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 3d‐orbital electronic configuration performs a key function in promoting CO2 adsorption and reducing activation barrier. Hence, the spin manipulation highlights a new insight into designing highly efficient biomimetic catalysts via optimizing spin state.

Enhanced Photocatalytic CO2 Reduction Performance via Photothermal–Magnetic Synergistic Effects for Solar Fuel Production

“…The photocatalytic performance is highly dependent on the electronic structure, such as spin and valence states, of catalytic active centers . At the same time, an external stimulus such as temperature or light irradiation can induce a transition of the spin state of the metal center from high-spin state to low-spin state . Herein, the concentrated light-induced temperature elevation resulted in a reduction of the internal magnetic moment within the ZFO/TO heterojunction.…”

“…40 At the same time, an external stimulus such as temperature or light irradiation can induce a transition of the spin state of the metal center from high-spin state to low-spin state. 41 Herein, the concentrated light-induced temperature elevation resulted in a reduction of the internal magnetic moment within the ZFO/TO heterojunction. This change in the magnetic moment influenced the effectiveness of the B external enhanced catalytic performance.…”

On–Off Switching of a Photocatalytic Overall Reaction through Dynamic Spin-State Transition in a Hofmann Clathrate System

“…There are mainly two reasons for the difficulties in uncovering such structural−catalytic relationships: (1) precisely controlling the spin states without changing the coordination structures or metallic valences of the catalysts is challenging 7,14 and (2) the spin states of the active catalytic metal sites might change during the substrate absorption and desorption processes. 13,16 With regard to overcoming the above obstacles, spin-crossover (SCO) materials might provide a perfect connatural platform, as SCO materials can exhibit reversible spin-state transitions in the presence of external chemical or physical stimuli, including guest, temperature, pressure, and light irradiation. 17−20 Fe(II) compounds with an FeN 6 octahedral coordination environment are the most studied SCO systems; their 3d-orbital electronic configurations experience a t 2g 6 e g 0 ( 1 A 1 ) to t 2g 4 e g 2 ( 5 T 2 ) transformation during the SCO process.…”

“…Only 1-I was detected to show photocatalytic activity, with a H 2 O 2 photosynthetic rate of 100 μM h −1 , and almost no dioxygen was be detected under these conditions. Moreover, an isotopic experiment to simulate the real system (without AgNO 3 ) was conducted for 1-I to verify the as-proposed mechanism of the ORR by using 18 O 2 (as an electron acceptor) and H 2 16 O (as an electron donor). 18 O 2 (m/z = 36) could be detected in the decomposition product of the reaction between photogenerated H 2 O 2 and MnO 2 (Figure S23), indicating the H 2 O 2 photosynthesis process from ORR.…”