Versatile Three-Dimensional Porous Cu@Cu2O Aerogel Networks as Electrocatalysts and Mimicking Peroxidases

Article abstract of DOI:10.1002/anie.201801369

A facile strategy is presented to form 3D porous Cu@Cu₂O aerogel networks by self-assembling Cu@Cu₂O nanoparticles with the diameters of ca. 40 nm for constructing catalytic interfaces. Unexpectedly, the prepared Cu@Cu₂O aerogel networks display excellent electrocatalytic activity to glucose oxidation at a low onset potential of ca. 0.25 V. Moreover, the Cu@Cu₂O aerogels also can act as mimicking-enzymes including horseradish peroxidase and NADH peroxidase, and show obvious enzymatic catalytic activities to the oxidation of dopamine (DA), o-phenyldiamine (OPD), 3,3,5,5-tetramethylbenzidine (TMB), and dihydronicotinamide adenine dinucleotide (NADH) in the presence of H₂O₂. These 3D Cu@Cu₂O aerogel networks are a new class of porous catalytic materials as mimic peroxidases and electrocatalysts and offer a novel platform to construct catalytic interfaces for promising applications in electrochemical sensors and artificial enzymatic catalytic systems.

Full text of DOI:10.1002/anie.201801369

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Accepted Article
Title: Versatile Three-dimensional Porous Cu@Cu2O Aerogels
Networks as Electrocatalysts and Mimicking Peroxidases
Authors: Pinghua Ling, Qiang Zhang, Tingting Cao, and Feng Gao
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To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.201801369
Angew. Chem. 10.1002/ange.201801369
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10.1002/anie.201801369
Angewandte Chemie International Edition
Versatile Three-dimensional Porous Cu@Cu2O Aerogels Networks as
Electrocatalysts and Mimicking Peroxidases
Pinghua Ling, Qiang Zhang, Tingting Cao, Feng Gao*
[*] P. Ling, Q. Zhang, T. Cao, Prof. Dr. F. Gao*
Laboratory of Functionalized Molecular Solids, Ministry of Education, Anhui Key Laboratory of
Chemo/Biosensing, Laboratory of Optical Probes and Bioelectrocatalysis (LOPAB), College of Chem-
istry and Materials Science, Anhui Normal University, Wuhu 241002, P. R. China
E-mail: fgao@mail.ahnu.edu.cn.
Supporting information for this article is given via a link at the end of the document.
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Abstract
Much attention has been focused on self-or directed-assembling nanoparticles into three-dimensional
porous nanostructures due to their collective performances and unexpected applications. In this study,
we report a facile strategy to form three-dimensional (3D) porous Cu@Cu2O aerogels networks by self-
assembling Cu@Cu2O nanoparticles with the diameters of ca. 40 nm for constructing catalytic interfac-
es. Unexpectedly, the prepared Cu@Cu2O aerogels networks display excellent electrocatalytic activity
to glucose oxidation at a low onset potential of ca. 0.25 V. Moreover, the Cu@Cu2O aerogels also can
act as mimicking-enzymes including horseradish peroxidase and NADH peroxidase, and show obvious
enzymatic catalytic activities to the oxidation of dopamine (DA), o-phenyldiamine (OPD), 3,3,5,5-
tetramethylbenzidine (TMB), and dihydronicotinamide adenine dinucleotide (NADH) in the presence
of H2O2. The designed 3D Cu@Cu2O aerogels networks in this study may represent a new class of po-
rous catalytic materials as mimic peroxidases and electrocatalysts and offer a novel platform to con-
struct catalytic interfaces for promising applications in electrochemical sensors and artificial enzymatic
catalytic systems.
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Introduction
In recent years, self- or directed-assembling nanoparticles into one-, two-, and three-dimensional po-
rous nanostructures with collective properties such as high electrocatalytic activity or mimicking-
enzyme functions has attracted growing interest.[1] Some metal oxide nanoparticles[2] such as MnO2,
Cu2O, Fe3O4, metal nanoparticles,[3] alloy nanomaterials,[4] metal-organic frameworks,[5] Cu2+-modified
graphene oxide nanoparticles,[6] Cu2+-modified carbon nitride or carbon dots,[7] hemin-modified pep-
tides,[8] and hemin/G-quadruplex[9] have been reported to mimic the functions of horseradish peroxi-
dase (HRP) for bioanalytical applications or used as electrocatalysts to construct non-enzymatic elec-
trochemical sensors. However, some nanoparticles are easily aggregated or oxidized in the ambient at-
mosphere, which thus limits their catalytic activities and further applications in different areas. Obvi-
ously, it is still a challenge and highly desired to develop facile and environmental-friendly approaches
to assembly nanosized entities with unique optical and electronic properties into macroscopic
nanostructures endowed with the abilities of high electrocatalytic activity or mimicking-enzyme.
Among the developed nanostructures, the porous nanostructures have attracted much attention in the
catalytic systems due to their large surface area, abundant active sites, high stability and good solubility.
As highly porous materials, aerogels possess fascinating structures such as ultralow density, large sur-
face area, open interconnected pores, various composition and size, and morphology effect.[10] Com-
pared to traditional porous materials, the aerogels display unique electronic, catalytic, and optical char-
acteristics, and thus have been explored for a wide range of applications.[11] In particular, the noble
metal nanoparticles based aerogels have been widely exploited. For example, Au hydrogel networks
with the dopamine-induced 3D assembly of Au NPs have been designed for electrocatalytic oxidation
of glucose.[12] Multimetallic hierarchical aerogels, Ni-PdxPty, have also been reported for efficient elec-
trocatalysis of ethanol oxidation.[13] However, these original metal nanoparticles are cost-expensive and
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therefore restrict their further applications. The 3D porous aerogels networks as assembled with cheap
metal Cu or their oxide nanoparticles have been rarely reported so far for electrocatalysts and mimick-
ing enzymes.
In this work, a facile strategy has been developed for designing multifunctional 3D Cu@Cu2O aero-
gels networks, which may represent a new class of biomimetic catalytic materials as mimic peroxidases
and heterogeneous electrocatalysts to the oxidation of some small molecules. As shown in Scheme 1,
the 3D Cu@Cu2O aerogels networks exhibit electrocatalysis toward glucose oxidation with high sensi-
tivity and excellent selectivity. And also, the 3D Cu@Cu2O aerogels networks show distinguished pe-
roxidase-like catalytic activities to the oxidation of a variety of substrates including dopamine (DA), o-
phenyldiamine (OPD), 3,3,5,5-tetramethylbenzidine (TMB), and dihydronicotinamide adenine dinucle-
otide (NADH) in the presence of H2O2. The versatile catalytic functions of 3D Cu@Cu2O aerogels
networks could broaden the scope of Cu2O applicability in bioanalysis and pave a new platform for
constructing electrochemical sensing systems.
Scheme 1. Schematic illustration of a) the preparation, and b) versatile biomimetic catalytic properties
of 3D Cu@Cu2O aerogels networks.
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Results and discussion
The nanoscaled 3D Cu@Cu2O aerogels networks were synthesized with one simple step through the
redox reaction of the mixed aqueous solution of NaOH and CuCl2 with fresh NaBH4 solution under
strong stirring at room temperature. The obtained products were collected by centrifugation with water
and ethanol, respectively, and then dried at room temperature. It is worthy to note that the present
method is simple, rapid, stable, easy operation, and wild preparation conditions without any heating
steps, compared with other methods.[14] The 3D Cu@Cu2O aerogels networks are firstly examined us-
ing scanning electron microscopy (SEM). The SEM images shown in Figure 1a indicate that the 3D
structures are highly porous and composed of interconnected networks of ultrathin spongy-like struc-
tures. High-magnification SEM image (inset of Figure 1a) depicts that the prepared network-like
nanostructures are composed of nanoparticles with a mean size of ca. 40 nm.
Figure 1. a) SEM images (inset: high-magnification SEM morphology). b) low-magnification TEM
images. c) high-resolution TEM (inset: The interplanar spacing of high-resolution TEM). d) selected
area electron diffraction pattern of Cu@Cu2O aerogels networks.
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The size and the composition of the prepared 3D Cu@Cu2O aerogels networks were further charac-
terized using transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy
(EDX). The TEM (Figure 1b) shows that Cu@Cu2O aerogels are formed into network-like morpholo-
gies and the formed nanoparticles are approximately 40 nm in diameter, which are consistent with the
SEM results. The EDX spectra (Figure S1) and percentage analysis of elements in Cu@Cu2O (Table
S1) indicate that these Cu@Cu2O aerogels are mainly composed of Cu and a little amount of O. The
absorption bands at 450-510 nm in the UV-vis spectrum suggest that the formation of Cu2O (Figure
S2A) in the preparation of aerogels.[14a] The Fourier transform infrared spectrum (Figure S2B) shows
no other obvious peaks except for the absorption bands of H2O and CO2, suggesting that these prepared
Cu@Cu2O aerogels are very pure and are suitable to investigate the catalytic activities. The high-
resolution TEM (Figure 1c) and selected area electron diffraction pattern (Figure 1d) reveal the diffrac-
tion rings and the polycrystalline nature of Cu@Cu2O aerogels.
To verify the purity and phase of 3D Cu@Cu2O aerogels networks, the XRD are characterized and
shown in Figure 2a. The XRD peaks (2θ) at 36.4o, and 61.3o are agreed well with the (111) and (220)
reflections of Cu2O (JCPDS no. 78-2076), respectively. Moreover, three diffraction peaks located at
43.3o, 50.4o and 74.1o are indexed to the (111), (200) and (220) of the face centered cubic (fcc) of Cu
(JCPDS no. 04-0836), respectively, and ascribed to the pure phase of its bulky sample. In order to con-
firm the element information of the Cu@Cu2O aerogels networks, the X-ray photoelectron spectrosco-
py (XPS) was also carried out. As shown in Figure 2b, the XPS survey spectrum of Cu2p shows the
typical bands at 932.4 eV and 952.2 eV, respectively, which are the typical characteristic of Cu2O and
can be attributed to Cu/Cu2O (Cu0/Cu+).[15] Whereas, the presence of peaks located at 934.0 and 954.1
eV confirm the presence of CuO/Cu(OH)2 (Cu2+).[16] The weak satellite peaks at 941.1 eV, 943.5 eV
and 962.1 eV are corresponded to the Cu2+, and attributed to the open 3d9 shell of Cu(II).[16b,17] The tiny
amounts of Cu2O on the surface could be oxidized to CuO and/or Cu(OH)2 species when the surface is
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exposed in air with humidity.[18] Owing to the different detection sensitivity and detection depth be-
tween XPS and XRD, the Cu2+can be detected by the XPS on the Cu2O, while the CuO and Cu(OH)2
cannot be detected by XRD.[18a,19] In addition, the peak difference between Cu 2p3/2 (932.4 eV) and Cu
2p1/2 (952.2 eV) is 19.8 eV, suggesting that Cu2+ is present[20] and is consistent with the results of XRD.
As shown in Figure 2c, the Auger electron spectrum (Cu L3M4.5M4.5) shows the binding energy peak at
569.8 eV, which is corresponding to the electron state of Cu2O.[15a] The O1s XPS spectrum (Figure 2d)
suggests that O1s is mainly at 531.7 eV, which can be attributed to the absorbed oxygen. The peak at
530.3 eV indicates that oxygen is present in the Cu2O lattice, while the main peak present at 533.0 eV
is attributed to surface species in the Cu@Cu2O aerogels.[15b] The abundant surface chemical composi-
tion and the difference of adsorbed oxygen species may greatly have effects on the catalytic activity of
3D Cu@Cu2O aerogels networks.[21]
Figure 2. a) XRD pattern, b) XPS spectrum (Cu 2p3/2 core peaks), c) Auger spectrum (Cu L3M4.5M4.5
peak) and d) XPS spectrum (O1s core peaks) of Cu@Cu2O aerogels networks.
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To examine the electrocatalytic behavior of Cu@Cu2O aerogels towards glucose oxidation, the cy-
clic voltammogram (CV) measurements were carried out. Figure 3a shows the CVs of the Cu@Cu2O
modified glassy carbon electrode (Cu@Cu2O/GCE) in 0.1 M NaOH aqueous solution containing vari-
ous glucose concentrations of 0 mM, 0.1 mM, 0.5 mM and 1.8 mM, respectively, at a scan rate of 50
mV s−1 in ambient atmosphere. As shown in Figure 3a, with the increasing in glucose concentration,
the anodic currents are gradually enhanced accompanying by the obvious decrease of the cathodic peak
currents, which is typical electrocatalytical features. The oxidation of glucose occurs at the onset poten-
tial of ca. 0.25 V, which is lower than the value of 0.3 V using metal and metal oxide nanotube network
and carbon nanotube-nickel nanocomposites as electrocatalysts,[22] indicating that the 3D
Cu@Cu2Oaerogels networks display highly efficient electrocatalytic activity toward glucose oxidation.
The glucose is oxidized to glucolactone in the potential range of 0.25 V to 0.7 V, where the glucose
oxidation is catalyzed by Cu(II) to Cu(III) conversion.[23] These phenomena suggest that the Cu(III)
specie, rather than Cu(I) or Cu(II), act as an electron mediator in the glucose oxidation.[24] The electro-
chemical process is followed by chemical catalytic process, in which Cu(I) is first oxidized to Cu(OH)2
species and then transformed to CuO, and CuO is finally oxidized to CuOOH. The redox couple of
CuO/CuOOH could catalyze the oxidation of glucose to form gluconolactone, leading to the increasing
in anodic currents and decreasing in the cathodic currents.[2c,25]The catalytic mechanisms could be ex-
pressed by the following equations.[25]
Based on the electrocatalytic activity of the Cu@Cu2O aerogels networks to glucose oxidation, a
non-enzymatic glucose sensor has been fabricated. To optimize the poised potential for non-enzymatic
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glucose sensor with high sensitivity, the amperometric responses of the Cu@Cu2O/GCE at various po-
tentials ranging from 0.25 to 0.6 V (vs Ag/AgCl) were recorded in 0.1 M NaOH solution with the suc-
cessive addition of 0.1 mM glucose (Figure S4A). As shown in Figure S4A, with the increasing in ap-
plied potential, both the current response and the sensitivity are notably enhanced. However, the back-
ground noise currents are also increased with the increased poised potentials. To get the highest sensi-
tivity and avoid the potential interference as possible, 0.55 V was employed as the optimal poised po-
tential for the amperometric measurements, which is lower than that of the Cu2O nanocubes modified
electrode (0.6 V)[14b] and Cu2O/Cu electrode (0.6 V)[25] for glucose oxidation. In addition, Figure S4B
shows good linear correlations between current responses and the glucose concentrations with different
poised potentials. The response of glucose concentration was quantified by the chronoamperograms
peak current at 0.55 V in Figure 3b. The currents exhibited a good liner relation to the glucose concen-
tration in the range from 50 μM to 8.0 mM with a detection limit of 15 μM at the S/N = 3. The detec-
tion of limit was lower than that of the Cu2O nanocubes based electrode (38 μM)[17b] and Cu2O/Cu
electrode (37 μM)[26] for glucose detection. The potential interfering species in the detection of glucose
were also investigated. The amperometric response to the continuous addition of 1.0 mM glucose, fol-
lowed by 2.5 mM dopamine (DA), 2.5 mM ascorbic acid (AA), 2.5 mM uric acid (UA), 2.5 mM fruc-
tose and 2.5 mM lactose at Cu@Cu2O/GCE was examined in 0.1 M NaOH solution. As presented in
Figure S5, the current responses of glucose exhibited remarkable enhancement, whereas the current
change for DA, AA, UA, fructose and lactose was negligible. These data demonstrate that the
Cu@Cu2O aerogels show excellent selectivity to electrocatalytic oxidation of glucose and can be used
for the detection of glucose in complex samples.
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Figure 3. a) CV curves of the Cu@Cu2O/GCE in a 0.1 M NaOH solution containing 0 mM, 0.1 mM,
0.5 mM and 1.8 mM glucose at a scan rate of 50 mV s−1. b) Chronoamperograms responses of the
Cu@Cu2O/GCE to different glucose concentrations of 0.05 mM, 0.5 mM, 1.0 mM, 2.0 mM, 3.0 mM,
4.0 mM, 5.0 mM, 6.0 mM, 7.0 mM and 8.0 mM (from down to top). Inset: calibration curve of current
vs. the concentration of glucose.
Artificial enzymes are very important components of biomimetic chemistry and widely applied in
biosensors, immunoassays, cancer diagnostics.[27] In this study, 3D Cu@Cu2O aerogels with potentially
catalytically active centers and exceptionally high water-stability could meet all the prerequisites for a
biomimetic system. In order to test the catalytic activity of 3D Cu@Cu2O aerogels networks as mimic
enzymes, we first investigated the mimic peroxidase activity of Cu@Cu2O aerogels in the DA-H2O2
system. As shown in Figure 4a, Cu@Cu2O aerogels did not show obvious absorption peak, while DA
and DA-H2O2 systems displayed weak adsorption peak at 480 nm, which is attributed to the oxidation
product of dopamine, aminochrome. However, when Cu@Cu2O aerogels was introduced into DA-
H2O2 reaction system, the absorption peak at 480 nm was enhanced greatly. This result indicates that
the reaction of dopamine and H2O2 was catalyzed by Cu@Cu2O aerogels. The time-dependent absorp-
tion spectra and the rates of DA-H2O2 in the presence of various concentrations of Cu@Cu2O aerogels
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are shown in Figure S6, from which we can see that the absorbance at the 480 nm increases with the
increasing of both the concentration of the Cu@Cu2O and the reaction time, and the derived Vmax value
reaches a saturation value corresponding to 10 μg mL−1 Cu@Cu2O with a fixed concentration of 5.0
mM dopamine and 10 mM H2O2. As the concentration of H2O2 increases, the rates of DA oxidation to
aminochrome were increased with a fixed concentration of 40 μg mL−1 Cu@Cu2O aerogels and 10 mM
dopamine (Figure S7). The reaction rates are also enhanced with the concentrations of DA increase and
reach the saturation rate with the DA at ca. 5.0 mM in the presence of 40 μg mL−1 Cu@Cu2O areogels
and 10 mM H2O2 (Figure S8). The results of the kinetic studies on the DA-H2O2-Cu@Cu2O aerogels
reaction system are good agreement with the typical characteristics of enzyme-catalyzed chemical reac-
tion, further suggesting that 3D Cu@Cu2O aerogels networks could act as the mimetic horseradish pe-
roxidase in the DA-H2O2 system.
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Figure 4. UV-vis absorption spectra of a) DA-H2O2, b) OPD-H2O2, c)TMB-H2O2, and d) NADH-H2O2
systems mediated by 3D Cu@Cu2O aerogels networks. The used concentrations of DA, OPD, TMB,
and NADH are all 10 mM, and the concentrations of 3D Cu@Cu2O aerogels networks and H2O2 are 10
μg mL−1 and 10 mM, respectively.
In order to further demonstrate the general applicability of 3D Cu@Cu2O aerogels networks as en-
zyme mimics, other substrates, such as OPD and TMB, have also been examined, and similar catalytic
behaviors are observed. As shown in Figure 4b, for the oxidation of OPD, the absorbance at 420 nm
generated from the oxidation product of OPD, phenazine-2,3-diamine, was obviously enhanced when
the 3D Cu@Cu2O networks were added into the OPD-H2O2 reaction system. The time-dependent ab-
sorbance spectra of phenazine-2,3-diamine generated in the presence of variable concentrations of
Cu@Cu2O aerogels networks with the fixed concentrations of 10 mM OPD and 10 mM H2O2 are
shown in Figure S9, and the concentration of Cu@Cu2O aerogels reach a saturation value at 20 μg mL-
1. Similarly, the rates of OPD oxidation in the presence of variable concentrations of OPD are depicted
in Figure S10, and the Vmax value reached a plateau at 20 mM. For the oxidation reaction of TMB-H2O2
system, the absorbance band at 650 nm originated from the oxidation product of TMB is greatly in-
creased in the presence of Cu@Cu2O aerogels, as shown in Figure 4c. The rate of TMB oxidation ap-
proached a platform at 20 μg mL−1 in the present of 1.0 mM TMB and 5 mM H2O2, as shown in Figure
S11. From Figure S12 and S13, we can see that the rate of TMB oxidation reaches at 10 μg mL−1. All
of the above phenomena demonstrate that the Cu@Cu2O aerogels exhibit excellent horseradish peroxi-
dase-like catalytic activity. The catalytic activity of 3D Cu@Cu2O aerogels was further investigated in
mimicking the NADH peroxidase biocatalytic system. As shown in Figure 4d, comparing to the ab-
sorption spectra of NADH, and NADH-H2O2, the NADH-H2O2-Cu@Cu2O system displays an obvi-
ously decreased absorbance at the 340 nm, indicating that the oxidation of NADH is catalyzed by the
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3D Cu@Cu2O aerogels. In the experiment, we also compare the rate of oxidation of NADH to NAD+ in
the presence of variable concentrations of H2O2 or NADH and a fixed concentration of 3D Cu@Cu2O
aerogels. Figure S14 shows that the rates of conversion of NADH to NAD+ are increased with the in-
creasing concentrations of H2O2. Similarly, with the concentration of NADH is increasing, the rates of
oxidation of NADH to NAD+ are enhanced in the presence of Cu@Cu2O aerogels (20 μg mL−1) (Figure
S15). These results demonstrate that the Cu@Cu2O aerogels also could mimic NADH peroxidase.
In order to get further insights, the enzyme kinetics was employed to study the performances of cata-
lytic activity of the 3D Cu@Cu2O aerogels networks to the oxidation reactions of different substrates.
Based on the different oxidation rates with variable substrate concentrations, nearly ideal hyperbola
relationships can be obtained and comply with the classic Michiaelis-Menten equation via nonlinear
Hill function simulation[28], as shown in Figure 5. From these plots, some important kinetic parameters
including apparent Michaelis−Menten constant (Km), maximum initial velocity (Vmax), and catalytic
constant (Kcat) can be estimated, as summarized in Table 1. The apparent Km of TMB, OPD, DA and
NADH is 0.94 mM, 8.88 mM, 0.47 mM and 0.37 mM, respectively. For the TMB oxidation reaction,
the apparent Km value is lower than the value of 1.63 mM with of zirconium-metalloporphyrin (PCN-
222), and 2.448 mM with Cu(OH)2 supercages[29] as mimic peroxidases. Moreover, the apparent Kcat
values of Cu@Cu2O with TMB and OPD are higher than the values of 14.0 min-1, 7.3 min-1 with PCN-
222 and 0.1 min-1, 0.8 min-1 with hemin as catalyst, respectively.[5a,30] The fast rate of such a catalytic
reaction is ascribed to the high surface area and the exposed activity sits in Cu@Cu2Oaerogels net-
works.
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Figure 5. The results of nonlinear fitting of Michaelis-Menten curves for a) DA, b OPD), c) TMB and
d) NADH oxidation catalyzed by 3D Cu@Cu2O aerogels networks.
Table 1. Kinetic parameters of different catalytic oxidation reactions
Substrate
Km/ mM Vmax/ μM min-1
Kcat/ min-1
100
kcat/Km/ M-1 min-1
1.06×105
3,3,5,5-tetrame-thylBenzidine
o-phenylenedi-amine
dopamine
0.94
8.88
0.47
0.37
5.71
1.42
8.73
3.68
25.00
2.82×103
38.45
8.18×104
NADH
32.57
8.80×104
It is worthy to note that some other sensing systems could also be constructed by directly detecting
H2O2 or indirectly monitoring generated H2O2 on the basis of the excellent peroxidase-like catalytic
activity of 3D Cu@Cu2O aerogels networks for the H2O2-involved oxidation reactions. In this study,
the detection of glucose by glucose oxidase (GOD)-catalyzed aerobic oxidation is taken as the model
system. By probing the UV-vis absorbance at λ = 650 nm of the oxidized product of TMB by H2O2
with the catalysis of Cu@Cu2O aerogels, as demonstrated above. The absorbances can be generated by
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the oxidation of TMB with the H2O2 produced by the GOD-catalyzed aerobic oxidation of variable
concentrations of glucose. In these experiments, the oxidation of glucose with variable concentrations
is catalyzed by GOD under the aerobic conditions for 30 min at room temperature. The calibration
curve shows that the Vabs value is increased with the increasing concentration of glucose, which is
agreed with the higher concentration of H2O2 generated in the biocatalytic system, as shown in Figure
S16. Obviously, Cu@Cu2O aerogels could be applied to sense glucose.
Conclusions
In summary, we provide the first example of Cu@Cu2O aerogels networks with a diameter of ca. 40
nm as electrocatalytic interfaces for glucose and mimicking horseradish peroxidase and NADH peroxi-
dase. Serving as an electrode material, Cu@Cu2O aerogels networks modified electrodes exhibit high
activities toward the non-enzymatic oxidation of glucose with high sensitivity and excellent selectivity,
which could be as a potential platform for the glucose sensors. Furthermore, Cu@Cu2O aerogels net-
works exhibit biomimetic catalytic activities and show good catalytic activity to the oxidation of a vari-
ety of substrates including DA, OPD, TMB and NADH in the presence of H2O2 as HRP and NADH
peroxidase. Specifically, glucose sensor can also be constructed by the 3D Cu@Cu2O aerogels net-
works based catalysis systems because H2O2 could be quantitatively detected by detecting the UV-vis
absorbances of the oxidized sate of TMB, in the presence of glucose and glucose oxidase. Future work
is focused on examining the cytotoxicity of the Cu@Cu2O aerogels networks and developing
Cu@Cu2O aerogels networks capable of monitoring intracellular biomolecules.
Acknowledgment
This work was financially supported by National Natural Science Foundation of China (21675084，
21575004) and creative research group of bioanalytical chemistry of Anhui Province.
Keywords: Cu@Cu2O aerogels networks • electrocatalysts • mimicking peroxidases • nanoassembly
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For Table of Contents Only
A facile strategy to form three-dimensional (3D) porous Cu@Cu2O aerogels networks by self-
assembling Cu@Cu2O nanoparticles for constructing catalytic interfaces as electrocatalysts and mim-
icking peroxidases has been reported. The 3D Cu@Cu2O aerogels networks exhibit excellent electroca-
talysis ability toward glucose oxidation and peroxidase-like catalytic activity to the oxidation of a va-
riety of substrates including dopamine, o-phenyldiamine, 3,3,5,5-tetramethylbenzidine, and dihy-
dronicotinamide adenine dinucleotide in the presence of H2O2.
20
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