第一作者：复旦大学Sizhe Li
通讯作者：复旦大学 赵岩，湖南大学 李润
DOI：https://doi.org/10.1002/anie.202421040
作为非均相光催化剂的重要候选者，共轭聚合物在供体和受体交替单元之间表现出随机电荷转移，严重限制了其催化效率。本文受自然光系统的启发，采用引导电荷迁移到特定反应位点的概念，通过创建从主链到其垂链部分的程序化电荷转移通道，显著提高具有垂链官能团的线性共轭聚合物（LCPs）的光催化性能。原位X射线光电子能谱（XPS）和密度泛函理论（DFT）计算表明，悬垂的苯并噻唑可以作为电子“储层”，在活性位点聚集电子。此外，瞬态吸收光谱（TAS）证明，电荷转移通道的存在加速了电子转移，阻止了电子和空穴的复合。因此，在这种精心设计的结构中，光生电子可以顺利地向还原位点移动，促进O2还原为H2O2，而剩余的空穴则指向氧化中心，同时将糠醇氧化为糠酸。优化后的光催化剂LCP-BT具有较好的催化性能，H2O2产率为868.3 μmol L-1 h-1，是常规随机电荷转移聚合物LCP-1的9.8倍，6 h后糠醇转化率超过95%。
Scheme 1. Illustration of the synthetic route and the design strategy of directional charge transfer channels in LCPs.
Figure 1. Structural characterizations and photoelectrochemical analysis of LCPs. FT-IR spectra (a), UV/Visible diffuse reflectance spectra (b), steady-state photoluminescence (PL) spectra (c), transient photocurrents (d), and electrochemical impedance spectroscopy (EIS) Nyquist plots (e) of LCP-1, LCP-Ph, LCP-Py, and LCP-BT, respectively. Integrated PL emission intensity as a function of temperature of LCP-1 (f) and LCP-BT (g). (h) Open circuit/–0.1 vs NHE, zeta potentials/–1 mV, and built-in electric fields of the LCP-1, LCP-Ph, LCP-Py, and LCP-BT, respectively. The PL in (c) was excited at 420 nm. The transient photocurrents in (d) were carried out under the irradiation of Xe lamp with light wavelength higher than 420 nm. The Nyquist plots in (e) were conducted with an applied potential of 10 mV over a frequency range of 0.01 Hz to 1 MHz in a deoxygenated solution of 1 mmol L-1 K₃[Fe(CN)₆], 1 mmol L-1 K₄[Fe(CN)₆], and 0.1 mmol L-1 KCl while using photocatalyst-coated ITO plate, Pt plate and Ag/AgCl as working, counter and reference electrode, respectively. The inset in (f) and (g) are temperature-dependent PL spectra.
Figure 2. Photocatalytic performance and mechanisms analyse of LCPs in H2O2 photosynthesis coupled with FFA photo-oxidation. (a) Photocatalytic H2O2 evolution yields of LCPs. (b) Yields of H2O2 and furoic acid over LCPs in 6 h. (c) Active species trapping experiments for LCP-BT-30. (d) EPR signals of DMPO-•O2− on LCPs in O2-saturated methanol. (e) EPR signals of DMPO-•OH on LCPs in water. (f) EPR signals of DMPO-•C5H5O2 over LCP-BT-30 in FAL solution in dark and under light irradiation. In-situ DRIFTS spectra of LCP-BT-30 under the exposure of H2O, FAL and O2 in dark (g) and under light irradiation (h). (i) Proposed reaction pathway of photocatalytic FAL oxidation coupled with H2O2 production.
Figure 3. In situ analyses and theoretical calculations. In situ X-ray photoelectron spectroscopy (XPS) spectra of N 1s (a), and S 2p (b) for LCP-BT-30 in dark and under 420 nm LED illumination; (c) Charge density distribution of the HOMO and LUMO for the model molecule of LCPs from DFT calculations; (d) Molecular electrostatic potential (MESP) and map molecular dipoles of LCPs.
Figure 4. Surface morphologies and corresponding KPFM images. AFM images and corresponding surface potential maps of LCP-1 (a, c) and LCP-BT (b, d), respectively. The line-scanning surface potentials of LCP-1 (e) and LCP-BT (f) in darkness and under irradiation.
Figure 5. Femtosecond transient absorption measurements. 2D transient absorption surface plots of LCP-1 (a) and LCP-BT (b). Transient absorption signals of LCP-1 (c) and LCP-BT (d). The decay signals of LCP-1 (e) and LCP-BT (f).
Programmed Charge Transfer in Conjugated Polymers with Pendant Benzothiadiazole Acceptor for Simultaneous Photocatalytic H2O2 Production and Organic Synthesis
https://doi.org/10.1002/anie.202421040
