Immobilizing cobalt phthalocyanine into a porous carbonized wood membrane as a self-supported heterogenous electrode for selective and stable CO2electroreduction in water

Article abstract of DOI:10.1039/d0dt03304a

Immobilizing a cobalt phthalocyanine (CoPc) molecular electrocatalyst into a porous carbonized wood membrane (CoPc/CWM) results in a self-supported heterogenous electrode. The CoPc/CWM electrode with an ultralow CoPc loading of 8.2 × 10-6 mol cm-2 exhibits a faradaic efficiency (FE) over 90% for CO production at a wide potential range from-0.59 to-0.78 V versus reversible hydrogen electrode (RHE) and excellent long-term durability during a 12 h electrolysis reaction. This journal is

Full text of DOI:10.1039/d0dt03304a

Dalton
Transactions
View Article Online
View Journal
COMMUNICATION
Immobilizing cobalt phthalocyanine into a porous
carbonized wood membrane as a self-supported
heterogenous electrode for selective and stable
CO2 electroreduction in water†
Cite this: DOI: 10.1039/d0dt03304a
Received 23rd September 2020,
Accepted 26th October 2020
DOI: 10.1039/d0dt03304a
Haidong Zhang,a,b,c Shixiong Min,
*
a,b,c Fang Wanga,b,c and Zhengguo Zhanga,b,c
rsc.li/dalton
Immobilizing a cobalt phthalocyanine (CoPc) molecular electroca- performance as the presence of carbon materials can effec-
talyst into a porous carbonized wood membrane (CoPc/CWM) tively improve the electron transfer kinetics and prevent CoPc
results in a self-supported heterogenous electrode. The CoPc/ molecules from aggregation, consequently enhancing the
CWM electrode with an ultralow CoPc loading of 8.2 × 10−6 mol CO2RR performance of CoPc/carbon heterogeneous electroca-
cm−2 exhibits a faradaic efficiency (FE) over 90% for CO production talysts in water.
at a wide potential range from −0.59 to −0.78 V versus reversible
However, the CoPc/carbon electrocatalysts reported so far
hydrogen electrode (RHE) and excellent long-term durability are mostly in the form of fine powder, and their practical
during a 12 h electrolysis reaction.
applications usually require the tedious slurry-based procedure
with an aid of polymer binders to fabricate a practical elec-
trode. This will inevitably lead to the blocking of active sites
and increase contact resistance that are unfavourable for elec-
tron transfer and multiphase reactant/product mass diffusion.
Moreover, due to the weak adhesion between the active com-
ponent and the substrate, the electroactive species are easily
stripped from the electrode surface during the long-term oper-
ation, thus limiting the large-scale applications. Alternatively,
directly immobilizing CoPc molecules within a highly conduc-
tive and well-defined hierarchically porous carbon-based mem-
brane as a self-supported electrocatalyst can effectively address
the aforementioned intrinsic drawbacks of powdery counter-
parts. First, owing to the structural integrity, the porous
carbon membrane-immobilized CoPc can be directly used as a
self-supported electrode for CO2 electroreduction, avoiding the
tedious solution-based electrode assembly process, and it
holds a great potential as a device-compatible electrode.
Second, unlike the powdery carbons as the support of CoPc,
the porous carbon membrane has unique structural merits
such as large exposed surface area, high porosity, and abun-
dant microchannels, which can enable the high dispersion of
CoPc within the carbon membrane for providing more
exposed active sites and ensuring fast electrolyte transport and
reactant/product diffusion. All these merits would be expected
to endow the carbon membrane-immobilized CoPc electrocata-
lyst with high activity and stability for CO2 reduction. For the
design of a porous carbon membrane-immobilized CoPc elec-
trocatalyst, natural wood (NW), owing to its high sustainability
and unique mesoporous structures as well as abundant
The direct production of value-added chemicals and fuels via
electrocatalytic CO2 reduction is a promising strategy to miti-
gate the greenhouse effect and simultaneously benefit energy
storage, ultimately leading to a carbon-neutral energy cycle.1–4
Among the various electrocatalysts developed for CO2
reduction reaction (CO2RR),5–12 metallophthalocyanine (MPc)
molecular electrocatalysts are an attractive class of materials
owing to their unique electronic structures and excellent cata-
lytic activities, which can be further regulated by varying the
metal centre or peripheral substituents on the ligand.13
Particularly, cobalt phthalocyanine (CoPc) has been identified
as one of the most promising electrocatalysts for CO2RR owing
to its ultrahigh selectivity and activity for CO production.14
However, CoPc usually works in an organic medium, exhibits
poor conductivity, and tends to form agglomerates at high
loading, which would greatly influence the CO2RR perform-
ance of CoPc. Immobilizing CoPc on conductive carbon
materials to form a hybrid heterogeneous electrocatalyst has
been shown to be an effective strategy to enhance its CO2RR
aSchool of Chemistry and Chemical Engineering, Key Laboratory of Electrochemical
Energy Conversion Technology and Application, North Minzu University, Yinchuan,
750021, P. R. China. E-mail: sxmin@nun.edu.cn
bKey Laboratory of Chemical Engineering and Technology, State Ethnic Affairs
Commission, North Minzu University, Yinchuan, 750021, P. R. China
cNingxia Key Laboratory of Solar Chemical Conversion Technology, North Minzu
University, Yinchuan 750021, P. R. China
†Electronic supplementary information (ESI) available: Experiment details and
additional figures. See DOI: 10.1039/d0dt03304a
This journal is © The Royal Society of Chemistry 2020
Dalton Trans.

View Article Online
Communication
Dalton Transactions
aligned channels, would be an ideal carbon-based precursor CWM electrode. Scanning electron microscopy (SEM) images
for fabricating a porous conductive carbon membrane with show that CWM has naturally porous, elongated and aligned
well-preserved hierarchically structures.15
microchannels along its growth direction (Fig. S1, ESI†). After
Herein, we directly immobilized the CoPc molecular electro- immobilizing CoPc molecules, the resulting CoPc/CWM can
catalyst within the porous carbonized wood membrane (CoPc/ perfectly retain the microstructures of CWM. Specifically, the
CWM) as an efficient and selective self-supported hetero- top-view SEM images clearly reveal that the CoPc/CWM elec-
geneous electrode for CO2RR in water. The numerous open trode has numerous open pores on its surfaces with diameters
and interconnected microchannels, abundant porosity, large ranging from 5 to 50 μm (Fig. 1b and c). The side-view SEM
surface areas, and high conductivity of CWM ensure rapid images (Fig. 1d and e) show abundant well-aligned elongated
mass transport, whereas the firmly immobilized CoPc mole- and open microchannels crossing the CoPc/CWM electrode,
cules on the walls of microchannels via strong π–π interactions which will facilitate the fast mass transport of reactants and
provide an abundance of highly exposed active sites. These electrolytes. Transmission electron microscopy (TEM) and
structural merits make the CoPc/CWM electrode highly active high-resolution TEM (HRTEM) images reveal that the CoPc/
and selective for CO2RR, and the best CoPc/CWM electrode CWM catalyst presents a clear sheet-like structure (Fig. 1f and
with an ultralow CoPc loading of 8.2 × 10−6 mol cm−2 exhibits g), indicating that CoPc/CWM is mainly composed of carbon
a FE of >90% for CO production over a wide potential range sheets. No aggregated CoPc particles are observed, revealing
from −0.59 to −0.78 V vs. RHE and excellent long-term that CoPc is possibly dispersed on the carbon framework at
durability.
the molecular level. The high-angle annular dark-field scan-
The fabrication process of the self-supported heterogeneous ning transmission electron microscopy (HAADF-STEM) image
CoPc/CWM electrode is schematically illustrated in Fig. 1a (see and the corresponding energy dispersive X-ray (EDX) elemental
experimental details in ESI†). First, the natural wood (NW) was maps reveal that C, O, N, and Co elements are homogeneously
cut perpendicular to its growth direction into thin slices (thick- distributed on the entire carbon framework of the CoPc/CWM
ness: ∼1.5 mm) and carbonized to obtain a hierarchically electrode (Fig. 1h).
porous CWM. Then, CoPc molecules were firmly immobilized
The crystalline structure of the samples was investigated
within the as-fabricated CWM via strong π–π interactions in using the X-ray diffraction (XRD). As shown in Fig. 2a, it can
the N,N-dimethylformamide (DMF) solvent to obtain the CoPc/ be seen that both the CWM and CoPc/CWM electrodes display
Fig. 1 (a) Schematic of the synthesis process of the CoPc/CWM electrode. (b and c) Top-view and (d and e) side-view SEM images of the CoPc/
CWM electrode. (f) TEM and (g) HRTEM images of the CoPc/CWM electrode. (h) HAADF-STEM image of the CoPc/CWM electrode and the corres-
ponding EDX elemental maps (C, O, N, and Co).
Dalton Trans.
This journal is © The Royal Society of Chemistry 2020

View Article Online
Dalton Transactions
Communication
structure and the Brunauer–Emmett–Teller (BET) specific
surface area (SBET) of the CoPc/CWM electrode (Fig. S3, ESI†).
The calculated SBET, average pore size, and total pore volume
are 347.29 m2 g−1, ∼3.0 nm, and 0.27 cm3 g−1, respectively.
The presence of numerous mesopores is beneficial for fast
mass transport and provides a large surface area for loading
CoPc molecules with high dispersion, thus providing an abun-
dance of accessible active sites.
X-ray photoelectron spectroscopy (XPS) was then performed
to investigate the composition and chemical states of the elec-
trodes. The XPS survey spectrum shown in Fig. S4, ESI,†
reveals that CWM is composed of C, O, and N elements, while
the pristine CoPc consists of C, N, and Co elements. The
survey spectrum of the CoPc/CWM is the superposition of the
spectrum of CWM on that of CoPc, confirming the immobiliz-
ation of CoPc molecules on the CWM framework, consistent
with the EDX results. The high-resolution C 1s XPS spectrum
of the CoPc/CWM electrode can be well-fitted into five peaks:
284.5 eV (CvC), 285.2 eV (C–O/C–N), and 286.2 eV
(CvO/CvN) originated from CWM18 and 284.1 eV (24
benzene carbons (C(1)) and 285.5 eV (eight pyrrole carbons
(C(2)) from CoPc.19 In addition, all of the characteristic N
species in both CWM (pyridinic-N at 398.1 eV, pyrrolic-N at
399.6 eV, and graphitic-N at 401.2 eV)20 and CoPc (four pyrro-
lic-N atoms coordinated directly to the Co atom (N(a)) and four
meso-bridging aza N atoms (N(b)))21,22 can be observed in the
fitted N 1s spectrum of the CoPc/CWM electrode (Fig. 2c).
These results further indicate the presence of CoPc on CWM
in the CoPc/CWM electrode. Compared to those of CWM and
CoPc, a shift of C 1s and N 1s peaks to the high binding
Fig. 2 (a) XRD patterns of CoPc, CWM and CoPc/CWM. The high-
resolution XPS spectra of (b) C 1s and (c) N 1s of CWM, CoPc, and CoPc/
CWM. (d) The Co 2p XPS spectra of CoPc and CoPc/CWM. The 24
benzene carbons and eight pyrrole carbons in CoPc are denoted as C(1) energy can be found for the CoPc/CWM electrode, indicating
and C(2), respectively. The four pyrrolic-N atoms coordinated directly to
the Co atom and four meso-bridging aza N atoms in CoPc are denoted
as N(a) and N(b), respectively.
that there is a strong interaction between CoPc and the CWM
substrate, which probably originates from the π–π stacking
interaction between the ligand of CoPc and the graphitic
domains of CWM. The Co 2p XPS spectrum of the CoPc/CWM
electrode reveals that Co 2p3/2 and Co 2p1/2 peaks occur at
two broad peaks at 23.1° and 43.7°, corresponding to the (002) 780.5 and 796.2 eV (Fig. 2d), respectively, which are in accord-
and (100) crystal planes of carbon, respectively. Compared to ance with those of pristine CoPc, further verifying the existence
that of the CWM electrode, the intensity of diffraction peaks of CoPc molecules on CWM. The loading amount of CoPc in
for carbon is reduced for the CoPc/CWM electrode due to the the CoPc/CWM electrode was determined to be 8.2 × 10−6 mol
surface coverage of the carbon membrane by CoPc. In cm−2 by the inductively coupled plasma optical emission spec-
addition, no diffraction peaks of CoPc are observed in the XRD trometry (ICP-OES) analysis (Table S1, ESI†).
pattern of the CoPc/CWM electrode, implying that CoPc mole-
The electrochemical CO2 reduction activity of the as-pre-
cules are anchored on the CWM surface with high dispersion. pared electrodes was first evaluated by linear sweep voltamme-
Fig. 2b shows the Raman spectra of the CWM and CoPc/CWM try (LSV) in an N2- or CO2-saturated 0.1 M KHCO3 solution. It
electrodes. The Raman spectrum of the CoPc/CWM electrode should be mentioned that the as-prepared electrodes can be
exhibits two characteristic peaks at 1337 and 1580 cm−1, which directly utilized as a self-supported cathode without the need
can be assigned to the disordered carbon (D-band) and graphi- for a binder and conductive additives. As shown in Fig. 3a, the
tic carbon (G-band), respectively.16,17 Notably, no vibration fea- CWM electrode exhibits a lower current density than the CoPc/
tures of CoPc molecules can be observed in the Raman spec- CWM electrode in the CO2-saturated 0.1 M KHCO3 solution,
trum of the CoPc/CWM electrode probably due to the extre- implying that the CWM electrode exhibits inferior catalytic
mely low loading of CoPc. The relative intensity ratio of D to activity for CO2RR. The control potential electrolysis experi-
G-band (ID/IG) increases from 1.05 for CWM to 1.11 for CoPc/ ments were then performed to assess the activity and selecti-
CWM, further suggesting the successful immobilization of vity of CO2 reduction over the electrodes. The gas products
CoPc molecules on CWM. The N2 adsorption–desorption iso- were analyzed via on-line gas chromatography (GC), while the
therm measurement was performed to characterize the porous liquid products were measured via high-performance liquid
This journal is © The Royal Society of Chemistry 2020
Dalton Trans.

View Article Online
Communication
Dalton Transactions
CoPc/CWM electrode is also comparable to those of many pre-
viously reported powdered carbon-supported CoPc electrocata-
lysts (Table S2, ESI†). Partial current density for CO formation
( jCO) as a function of applied potential is presented in Fig. 3c.
It is clear that the CoPc/CWM electrode exhibits much higher
jCO than the CWM electrode over the tested potential range,
and the largest jCO acheived on the CoPc/CWM electrode is
4.58 mA cm−2 at a relatively low applied potential of −0.78 V
vs. RHE, which is 143 times higher than that of the CWM elec-
trode (0.032 mA cm−2), indicating its higher catalytic activity
towards CO2RR. The electrochemical surface areas (ECSAs) of
the electrodes were determined by measuring the double-layer
capacitance (Cdl) (Fig. S6, ESI†). The Cdl of the CoPc/CWM
electrode is determined to be 0.34 mF cm−2, which is higher
than that of the CWM electrode (0.10 mF cm−2) (Fig. 3d).
These results suggest that the enhanced CO2 reduction per-
formance for the CoPc/CWM electrode could be attributed to
the high dispersion of CoPc for providing abundance of active
sites and the porous structure of CWM for facilitating mass
transport. However, the jCO curve for the CoPc/CWM electrode
decreases as the applied potential is negative than −0.78 V vs.
RHE, which could be ascribed to the mass transport limitation
of CO2 to the electrode surface.23 The previous studies have
proposed that the CO2 electroreduction to CO using a CoPc
electrocatalyst follows
a
dual-active sites mechanism.24,25
Initially, CO2 is chemically adsorbed on the N-site of the Pc
ligand and protonated to form a COOH* intermediate. The
COOH* intermediate is then transferred from the N sites to
the center Co site of the CoPc at a feasible reaction potential.
Subsequently, the hydroxide group is attacked by protons to
form H2O and dissociates from the carboxyl group. Finally,
CO* is dissociated from the center Co sites of the CoPc, and
the CoPc is regenerated to complete the electrocatalytic cycle.
In order to further clarify the electrocatalytic mechanism of
the CO2RR on our CoPc/CWM electrode, the Tafel analysis was
performed (Fig. 3e). The measured Tafel slope for the CoPc/
CWM electrode is 167 mV dec−1, which clearly indicates that
Fig. 3 (a) LSV curves of CWM and CoPc/CWM recorded in N2- (dotted
line) and CO2-saturated (solid line) 0.1 M KHCO3 solution at a scan rate
of 1.0 mV s−1. (b) FE for CO production on CWM and CoPc/CWM at
various applied potentials. (c) jCO for CWM and CoPc/CWM at different
potentials. (d) Current density differences (Δj ) plotted against scan rates.
(e) Tafel plots of CO production for the CoPc/CWM electrode. (f)
Stability of the CoPc/CWM electrode for CO2 reduction at −0.59 V vs.
RHE. The high-resolution XPS spectra of (g) N 1s and (h) Co 2p for the
CoPc/CWM electrode after 12 h of electrolysis.
chromatography (HPLC) at the end of electrolysis. It was found the initial electron transfer to CO2 to generate the
−
that H2 and CO were the major gas products of CO2 reduction, adsorbed*CO2 intermediate is a rate-determining step for
and no liquid products could be detectable in the reaction CO2RR, consistent with the observations in the literature.24–26
solution. The CWM electrode produces H2 as the main However, this value is larger than that of the theoretic value
product over a wide potential range with a small amount of CO for initial one electron transfer to CO2 (118 mV dec−1),
(maximum FE < 5%). In contrast, the CoPc/CWM electrode suggesting that there is a transport limitation for CO2 mole-
shows high selectivity towards CO production over the same cules in access to active sites.27
applied potential range. The FE for CO production (FECO) is
The electrocatalytic stability of the CoPc/CWM electrode
found to be as high as 34.0% for the CoPc/CWM electrode at a was performed at a constant potential of −0.59 V vs. RHE
low potential of −0.4 V vs. RHE. The FECO increases with (Fig. 3F). The current density of CoPc/CWM maintains a steady
increasing applied cathodic potential, and reaches over 90% value and the FECO shows a stable value of ∼90% without
from −0.59 to −0.78 V vs. RHE (Fig. 3b). When further polariz- noticeable decrease during 12 h of electrolysis, showing the
ing the CoPc/CWM electrode to a more negative potential, the excellent catalytic stability. The SEM analysis indicates that the
FECO dramatically decreases, indicating that the HER becomes microstructures of the CoPc/CWM electrode are perfectly
more competitive to the CO2 reduction (Fig. S5, ESI†). These retained after the stability test, demonstrating the good struc-
results indicate that the enhancement of the activity and tural integrity of the CWM substrate. The corresponding EDX
selectivity of the CoPc/CWM electrode for CO2 reduction to CO maps reveal the preservation of C, O, N, and Co elements, indi-
can be attributed to the immobilization of highly dispersed cating that the CoPc molecules are still firmly immobilized on
CoPc molecules on the CWM. The CO2RR performance of our the walls of microchannels (Fig. S7, ESI†). The HRTEM image,
Dalton Trans.
This journal is © The Royal Society of Chemistry 2020

View Article Online
Dalton Transactions
Communication
HAADF-STEM image, and the corresponding EDX maps show
that no noticeable aggregation of CoPc molecules can be
observed in the electrolyzed CoPc/CWM electrode (Fig. S8,
ESI†), indicating that the immoblized CoPc molecules are still
highly dispersed on CWM. Moreover, the XPS analysis reveals
that the chemical states of C, N, and Co in the electrolyzed
CoPc/CWM electrode are well-retained (Fig. S9, ESI,† Fig. 3g
and h), suggesting that the molecular structure of CoPc is
stable during the long-term electrolysis.
5 D. Plana, J. Flórez-Montaño, V. Celorrio, E. Pastor and
D. J. Fermín, Chem. Commun., 2013, 49, 10962–10964.
6 S. Sarfraz, A. T. Garcia-Esparza, A. Jedidi, L. Cavallo and
K. Takanabe, ACS Catal., 2016, 6, 2842–2851.
7 X. Guo, Y. Zhang, C. Deng, X. Li, Y. Xue, Yi. Yan and
K. Sun, Chem. Commun., 2015, 51, 1345–1348.
8 J. Rosen, G. S. Hutchings, Q. Lu, R. V. Forest, A. Moore and
F. Jiao, ACS Catal., 2015, 5, 4586–4591.
9 C. Finn, S. Schnittger, L. J. Yellowlees and J. B. Love, Chem.
Commun., 2012, 48, 1392–1399.
In summary, we have designed a self-supported carbonized
wood membrane-immobilized CoPc heterogeneous electrocata- 10 P. Lu, D. Gao, H. He, Q. Wang, Z. Liu, S. Dipazir, M. Yuan,
lyst for highly active and selective CO2RR in water. The numer- W. Zu and G. Zhang, Nanoscale, 2019, 11, 7805–7812.
ous open and interconnected microchannels, high porosity, 11 H. Shen, Y. Li and Q. Sun, Nanoscale, 2018, 10, 11064–
large surface areas, and high conductivity of CWM can enable 11071.
the high dispersion of CoPc within the carbon membrane for 12 F. Zhang, T. Sheng, N. Tian, L. Liu, C. Xiao, B. Lu, B. Xu,
providing more exposed active sites and ensuring fast Z. Zhou and S. Sun, Chem. Commun., 2017, 53, 8085–8088.
electron transfer and mass transport. Consequently, the as-fab- 13 T. Abe, H. Imaya, T. Yoshida, S. Tokita, D. Schlettwein,
ricated CoPc/CWM electrode exhibits remarkable activity,
selectivity (FECO > 90%), and durability for CO2RR. This work
D. WÖHrle and M. Kaneko, J. Porphyrins Phthalocyanines,
1997, 01, 315–321.
opens up a new way of using a porous membrane as an inte- 14 M. Wang, K. Torbensen, D. Salvatore, S. Ren, D. Joulié,
grated three-dimensional current collector and host matrix of
molecular metal complexes in the design of self-supported
heterogeneous electrocatalysts for high-performance CO2
electroreduction.
F. Dumoulin, D. Mendoza, B. Lassalle-Kaiser, U. Işci,
C. P. Berlinguette and M. Robert, Nat. Commun., 2019, 10,
3602.
15 J. Huang and L. Wang, Electrochim. Acta, 2019, 319, 569–
576.
16 X. Li, S. Kurasch, U. Kaiser and M. Antonietti, Angew.
Chem., Int. Ed., 2012, 51, 9689–9692.
17 W. Li, B. Herkt, M. Seredych and T. J. Bandosz, Appl. Catal.,
B, 2017, 207, 195–206.
Conflicts of interest
There are no conflicts to declare.
18 A. S. Jalilov, Y. Li, J. Tian and J. M. Tour, Adv. Energy Mater.,
2017, 7, 1600693.
19 J. Ahlund, K. Nilson, J. Schiessling, L. Kjeldgaard,
S. Berner, N. Martensson, C. Puglia, B. Brena, M. Nyberg
and Y. Luo, J. Chem. Phys., 2006, 125, 34709.
Acknowledgements
This work is supported by the Foundation of Academic Top-
notch Talent Support Program of North Minzu University 20 Z. Xu, X. Zhuang, C. Yang, J. Cao, Z. Yao, Y. Tang, J. Jiang,
(Grant No. 2019BGBZ08), the West Light Foundation of the D. Wu and X. Feng, Adv. Mater., 2016, 28, 1981–1987.
Chinese Academy of Sciences (Grant No. XAB2018AW13), the 21 Y. Alfredsson, B. Brena, K. Nilson, J. Ahlund, L. Kjeldgaard,
Cooperative Scientific Research Project of Chunhui Plan of
Ministry of Education of China, and the Foundation of
M. Nyberg, Y. Luo, N. Martensson, A. Sandell, C. Puglia
and H. Siegbahn, J. Chem. Phys., 2005, 122, 214723.
Training Program for Yong and Middle-aged Talents of State 22 L. Lozzi, L. Ottaviano and S. Santucci, Surf. Sci., 2001, 470,
Ethnic Affairs Commission of China.
265–274.
23 J. Wu, R. M. Yadav, M. Liu, P. P. Sharma, C. S. Tiwary,
L. Ma, X. Zou, X.-D. Zhou, B. I. Yakobson, J. Lou and
P. M. Ajayan, ACS Nano, 2015, 9, 5364–5371.
24 Y. Xia, S. Kashtanov, P. Yu, L.-Y. Chang, K. Feng, J. Zhong,
J. Guo and X. Sun, Nano Energy, 2020, 67, 104163.
25 M. Zhu, R. Ye, K. Jin, N. Lazouski and K. Manthiram, ACS
Energy Lett., 2018, 3, 1381–1386.
26 A. Wuttig, Y. Yoon, J. Ryu and Y. Surendranath, J. Am.
Chem. Soc., 2017, 139, 17109–17113.
27 S. Lin, C. S. Diercks, Y.-B. Zhang, N. Kornienko,
E. M. Nichols, Y. Zhao, A. R. Paris, D. Kim, P. Yang,
O. M. Yaghi and C. J. Chang, Science, 2015, 349, 1208–1213.
References
1 N. S. Lewis and D. G. Nocera, Proc. Natl. Acad. Sci. U. S. A.,
2006, 103, 15729–15735.
2 C. Costentin, M. Robert and J.-M. Savéant, Acc. Chem. Res.,
2015, 48, 2996–3006.
3 E. E. Benson, C. P. Kubiak, A. J. Sathrum and J. M. Smieja,
Chem. Soc. Rev., 2009, 38, 89–99.
4 C. Costentin, M. Robert and J. M. Savant, Chem. Soc. Rev.,
2013, 42, 2423–2436.
This journal is © The Royal Society of Chemistry 2020
Dalton Trans.