Photocatalytic conversion of diluted CO2 into solar fuel is highly appealing yet still in its infancy. Herein, we demonstrate the metal‐node‐dependent performance for photoreduction of diluted CO2 by constructing Ni metal–organic framework (MOF) monolayers (Ni MOLs). In diluted CO2 (10 %), Ni MOLs exhibit a highest apparent quantum yield of 1.96 % with a CO selectivity of 96.8 %, which not only exceeds reported systems in diluted CO2 but also is superior to most catalysts in pure CO2. Whereas isostructural Co MOLs is almost inactive in diluted CO2, indicating the performance is dependent on the metal nodes. Experimental and theoretical investigations show that strong CO2 binding affinity of Ni MOLs is the crucial factor, which stabilizes the Ni‐CO2 adducts and facilitates CO2‐to‐CO conversion.

Fluorescence imaging in the second near-infrared window (NIR-II, 1000–1700 nm) using small-molecule dyes has high potential for clinical use. However, many NIR-II dyes suffer from the emission quenching effect and extremely low quantum yields (QYs) in the practical usage forms. The AIE strategy has been successfully utilized to develop NIR-II dyes with donor–acceptor (D–A) structures with acceptable QYs in the aggregate state, but there is still large room for QY improvement. Here, we rationally designed a NIR-II emissive dye named TPE-BBT and its derivative (TPEO-BBT) by changing the electron-donating triphenylamine unit to tetraphenylethylene (TPE). Their nanoparticles exhibited ultrahigh relative QYs of 31.5% and 23.9% in water, respectively. By using an integrating sphere, the absolute QY of TPE-BBT nanoparticles was measured to be 1.8% in water. Its crystals showed an absolute QY of 10.4%, which is the highest value among organic small molecules reported so far. The optimized D–A interaction and the higher rigidity of TPE-BBT in the aggregate state are believed to be the two key factors for its ultrahigh QY. Finally, we utilized TPE-BBT for NIR-II photoluminescence (PL) and chemiluminescence (CL) bioimaging through successive CL resonance energy transfer and Förster resonance energy transfer processes. The ultrahigh QY of TPE-BBT realized an excellent PL imaging quality in mouse blood vessels and an excellent CL imaging quality in the local arthrosis inflammation in mice with a high signal-to-background ratio of 130. Thus, the design strategy presented here brings new possibilities for the development of bright NIR-II dyes and NIR-II bioimaging technologies.

The interaction of two-dimensional (2D) nanomaterials and bacterial membranes has attracted tremendous attention in antibacterial applications. Various peculiarities of 2D nanomaterials may lead to multiple mechanisms of their interactions with membranes. Here, we investigated the interaction between molybdenum disulfide (MoS2) nanosheets and the bacterial membrane by using both theoretical and experimental approaches. Molecular dynamics simulation presented that MoS2 nanosheets can disrupt the structure of the lipid membrane by making dents on its surface and extracting phospholipid molecules to reduce the integrity of the membrane. This is attributed to the combination of the dispersion interaction of lipid tails with S atoms and the electrostatic interactions of lipid head groups with the Mo and S atoms in the lateral edges of the MoS2 nanosheet. Scanning electron microscopy and transmission electron microscopy confirmed the dents and the destruction of the cell membrane, which would lead to the loss of cytoplasm and the death of bacteria. It should be noted that the phenomenon where MoS2 induces a dent is different from the direct insertion of graphene-based nanomaterials, which might be due to the thicker and stiffer structure of MoS2. Therefore, we believe that the molecular interactions of 2D nanomaterials with bacterial membranes should be highly correlated with their structural characteristics. This newly discovered mechanism of MoS2 nanomaterials to disrupt the cell membrane may promote the application of transition metal dichalcogenide (TMD) nanomaterials in designing remarkable antibacterial materials in the near future.

Photocatalytic oxygen reduction reaction (ORR) offers a promising hydrogen peroxide (H2O2) synthetic strategy, especially the one‐step two‐electron (2e−) ORR route holds great potential in achieving highly efficient and selectivity. However, efficient one‐step 2e− ORR is rarely harvested and the underlying mechanism for regulating the ORR pathways remains greatly obscure. Here, by loading sulfone units into covalent organic frameworks (FS‐COFs), we present an efficient photocatalyst for H2O2 generation via one‐step 2e− ORR from pure water and air. Under visible light irradiation, FS‐COFs exert a superb H2O2 yield of 3904.2 μmol h−1 g−1, outperforming most reported metal‐free catalysts under similar conditions. Experimental and theoretical investigation reveals that the sulfone units accelerate the separation of photoinduced electron‐hole (e−‐h+) pairs, enhance the protonation of COFs, and promote O2 adsorption in the Yeager‐type, which jointly alters the reaction process from two‐step 2e− ORR to the one‐step one, thereby achieving efficient H2O2 generation with high selectivity.