Mengning Ding

Chemical Sensing with Polyaniline Coated Single‐Walled Carbon Nanotubes

Single-walled carbon nanotube/polyaniline (SWNT/PAni) nanocomposite with controlled core/shell morphology was synthesized by a noncovalent functionalization approach. Unique electron interactions between the SWNT core and the PAni shell were studied electrochemically and spectroscopically, and superior sensor performance to chemical gases and vapors was demonstrated.

Understanding Interfaces in Metal-Graphitic Hybrid Nanostructures.

Metal-graphitic interfaces formed between metal nanoparticles (MNPs) and carbon nanotubes (CNTs) or graphene play an important role in the properties of such hybrid nanostructures. This Perspective summarizes different types of interfaces that exist within the metal-carbon nanoassemblies and discusses current efforts on understanding and modeling the interfacial conditions and interactions. Characterization of the metal-graphitic interfaces is described here, including microscopy, spectroscopy, electrochemical techniques, and electrical measurements. Recent studies on these nanohybrids have shown that the metal-graphitic interfaces play critical roles in both controlled assembly of nanoparticles and practical applications of nanohybrids in chemical sensors and fuel cells. Better understanding, design, and manipulation of metal-graphitic interfaces could therefore become the new frontier in the research of MNP/CNT or MNP/graphene hybrid systems.

Welding of gold nanoparticles on graphitic templates for chemical sensing.

Controlled self-assembly of zero-dimensional gold nanoparticles and construction of complex gold nanostructures from these building blocks could significantly extend their applications in many fields. Carbon nanotubes are one of the most promising inorganic templates for this strategy because of their unique physical, chemical, and mechanical properties, which translate into numerous potential applications. Here we report the bottom-up synthesis of gold nanowires in aqueous solution through self-assembly of gold nanoparticles on single-walled carbon nanotubes followed by thermal-heating-induced nanowelding. We investigate the mechanism of this process by exploring different graphitic templates. The experimental work is assisted by computational studies that provide additional insight into the self-assembly and nanowelding mechanism. We also demonstrate the chemical sensitivity of the nanomaterial to parts-per-billion concentrations of hydrogen sulfide with potential applications in industrial safety and personal healthcare.

Photoinduced Charge Transfer and Acetone Sensitivity of Single-Walled Carbon Nanotube–Titanium Dioxide Hybrids

The unique physical and chemical properties of single-walled carbon nanotubes (SWNTs) make them ideal building blocks for the construction of hybrid nanostructures. In addition to increasing the material complexity and functionality, SWNTs can probe the interfacial processes in the hybrid system. In this work, SWNT-TiO2 core/shell hybrid nanostructures were found to exhibit unique electrical behavior in response to UV illumination and acetone vapors. By experimental and theoretical studies of UV and acetone sensitivities of different SWNT-TiO2 hybrid systems, we established a fundamental understanding on the interfacial charge transfer between photoexcited TiO2 and SWNTs as well as the mechanism of acetone sensing. We further demonstrated a practical application of photoinduced acetone sensitivity by fabricating a microsized room temperature acetone sensor that showed fast, linear, and reversible detection of acetone vapors with concentrations in few parts per million range.

Selecting Fruits with Carbon Nanotube Sensors

Sensor strategy bears fruit: A nature-inspired Cu(I) complex was employed to fabricate single-walled carbon nanotube sensors that can selectively detect ethylene gas at concentrations as low as 0.5 ppm. Such nanosensors may be used to monitor ethylene gas emitted from fruits to monitor their ripening.