A Universal Electrochemical Synthetic Strategy for the Direct Assembly of Single-Atom Catalysts.

Single-atom catalysts (SACs) have been one of the frontiers in the field of catalysis in recent years owing to their high atomic utilization and unique electronic structure. To facilitate the practical application of single-atom, it is vital to develop a sustainable, facile single-atom preparation method with mass production potential. Herein, a universal one-step electrochemical synthesis strategy is proposed, and various metal-organic framework-supported SACs (including Pt, Au, Ir, Pd, Ru, Mo, Rh, and W) are straightforwardly obtained by simply replacing the guest metal precursors. As a proof-of-concept, the electrosynthetic Pt-based catalysts exhibit outstanding activity and stability in the electrocatalytic hydrogen evolution reaction (HER). This study not only enriches the single-atom synthesis methodology, but also extends the scenario of electrochemical synthesis, opening up new avenues for the design of advanced electro-synthesized catalysts.

Construction of organic-inorganic "chelate" adsorption sites on metal oxide semiconductor for room temperature NO2 sensing.

Metal oxide semiconductors (MOS) have been extensively studied for gas sensing due to their excellent chemical stability and adjustable electronic properties. However, there is still a lack of ingenious design strategies to achieve customizable gas detection in complex environments. Herein, a novel and scalable strategy of constructing organic-inorganic "chelate" adsorption sites is proposed to promote the affinity of MOS sensing materials to target molecules. Specifically, 3-aminopropyltriethoxysilane (APTES)-functionalized reduced graphene oxide (rGO) was decorated on In2O3 tubes (AG/Inx), and its NO2 sensing performance was studied. As a result, the optimal AG/Inx shows boosted room-temperature NO2 response, and its response to 1 ppm NO2 is 4.8 times that of In2O3. More attractively, the optimal AG/Inx exhibits good selectivity, as well as outstanding detection ability (Rg/Ra = 1.6) for low concentration NO2 (20 ppb). Experimental results suggest that APTES-rGO not only acts as the electron acceptor to accelerate charge transfer, but also enhances NO2 adsorption. Further theoretical calculations reveal that NO2 is simultaneously adsorbed at rGO and APTES via a flexible "chelate" mechanism. The multidentate adsorption configuration remarkably strengthens the NO2-host interaction, which is conducive to improving sensing performance. This work may inspire the material design of a new generation high-performance gas sensors.

Atom-precise fluorescent copper cluster for tumor microenvironment targeting and transient chemodynamic cancer therapy.

BACKGROUND: Reactive oxygen species (ROS) have been widely studied for cancer therapy. Nevertheless, instability and aspecific damages to cellular biomolecules limit the application effect. Recently, significant research efforts have been witnessed in the flourishing area of metal nanoclusters (NCs) with atomically precise structures for targeted release of ROS but few achieved success towards targeting tumor microenvironment. RESULTS: In this work, we reported an atomically precise nanocluster Cu6(C4H3N2S)6 (Cu6NC), which could slowly break and generate ROS once encountered with acidic. The as-prepared Cu6NC demonstrated high biological safety and efficient chemodynamic anti-tumor properties. Moreover, Cu6NC enabled transient release of ROS and contained targeting behavior led by the tumor microenvironment. Both in vitro and in vivo experiments confirmed that Cu6NC demonstrated a low cytotoxicity for normal cells, while presented high cytotoxicity for tumor cells with a concentration-dependent manner. CONCLUSIONS: This work not only reported a promising candidate for chemodynamic cancer therapy, but also paved the route to address clinical issues at the atomic level.

Uniformly Dispersed Ru Nanoparticles Constructed by In Situ Confined Polymerization of Ionic Liquids for the Electrocatalytic Hydrogen Evolution Reaction.

Design and development of cost-effective electrocatalysts with high efficiency and stability for scalable and sustainable hydrogen production through water splitting is still challenging. Herein, with the aid of divinyl functionalized ionic liquids, uniformly distributed Ru nanoparticles (NPs) on nitrogen-doped carbon frameworks are obtained via an in situ confined polymerization strategy. Attributed to the unique lamellar structure and confinement effect of carbon supports, the optimized homo-PIL-Ru/C-600 (with Ru 10 wt%) catalyst exhibits superior catalytic efficiency for the hydrogen evolution reaction with the overpotential of only 16 mV at a current density of 10 mA cm-2 and the corresponding Tafel slope of only 42 mV dec-1 . Moreover, the performance can be well reserved even after 10 000 cycles, demonstrating excellent stability and promising potentials for industrial application. This work not only provides a facile approach for the preparation of highly efficient Ru-based catalysts, but also guides the synthesis of other highly dispersed metallic NPs for special applications.

Multifunctional graphene-based nanocomposites for simultaneous enhanced photocatalytic degradation and photothermal antibacterial activity by visible light.

A new strategy for the wastewater treatment was proposed by combining polyvinylpyrrolidone-functionalized silver nanoparticles with reduced graphene oxide (AgNPs-PVP@rGO) as a visible light-triggered photoactive nanocomposite. The nanocomposite with enhanced photocatalytic degradation and photothermal antibacterial activity can simultaneously decrease the content of organic pollutants and bacteria in the wastewater under visible light irradiation. The efficiency of photocatalytic degradation can be significantly improved by the conjugation of AgNPs onto the rGO surface. The water solubility and dispersion of nanocomposite can be increased via PVP functionalization, without stirring during the photocatalytic process. Under the optimal synthesis condition, AgNPs-PVP@rGO has a photocatalytic degradation efficiency of 90.1% for rhodamine B, which is 6.9 and 1.8 times higher than that of polyvinylpyrrolidone-functionalized silver nanoparticles and rGO alone, respectively. More importantly, the degradation efficiency of optimal AgNPs-PVP@rGO sol on rhodamine B is significantly higher than that of its block suspension in the same amount, indicating that the sol with more specific surface area is conducive to the photocatalytic reaction. Meanwhile, the AgNPs-PVP@rGO with excellent photothermal activity can effectively inhibit the bacterial growth. This functional modification of graphene provides a new strategy for simultaneous treatment of multiple pollutants in wastewater. The AgNPs-PVP@rGO nanocomposites for simultaneous enhanced photocatalytic degradation and photothermal antibacterial activity by visible light.

N-Doped Graphene Quantum Dot-Decorated Three-Dimensional Ordered Macroporous In2O3 for NO2 Sensing at Low Temperatures.

Nitrogen dioxide (NO2) detection is of great importance because the emission of NO2 gas profoundly endangers the natural environment and human health. However, a few challenges, including lowering detection limit, improving response/recovery kinetics, and reducing working temperature, should be further addressed before practical applications. Herein, a series of N-doped graphene quantum dot (N-GQD)-modified three-dimensional ordered macroporous (3DOM) In2O3 composites are constructed and their NO2 response properties are studied. The results show that compared to pure 3DOM In2O3, reduced graphene oxide (rGO)/3DOM In2O3, and N-doped graphene sheets (NS)/3DOM In2O3, the N-GQDs/3DOM In2O3 sensing materials exhibit higher NO2 responses with fast response and recovery speed and low working temperature (100 °C). In addition, the detection limit of NO2 response for the optimal N-GQDs/In2O3 sensor is as low as 100 ppb. Upon exposure to CO, CH4, NH3, acetone, ethanol, toluene, and formaldehyde, only very weak responses could be observed, indicating good selectivity for the synthesized material. More attractively, the responses of the optimized N-GQDs/In2O3 sensor exhibit no obviously big fluctuation over 60 days, implying good long-term stability. We suggest that the formation of heterojunctions between 3DOM In2O3 and N-GQDs and the doping N atoms in N-GQDs play crucial roles in improving the NO2 sensing properties.