Publications

Laser-assisted nanolithography of commercially available photoresists is offering a limitless designing opportunity in the micro- and nanostructuring of 3D organotypic cell culture scaffolds. Among them, chemically functionalized OrmoComp has shown promising improvement in cell adhesion that paves the way to assemble cellular entities on a desirable geometry. Establishing a photoswitchable chemistry on the OrmoComp surface may offer an additional degree of freedom to manipulate the surface chemistry locally and selectively. We have established the methods for functionalization of the photopolymerized OrmoComp surface with visible-light-switchable donor-acceptor Stenhouse adducts. Unlike other polymers, a photopolymerized OrmoComp surface appears to be optimal for reversible photothermal switching, offering the possibility to influence surface properties like absorption and hydrophilicity tremendously. Light-assisted chemical modulation between colored triene-2-ol and colorless cyclopentenone can be achieved to a size region as narrow as 20 μm. Thermal reversion to the original triene-2-ol state can be analyzed spectroscopically and observed with the naked eye.

Hysteresis effects and their tuning with electric fields and light were studied in thin film molybdenum disulfide transistors fabricated from sulfurized molybdenum films. The influence of the back-gate voltage bias, voltage sweep range, illumination, and AlOx encapsulation on the hysteresis effect of the back-gated field effect transistors was studied and quantified. This study revealed the distinctive contribution of MoS2 surface, MoS2/SiO2 interface defects and their associated traps as primary sources of of hysteresis.

Inhomogeneous and fragile solid electrolyte interphase (SEI) leads to poor battery cycle life and safety hazards, which is a key challenge that limits the practical application of low-cost sodium metal anodes. Although sodium metal batteries based on non-aqueous liquid and solid electrolytes have made great progress in terms of interfacial chemistry and SEI regulation strategies, the relevant evaluation of SEI from the perspective of the electrolyte is not well understood. This paper reviews the formation mechanism, physicochemical properties, and failure mechanism of SEI at the interface between the sodium metal and the liquid/solid electrolyte, focusing on poor stability, compatibility, interfacial ion transport problems, and influencing factors. Recent advances in SEI regulation are summarized in terms of electrolytes, artificial interphases, and electrode engineering to achieve ideal electrochemical reversibility. The effectiveness of the SEI engineering strategies was evaluated based on a comprehensive review of the interfacial stability in different electrolyte systems. Finally, the challenges associated with rational interface design for long-lasting sodium metal batteries are discussed, along with promising avenues for the same.

As the accumulation of waste tires continues to rise year by year, effectively managing and recycling these discarded materials has become an urgent global challenge. Among various potential solutions, pyrolysis stands out due to its superior environmental compatibility and remarkable efficiency in transforming waste tires into valuable products. Thus, it is considered the most potential method for disposing these tires. In this work, waste tire powder is pyrolyzed at 560 ˚C to yield pyrolysis carbon black, and meanwhile, the purification effects of base-acid solutions on pyrolysis carbon black are discussed. High-purity few-layer graphene flakes and carbon nanohorns are synthesized by a direct current arc plasma with H2 and N2 as buffer gases and high-purity pyrolysis carbon black as raw material. Under an H2 atmosphere, hydrogen effectively terminates the suspended carbon bonds, preventing the formation of closed structures and facilitating the expansion of graphene sheets. During the preparation of carbon nanohorns, the nitrogen atoms rapidly bond with carbon atoms, forming essential C-N bonds. This nitrogen doping promotes the formation of carbon-based five-membered and seven-membered rings and makes the graphite lamellar change in the direction of towards negative curvature. Consequently, such change facilitates the formation of conical structures, ultimately yielding the coveted carbon nanohorns. This work not only provides an economical raw material for efficient large-scale synthesis of few-layer graphene and carbon nanohorns but also broadens the intrinsic worth of pyrolysis carbon black, which is beneficial to improving the recycling value of waste tires.

Reduced graphene oxide (rGO) flexible film humidity sensor has received increasing attention, but the low sensing response caused by lack of available hydrophilic functional groups is still a limitation. Herein, a slightly reduced graphene oxide (SrGO) ordered-pore-array, fabricated via a monolayer colloid crystal template method, was introduced as a resistive humidity sensor. It was obtained based on adsorption between the GO sheets and the template microspheres, in-situ slight reduction of the GO shells and the removal of template. The reduction way allows the functional groups of GO to be retained as much as possible, and the unique structures (e.g., spherical double surfaces and small through-holes on pore-walls) facilitate the substantial exposure of functional groups, the penetration of water molecules and the utilization of buried functional groups. The available functional groups are thereby efficiently increased, giving the sensor an unprecedented high sensing response, more than 2600 times the maximum response of existing rGO sensors. The sensor also demonstrated excellent practical characteristics, and by detecting a single exhale, it could be employed in quick and quantitative evaluation of human activities and health. This strategy paves a facile and promising route to improve the sensing response and application of graphene-based humidity sensors or gas sensors.