Hydrogen-Bonded organic framework Containing stacked Cu2+ for photocatalytic reduction of CO2 to C2H4

In this work, the strategy of constructs stacked Cu2+ sites to achieve photocatalytic CO2 reduction into C2H4, the unique metallization design regulates the molecular spacing of active centers and promote multiple electron transfer steps. The light trapping sites, catalytically active centers, and efficient charge/mass transfer configurations were successfully integrated into the HOF which facilitated the C-C coupling of PFC-11(Cu). This work will inspire more future research on photocatalysts with tunable molecular layer spacing, and it provides useful guidance for the design and optimization of efficient CO2RR for C2H4 generation. [Display omitted] •Metallization of hydrogen-bonded organic framework leads to the stacked Cu2+ sites.•The stacked active Cu2+ sites in PCF-11(Cu) promote C-C coupling of C1 intermediates.•PFC-11(Cu) achieves CO2 photoreduction to C2H4 with an electron selectivity of 92.3 %. Solar-driven photocatalytic conversion of carbon dioxide (CO2) to high-value ethene (C2H4) is a promising and environmentally friendly reaction, but key challenges such as low C–C coupling performance and poor electron transfer efficiency need to be addressed. Herein, Cu2+ ions are precisely stacked via the metallization of 4,4′,4″-(1,3,5-triazine-2,4,6-triyl)tribenzoic acid-based hydrogen-bonded organic framework (PFC-11) to obtain PFC-11(Cu). Compared with PFC-11, the abundant catalytically active Cu2+ sites of PFC-11(Cu) provide good light-harvesting and efficient charge-transfer performance. This is confirmed by photoluminescence spectroscopy and transient photocurrent measurements. Consequently, PFC-11(Cu) can photocatalytically reduce CO2 to C2H4 with a yield of 2.4 μmol⋅g−1 within 10 h and an electron selectivity of 92.30 % in water without any photosensitizer or sacrificial agent. In-situ diffuse reflectance Fourier transform infrared spectroscopy and density functional theory calculations are used to confirm the achievement of C–C coupling over PFC-11(Cu) due to the reasonable distribution of Cu2+ ions in the framework structure. This study provides a new approach to design photocatalysts with tunable activity center layer spacing for efficient CO2 reduction to multi-carbon compounds.