Supporting Information

NH2-UiO-66(Zr) with Fast Electron Transfer Routes for

Breaking Down Nitric Oxide via Photocatalysis

Xiaolang Chen, Yong Cai, Rui Liang, Ying Tao, Wenchao Wang, Jingjing Zhao,

Xiaofeng Chen, Hexing Li, Dieqing Zhang*

The Education Ministry Key Lab of Resource Chemistry, Shanghai Key Laboratory of

Rare Earth Functional Materials, College of Chemistry and Materials Science,

Shanghai Normal University, Shanghai,200234, China

*Corresponding authors: *dqzhang@shnu.edu.cn

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Materials and Characterization

Materials

2-aminoterephthalic acid (H2ATA) was obtained from Sigma–Aldrich. EDTA

disodium salt dehydrate (EDTA-2Na2H2O), ZrCl4, FeCl3, Cu(NO3)23H2O,

Co(OAc)24H2O, and Cu(OAc)2H2O were obtained from Aladdin. CuCl22H2O was

offered by MACKLIN. N, N-dimethylformamide (DMF), and anhydrous ethanol

(EtOH) were supplied by Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China).

All materials were used as received without further purification.

Experimental Procedures

Synthesis of Fe-NU7and Co-NU7:

Based on the same method for synthesizing Cu-NU7, 0.4 g NH2-UiO-66 was

dispersed into an ethanol solution (20 mL) containing FeCl3 or Co(OAc)2 (7 mM) at

room temperature, , and stirred for 1 h. The resulting solids were washed two times,

collected by centrifugation, and dried for 12 h at 80 oC in an oven. Finally, Fe-NH2-

UiO-66(Zr) and Co-NH2-UiO-66(Zr) were obtained and denoted as Fe-NU7 and Co-

NU7.

Synthesis of Cu-MS7:

0.4 g mesoporous SiO2, prepared based on literature1 was dispersed into an ethanol

solution (20 mL) containing Cu(OAc)2 (7 mM) at room temperature. The mixture was

stirred and heated at 80 oC until all of the ethanol solvent was evaporated, the final

product was named as Cu-MS7. Pure as-formed mesoporous SiO2 was denoted as Cu-

MS0.

Synthesis of Cu-EDTA-NU7:

Firstly，EDTA-2Na•2H2O aqueous solution (13 mL, 11 mM) was mixed with an

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ethanol solution of Cu(OAc)2 (7 mL, 0.02 mol/L) at room temperature to obtain the

mixture solution of Cu(EDTA). Then Cu-NU0 was dispersed into the above mixture

solution, and stirred for 1 h. Then the mixture solution was evaporated at 110 oC to

obtain the final solid product, which was denoted as Cu-EDTA-NU7.

Electrode preparation

20 mg of catalyst and 2 mg of Polyethylene glycol were dispersed in 200 μL EtOH,

then grinded and mixed evenly. The as-prepared slurry was dropped on FTO with an

active area of ca. 1.0 cm2 (1.0 * 1.0 cm) to achieve a uniform coverage with thickness

of about 50 μm, and then dried at 100 oC for further characterization. All electrodes

were prepared through the same process.

Photoelectrochemical measurement

The photocurrents and electrochemical impedance spectroscopy (EIS)

measurements were performed on an electrochemical station (CHI 660D) with a

traditional three electrode system in a single-compartment quartz cell. The saturated

calomel electrode (SCE) and platinum sheet were the reference electrode and counter

electrode, respectively. Samples with an active area of ca. 1.0 cm2 (1.0 *1.0 cm) on an

FTO glass were served as working electrode. Na2SO4 (0.5 M) aqueous solution was

applied as electrolyte. A bias voltage (0.50 V) was used for driving the photo-

generated electrons transfer. A 300 W Xe lamp with an ultraviolet filter (λ > 420 nm)

was used as the visible light source and positioned 10 cm away from the

photoelectrochemical cell. The EIS tests were carried out at the bias voltage of 0.3 V

and recorded over a frequency ranged from 0.01 to 1*105 Hz with an amplitude at 5

mV. The cyclic voltammograms (CV) curves were obtained with a scan rate of 100

mV•s-1.

Mott-Schottky measurement:

The Mott–Schottky plots were determined to obtain the flat-band potential and

carrier density. In addition, the capacitance measurement was performed on the

electrode/electrolyte according to the Mott-Schottky equation:

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1C2 =

2N D e ℇ0ℇ

(E−EFB−kTe

)

Where C is the space charge capacitance in the semiconductor, ND is the electron

carrier density, e is the elemental charge, ε0 is the permittivity of a vacuum, ε is the

relative permittivity of the semiconductor, E is the applied potential, EFB is the flat

band potential, T is the temperature, and k is the Boltzmann constant.

Extended X-ray absorption fine-structure (EXAFS):

EXAFS was analyzed by the IFEFFIT analysis package with the following standard

procedures: the pre-edge region onto the EXAFS region was extrapolated for

removing the background, and the Athena program of the IFEFFIT package was

employed to normalize the χ(E) data with respect to the edge jump step. With the χ(k)

multiplied by k3 to compensate for the oscillations in the high k region, the

normalized χ(E) was transformed from the energy space to the k-space. The k range

was measured from 2.3 to 11.5 Å. The k3χ(k) data were fitted in the R-space ranging

from 1.0 to 2.4 Å through the Artemis program of the IFEFFIT package. Structural

parameters including coordination number (CN), coordination distance (R), Debye-

Waller factor (Δσ2), and inner potential correction (ΔE) were obtained.

Time-resolved transient absorption spectroscopy (TA):

The femtosecond transient absorption (fs-TA) experiments were done with a

femtosecond time-resolved transient absorption. The femtosecond regenerative

amplified Ti: sapphire regenerative amplifier laser (Spectra Physics, Spitfire-Pro) and

a transient absorption spectrometer were employed. In the experiment procedures,

about 95% of these fundamental amplified 800 nm pulses were utilized to pump a

third harmonic generator for obtaining the laser with a wavelength at 400 nm, which

was employed as the pump pulse, while the probe was obtained by employing the

remaining part light (5%) from 800 nm to gain a white-light continuum (420−780 nm)

in a one-dimensional CaF2 crystal. A flow cell with a 2 mm optical path length was

applied to impede the generation of photoinduced products. The instrument resolution

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in this setup is 150 fs. The weighted average decay lifetime was calculated by the

following equation S1: τ ave=Σ i=1i=n Ai τ i

2/ Σi=1i=n A iτ i

Where Ai are the pre-exponential factors and τ i are the lifetimes obtained in the

multi-exponential fitting of the decay kinetics.

Photocatalytic H2 evolution

The photocatalytic H2 production experiments were carried out in a 100 mL Pyrex

flask at atmospheric pressure and ambient temperature, and the openings of the flask

were sealed with a silicone rubber septum. Four LEDs (420 nm, Shenzhen LAMPLIC

Science Co. Ltd. China) were placed at 2 cm away from the reactor from four

different directions to trigger the photocatalytic reaction. In a typical photocatalytic

experiment, 50 mg of photocatalyst was suspended in 80 mL mixed solution (79:19:2

v/v %) of 63 mL of acetonitrile, 15 mL of triethylamine and 2 mL of water. Before

light irradiation, the suspension of the catalysts was dispersed by an ultrasonic bath

for 2–3 min, and then bubbled with nitrogen through the reactor for 10–15 min to

completely remove the dissolved oxygen. An uninterrupted magnetic stirrer was

applied at the bottom of the reactor to keep the photocatalyst particles at suspension

status during the experiment process. A 0.5 mL gas was intermittently sampled

through the septum, and H2 was detected by gas chromatography (GC 9800N,

Kechuang, China, TCD, nitrogen as a carrier gas and 5 Å molecular sieve column).

For better comparison, 50 mg of NH2-UiO-66(Zr) was also suspended in 80 mL

mixed solution (79:19:2 v/v %) of 63 mL of acetonitrile, 15 mL of triethylamine and 2

mL of water, and 0.0175 mmol Cu(OAc)2 was dissolved in the above suspension

solution. Other reaction conditions were maintained unchanged. For the recycling

testing, it was run for 7 cycles with intermittent exposure to atmospheric conditions

every 2 hrs. The photocatalysts were recollected, washed and dried for the further

using.

Trapping active species in the photocatalytic oxidation of NO gas

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Silver nitrate (AgNO3), p-benzoquinone (PB), MeOH were selected as

photogenerated electron (e-), superoxide (•O2-), and photoinduced hole (h+)

scavengers, respectively. 5 mL AgNO3 or PB(20 wt%) aqueous solution was added

into 20 mL of ethanol containing 0.2 g as-formed photocatalyst under ultrasonication

for 30 min. The as-obtained aqueous suspensions were uniformly coated onto two

glass dishes. The coated dishes were dried at 80 oC in an oven. Ultimately, such two

dried dishes were utilized for the photocatalytic oxidation of NO. For introducing

MeOH as holes capture, methanol-water with a 1:1 volume ratio was added in the

humidifier for producing 550 ppb NO (humidity level: 70%), while keeping other

reaction conditions unchanged. For excluding the the effect of hydroxyl radicals

(•OH), the moist NO gas (humidity level: 70%) was substituted with dried NO gas.

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Characterization of the as-formed samples

Figure S1. (a) N2 isotherm plots at 77 K for Cu-NU0 and Cu-NU7. (b)The pore size

distribution of CuN0 and CuN7.

Table S1. Structural parameters of different samples.

Sample SBET (m2·g-1) Vp (cm3·g-1) DP (nm)

Cu-NU0 844.0 0.5 2.2

Cu-NU7 811.7 0.5 2.2

SBET = BET surface area, Vp = pore volume, DP = pore diameter.

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Figure S2. The UV-vis diffuse reflection spectra of Cu-NUx.

Figure S3. The FTIR spectra of Cu-NU0 and Cu-NU7.

The absorption peaks at 653 and 769 cm-1 (600-800 cm−1) correspond to Zr-O2 as

longitudinal and transverse modes.2 The peaks at 1256 cm−1 are assigned to the C-N

stretching absorption. The intense doublet at 1385 and 1432 cm-1 correspond to the

stretching modes of the carboxylic groups from H2ATA. The skeleton vibrations of

the benzene results in the IR absorption band at 1567 and 1653 cm−1.3 The peaks at

1060 and 1620 cm−1 can be assigned to the −NH2 scissoring and rocking vibrations,

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respectively.

Table S2. Cu K-edge EXAFS curves fitting parameters.

Catalyst Path CN R (Å) E0 (eV)

Cu-NU7Cu-N 3.943 ± 0.04 2.01 ± 0.02 0.118

Cu-O 1.222 ± 0.01 2.26 ± 0.02 33.09

[a] Coordianation number. [b] Coordination distance. [c] Debye-Waller factor. [d]

Inner potential correction (E0).

Figure S4. The corresponding EXAFS k space fitting curves (a) and r space fitting

curves (b) of Cu-NU7.

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Figure S5. Photocatalytic performances of NO oxidation (550 ppb) over various Cu-

NUx samples under visible-light irradiation (λ > 420 nm).

Figure S6. Photocatalytic performances for removing NO gas over Cu-NU7 washed

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with ethanol for 2, 4 and 6 times during the typical synthesis process.

Table S3. The ICP results for different cations.

Cations in different catalyst ICP results

Fe in Fe-NU7 0.91 wt%

Co in Co-NU7 0.76 wt%

Cu in Cu-NU7 0.80 wt%

Figure S7. The digital image of Cu-NU0, Cu-NU7, Fe-NU7, Co-NU7.

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Figure S8. Photocatalytic performances of NO oxidation over Cu-NU7 and Cu-

EDTA-NU7.

Figure S9. Photoluminescence (PL) emission spectra (λex = 365 nm) of Cu-NU0 and

Cu-NU7.

References:1) Li, Q. B.; Zhou, T.; Yang, H. Q. ACS Catal. 2015, 5 (4): 2225-2231.2) Yang, J.; Dai, Y.; Zhu, X. Y.; Wang, Z.; Li, Y. S.; Zhuang, Q. X.; Shi, J. L.; Gu, J. L. J. Mater. Chem. A 2015, 3 (14) 7445-7452.3) Tang, P. X.; Wang, R.; Chen, Z. L. Electrophoresis 2018, 39 (20): 2619-2625.

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