Research Article Issue
Double-stretching as an effective and generalizable strategy towards thinner nanofibers in solution blow spinning
Nano Research 2023, 16 (4): 5709-5714
Published: 29 December 2022

Solution blow spinning (SBS) applies high-speed airflow to prepare fibers by generating a strong stretching force. It has the advantages of scalable production, tailorable morphologies, and wide applicability. Yet, the SBS strategy can hardly prepare fibers down to the sub-100 nanometers, which limits its performance in demanding applications. Herein, we overcome the limitation of SBS by introducing a second airflow. This novel strategy is termed double-stretching SBS (DS-SBS) because an extra stretching force is exerted on the fiber when it converges with the second airflow. Polyamide6 nanofibers with an average diameter of 80 nm are successfully prepared with the DS-SBS strategy, while the SBS strategy could only prepare submicron fibers with an average diameter of 120 nm. Further, the generality of the DS-SBS strategy to reduce fiber diameter is verified on numerous solute–solvent pairs.

Research Article Issue
Nucleation growth quenching for superior cluster catalysts
Nano Research 2022, 15 (9): 7933-7939
Published: 30 June 2022

Cluster catalysts are rapidly growing into an important sub-field in heterogeneous catalysis, owing to their distinct geometric structure, neighboring metal sites, and unique electronic structure. Although the thermodynamics and kinetics of the formation of nanoparticles have been largely investigated, the precise synthesis of clusters in wet chemical methods still faces great challenges. In the study, a quenching strategy of asymmetric temperature in solution for the rapid generation of vacancy-defect rich clusters is reported. The quenching process can be used to synthesize multitudinous metal compound clusters, including metal oxides, fluorides, oxygen-sulfur compounds, and tungstate. For oxygen evolution reaction (OER), IrO2 clusters with abundant oxygen vacancies were obtained and uniformly dispersed in the solution. Compared to commercial IrO2, the prepared IrO2 cluster can be directly loaded on carbon paper and used as binder-free electrodes, which exhibit higher OER activity and long-term operational stability in alkaline electrolytes. The quenching strategy provides a simple and efficient method for the synthesis of clusters, which has tremendous potential for industrial-scale preparation and application, especially can be further applied to flow electrochemical generators.

Research Article Issue
A garnet-electrolyte based molten Li-I2 battery with high performance
Nano Research 2022, 15 (5): 4076-4082
Published: 31 December 2021

Lithium-iodine (Li-I2) battery exhibits high potential to match with high-rate property and large energy density. However, problems of the system, such as evident sublimation of iodine elements, dissolution of iodine species in electrolyte, and lithium anode corrosion, prevent the practical use of rechargeable Li-I2 batteries. In this work, a molten Li-I2 typical cell design which has distinct advantages based on the solid-state garnet electrolyte with the eutectic iodate cathode is firstly developed. The U-shaped ceramic electrolyte tube can separate Li anode from the eutectic iodate cathode, so as to better tackle the above-mentioned inherent challenges for the liquid electrolyte systems. Without self-discharging and lithium anode corrosion, this solid-state battery system demonstrates high safety margin and excellent electrochemical performance. Also, the simple battery structure also indicates the easy assembly process and recycling of electrode materials. With the cathode loading of 593 mg in a single cell, an energy density of ~ 506.7 Wh·kg−1 was achieved at 1 C and a long-term cycling life for 2,000 cycles also displays negligible capacity decay.

Research Article Issue
Wet-milling synthesis of immobilized Pt/Ir nanoclusters as promising heterogeneous catalysts
Nano Research 2022, 15 (4): 3065-3072
Published: 12 December 2021

Being a typical state of the art heterogeneous catalyst, supported noble metal catalyst often demonstrates enhanced catalytic properties. However, a facile synthetic method for realizing large-scale and low-cost supported noble metal catalyst is strictly indispensable. To this end, by making use of the strong metal–support interaction (SMSI) and mechanochemical reaction, we introduce an efficient synthetic route to obtain ultrafine Pt and Ir nanoclusters immobilized on diverse substrates by wet chemical milling. We further demonstrate the scaling-up effect of our approach by large-scale ball-milling production of Pt nanoclusters immobilized on TiO2 substrate. The synthesized Pt/Ir@Co3O4 catalysts exhibit superior oxygen evolution reaction (OER) performance with only 230 and 290 mV overpotential to achieve current density of 10 and 100 mA·cm−2, beating the catalytic performance of Co3O4 supported Pt or Ir clusters and commercial Ir/C. It is envisioned that the present work strategically directs facile ways for fabricating supported noble metal heterogeneous catalysts.

Research Article Issue
Large-scale blow spinning of heat-resistant nanofibrous air filters
Nano Research 2020, 13 (3): 861-867
Published: 09 March 2020

Particulate matter (PM) pollution has become a serious problem worldwide and various kinds of nanofibrous filters aiming to solve the problem have been developed. It is urgent to remove PM from high-temperature pollution sources, such as industrial emissions, coal furnaces, and automobile exhaust gases. However, filtration at pollution sources remains challenging because most existing air filters are not resistant to high temperature. Herein, heat-resistant polyimide (PI) nanofibrous air filters are fabricated via a simple and scalable solution blow-spinning method. These air filters show excellent thermal stability at high temperature up to 420 °C. They exhibit a filtration efficiency as high as 99.73% at ambient temperature and over 97% at 300 °C. In addition, a field test shows that the filters remove > 97% of PM from the car exhaust fumes. Hence, the blow-spun PI nanofibrous membranes combined with the facile preparation strategy have great potential in high temperature air filtration fields and other similar applications such as water purification and protein separation.

Review Article Issue
Oxygen-deficient metal oxides: Synthesis routes and applications in energy and environment
Nano Research 2019, 12 (9): 2150-2163
Published: 02 April 2019

Oxygen vacancies implantation is an efficient way to adjust the physical and chemical properties of metal oxide nanomaterials to meet the requirements for particular applications. Through reasonable defects design, oxygen-deficient metal oxides with excellent optical and electrical properties are widely applied for environmental protection and energy uses. This review discusses recent advances in synthetic approaches of oxygen-deficient metal oxides and their applications in photocatalysis, electrocatalysis, and energy storage devices. The perspectives of oxygen-deficient metal oxides for increased energy demand and environmental sustainability are also examined.

Research Article Issue
Defective molybdenum sulfide quantum dots as highly active hydrogen evolution electrocatalysts
Nano Research 2018, 11 (2): 751-761
Published: 27 July 2017

Molybdenum disulfide (MoS2), a promising non-precious electrocatalyst for the hydrogen evolution reaction with two-dimensional layered structure, has received increasing attention in recent years. Its electrocatalytic performance has been limited by the low active site content and poor conductivity. Herein, we report a facile and general ultrafast laser ablation method to synthesize MoS2 quantum dots (MS-QDs) for electrocatalytic HER with fully exposed active sites and highly enhanced conductivity. The MS-QDs were prepared by ultrafast laser ablation of the corresponding bulk material in aqueous solution, during which they were partially oxidized and formed defective structures. The as-prepared MS-QDs demonstrated high activity and stability in the electrocatalytic HER, owing to their very large surface area, defective structure, abundance of active sites, and high conductivity. The present MS-QDs can also find application in optics, sensing, energy storage, and conversion technologies.

Research Article Issue
Photothermal therapy by using titanium oxide nanoparticles
Nano Research 2016, 9 (5): 1236-1243
Published: 29 September 2016

The photothermal therapy (PTT) technique is regarded as a promising method for cancer treatment. However, one of the obstacles preventing its clinical application is the non-degradability and biotoxicity of the existing heavy-metal and carbon-based therapeutic agents. Therefore, a PTT material with a high photothermal efficiency, low toxicity, and good biocompatibility is urgently wanted. Herein, we report a titanium oxide-based therapeutic agent with a high efficacy and low toxicity for the PTT process. We demonstrated that Magnéli-phase Ti8O15 nanoparticles fabricated by the arc-melting method exhibit > 98% absorption of near infrared light and a superior photothermal therapy effect in the in vivo mouse model. The Ti8O15 nanoparticle PTT material also shows a good biocompatibility and biosafety. Our study reveals Magnéli-phase titanium oxide as a new family of PTT agents and introduces new applications of titanium oxides for photothermal conversion.

Research Article Issue
Aerodynamic levitated laser annealing method to defective titanium dioxide with enhanced photocatalytic performance
Nano Research 2016, 9 (12): 3839-3847
Published: 10 September 2016

Defective TiO2 has attracted increasing attention for use in photocatalytic and electrochemical materials because of its narrowed band-gap and improved visible-light photocatalytic activity. However, a facile and efficient approach for obtaining defect-rich TiO2 still remains a challenge. Herein, we demonstrate such an approach to narrow its bandgap and improve visible-light absorption through implanting abundant defects by aerodynamic levitated laser annealing (ALLA) treatment. Note that the ALLA method not only provides rapid annealing, solidifying and cooling process, but also exhibits high efficiency for homogeneous and defective TiO2 nanoparticles. The laser-annealed TiO2 achieves a high hydrogen evolution rate of 8.54 mmol·h–1·g–1, excellent decomposition properties within 60 min, and outstanding recyclability and stability, all of which are superior to the corresponding properties of commercial P25.

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