posted on 2023-11-28, 19:20authored byXiaoxue Ma, Lu Zhang, Ronghua Liu, Xin Li, Hui Yan, Xin Zhao, Yikai Yang, Hongjie Zhu, Xiangjin Kong, Jie Yin, Huawei Zhou, Xia Li, Lingqian Kong, Hongguo Hao, Dichang Zhong, Fangna Dai
The design and development of proton conduction materials
for clean
energy-related applications is obviously important and highly desired
but challenging. An ultrastable cobalt-based metal–organic
framework Co-MOF, formulated as [Co2(btzip)2(μ2–OH2)] (namely, LCUH-103, H2btzip = 4, 6-bis(triazol-1-yl)-isophthalic
acid) had been successfully synthesized via the hydrothermal method. LCUH-103 exhibits a three-dimensional framework and a one-dimensional
microporous channel structure with scu topology based
on the binuclear metallic cluster {Co2}. LCUH-103 indicated excellent chemical and thermal stability; peculiarly,
it can retain its entire framework in acid and alkali solutions with
different pH values for 24 h. The excellent stability is a prerequisite
for studying its proton conductivity, and its proton conductivity
σ can reach up to 1.25 × 10–3 S·cm‑1 at 80 °C and 100% relative humidity
(RH). In order to enhance its proton conductivity, the proton-conducting
material Im@LCUH-103 had been prepared by encapsulating
imidazole molecules into the channels of LCUH-103. Im@LCUH-103 indicated an excellent proton conductivity of 3.18
× 10–2 S·cm‑1 at 80 °C and 100% RH, which is 1 order of magnitude higher
than that of original LCUH-103. The proton conduction
mechanism was systematically studied by various detection means and
theoretical calculations. Meanwhile, LCUH-103 is also
an excellent carrier for palladium nanoparticles (Pd NPs) via a wetness
impregnation strategy, and the nitrophenols (4/3/2-NP) reduction in
aqueous solution by Pd@LCUH-103 indicated an outstanding
conversion efficiency, high rate constant (k), and
exceptional cycling stability. Specifically, the k value of 4-NP reduction by Pd@LCUH-103 is superior
to many other reported catalysts, and its k value
is as high as 1.34 min–1 and the cycling stability
can reach up to 6 cycles. Notably, its turnover frequency (TOF) value
is nearly 196.88 times more than that of Pd/C (wt 5%) in the reaction,
indicating its excellent stability and catalytic activity.