Rapid charge transfer in covalent organic framework via through-bond for enhanced photocatalytic CO2 reduction

Photocoupled Electroreduction of CO2 over Photosensitizer-Decorated Covalent Organic Frameworks

“…Furthermore, X-ray absorption near-edge structure (XANES) spectra of Co-Bpy-COF-Ru 1/2 and Co-Bpy-COF 2/3 at the Ru K-edges (Figure a) are similar to those of Ru­(bpy) 3 Cl 2 , indicating the bivalent nature of Ru involved in the two COFs. The Fourier transformed (FT) k 2 -weighted extended X-ray absorption fine structure (EXAFS, Figure b) curves suggest that both of the COFs exhibit one prominent peak at 1.57 Å, corresponding to the scattering of the Ru–N coordination of the first shell . No obvious signals of Ru–Ru (2.37 Å) and Ru–O (1.47 Å) are detected in either material, revealing the predomination of the atomic Ru–N x species and the absence of Ru and RuO 2 particles in both samples.…”

“…In view of the key scientific issues above, it is recommended to integrate an acceptor with strong CO 2 reduction ability, as well as powerful donor characterized by long-lived triplet excited states, into a crystalline material to establish a built-in electric field. − This approach can thus effectively extend the excited-state lifetime of the CO 2 reduction sites, thereby augmenting the efficacy of photoinduced excited-state CO 2 electrocatalysis. As an emerging class of crystalline porous materials constructed by functional organic building blocks with covalent bonds, two-dimensional (2D) COFs would be promising platforms to incorporate CO 2 reduction sites and light harvesters into their backbones. − Furthermore, the ordered π-array structures in highly crystalline 2D COFs can provide preorganized channels for high-rate intra-framework excited-electron transfer. , Notably, it is difficult to integrate these advantages in a MOF, due to the energetically unfavored ligand-to-node charge transfer. , To date, there is, to the best of our knowledge, no report of donor–acceptor (D–A) characteristic 2D COFs with a giant built-in electric field for light-coupled CO 2 electroreduction.…”

Immobilization of metal active centers in reticular framework materials for photocatalytic energy conversion

“…118 The self-properties of porphyrin and the extended π-conjugated plane of the 2D COFs resulted in excellent light absorption, efficient charge separation, and fast interfacial charge transfer, making H 2 PReBpy-COF a preeminent photocatalyst for CO 2 reduction. On the other hand, Cao et al utilized [Ru(bpy) 3 ] 2+ (bpy = 2,2′ bipyridine) and activated cobalt porphyrin (Co-Por) to prepare COF-RuBpy-Co. 119 The efficient photoelectron transfer from [Ru(bpy) 3 ] 2+ to Co-Por enabled a CO generation rate of 547 μmol g −1 h −1 , which was a 1.4-fold improvement over both physical mixtures. It is worth noting that the fs-TA results provided evidence for a faster transfer of photogenerated charge (44.2 ps, Fig.…”

Two-Dimensional Kagome Covalent Organic Frameworks with Single Atomic Co Sites for Superior Photocatalytic CO2 Reduction

“…Three obvious peaks present in the C 1s XPS spectra of all studied samples and the peaks at the binding energies (BEs) of 284.6, 285.5, and 287 eV can be assigned to CC, CN, and C–N, respectively (see Figure a, as well as Figures S18–S20 in the Supporting Information). The N 1s XPS spectrum of ETTA-Bpy-COF can be deconvoluted into two types of N species, namely pyridine N (399.2 eV) and imine N (398.8 eV). , Compared with the N 1s XPS spectrum of ETTA-Bpy-COF, the N 1s XPS spectra of all ETTA-Bpy-COF-M samples show a new peak at the BE of 406.4 eV, which is due to the integration of NO 3 – (see Figure b, as well as Figures S21–S23 in the Supporting Information) . Also, the N 1s peaks attributing to the pyridine N in the ETTA-Bpy-COF-M samples show movement similar to a higher energy, compared to that in pristine ETTA-Bpy-COF, indicating the successful introduction of metals in the ETTA-Bpy-COF host.…”

“…Covalent organic frameworks (COFs) are a class of crystalline porous material and feature many advantages, including good chemical and thermal stability, high porosity, and adjustable structure, and thus render them an ideal choice in various applications, such as heterogeneous catalysis, energy storage, drug delivery, photoelectric devices, and gas separation and storage. − To date, versatile two-dimensional (2D) and three-dimensional (3D) COFs with different topologies, such as kgd , hcb , sql , hxl , pcb , flu , and kg m , are constructed and investigated for the applications in above-mentioned fields. The kg m topology is a typical 2D COF structure that has a characteristic double-pore configuration consisting of triangular micropores and hexagonal mesopores.…”