Spin Manipulation in a Metal–Organic Layer through Mechanical Exfoliation for Highly Selective CO2Photoreduction

Abstract Spin manipulation of transition‐metal catalysts has great potential in mimicking enzyme electronic structures to improve activity and/or selectivity. However, it remains a great challenge to manipulate room‐temperature spin state of catalytic centers. Herein, we report a mechanical exfoliation strategy to in situ induce partial spin crossover from high‐spin ( s =5/2) to low‐spin ( s =1/2) of the ferric center. Due to spin transition of catalytic center, mixed‐spin catalyst exhibits a high CO yield of 19.7 mmol g −1 with selectivity of 91.6 %, much superior to that of high‐spin bulk counterpart (50 % selectivity). Density functional theory calculations reveal that low‐spin 3 d ‐orbital electronic configuration performs a key function in promoting CO 2 adsorption and reducing activation barrier. Hence, the spin manipulation highlights a new insight into designing highly efficient biomimetic catalysts via optimizing spin state.