10.1002/anie.201903936
Angewandte Chemie International Edition
COMMUNICATION
Paired electrocatalytic oxygenation and hydrogenation of organic
substrates using water as oxygen and hydrogen source
Peili Zhang,[a,b] Xia Sheng,[a] Xiaoyu Chen,[c] Zhiyong Fang,[b] Jian Jiang,[b] Mei Wang,[b] Fusheng Li,[b]
Lizhou Fan,[a] Yansong Ren,[a] Biaobiao Zhang,[a] Brian J.J. Timmer,[a] Mårten S.G.Ahlquist,[c] Licheng
Sun*[a,b]
Abstract: The use of water as an oxygen and hydrogen source for
the paired oxygenation and hydrogenation of organic substrates to
produce valuable chemicals is of utmost importance as a means of
establishing green chemical syntheses. Inspired by the active Ni3+
intermediates involved in electrocatalytic water oxidation by Ni-based
materials, we prepared NiBx as a catalyst and used water as the
oxygen source for the oxygenations of various organics. NiBx was
further employed as both an anode and cathode in a paired
electrosynthesis cell for the respective oxygenation and
hydrogenation of organic compounds, with water as both the oxygen
and hydrogen source. Conversions efficiencies and selectivities of
coupled attenuated total reflection infrared spectroscopy with NixB
as the catalyst.[3d] To date, the majority of literature reports have
water active process, the catalytic active sits and the oxygen atom
transfer mechanism are ambiguity. [3]
In electrocatalytic oxygenation reactions, protons are
generated as a by-product.[4] Recently, these reactions have been
paired with electrocatalytic hydrogen evolution reaction (HER) to
increase the energy conversion efficiency.[3] However, compared
with HER, the organic oxygenation reactions are kinetically
sluggish, especially in the late stages of the reaction, owing to the
decrease in reactant concentrations. Thus, both catalytic
efficiency and electron economy could be improved by pairing
organic oxygenation with a rate-matched organic hydrogenation
to create sustainable chemical synthesis strategies.[4]
≥99%
were achieved during the oxygenation of 5-
hydroxymethylfurfural to 2,5-furandicarboxylic acid and the
simultaneous hydrogenation of p-nitrophenol to p-aminophenol. This
paired electrosynthesis cell has also been coupled to a solar cell as a
stand-alone reactor in response to sunlight.
Herein, the electrocatalytic oxygen atom transfer mechanism
was investigated in 1 M KOH with NiBx (x = 0.40 ± 0.05) as
catalyst and the oxygenation of HMF to 2,5-furandicarboxylic acid
(FDCA) as a model reaction. Experiment results indicated that the
electrogenerated Ni3+ species are the active intermediates.
Furthermore, paired electrolysis system was constructed by
combining the electrocatalytic oxygenation of HMF to FDCA and
the hydrogenation of p-nitrophenol (p-NP) to p-aminophenol (p-
as high as ≥99% were achieved on both sides with water as
oxygen and hydrogen source. This paired electrolyser uses
electricity to drive the organic oxygenation and hydrogenation
reactions in aqueous solutions, without the need to handle
hazardous gaseous hydrogen or oxygen or to incorporate
external oxidants/ reductants.
The NiBx working electrode (WE) was prepared by
electroless plating for 2 hours with a nickel foam (NF) substrate
at 90 °C in NaOH aqueous solutions (pH 13.5) containing
Ni(Cl)2·6H2O (125 mM), ethanediamine (750 mM) and NaBH4 (55
mM).[5] The Ni:B atomic ratio (1:0.40 ± 0.05) was verified by
inductively coupled plasma optical emission spectroscopy and the
NiBx loading on the NF surface was 2.47 ± 0.10 mg cm2. Top-
view scanning electron microscopy (SEM) images showed that
NiBx was uniformly deposited on the NF to provide a rough
surface (Figures 1a, 1b). High-resolution transmission electron
microscopy (TEM) images (Figure 1c) suggested that the surface
particles were composed of amorphous nickel boride and nickel.
X-ray photoelectron spectroscopy (XPS) analysis confirmed that
Ni and B were the main components (Figure S1). The Ni 2p3/2
peak at 852.7 eV can be assigned to Ni0, while the B 1s peak at
187.8 eV can be assigned to B0, as expected for nickel borides.[6]
The weak B 1s hump at 192.1 eV and the O 1s peak at 532.5 eV
are due to small amounts of boron oxide (Figures 1j–l).[6b]
Water is an abundant resource on earth and is widely used as
either an oxygen or hydrogen source during naturally occurring
biosynthetic oxygenation and hydrogenation reactions.[1,2]
Inspired by natural systems, we consider water to represent an
ideal source of oxygen and hydrogen instead of high-cost H2 or
chemical oxidants/reductants for catalytic oxygenation and
hydrogenation in green chemical processes.
During the last decade, electrocatalytic oxygenation of
organic compounds to value-added products with water as
oxygen source has started to attract increased attention. Several
interesting electrocatalytic systems have been reported with
improving performance. Ni2P,[3a] Co-P, [3b] Ni3S2, [3c] NixB, [3d] NiFe
LDH, [3e] noble metals (Au and Pd) and their alloys[3f] are used as
efficient electrocatalysts for the oxidation of furanics and other
biomass-derived platform chemicals. Recently, Schuhmann
group provided new insight into the oxidation pathway of 5-
hydroxymethylfurfural (HMF) through operando electrochemistry
[a]
[b]
[c]
Dr. P. Zhang, Dr. X. Sheng, L. Fan, Dr. Y. Ren, Dr. B. Zhang, Dr.
B.J.J. Timmer, and Prof. L. Sun, Department of Chemistry, School of
Engineering Sciences in Chemistry, Biotechnology and Health, KTH
Royal Institute of Technology, 10044 Stockholm, Sweden E-mail:
Dr. P. Zhang, Z. Fang, J. Jiang, Prof. M. Wang, Dr. F. Li, and Prof. L.
Sun, State Key Laboratory of Fine Chemicals, Institute of Artificial
Photosynthesis, DUT-KTH Joint Education and Research Centre on
Molecular Devices, Dalian University of Technology, 116024 Dalian,
China
X. Chen and Dr. M.S.G. Ahlquist, Department of Theoretical
Chemistry & Biology, School of Engineering Sciences in Chemistry
Biotechnology and Health, KTH Royal Institute of Technology, 10691
Stockholm, Sweden
Supporting information for this article is given via a link at the end of the
document.
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