AM：乙烯键连COFs超分子工程--高活性质子交换膜水电解

本文要点：

1. 在催化剂-水界面上控制功能附着层的形成是一个极具挑战性但潜在强大的策略，以加速质子转移和去质子化，最终改善质子交换膜水电解(PEMWE)的性能。

2. 在这项研究中，报道了具有高质子传导率的坚固的亚乙烯基连接的共价有机框架(COFs)的合成，其随后与二氧化钌杂化，产生用于酸性析氧反应(OER)的高性能阳极催化剂。

3. 由理论计算证实的原位光谱测量揭示了在COFs和吸附的氧代中间体之间形成的组装氢键有效地定向了界面水分子，稳定了OER中间体形成的过渡态。这决定了质子转移和去质子化的能垒降低，从而产生了优异的酸性OER性能。

4. 当集成到PEMWE器件中时，该系统仅在1.54 V电池电压下就实现了1.0 A cm-2的创纪录电流密度，在工业级200 mA cm-2下长期稳定性超过180 h。

5. 该方法依赖于定向氢键结合的附着层的自组装，突出了COFs的破坏性潜力，其具有可定制的结构和多功能位点，用于推进PEMWE技术。

   
   

Figure 1. a) Challenges in the traditional catalytic system for acidic OER. b) The structural models of COF-O(n), where n = 0, 1, 2, and 3 correspond to the ethoxy side chains of varying lengths. Red denotes oxygen (O); blue represents nitrogen (N); gray indicates carbon (C), and white shows hydrogen (H). c) Proton conductivity at 80 °C of COF-O(n). d) Schematic illustration of a hydrogen-bonded network at the catalyst-water interface during the transformation of intermediates for high performance PEM device.

Figure 2. a) Structural models and b) XRD patterns for COF-O(n), where n = 0, 1, 2, and 3. c) Pawley refined pattern (black), experimental pattern (red), differences (green), simulated eclipsed (AA) stacking pattern (purple), and simulated eclipsed (AB) stacking pattern (pink). d) FT-IR spectra of COF-O(3) and corresponding BOPA and TMT monomers. e) 13C CP/MAS NMR spectrum of COF-O(3). f) HRTEM images of COF-O(n) (where n = 0, 1, 2, and 3) are presented sequentially from left to right, with the corresponding layer-to-layer distances indicated in the images.

Figure 3. a) Polarization curves and b) Tafel slopes of RuO2@COF-O(n), n = 0, 1, 2, and 3, and commercial RuO2. c) Relationship between proton conductivity (??) at 80 °C and ECSA normalized current density at 1.5 V for RuO2@COF-O(n), n = 0, 1, 2, and 3. d) Arrhenius plots of protonated COF-O(3) and protonated COF-O(2) under 100% relative humidity (RH). e) Polarization curves of RuO2@COF-O(3) before and after 1000 cyclic voltammetry cycles. f) Raman spectra of RuO2@COF-O(3) during OER tests, displaying several characteristic peaks corresponding to COF-O(3) and RuO2, respectively.

Figure 4. Part of in situ ATR-FT-IR spectra for a) RuO2@COF-O(3) and b) RuO2. c) Stark tuning rate of RuO2@COF-O(3). d) The variation in the fraction of the peak related to strong hydrogen bonding as the potential increased. e) Contour plots of independent gradient model based on Hirshfeld partition (IGMH) isosurfaces for RuO2@COF-O(3) model adsorbed with *OOH intermediate, with blue surfaces indicating the hydrogen bonding and green surfaces indicating the van der Waals interactions. C, H, O, N, and Ru atoms are represented by grey, white, red, blue, and cyan. Free energy diagrams of reaction and kinetics barriers for f) RuO2@COF-O(3) and g) RuO2 at applied potentials of 0 V and 1.23 V, illustrating the charge redistribution during intermediates adsorption at active sites for OER.

Figure 5. a) Schematic of the anodic composition layers and the reaction pathway in the PEMWE device. b) Polarization curves of the PEMWE electrolyzer obtained at 80 °C. c) Comparisons of the cell voltage required to achieve a 1.0 A cm−2 current density and anode noble metal cost for various RuO2-based electrocatalysts in PEMWE. Bode phase plots of d) RuO2@COF-O(3) and e) RuO2, respectively. f) Response of the phase angle to the applied potentials of RuO2@COF-O(3) and RuO2. g) Chronopotentiometry curves at a current density of 200 mA cm−2.

https://doi.org/10.1002/adma.202417374