Photoreduction of CO₂ to a single gas product requires catalysts with remarkable product selectivity because CO and CH₄ are usually produced simultaneously. We propose that the charge-density regulation within metal-organic frameworks (MOFs) could effectively manage the binding energy required for reduction intermediates, thereby controlling the ultimate product formation to obtain CO with 100% selectivity. Herein, two iso-structured Fe-based MOFs bearing linkers with different electronic properties were prepared and exhibited favorable CO₂ photoreduction performance without any cocatalyst or photosensitizer. In particular, the linker was altered to reduce the transfer of charges from Fe to the surrounding ligands, regulating the charge-density distribution. The binding affinity with the key COH∗ was remarkably weakened and behaved thermodynamically unfavorably compared with CO desorption, resulting in 100% CO generation. These insights provide a catalyst design strategy for controlling reduction species and improving product selectivity, which could encourage the development of intriguing MOF material customization for photocatalysis.

中文翻译：

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通过电荷密度调节金属有机框架将 CO2 光还原成完整的 CO


将 CO₂ 光还原为单一气体产物需要具有出色产品选择性的催化剂，因为 CO 和 CH₄ 通常是同时产生的。我们提出，金属有机框架 （MOF） 内的电荷密度调节可以有效地管理还原中间体所需的结合能，从而控制最终产物的形成以获得具有 100% 选择性的 CO。在此，制备了两种具有不同电子性质的等结构的带有连接子的 Fe 基 MOFs，并在没有任何助催化剂或光敏剂的情况下表现出良好的 CO₂ 光还原性能。特别是，接头被改变以减少电荷从 Fe 转移到周围的配体，调节电荷密度分布。与 CO 解吸相比，与关键 COH∗ 的结合亲和力显著减弱，热力学表现不利，导致 100% CO 生成。这些见解为控制还原种类和提高产品选择性提供了一种催化剂设计策略，这可以鼓励开发用于光催化的有趣的 MOF 材料定制。