Photoredox-Catalyzed Simultaneous Olefin Hydrogenation and Alcohol Oxidation over Crystalline Porous Polymeric Carbon Nitride

Article abstract of DOI:10.1002/cssc.202101041

Booming of photocatalytic water splitting technology (PWST) opens a new avenue for the sustainable synthesis of high-value-added hydrogenated and oxidized fine chemicals, in which the design of efficient semiconductors for the in-situ and synergistic utilization of photogenerated redox centers are key roles. Herein, a porous polymeric carbon nitride (PPCN) with a crystalline backbone was constructed for visible light-induced photocatalytic hydrogen generation by photoexcited electrons, followed by in-situ utilization for olefin hydrogenation. Simultaneously, various alcohols were selectively transformed to valuable aldehydes or ketones by photoexcited holes. The porosity of PPCN provided it with a large surface area and a short transfer path for photogenerated carriers from the bulk to the surface, and the crystalline structure facilitated photogenerated charge transfer and separation, thus enhancing the overall photocatalytic performance. High reactivity and selectivity, good functionality tolerance, and broad reaction scope were achieved by this concerted photocatalysis system. The results contribute to the development of highly efficient semiconductor photocatalysts and synergistic redox reaction systems based on PWST for high-value-added fine chemical production.

Full text of DOI:10.1002/cssc.202101041

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Photoredox-Catalyzed Simultaneous Olefin Hydrogenation
and Alcohol Oxidation over Crystalline Porous Polymeric
Carbon Nitride
Chuntian Qiu+,[b] Yangyang Sun+,[a] Yangsen Xu,[b] Bing Zhang,[b] Xu Zhang,[a] Lei Yu,*[a] and
Chenliang Su*[b]
Booming of photocatalytic water splitting technology (PWST)
opens a new avenue for the sustainable synthesis of high-value-
added hydrogenated and oxidized fine chemicals, in which the
design of efficient semiconductors for the in-situ and synergistic
utilization of photogenerated redox centers are key roles.
Herein, a porous polymeric carbon nitride (PPCN) with a
crystalline backbone was constructed for visible light-induced
photocatalytic hydrogen generation by photoexcited electrons,
followed by in-situ utilization for olefin hydrogenation. Simulta-
neously, various alcohols were selectively transformed to
valuable aldehydes or ketones by photoexcited holes. The
porosity of PPCN provided it with a large surface area and a
short transfer path for photogenerated carriers from the bulk to
the surface, and the crystalline structure facilitated photo-
generated charge transfer and separation, thus enhancing the
overall photocatalytic performance. High reactivity and selectiv-
ity, good functionality tolerance, and broad reaction scope were
achieved by this concerted photocatalysis system. The results
contribute to the development of highly efficient semiconduc-
tor photocatalysts and synergistic redox reaction systems based
on PWST for high-value-added fine chemical production.
Introduction
for producing valuable reduced and oxidized chemicals, while
remaining more atom-economic; thus, PWST-based hydrogena-
tion is of great significance to promote practical input/output
efficiency.[23,24] In this regard, the rational design of efficient
semiconductor photocatalysts and the construction of syner-
gistic systems for hydrogen generation, in-situ utilization, and
simultaneous oxidation reactions are the key factors that remain
a great challenge.
Photocatalytic water splitting technology (PWST) serves as a
green route for the chemical utilization of solar energy to
produce green H2 energy that contributes to solving the current
environmental and energy crisis.[1–6] To date, solar-driven H2
production from water is still considered fundamental research
due to the low efficiency of overall water decomposition and/or
the consumption of hole scavengers.[7–11] Recently, as
a
Generally, semiconductor photocatalysis can be divided into
two major parts including photoelectric processes and organic
transformation,[25,26] while the overall course of the reaction can
be broken down into multiple steps: (1) light absorption and
substrate adsorption; (2) photogenerated charge carrier separa-
tion (electron-hole pairs); (3) charge transfer from the bulk to
the interface and/or surface to form redox centers; (4) interfacial
electron charge transfer from and/or to surface adsorbed
substrates to form redox intermediates (substrate activation);
and (5) product formation and desorption. The design and
synthesis of efficient semiconductors and matched cocatalysts
for specific redox reactions are complicated and challenging,
and the structural and textural properties of semiconductors
are important for both the photoelectric and organic trans-
formation processes.[27–33] Crystalline K-intercalated polymeric
carbon nitrides (KPCNs), which demonstrate appropriate redox
potential and good photoelectric properties, can serve as
efficient and cost-effective photocatalyst candidates.[16,32–38] The
crystalline structure can significantly facilitate photogenerated
charge transfer and separation [steps (1)–(3)]. However, bulk
morphology with its limited number of active sites hinders the
photogenerated charge transfer from and/or to surface
adsorbed substrates and chemical-mass transfer processes
[steps (4) and (5)]. In this regard, improved textural features,
promising alternative strategy, the manufacture of high-value-
added hydrogenated fine chemicals by the in-situ utilization of
photogenerated active H-species from water splitting has been
increasingly studied.[12–14] Compared with traditional thermal-
driven hydrogenation reactions, PWST-based hydrogenations
can be achieved at room temperature and atmospheric
pressure without pressurized H2 gas and elaborate experimental
setups.[15–22] This technology puts us one step closer to the
simultaneous utilization of photogenerated electrons and holes
[a] Y. Sun,+ Prof. X. Zhang, Prof. L. Yu
School of Chemistry and Chemical Engineering
Yangzhou University
Yangzhou, 225002 (P. R. China)
E-mail: yulei@yzu.edu.cn
[b] Dr. C. Qiu,+ Dr. Y. Xu, Dr. B. Zhang, Prof. C. Su
SZU-NUS Collaborative Center and
International Collaborative Laboratory of 2D Materials for
Optoelectronic Science & Technology of Ministry of Education
Institute of Microscale Optoelectronics
Shenzhen University
Shenzhen 518060 (P. R. China)
E-mail: chmsuc@szu.edu.cn
[+] These authors contributed equally to this work.
Supporting information for this article is available on the WWW under
https://doi.org/10.1002/cssc.202101041
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such as a higher porosity, larger surface area, and retention of
inherent crystallinity, are highly desired to further enhance the
overall photocatalytic performance.
improved textural properties support more active sites and
facilitate mass transfer, thereby enhancing catalytic activity.
Next, the photoelectric properties, such as the light harvest-
ing behavior, band structure, and charge transfer of the as-
synthesized PCN-based semiconductors were determined (Fig-
ure 2). UV/Vis diffuse reflectance spectra (DRS) showed that the
light absorption of PPCN had a slight blueshift compared with
KPCN but had better absorption than that of pristine PCN in the
visible light region (Figure 2a). Sharp light absorption edges for
both PPCN and KPCN were observed at approximately 465 nm
(Figures S2 and S3). Combined with the XRD analysis, the sharp
light absorption edges further proved that PPCN possessed a
crystalline structure similar to that of KPCN (Figure S4). Calcu-
lation of the Kubelka-Munk function plots revealed that the
bandgap of PPCN was approximately 2.65 eV (Figure 2a). The
deduced flat-band potential measured by Mott-Schottky plots is
À 1.19 V (vs. Ag/AgCl), which is converted to be À 0.99 V [vs.
normal hydrogen electrode (NHE)] (Figure 2b). Thus, the
conduction band (CB) and valence band (VB) positions are
À 0.99 and 1.66 eV (vs. NHE), respectively. Subsequently, the
photocurrent intensities of the PPCN, KPCN, and PCN photo-
catalysts were detected. PPCN and KPCN showed almost the
same photocurrent intensity, which was approximately 10 times
higher than that of PCN under both UV and visible light
irradiation (Figure 2c and Figure S6). This result strongly
revealed that PPCN and KPCN with crystalline structures had
more efficient charge separation and transfer (Figure S7), which
were crucial for the subsequent redox reactions. As a model
reaction and pre-step, H2 generation from water could reflect
the activities of semiconductor photocatalysts and provide an
abundance of active H-species for the subsequent hydro-
genation reactions. Apparently, owing to its better light
absorption and more efficient charge separation and transfer,
crystalline KPCN had remarkably enhanced activity compared to
pristine PCN towards H2 production under visible light irradi-
ation. PPCN maintained its crystalline structure and had
improved textural properties, showing a H2 generation rate (
�2500 μmolgÀ 1 hÀ 1) that was 3 times higher than that of KPCN
(�600 μmolgÀ 1 hÀ 1) (Figure 2d and Figure S8). In this regard,
porous PPCN with a crystalline structure could be considered an
improved photocatalyst candidate for photocatalytic hydrogen
generation and in-situ utilization.
Herein, we synthesize porous polymeric carbon nitride
(PPCN), which maintains a crystalline structure backbone and
possesses far improved textural properties. PPCN exhibits
comparable efficiency to KPCN and far beyond PCN in regard to
its photoexcited charge carrier separation and migration from
bulk to surface. Owing to its porous structure and large surface
area, the PPCN-based photocatalyst achieves remarkably en-
hanced activities towards hydrogen evolution and in-situ
utilization for olefin hydrogenation and simultaneous alcohol
oxidation. Results not only reveal the relationships among the
photocatalytic performance as well as the structural, textural,
and photoelectric properties but also attest to the promising
potential of PWST for the simultaneous synthesis of both high-
value-added reduced and oxidized fine chemicals under mild
conditions.
Results and Discussion
The as-synthesized PPCN, KPCN, and PCN were first subjected
to X-ray diffraction (XRD) to identify their crystalline structures
°
(Figure 1a and Figure S1). A sharp peak at approximately 28.1
ascribed to the (002) plane of typical carbon nitride was
observed in three of those PCN-based samples.[35,39,40] Diffraction
peaks belonging to K-inserted polymeric carbon nitride at 8.0,
°
10.2, 32.2, 35.4, and 43.1 were observed in both KPCN and
PPCN.[16] These two similar XRD patterns suggested that PPCN
possessed the same crystalline structure as KPCN. Moreover, the
textural properties of PPCN were greatly improved as shown in
Figure 1b. Because of the bulk crystalline structure, KPCN had a
low Brunauer-Emmett-Teller (BET) surface area of approximately
7.7 m2 gÀ 1, which was even lower than that of pristine PCN
(19.4 m2 gÀ 1). After a pore-making process, crystalline PPCN
showed a far improved surface area of 68.3 m2 gÀ 1. The N2
absorption-desorption isotherms of the three samples showed
typical characteristics of a mesoporous material, indicating the
absence of the inherent porosities of the PCNs. The majority of
pores in the bulk KPCN and pristine PCN were in a narrow range
of 2–3 nm (Figure 1c). In contrast, PPCN showed a broad pore-
size distribution in the mesoporous region (2–50 nm). These
Figure 1. Structural and textural properties of the as-synthesized PPCN, KPCN, and PCN photocatalysts: (a) XRD patterns; (b) N2 adsorption-desorption
isotherms; and (c) pore-size distributions.
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Figure 2. Photoelectric properties of the as-synthesized PPCN, KPCN, and PCN photocatalysts. (a) UV/Vis DRS; the inset shows the Kubelka-Munk function plots
of PPCN. (b) Mott-Schottky plots of PPCN photocatalyst in a 0.5 m Na2SO4 aqueous solution. (c) Photocurrent intensity of PPCN, KPCN, and PCN photocatalysts
under visible light irradiation (λ>420 nm). (d) H2 evolution from water under visible light irradiation (420 nm �λ�780 nm) with a 300 W Xe lamp at 283 K
over PPCN, KPCN, and PCN. Reaction conditions: 20 mg catalyst, 3 wt% Pd co-catalyst, 45 mL H2O, and 5 mL methanol (or ethanol over PPCN).
Subsequently, PPCN as a photocatalyst and support was
combined with Pd nanoparticles to realize a bifunctional
photocatalyst. As shown in Figure 3, approximately 3 wt%
metallic Pd nanoparticles were uniformly loaded onto PPCN via
photo-deposition (Figure 3d–f and Figure S9). In addition, unlike
the bulk morphology of KPCN (Figure 3a), PPCN showed a
porous structure and had a crystalline backbone that could be
directly observed in the transmission electron microscopy (TEM)
images (Figure 3b–e). This result was consistent with the
previous characterizations, further verifying the construction of
a porous and crystalline structure, which provided a large
surface area and broad range of mesopores while also
facilitating charge transfer from the bulk to the surface. These
improved properties could enhance both the hydrogen evolu-
tion and hydrogenation reactions.
The PCN, KPCN, and PPCN photocatalysts were then
optimized and employed for the synergistic hydrogen evolution
and olefin hydrogenation reactions (Figure 4a and Figure S10).
PPCN with 3 wt% Pd cocatalyst provided 58% yields of hydro-
genated alkane products within 2 h, which was almost twice
that of KPCN. Compared with the trace yield obtained over the
PCN photocatalyst, these results highlighted the importance of
the electronic, structural, and textural properties of semi-
conductors for heterogeneous photocatalytic reactions. Clearly,
the photocatalytic water splitting process for producing an
abundance of active H species was the first step and an
indispensable process for the following hydrogenation reac-
Figure 3. TEM images of (a) KPCN, (b,c) PPCN, and (d,e) 3%Pd/PPCN. (f) Elemental mappings of 3%Pd/PPCN (scale bars: 250 nm).
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Figure 4. Optimization of the PPCN-based photocatalysts for photocatalytic H2 generation and their in-situ utilization for olefin hydrogenation. (a) Product
yields over 3 wt% Pd-loaded PCN, KPCN, and PPCN. (b) Product yields over PPCN with different active metals and various loading amounts. (c) Product yields
over a 3% Pd/PPCN catalyst using different alcohols as solvents and hole scavengers. Reaction conditions: 20 mg catalyst, 0.5 mmol substrate (α-methyl
°
styrene), 0.5 mmol AlCl3, 20 W LED light (420 nm), 20 C, 2 h, CH3CN/H2O/alcohol=2:1.5:1.5 mL. (d) Graphic illustration of the synergistic multiple-functional
redox systems for valuable hydrogenated and oxidized products.
tions. With the assistance of Lewis acid AlCl3, high concentration
of protons could be dissociated from water, thus facilitating the
generation of active H species.[12,13,41] In addition, the light
absorption, bandgap, charge separation, and transfer of semi-
conductors that highly related to photocatalytic activity were
primary considerations for high overall performance. Semi-
conductors, such as ZnS and TiO2, commonly achieved higher
H2 evolution activity than the PCN-based photocatalysts with
the assistance of Pd or Pt cocatalysts under UV light irradiation.
However, side-reactions, such as photodegradation and poly-
merization, might occur under UV light irradiation, which
greatly reduced the yield of hydrogenated products (Fig-
ure S11). Moreover, transition metal sulfide-based photocata-
lysts, such as ZnS, showed trace yields of hydrogenated
products under UV light irradiation. The same trace yield was
also obtained over CdS under visible light irradiation, indicating
that sulfide-based photocatalysts were not available for the
hydrogenation reactions due to the toxicity of sulfur to
palladium.
In addition to the semiconductor supports, different active
bifunctional metals such as Au and Pt, and various Pd loading
on PPCN (Figure 4b,c, and Figures S12–S14), would also greatly
affect the final yields of hydrogenated products. As shown in
Figure 4b, a low Pd loading might not provide a sufficient
number of active sites, while a high loading would lead to the
aggregation of Pd particles. Hence, the highest yield was
achieved over the optimized 3 wt% Pd-loaded catalyst, which
was also higher than that of Pt- and Au-based photocatalysts.
More importantly, due to its lower redox potential than that of
water to oxygen, methanol is commonly used as a hole
scavenger to accelerate charge separation and thus enhance
the hydrogen evolution process. Herein, alcohol could also act
as a secondary solvent to mix with water, organic solvents, and
substrates, forming a homogeneous reaction system. Remark-
ably, other alcohols, including ethanol, ethylene glycol, prop-
anol, glycerin, and benzyl alcohol, can be used as efficient hole
scavengers to achieve moderate to high product yields (Fig-
ure 4c). Bio-based ethanol, as
a green and inexpensive
candidate, achieves a comparable yield (52%) to that of
methanol (58%); thus, it could be a more economical and
sustainable hole-scavenger. Moreover, this half oxidation route
could be used to produce valuable oxidation products, such as
benzyl alcohol to benzaldehyde, thus showing high potential to
simultaneously produce hydrogenated and oxidized chemicals
by photoexcited redox centers under mild conditions (Fig-
ure 4d).[42] In this work, we progressively constructed and
developed two concerted photocatalysis systems: (1) hydrogen
evolution and in-situ utilization for olefin hydrogenation using
water as the H-source and bio-ethanol as a sustainable hole
scavenger; and (2) hydrogen evolution from water and in-situ
utilization for olefin hydrogenation coupled with simultaneous
alcohol oxidation, which were separately investigated as
follows.
The above characterizations suggested that PPCN with a
crystalline backbone was a promising candidate to utilize the
photogenerated H-species in situ for olefin hydrogenation with
the use of sustainable ethanol as a hole scavenger. As shown in
Scheme 1, typical olefins such as α-methyl styrene (2a), β-
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be simultaneously produced by the oxidation half reaction
(Scheme 2). Benzyl alcohol (4a) and its derivatives with
electron-withdrawing and electron-donating groups (4b–4f)
were effectively converted into their corresponding aldehydes.
Both the hydrogenation and oxidation half reactions showed
good to high yields. The 1,2-diphenylethene (2d) and nicotinyl
alcohol (4g) coupled reaction showed high yields (83 and 95%,
respectively), indicating that this concerted photocatalysis
system might be available for various heterocycle-alcohols.
Aliphatic alcohol [i.e., cyclohexyl methanol (4h)] was also
suitable for this concept; however, the activities of both
hydrogenation and oxidation reactions were relatively lower
than those of the aromatic alcohols. In addition, secondary
alcohols such as 2-benzyl alcohol and its derivatives (4i–4l)
could be converted into their corresponding ketones, although
the obtained yields were unsatisfactory within the reaction
time.
Finally, the reaction route and possible mechanisms were
investigated. When TEMPO was added (2b in Scheme 1), a trace
yield was obtained, indicating that the reaction may proceed
through a photocatalytic radical route (Figure 5a). In addition,
the “waterless-route” was available for the synergistic hydro-
genation reaction but showed much less activity (Figure S15).
Furthermore, when the H-source was replaced by H2 gas, a trace
yield of the hydrogenation product was obtained under either a
light or dark environment. Instead, polymerized olefins such as
dimers and trimers were the main products (Figure S16),
indicating that water was the H-source and that the in-situ
generated H-species that were adsorbed on the material surface
Scheme 1. Substrate scope of photocatalytic H2 generation and in-situ
utilization for olefin hydrogenation over PPCN-based catalyst. Reaction
conditions: 0.5 mmol reactant, 30 mg 3 wt% Pd/KPCN, 1.5 mL H2O, 1.5 mL
°
CH3CH2OH, 2 mL CH3CN, 0.5 mmol AlCl3, 20 W LED light (420 nm), 20 C for
6 h; GC yields were analyzed using standard calibration curves (0.5 mmol
mesitylene as internal standard). [a] 2,2,6,6-Tetramethylpiperidinooxy (TEM-
PO, 2 equiv.) was added. [b] Isolated yield. The isolated product yield was
calculated by dividing the amount of the obtained desired product.
methylstyrene (2c), and 1,2-diphenylethene (2d) achieved high
yields of over 90% of the hydrogenated products over the Pd/
PPCN catalyst under LED light (420 nm) irradiation. Representa-
tive aromatic α,β-unsaturated ketones such as acetocinnamone,
ethyl
cinnamate,
E-chalcone,
and
3,4-dimeth-
oxybenzylideneacetone were effectively converted to the
corresponding hydrogenated alkanes in high yields (2e 93%, 2f
90%, 2g 83%, and 1h 88%, respectively). Aliphatic α,β-
unsaturated ketone also showed very high yield (2i 94%) within
a longer reaction time (24 h). Remarkably, 4-vinylphenylboronic
acid was well tolerated in the reaction system and afforded the
corresponding product (2j) in 82% yield, which could be used
as a typical phenylboronic acid intermediate in cross-coupling
reactions. Benzalmalononitrile and benzo-γ-pyrone could also
be subjected to the reaction, and moderate yields (2k, 2l) of
the products were obtained. In addition, aromatic aldehydes
and acids bearing C=C bonds provided the corresponding
olefin hydrogenated products in moderate to high yields (2m–
2p) with high selectivity. N-alkyl amines are universally present
in pharmaceuticals and natural products. With this mild
protocol, both hydrogenated aromatic and aliphatic amines
(2q–2t) could be easily obtained in moderate to high yields,
highlighting the good functionality tolerance of this protocol.
The simultaneous olefin hydrogenation and alcohol oxida-
tion induced by photogenerated electrons and holes were then
conducted over crystalline PPCN with Pd. In addition to hole
scavengers (i.e., methanol or ethanol) valuable alcohols could
Scheme 2. Concerted photocatalysis of olefin hydrogenation and alcohol
oxidation over the Pd/PPCN catalyst. Reaction conditions: 0.3 mmol olefin
(1,2-diphenylethene), 0.9 mmol alcohol substrate, 30 mg 3 wt% Pd/KPCN,
°
3 mL H2O, 5 mL CH3CN, 0.5 mmol AlCl3, 20 W LED light (420 nm), 20 C, 20 h.
GC yields were calculated by standard calibration curves (0.3 mmol biphenyl
as an internal standard).
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Figure 5. Study on the mechanism (a) and proposed reaction paths (b). Reaction conditions: 20 mg catalyst, 0.5 mmol substrate (α-methyl styrene), 0.5 mmol
°
AlCl3, 2 mL CH3CN, 3 mL H2O and/or methanol, 1 atm H2, 20 W LED light (420 nm), 20 C, 2 h.
were critical for effective olefin hydrogenation.[16,25,43,44] On these
basis, the possible mechanism was proposed in Figure 5b.
Owing to the simultaneous redox nature on the semiconductor
surface, both the reduction and oxidation half reactions can be
utilized for valuable chemical production.
Preparation of Pd/PPCN catalysts
Approximately 3.0 wt% of Pd supported on PPCN (or KPCN, PCN)
was prepared by photodeposition process. Briefly, a mixed solution
with glycol (20 mL), deionized water (80 mL), and as-synthesized
catalysts (300 mg) was ultrasonically treated for 2 h. Then 84 μL of
1.0 m H2PdCl4 was added, and the solution was illuminated under
300 W Xe lamp for 1 h to reduce Pd2+. After centrifugation and
washing with deionized water and ethanol, the obtained deposition
Conclusions
°
was dried at 80 C overnight, and as-prepared samples were
denoted as Pd/PPCN (or Pd/KPCN, Pd/PCN).
We designed and synthesized a porous polymeric carbon
nitride (PCN) with a crystalline backbone by using CaCO3 as a
template. The obtained porous (P)PCN showed improved
structural, textural and photoelectric properties compared with
K-intercalated PCN and pristine PCN. The porous and crystalline
structure endowed PPCN with a large surface area and a broad
mesopore size distribution that facilitated mass transfer and
charge transfer from the bulk to the surface. Hence, the
concerted photocatalysis system involving hydrogen genera-
tion, in-situ utilization, and simultaneous alcohol oxidation
reactions were constructed. The results show high potential to
further develop efficient semiconductor photocatalysts for the
synergistic production of valuable hydrogenated and oxidized
chemicals based on photocatalytic water splitting technology
using photogenerated electrons and holes under mild con-
ditions instead of with a heat source, high pressure and H2 gas.
Photocatalytic H2 evolution
Briefly, the Pd-loaded photocatalyst (20 mg) was suspended in an
aqueous solution (50 mL) containing 10 vol% alcohol (5 mL)
solution under visible light (420 nm�λ�780 nm) irradiation at
°
10 C using Labsolar VIAG (Perfectlight Technology Co., Ltd., Beijing,
China).
Hydrogenation of olefins
Typically, 30 mg of 3 wt% Pd/PPCN, 0.5 mmol of substrate and
additive (0.5 mmol AlCl3) were dispersed in a mixed solution with
CH3CN (2 mL), H2O (1.5 mL), and CH3CH2OH (1.5 mL). The reaction
was conducted under LED lamp (20 W, λ=420 nm, Suncat instru-
ments Co., Ltd., Beijing, China) irradiation for 6–24 h under Argon at
°
20 C. After reaction, 5 mL of CH2Cl2 was added to the reaction
mixture solution, and the organic phase was tested by GC-MS
(Agilent 7890 A). GC yields were analyzed using standard calibration
curves (0.5 mmol of mesitylene as internal standard), and the
isolated product yield was calculated dividing the amount of the
obtained product by the theoretical amount.
Experimental Section
Preparation of PPCN
Concerted photocatalysis of olefin hydrogenation and
alcohol oxidation
Firstly, melamine (2.0 g) was mixed with KCl (2.0 g) and a certain
amount of template CaCO3 (50, 100, 150, 200 mg), and then ground
with 2 mL of ethanol in a mortar for 10 min. The mixture was dried
Typically, 30 mg of 3 wt% Pd/PPCN, 0.3 mmol of olefin (1,2-
diphenylethene), 0.9 mmol of alcohol substrate, and additive
(0.3 mmol of AlCl3) were dispersed in a mixed solution of CH3CN
(5 mL) and H2O (3 mL). The reaction mixtures were irradiated with a
LED lamp (20 W, λ=420 nm, Suncat instruments Co., Ltd., Beijing,
°
and calcined at 580 C for 4 h in a muffle furnace under air
atmosphere. After being washed with equivalent hydrochloric acid
(2 molLÀ 1
)
and boiling deionized water (300 mL), the yellow
°
products were dried at 70 C overnight. As-synthesized materials
were named as PPCN-1, PPCN-2 (also denoted as PPCN), PPCN-3,
and PPCN-4, respectively. KPCN was prepared following the same
procedure without adding template CaCO3, while PCN was
prepared without adding neither KCl nor CaCO3.
°
China) for 20 h under Argon at 20 C. After reaction, 5 mL of CH2Cl2
was added into the reaction mixed solution, and the organic phase
was analyzed by GC-MS (Agilent 7890 A). GC yields were calculated
by standard calibration curves (0.3 mmol of biphenyl as internal
standard).
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[16] C. Qiu, Y. Xu, X. Fan, D. Xu, R. Tandiana, X. Ling, Y. Jiang, C. Liu, L. Yu, W.
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This work was financially supported by the National Natural
Science Foundation of China (21902105, 21972094), Guangdong
Basic and Applied Basic Research Foundation (2020A1515010471),
Foundation for Distinguished Young Talents in Higher Education
of Guangdong (2018KQNCX221), Shenzhen Innovation Program
[19] Y. Xu, Z. Zhang, C. Qiu, S. Chen, X. Ling, C. Su, ChemSusChem 2021, 14,
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Manuscript received: May 18, 2021
Revised manuscript received: June 23, 2021
Accepted manuscript online: June 27, 2021
Version of record online: ■■■, ■■■■
ChemSusChem 2021, 14, 1–8
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FULL PAPERS
A concerted effort: A crystalline
porous polymeric carbon nitride is
constructed for concerted catalysis
using photogenerated electron-hole
pairs, in which hydrogen generation
followed by in-situ utilization is
achieved for olefin hydrogenation. Si-
multaneously, various alcohols are
selectively transformed to valuable
aldehydes or ketones.
Dr. C. Qiu, Y. Sun, Dr. Y. Xu, Dr. B.
Zhang, Prof. X. Zhang, Prof. L. Yu*,
Prof. C. Su*
1 – 8
Photoredox-Catalyzed Simultane-
ous Olefin Hydrogenation and
Alcohol Oxidation over Crystalline
Porous Polymeric Carbon Nitride