摘要：随着减少碳足迹的迫切需求，光催化二氧化碳还原作为一种可持续的缓解方案，受到了越来越多的关注。考虑到催化活性位点（CASs）在催化过程中的重要作用，控制和设计CASs的密度及其环境可以显著提升催化剂性能。在此，作者报道了一种新型金属-共价有机框架（MCOF），即
本文要点：
随着减少碳足迹的迫切需求，光催化二氧化碳还原作为一种可持续的缓解方案，受到了越来越多的关注。考虑到催化活性位点（CASs）在催化过程中的重要作用，控制和设计CASs的密度及其环境可以显著提升催化剂性能。在此，作者报道了一种新型金属-共价有机框架（MCOF），即MCOF-Co-315，其特点是含有地球储量丰富的钴（Co）助催化剂，并通过共价键骨架实现共轭连接。在Ru(bpy)₃Cl₂作为光敏剂、三乙醇胺（TEOA）作为牺牲电子供体、1.5 AM滤光片、可见光镜模块（390–740 nm）以及1太阳光强度的照射条件下，MCOF-Co-315表现出1616 μmol g⁻¹ h⁻¹的CO生成速率，并在450 nm处具有9.13%的显著表观量子产率（AQY）。通过电子顺磁共振（EPR）光谱、X射线吸收近边结构（XANES）和原位同步辐射傅里叶变换红外（FT-IR）光谱对光催化反应进行了研究，并提出了一种潜在的反应机制。Figure 1. (a) Proposed linkage of MCOF-Co-315, viewed from the c axis (Co, orange; N, blue; C, gray; H omitted for clarity). (b) Diffraction pattern obtained from experimental PXRD and simulation. (c) Cryo-TEM of MCO-Co-315 at 20 nm resolution.
Figure 2. (a) Isothermal N2 adsorption–desorption of MCOF-Co-315 at 77 K. (b) Pore size distribution obtained from NLDFT. (c) XPS spectrum for illustrating Co oxidation state in MCOF-Co-315. (d) PESA measurement of drop-cast MCOF-Co-315. (e) UV–vis spectrum of the MCOF-Co-315 suspension in acetonitrile. (f) Calculated FMO energy level.
Figure 3. (a) CO production yield over MCOF-Co-315 in 8 h. (b) GCMS of isotope labeling experiment using 13CO2 as carbon source. (c) Cycle experiment based on the production yield in 8 h using MCOF-Co-315 as photocatalyst. (d) PXRD of MCOF-Co-315 before and after 5 cycles of photocatalysis. (e) AQY comparison of selected COF materials for CO2 photoreduction to CO in literature, more details in Table S2.
Figure 4. (a, b) In situ X-band EPR measurements performed as a function of time during photocatalysis with DMPO as a spin trap compared to simulations of DMPO adduct spectra. (c) EPR spectra of MCOF-Co-315 with Ru(bpy)3Cl2 before, during, and after illumination at 10 K.
Figure 5. (a) In situ synchrotron FT-IR spectroscopy of MCOF-Co-315 with incremental CO2 concentration in gas stream. (b) Normalized Co K-edge XANES spectra of MCOF-Co-315, MCOF-Co-315_post reaction, and reference samples (CoO and Co3O4). (c) Proposed reaction mechanism.
来源：华算科技