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Liu et al. Chem Synth 2023;3:24 https://dx.doi.org/10.20517/cs.2023.13 Page 3 of 14

metal-support interaction, the as-prepared Pd@NH -NC displays excellent catalytic performance for FA
2
dehydrogenation. Specifically, a 100 % conversion of FA into CO and H is completed over Pd@NH -NC
2
2
2
catalyst without additive at room temperature, providing a remarkable initial turnover frequency (TOF initial )
of 4,892 h and a low activation energy (E ) of 28.5 kJ·mol . These results highlight that proper
−1
−1
a
multifunctional modifications of the supports have a synergistic promoting effect on catalytic reaction,
providing a reference for the development of highly efficient heterogeneous catalysts.
EXPERIMENTAL
Chemicals
Sodium tetrachloropalladium (Na PdCl , 98 %), sodium borohydride (NaBH ), (3-aminopropyl)
4
2
4
triethoxysilane (APTS, 99 %), urea (AR, 99 %), and formic acid (FA, HCOOH, GR, ≥ 98 %) were purchased
from Aladdin Reagents Ltd. Ethanol was purchased from FuYu Chemical Reagents. Vulcan XC-72 carbon
was purchased from Cabot Carbon Ltd. All chemicals were used directly without subsequent treatment.

Preparation of nitrogen-functionalized carbon supports
Nitrogen-functionalized carbon supports (NCs) were prepared by a “soft nitriding” method according to
previously reported work . Typically, 1.5 g of urea was first ground into powder and mixed with 1.0 g of
[39]
Vulcan XC-72 carbon in a mortar. Then, the mixed powder was placed in a crucible, then wrapped in tinfoil
and heated at 150 °C for 2 h and 300 °C for another 2 h in a tube furnace. The obtained powder was
repeatedly washed with water and ethanol. Finally, the as-prepared NC was dried at 60 °C overnight.

Preparation of Pd cluster supported on nitrogen/amino co-functionalized carbon (Pd@NH -NC)
2
In a typical preparation of Pd@NH -NC, 120 mg of NC was added to 30 mL of water under ultrasound for 1
2
h. Then, 0.5 mL of APTS was added to the above solution with ultrasonic treatment for 1 h and stirring for 1
h. Then, 1.0 mL of 6 mg·mL Na PdCl was dripped into the mixed solution. After stirring for another 2 h,
-1
2
4
-1
3.0 mL of NaBH (10 mg·mL ) was introduced into the above solution, followed by stirring for 2 h. Finally,
4
the obtained Pd@NH -NC was centrifuged and repeatedly washed with water, and dried at 60 °C.
2
The reference Pd@NH -C catalyst was prepared by the same process as Pd@NH -NC catalyst except that
2
2
unfunctional carbon was used instead of NC. The reference Pd@NC catalyst was obtained with the same
process as Pd@NH -NC catalyst but in the absence of APTS. The reference Pd@C catalyst was prepared in
2
the same way as Pd@NH -NC catalyst, except for the addition of 100 mg of unfunctional carbon and in the
2
absence of APTS.
FA dehydrogenation reaction
The reaction was carried out in a set-up as shown in Supplementary Figure 1. Typically, 160 mg of catalyst
and 3.0 mL of water were mixed in the sealed round-bottom flask with ultrasonic treatment for 30 min, and
then placed in a water bath at 298 K with stirring. The sealed round-bottom flask was connected to an
inverted cylinder filled with water via a gas conduit. Then, the reaction started when 1.0 mL of FA solution
(3.0 M) was injected into the round-bottom flask with a syringe. The volume of gas released was determined
by the displacement of water in the cylinder over time. The displacement of water in the cylinder reached 10
mL as a unit, and the corresponding time was recorded to obtain the plots of gas volumes generated versus
time. The reaction thermodynamics of FA dehydrogenation was studied by setting test temperature as 298,
303, 313, 323, and 333 K, and the kinetics of FA dehydrogenation was determined by adjusting the
concentrations of Pd (5.75, 8.50, 11.25, and 14.00 mM) and the concentrations of FA (0.25, 0.50, 0.75, and
1.00 M).