Photoinduced Metastable Asymmetric Cu Single Atoms for Photoreduction of CO₂ to Ethylene

Abstract

Metastable structures are promising candidates for efficient catalysis owing to abundant active electronic states, strong electronic coupling with reactants, and energetic preference. Exerting the value of metastable structures while evading the difficulty in direct synthesis remains challenging. Herein, it is reported that light irradiation enables the generation and maintenance of the metastable state over copper single atoms for efficient carbon dioxide reduction. Under irradiation with light, photogenerated electrons transit to Cu‐3d orbits and initiate d‐orbital rearrangement. The initial symmetric Cu1─O4 coordination converts to the metastable asymmetric structure of Cu1─O2+1, and is reversibly restored after removing the light. The photoinduced metastable intermediate of Cu1─O2+1 promotes the Cu single‐atom catalyst to deliver an ethylene yield rate of 60.4 µmol gcat.−1 h−1. Mechanistic studies reveal that Cu1─O2+1 possesses stronger adsorption capability for reactants and intermediates. The reaction energy barrier over Cu1─O2+1 also shows an obvious decline compared to that over Cu1─O4.

Efficient Interfacial Charge Transfer Enables Nearly 100% Selectivity for Solar-Light-Driven CO2 Conversion

“…As shown in Figure e, the C K edge sXAS spectra of 2% ReSe 2 /C 3 N 4 composites and pristine C 3 N 4 show two similar characteristic resonances, i.e., π* (CC) and π* (C–N–C) . Furthermore, the peak intensities of 2% ReSe 2 /C 3 N 4 composites decrease after the incorporation of ReSe 2 UTNs, implying the presence of vacancy defects in 2% ReSe 2 /C 3 N 4 composites because of lattice distortion caused by ReSe 2 incorporation . Electron paramagnetic resonance spectroscopy (Figure S4) shows that 2% ReSe 2 /C 3 N 4 composites possess more vacancy defects than does pristine C 3 N 4 .…”

Manipulating the Spin State of Co Sites in Metal–Organic Frameworks for Boosting CO2 Photoreduction

“…To unveil the charge transfer mechanism in photocatalysis, in situ soft X-ray absorption spectroscopy (sXAS) and in situ electron paramagnetic resonance (EPR) have been performed over Co-OAc as a representative. The peaks at 778.4 and 793.7 eV correspond to the L 3 and L 2 edges, respectively (Figure a), which arise from the electron transition from p-orbitals to d-orbitals . Notably, the signals under light irradiation are apparently suppressed, suggesting that the Co sites accept electrons .…”

“…50 Notably, the signals under light irradiation are apparently suppressed, suggesting that the Co sites accept electrons. 50 Furthermore, in situ EPR shows a Co 2+ signal under dark conditions (Figure S20). 51 Upon exposure to light, a reduced signal can be observed as the Co 2+ accepting electrons is converted into EPR-silent Co + .…”

“…The peaks at 778.4 and 793.7 eV correspond to the L 3 and L 2 edges, respectively (Figure 3a), which arise from the electron transition from p-orbitals to dorbitals. 50 Notably, the signals under light irradiation are apparently suppressed, suggesting that the Co sites accept electrons. 50 Furthermore, in situ EPR shows a Co 2+ signal under dark conditions (Figure S20).…”

Perovskite Paradigm Shift: A Green Revolution with Lead-Free Alternatives in Photocatalytic CO2 Reduction

“…Besides, the SACs with LFHPs for other catalytic reactions were exclusively based on Pt SAs directly anchored on halide perovskites via Pt coordination with the halide anions in the halide perovskites. − With the aid of the surface coordination chemistry tuning, the exploration of other SAs to be anchored onto LFHPs through various coordination bonds could lead to new functionalities. In particular, it is envisaged that the incorporation of Cu SAs could be highly promising as Cu is regarded as one of the most attractive metal cocatalysts for CO 2 reduction owing to its optimal binding ability with CO 2 and reaction intermediates. , The superiority of Cu SAs on other photocatalysts for robust CO 2 reduction have also been validated. − Furthermore, the immobilization of dual-atom or dual-single atom catalysts (DACs) on LFHPs is also worth exploring for selectivity tuning. Attributed to the mutual action of neighboring two atoms, it has been reported that DACs can outperform SACs through two metal active sites engineering, where DACs could efficiently stabilize the target intermediates leading to the desired products. − …”