros-
copy (XPS), and the metallic state for Pt and mixed metal oxide
nanoparticles of Co3O4 and Co2O3 was obtained (Fig. S4 and
S5†), demonstrating that the products of Pt and CoOx were
formed via photo-reduction and photo-oxidation deposition,
respectively. The above results clearly indicate that the photo-
generated electrons and holes are indeed spatially separated on
the tip and lateral facets of CdSe nanorods. As Pt is an efficient
reduction cocatalyst and PdS is proved as the best oxidation
cocatalyst in most of the sulphide and selenide semiconductors,
we tried to use PdS nanoparticles as oxidative cocatalysts. The
PdS nanoparticles were synthesized by injecting a certain
amount of PdCl2 solution in situ into the photocatalytic reaction
suspension containing Na2S–Na2SO3 solution, which was soni-
cated and stirred vigorously for half an hour followed by the
addition of CdSe photocatalyst. A localized intrinsic electric
eld was induced upon photoexcitation on the surface of CdSe,
which directed the electrons lengthwise and holes perpendic-
ular to the rod as demonstrated in the case of Pt–CoOx/CdSe. It
has also been reported that PdS nanoparticles could be depos-
ited on the surface of semiconductors through a photo-induced
2 Results and discussion
1D nanostructured semiconductors have been recognized to
exhibit unique properties for charge separation along the axis of
the 1D structure and decoupling the direction of charge carrier
collection.34 As photogenerated electrons and holes possess
differences in properties such as diffusion lengths, charge
mobility and effective mass, they induce unique behaviours for
the separation of electrons and holes once excited under light
irradiation. Fig. 1 shows the proposed schematic description of
the preferential separation of electron–hole pairs in a typical 1D
nanostructured semiconductor. Due to their different natures,
the photogenerated electrons and holes in 1D semiconductors
are possibly separated and transferred in different directions,
e.g., parallel or perpendicular to the 1D structure regardless of
rod or wire morphology, such that the electrons and holes are
spatially separated along different surfaces (sites) for the cor-
responding redox reactions. CdSe is a representative semi-
conductor with a wide light absorption range (bandgap of ꢀ1.7
eV), which exhibits a wide range of electrical and optical prop-
erties that depend sensitively on both size and shape, thus
process using PdCl2 as a precursor combined with an aqueous
solution of S2À
.
Following the above process, we fabricated
39
Fig. 1 Scheme of spatial separation of photogenerated charge carries
on one-dimensional semiconductors after light illumination.
PdS nanoparticles on the surface of CdSe and found that almost
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Fig. 2 TEM images of CdSe nanorods after an in situ photodeposition of noble metals and metal oxides. (a) CdSe nanorods; (b and c) CdSe
nanorods after the photo-reduction deposition of Pt nanoparticles, denoted as Pt/CdSe; (d and e) CdSe nanorods after the photo-oxidation
deposition of CoOx nanoparticles, denoted as CoOx/CdSe; (f) CdSe nanorods after simultaneous deposition of both Pt and CoOx nanoparticles,
denoted as Pt–CoOx/CdSe; (g) photo-induced deposition of PdS on CdSe nanorods, denoted as PdS/CdSe; (h and i) dual-deposition of Pt and
PdS on CdSe nanorods, denoted as Pt–PdS/CdSe; and (j) schematic description of CdSe nanorods after depositing with different species.
all the PdS nanoparticles appeared only on the lateral facets of and oxidation reactions, were evaluated. The photocatalytic
CdSe nanorods (Fig. 2g). The chemical states of PdS were also performance in terms of photocatalytic hydrogen production in
analysed from the XPS spectra (Fig. S6†). The dual deposition of the presence of Na2S–Na2SO3 solution under visible light was
Pt and PdS was further veried to be spatially separated on the determined for various CdSe-based photocatalysts such as
tip and lateral facets of CdSe nanorods, as shown in Fig. 2h and CdSe, Pt/CdSe, PdS/CdSe and Pt–PdS/CdSe. As shown in Fig. 3a,
i. This implies that the construction of Pt and PdS on the bare CdSe exhibited negligible photocatalytic activity for
electron-accumulating and hole-accumulating sites of CdSe hydrogen production without any cocatalysts. Aer depositing
nanorods was successfully achieved. The deposited Pt and PdS Pt as a cocatalyst, we found that the photocatalytic hydrogen
nanoparticles on the different surfaces of CdSe nanorods were production activity was remarkably enhanced, which was about
further validated using high-resolution TEM (HRTEM) charac- 3 times higher than that for bare CdSe, as Pt is a well-known
terization (Fig. S7†) and elemental mapping (Fig. S8†). To know reduction cocatalyst. A comparable result was achieved when
well about the redox deposition sites, Fig. 2j gives a schematic PdS nanoparticles were deposited on the CdSe nanorod as PdS
description to show the deposition sites for the above- is reported to be an efficient cocatalyst for the oxidation of S2À
mentioned cocatalysts on CdSe nanorods. Based on the ions.40 Interestingly, when both Pt and PdS were selectively
results, we can draw a conclusion that the photogenerated deposited on different sites of the CdSe nanorod simulta-
electrons and holes of CdSe nanorods are separated and neously (denoted Pt–PdS/CdSe), as shown in Fig. 3a and b, the
transferred parallelly and perpendicularly to the rod due to the rate of photocatalytic H2 production drastically increased and
intrinsic electric eld induced by photoexcitation, resulting in reached 5300 mmol hÀ1 gÀ1, which was more than 20 times
the spatial separation of electrons and holes. This further higher than that of bare CdSe and nearly 10 times higher than
veried the scheme for the 1D nanostructured semiconductor those of Pt/CdSe and PdS/CdSe. The apparent quantum effi-
that was predicted in Fig. 1.
ciency (AQE) for photocatalytic hydrogen production on the Pt–
To recognize the effect of spatial charge separation on CdSe PdS/CdSe photocatalyst was measured to be ꢀ45% at 420 nm.
nanorods, the photocatalytic performance of photocatalysts As far as we know, it is one of the highest AQEs for CdSe-based
deposited with Pt and PdS, acting as active sites for reduction photocatalysts reported so far. The dual-deposition of Pt and
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Fig. 3 (a and b) Photocatalytic H2 evolution and apparent quantum yield under visible light irradiation over CdSe, Pt/CdSe, PdS/CdSe and Pt–
PdS/CdSe; (c and d) photoluminescence emission spectra and quenching percentage of CdSe after depositing different cocatalysts. Reaction
condition: catalyst, 100 mg; 0.1 M Na2S–Na2SO3 aqueous solution (100 mL); light source: Xe lamp (300 W) with an optical filter (l > 420 nm); the
amount of cocatalyst was fixed to 0.5% for both Pt and PdS.
CoOx was also found to exhibit a similar synergistic effect as photogenerated charges, which will reduce the charge recom-
that of Pt–PdS/CdSe although the total activity was lower, as bination. Comparably, Fig. 3d shows the quenching efficiency
shown in Fig. S9.† The results clearly demonstrate that the of the uorescence intensity of CdSe nanorods aer loading
superior photocatalytic properties can only be obtained when with different cocatalysts, which was calculated from the uo-
the reduction cocatalyst and oxidation cocatalyst are spatially rescence intensities in Fig. 3c. It is surprisingly found that the
separated on different sites of the semiconductors. To investi- trend of quenching efficiency of uorescence intensity with
gate why an extremely high photocatalytic activity is only ach- different cocatalysts is in good agreement with their photo-
ieved when dual-cocatalysts are spatially separated on CdSe catalytic hydrogen production activities. Predominantly, for Pt–
nanorods, photoluminescence (PL) emission spectra were ob- PdS/CdSe, more than 95% uorescence intensity was found to
tained to monitor the photoexcited energy/electron transfer and be quenched aer depositing Pt and PdS that were spatially
recombination processes of CdSe-based photocatalysts. Fig. 3c separated on CdSe nanorods. As conrmed by the photo-
shows the comparison of photoluminescence spectra of CdSe, luminescence spectra, Pt–PdS/CdSe exhibited the highest
Pt/CdSe, PdS/CdSe, and Pt–PdS/CdSe samples. The bare CdSe quenching efficiency, indicating that a rapid ow of photo-
displays an intense emission band centred at ꢀ675 nm, which generated electrons migrated to Pt nanoparticles located at the
is ascribed to its band-edge emission. The uorescence inten- tip of CdSe nanorods, and photogenerated holes were quickly
sities were drastically quenched by loading Pt and PdS cocata- extracted by PdS located on the lateral surface with light irra-
lysts and even further by co-loading both Pt and PdS on CdSe diation. Therefore, we can postulate that the superior photo-
nanorods. These results suggested that Pt and PdS cocatalysts catalytic performance of Pt–PdS/CdSe photocatalyst is
efficiently captured the photogenerated electrons and holes essentially owing to the effective prohibition of recombination
once they migrated to the surface, which effectively reduced the processes by spatially separated cocatalysts on different sites. In
probability of charge recombination. It should be noted that the this case, Pt nanoparticles are responsible for transferring the
Schottky junction at the interface of Pt (PdS)/CdSe nanorods can photogenerated electrons while the oxidative cocatalysts PdS
provide
a driving force for the spatial separation of are responsible for the effective removal of photogenerated
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holes.41,42 Therefore, we stress that the superior photocatalytic separated Pt and PdS on different sites (Fig. 4b). The photo-
activity is due to the unique one-dimensional nanostructure on catalytic activities of samples with different sizes have been
which the dual-cocatalysts are spatially separated, which compared by normalization in terms of the exposed surface of
decreases the probability of charge recombination and the cocatalysts.11 The results indicate that the drastic difference
improves the charge separation efficiency. The stability of the in the activity among the samples is primarily owing to the
synthesized sample of Pt–PdS/CdSe (NRs) is assessed by con- spatial separation of photogenerated charges instead of the
ducting the reaction for 16 h with the H2 generation amount in variation in sizes caused by different methods for cocatalyst
every four hours being measured. No plausible deactivation is deposition (Fig. S12†).
perceived in the consecutive three cycles (Fig. S10†), conrming
the extraordinary stability of the Pt–PdS/CdSe (NRs) semiconductors, we employed CdSe nanoparticles instead of
photocatalyst. CdSe nanorods and evaluated their photocatalytic activity under
To recognize the merits of spatial charge separation on 1D
Comparably, the dual-cocatalysts were randomly loaded on the same conditions for comparison (Fig. 4c). The photo-
CdSe nanorods through a traditional impregnation method catalytic H2 evolution of CdSe nanoparticles is observed to be
without any selectivity. Fig. 4a shows the TEM image of Pt and much inferior to that of CdSe nanorods at 5300 mmol hÀ1 gÀ1
PdS deposited on CdSe nanorods via an impregnation method, and 1280 mmol hÀ1 gÀ1 for nanorods and nanoparticles,
and along with this we have synthesized CdSe nanoparticles respectively (Fig. 4d). It should be emphasized that the surface
using a similar hot-injection method at the same temperature areas of CdSe nanoparticles are more than an order of magni-
using CdSe nanorods. We can see that all the Pt and PdS tude than those of CdSe nanorods. If the photocatalytic activi-
nanoparticles were randomly distributed on the surface of CdSe ties were normalized with respect to surface area, the difference
nanorods and nanoparticles (Fig. S11†). The corresponding in photocatalytic performances between nanoparticles and
photocatalytic activity of CdSe nanorods with a random distri- nanorods would be further enlarged. The apparent quantum
bution of dual-cocatalysts is found to be lower by more than an yield of Pt–PdS/CdSe nanoparticles was measured to be ꢀ15%,
order of magnitude than that of CdSe nanorods with spatially which was much lower than that of nanorods, possibly due to
Fig. 4 (a) TEM image of CdSe nanorods with random deposition of Pt and PdS by the impregnation method; (b) comparative H2 production of
CdSe nanorods with selective deposition and random deposition of dual-cocatalysts; (c) TEM image of CdSe nanoparticles prepared under the
similar conditions; (d) comparative H2 production of CdSe nanorods (NRs) and nanoparticles (NPs), S.D. means selective deposition and R.D.
means random deposition: catalyst, 100 mg; 0.1 M Na2S–Na2SO3 aqueous solution (100 mL); light source: Xe lamp (300 W) with an optical filter (l
> 420 nm).
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Fig. 5 TEM images of CdSe nanorods with controlling different lengths of rods, (a) small rod (SR) ꢀ2–3 mm, (b) medium rod (MR) ꢀ300–400 nm,
(c) large rod (LR) ꢀ20 nm; (d) time course of photocatalytic H2 generation by CdSe with different rod lengths in the presence of optimized
amount of Pt and PdS; (e) photocatalytic H2 production performances and apparent quantum yield by different nanocrystals; (f) the relation
between the aspect ratio length/diameter (L/D) of CdSe nanorods. Reaction conditions: catalyst, 100 mg; 0.1 M Na2S–Na2SO3 aqueous solution
(100 mL); light source: Xe lamp (300 W) with an optical filter (l > 420 nm).
the poor charge separation in nanoparticles as conrmed by the measurements under an excitation wavelength of 630 nm
photoluminescence emission spectra in Fig. S13.† From the (Fig. S14†). The PL quenching principally reects an inhibited
results obtained, it is expected that CdSe nanoparticles show recombination rate of charge carriers, which can greatly
phonon blockage for their energetic electrons during a photo- enhance H2 production by increasing the length of nanorods.
excitation process. Nevertheless, the photoexcited electrons in The increase in the lifetime of trapped holes for longer nano-
semiconductor nanoparticles relax very quickly compared to rods may be attributed to the larger volume available to the
those in nanorods, which decreases the lifetime of photo- electrons to remain separated from the hole. Further studies on
generated carriers in CdSe nanoparticles. Our results also the intrinsic mechanism of the relationship between the L/D
revealed that the photogenerated charges can be efficiently ratio and photocatalytic activity are being pursued.
separated on the 1D nanostructures compared with nano-
The above results indicate that the separation of dual-
particles. The unique property of spatial charge separation on cocatalysts on CdSe nanorod plays a key role in enhancing the
1D semiconductors will have a promising potential application
in photocatalysis.
As the spatial charge separation is dependent on the
geometrical structure of the nanorod, we synthesized different
CdSe nanocrystals with varied rod lengths to investigate the
effect of length/diameter ratio on spatial charge separation.
TEM images in Fig. 5a–c show that the average length of the as-
synthesized CdSe nanorods were tuned from ꢀ20 nm to
300 nm, even to more than 2 mm. We found that the photo-
catalytic activities over CdSe nanorods increased with an
increasing rod length, i.e., longer nanorods exhibited better
photocatalytic activities. It can be proposed that the increase in
the L/D ratio can optimize the intrinsic properties for spatial
charge separation of the nanorods, which further results in
different photocatalytic performances. The separation and
recombination rates of photo-excited charges of the H2 evolu-
tion system are also investigated using photoluminescence (PL)
Fig.
6 Scheme of the proposed mechanism for photocatalytic
hydrogen production on one-dimensional CdSe nanorods with spatial
separation of dual-cocatalysts.
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spatial charge separation and photocatalytic hydrogen genera-
tion activity. Fig. 6 shows a schematic description of the spatial
charge separation process on the CdSe nanorod. Upon light
irradiation on CdSe nanorods, the photogenerated electron–
hole pair separated and transferred to the surface and then the
electrons were quickly trapped by Pt nanoparticles, which
facilitated the catalytic reduction of protons to hydrogen, while
the holes migrated to the side surface of the nanorod trapped by
PdS. The quick trapping of electrons and holes by dual-
cocatalysts also increases the charge separation and prohibits
charge recombination. Therefore, both the unique spatial
charge separation for nanorods and the spatial distribution of
dual-cocatalysts contribute to the superior photocatalytic
activity in our experiment.
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There are no conicts to declare.
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Acknowledgements
This work is nancially supported by Key Research Program of
Frontier Sciences, Chinese Academy of Sciences (QYZDY-SSW- 25 Z. Liu, J. Zhang and W. Yan, ACS Sustainable Chem. Eng.,
JSC023), National Natural Science Foundation of China 2018, 6, 3565.
(21673230, 21761142018), Dalian Institute of Chemical Physics 26 A. A. Pawar, S. Halivni, N. Waiskopf, Y. Ben-Shahar,
(DICP ZZBS201610), Youth Innovation Promotion Association
of Chinese Academy of Sciences (2016167), Strategic Priority
M. Soreni-Harari, S. Bergbreiter, U. Banin and S. Magdassi,
Nano Lett., 2017, 17, 4497.
Research Program of Chinese Academy of Sciences 27 W. Lu, P. Gao, W. B. Jian, Z. L. Wang and J. Fang, J. Am.
(XDA21010207) and the R & D department of Petro China.
Chem. Soc., 2004, 126, 14816.
28 T. Simon, M. T. Carlson, J. K. Stolarczyk and J. Feldmann,
ACS Energy Lett., 2016, 1, 1137.
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