Publications

In order to study the importance of surface phonons on the electron−phonon relaxation in plasmonic nanoparticles, the effect of size, shape, and materials have recently been studied. Gold and silver nanoparticles have shown no dependence on size and shape while copper nanoparticles have shown some size dependence. This suggests that the bulk phonons, which are sensitive to the bulk-phase structure, are solely responsible for the relaxation of the hot electron in gold and silver plasmonic nanoparticles. The importance of bulk phonons should depend on the degree of crystallinity. In the present study, we have found that the electron−phonon relaxation rate decreases greatly when polycrystalline prismatic gold nanoparticles are annealed and transformed into nearly single-crystalline nanospheres. The results are explained by the presence of high-density grain boundaries with dense, high-frequency molecular type vibrations which are effective in removing the energy of the excited electrons in the polycrystalline prismatic nanoparticles.

We demonstrate a dynamic surface plasmonic modulation of graphene-nanowire hybrid structures in visible light range, which was thought to be a tough task for graphene based field effect transistor modulator previously. Static modulation depth of as high as 0.07 dB/μm has been achieved experimentally. Carefully simulation indicates the strongly focused electromagnetic field and dramatically enhanced electric field at the interface between a silver NW and a graphene sheet are key roles for bringing the optical response of the device to the visible range. Furthermore, the modulation behaviors near the Dirac point of monolayer graphene and the singularity of gap-induced bilayer graphene are investigated.

A flexible and low-cost triboelectric nanogenerator (TENG) based on a patterned aluminum–plastic film and an entrapped cantilever spring leaf is developed as a self-powered sensitive triboelectric sensor for sleep–body movement monitoring. The working mechanism and the impact factors of electric output performance were systematically investigated and elaborated. Due to the patterned nanostructures of the recently designed TENG, both the output voltage and current are greatly enhanced, and thereby the sensitivity of the device is significantly improved. The self-powered and sensitive device has been demonstrated as a smart body motion sensor of sleep monitoring for diagnosis of sleep disorders due to its high sensitivity and excellent stability. This work may promote the application of self-powered TENGs for healthcare and be helpful for the development of real-time mobile healthcare services and smart external portable electronics.

This paper presents a fully enclosed duck‐shaped triboelectric nanogenerator (TENG) for effectively scavenging energy from random and low‐frequency water waves. The design of the TENG incorporates the freestanding rolling mode and the pitch motion of a duck‐shaped structure generated by incident waves. By investigating the material and structural features, a unit of the TENG device is successfully designed. Furthermore, a hybrid system is constructed using three units of the TENG device. The hybrid system achieves an instantaneous peak current of 65.5 µA with an instantaneous output power density of up to 1.366 W m −2 . Following the design, a fluid–solid interaction analysis is carried out on one duck‐shaped TENG to understand the dynamic behavior, mechanical efficiency, and stability of the device under various water wave conditions. In addition, the hybrid system is experimentally tested to enable a commercial wireless temperature sensor node. In summary, the unique duck‐shaped TENG shows a simple, cost‐effective, environmentally friendly, light‐weight, and highly stable system. The newly designed TENG is promising for building a network of generators to harvest existing blue energy in oceans, lakes, and rivers.

Developing clean and renewable energy sources is an important strategy to reduce carbon emission and achieve carbon neutrality. As one of the most promising clean energy sources, large-scale, and efficient utilization of ocean blue energy remains a challenging problem to be solved. In this work, a hyperelastic network of wheel-structured triboelectric nanogenerators (WS-TENGs) is demonstrated to efficiently harvest low-frequency and small-amplitude wave energy. Different from traditional designs of smooth shell, the external blades on the TENG allow tighter interaction between the wave and the device, which can roll on the water surface like a wheel, continuously agitating internal TENGs. Moreover, the hyperelastic networking structure can stretch and shrink like a spring with stored wave energy, further intensifying the roll of the device, and connecting the WS-TENGs to form a large-scale network. Multiple driving modes with synergistic effects can be realized under wave and wind excitations. Self-powered systems are fabricated based on the WS-TENG network, showing the capability of the device in real wave environment. The work provides a new driving paradigm that can further enhance the energy harvesting capability toward large-scale blue energy utilization based on TENGs.

A pressure-sensor matrix (PSM) with full dynamic range can accurately detect and spatially map pressure profiles. A 100 × 100 large-scale PSM gives both electrical and optical signals by itself without applying an external power source. The device represents a major step toward digital imaging, and the visible display of the pressure distribution covers a large dynamic range.

Substrates are used to improve the photoresponse performance <italic>via</italic> a dual-photogating mechanism for the simplest possible device construction.

A flexible oxygen sensor based on individual ZnO nanowires is demonstrated with high sensitivity at room temperature and the influence of the piezotronic effect on the performance of this oxygen sensor is investigated. By applying a tensile strain, the already very high sensitivity due to the Schottky contact and pre-treatment of UV light is even further enhanced.