E. H. (2022). Quantum-size-tuned heterostructures enable efficient and stable inverted perovskite solar cells. Nature Photonics.

Singlet oxygen ( 1 O 2 ) is considered one of the most effective and selective oxygen agents. However, it is always obtained with the help of heavy atoms in the photosensitizers to sensitize 3 O 2 . Herein, metal−nitrogen (M−Nx) doped 1 O 2 photosensitizers were readily prepared from metal−nitrogen complex. Their relative metal centers (e.g., Co) chelated with the N/C moiety (Co−Nx/C) provide the primary active sites for 1 O 2 generation and selective oxidation. The structures of Co−Nx active sites are investigated by scanning and transmission electron microscopy and X-ray photoelectron, Fourier transform infrared, and X-ray absorption fine structure spectroscopy. Their functions for 1 O 2 generation are confirmed by electrons spin resonance, 1 O 2 emission, KSCN poisoning test, and H 2 SO 4 etching test. These Co−Nx photosensitizers show excellent selective photooxidation abilities for 1,5-dihydroxynaphthalene after irradiation by a light-emitting diode lamp. After simple concentration and filtration, it is easy to obtain the pure product (juglone), which is confirmed by 1 H NMR spectroscopy. On the basis of density functional theory calculations, metal (e.g., Co) chelated with N/C moiety, especially for the Co−pyridinic N structure, could effectively reduce the singlet−triplet energy gap (ΔE ST ). It is speculated that this strategy for lowering ΔE ST could benefit intersystem crossing from the singlet state to the triplet state and efficient sensitization of 3 O 2 (triplet state) into 1 O 2 for selective photooxidation.

Optimizing the shape, structure, and interface of noble metal bimetallic nanostructures significantly improves their catalytic properties. Recently, Au@Pd core–shell bimetallic nanostructures have attracted considerable interest for fuel cell applications. Regrettably, most of the research mainly focuses on the morphological and structural control whereas interfacial control is neglected. In this work, polyethylenimine (PEI) functionalized Au nanowires@Pd core–shell bimetallic nanohybrids (Au-NWs@Pd@PEI) are synthesized by a chemical reduction method using Au nanowires (Au-NWs) as seeds in the presence of PEI and demonstrate their application toward oxygen reduction reaction (ORR) in an alkaline solution. Electrochemical results display that Au-NWs@Pd@PEI with optimal component shows enhanced ORR activity, selectivity, and durability compared to Pt/C electrocatalyst. Physical characterizations demonstrate that the electronic property of Pd shell mainly is affected by PEI polymer rather than Au-NWs core. Relative to PEI functionalized Pd nanowires without Au core, ORR activity enhancement of Au-NWs@Pd@PEI is exclusively ascribed to the surface strain effect. Meanwhile, loose-packed PEI polymer on the Pd surface can work as barrier nanosieves to exclusively prevent the access of methanol to Pd sites, which imparts Au-NWs@Pd@PEI with enhanced methanol tolerance toward ORR in an alkaline solution.

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