Chuan Fu Tan

Design of a Metal Oxide–Organic Framework (MoOF) Foam Microreactor: Solar‐Induced Direct Pollutant Degradation and Hydrogen Generation

A macroporous carbon network combined with mesoporous catalyst immobilization by a template method gives a metal-oxide-organic framework (MoOF) foam microreactor that readily soaks up pollutants and localizes solar energy in itself, leading to effective degradation of water pollutants (e.g., methyl orange (MO) and also hydrogen generation. The cleaned-up water can be removed from the microreactor simply by compression, and the microreactor used repeatedly.

Self-Biased Hybrid Piezoelectric-Photoelectrochemical Cell with Photocatalytic Functionalities.

Utilizing solar energy for environmental and energy remediations based on photocatalytic hydrogen (H2) generation and water cleaning poses great challenges due to inadequate visible-light power conversion, high recombination rate, and intermittent availability of solar energy. Here, we report an energy-harvesting technology that utilizes multiple energy sources for development of sustainable operation of dual photocatalytic reactions. The fabricated hybrid cell combines energy harvesting from light and vibration to run a power-free photocatalytic process that exploits novel metal-semiconductor branched heterostructure (BHS) of its visible light absorption, high charge-separation efficiency, and piezoelectric properties to overcome the aforementioned challenges. The desirable characteristics of conductive flexible piezoelectrode in conjunction with pronounced light scattering of hierarchical structure originate intrinsically from the elaborate design yet facile synthesis of BHS. This self-powered photocatalysis system could potentially be used as H2 generator and water treatment system to produce clean energy and water resources.

Topotactic Consolidation of Monocrystalline CoZn Hydroxides for Advanced Oxygen Evolution Electrodes

We present a room temperature topotactic consolidation of cobalt and zinc constituents into monocrystalline CoZn hydroxide nanosheets, by a localized corrosion of zinc foils with cobalt precursors. By virtue of similar lattice orientation and structure coordination, the hybrid hydroxides amalgamate atomically without phase separation. Importantly, this in situ growth strategy, in combination with configurable percolated nanosheets, renders a high areal density of catalytic sites, immobilized structures, and conductive pathways between the nanosheets and underlying foils-all of which allow monocrystalline CoZn hydroxide nanosheet materials to function as effective electrodes for electrochemical oxygen evolution reactions. This convenient and eco-friendly topotactical transformation approach facilitates high-quality single crystal growth with improved multiphase purity and homogeneity, which can be extended to other transition metals for the fabrication of advanced functional nanocomposites.

Highly flexible solution processable heterostructured zinc oxide nanowires mesh for environmental clean-up applications

We report the fabrication of a fully solution-processed ZnO nanowires array on flexible stainless steel mesh. ZnO nanowires of uniform dimensions are radially and densely assembled over a large area of the mesh. Various metal and metal oxide nanoparticles are photochemically deposited onto the ZnO nanowires and the corresponding effects on the photocurrent are investigated. Furthermore, the stability and robustness of the heterostructured ZnO nanowires grown on the mesh are evaluated by assessing the photocurrent in response to on/off cycles as well as undergoing various bending configurations. Finally, the heterostructured nanowire mesh is preliminarily tested for photodegradation of organic compound and separation of oil–water mixture. The multifunctional heterostructured nanowire mesh has shown potential applications for environmental clean-up purposes.

Nanophotonic-Engineered Photothermal Harnessing for Waste Heat Management and Pyroelectric Generation

At present, there are various limitations to harvesting ambient waste heat which include the lack of economically viable material and innovative design features that can efficiently recover low grade heat for useful energy conversion. In this work, a thermal nanophotonic-pyroelectric (TNPh-pyro) scheme consisting of a metamaterial multilayer and pyroelectric material, which performs synergistic waste heat rejection and photothermal heat-to-electricity conversion, is presented. Unlike any other pyroelectric configuration, this conceptual design deviates from the conventional by deliberately employing back-reflecting NIR to enable waste heat reutilization/recuperation to enhance pyroelectric generation, avoiding excessive solar heat uptake and also retaining high visual transparency of the device. Passive solar reflective cooling up to 4.1 °C is demonstrated. Meanwhile, the photothermal pyroelectric performance capitalizing on the back-reflecting effect shows an open circuit voltage (Voc) and short circuit current (Isc) enhancement of 152 and 146%, respectively. In addition, the designed photoactive component (TiO2/Cu) within the metamaterial multilayer provides the TNPh-pyro system with an effective air pollutant photodegradation functionality. Finally, proof-of-concept for concurrent photothermal management and enhanced solar pyroelectric generation under a real outdoor environment is demonstrated.

Surface texturing and dielectric property tuning toward boosting of triboelectric nanogenerator performance

Triboelectric nanogenerators (TENGs) have revealed widespread success in converting ambient mechanical energy into electric power. However, the challenge remains to improve the output performance for extensive applications. Herein, a strategy of combining surface texturing and dielectric constant control is developed to enhance the output performance of poly-dimethylsiloxane (PDMS)-based TENGs. The introduction of highly dielectric particles significantly enhanced the dielectric constant and surface charge potential of the PDMS film, supported by both experimental analysis and COMSOL simulation. With an optimized weight ratio, an output voltage of ∼390 V (peak to peak), a short-circuit current density of ∼170 mA m−2, and a charge density of ∼108 μC m−2 were obtained, corresponding to the peak power density of 9.6 W m−2, showing a 10-fold power improvement compared with flat PDMS-based TENGs. This work demonstrates a promising strategy for exploring high performance triboelectric generators.

Spontaneous Electroless Galvanic Cell Deposition of 3D Hierarchical and Interlaced S–M–S Heterostructures

One-pot electroless galvanic cell deposition of a 3D hierarchical semiconductor-metal-semiconductor interlaced nanoarray is demonstrated. The fabricated 3D photoanode deviates from the typical planar geometry, and aims to optimize the effective surface area for light harvesting and long-range charge transfer-collection pathways.

Uniaxially Stretched Flexible Surface Plasmon Resonance Film for Versatile Surface Enhanced Raman Scattering Diagnostics

Surface-enhanced Raman scattering (SERS) spectroscopy affords a rapid, highly sensitive, and nondestructive approach for label-free and fingerprint diagnosis of a wide range of chemicals. It is of great significance to develop large-area, uniform, and environmentally friendly SERS substrates for in situ identification of analytes on complex topological surfaces. In this work, we demonstrate a biodegradable flexible SERS film via irreversibly and longitudinally stretching metal deposited biocompatible poly(ε-caprolactone) film. This composite film after stretching shows surprising phenomena: three-dimensional and periodic wave-shaped microribbons array embedded with a high density of nanogaps functioning as hot-spots at an average gap size of 20 nm and nanogrooves array along the stretching direction. The stretched polymer surface plasmon resonance film gives rise to more than 10 times signal enhancement in comparison with that of the unstretched composite film. Furthermore, the SERS signals with high uniformity exhibit good temperature stability. The polymer SPR film with excellent flexibility and transparency can be conformally attached onto arbitrary nonplanar surfaces for in situ detection of various chemicals. Our results pave a new way for next-generation flexible SERS detection means, as well as enabling its huge potentials toward green wearable devices for point-of-care diagnostics.

Spatially Probed Plasmonic Photothermic Nanoheater Enhanced Hybrid Polymeric-Metallic PVDF-Ag Nanogenerator

Surface plasmon-based photonics offers exciting opportunities to enable fine control of the site, span, and extent of mechanical harvesting. However, the interaction between plasmonic photothermic and piezoresponse still remains underexplored. Here, spatially localized and controllable piezoresponse of a hybrid self-polarized polymeric-metallic system that correlates to plasmonic light-to-heat modulation of the local strain is demonstrated. The piezoresponse is associated to the localized plasmons that serve as efficient nanoheaters leading to self-regulated strain via thermal expansion of the electroactive polymer. Moreover, the finite-difference time-domain simulation and linear thermal model also deduce the local strain to the surface plasmon heat absorption. The distinct plasmonic photothermic-piezoelectric phenomenon mediates not only localized external stimulus light response but also enhances dynamic piezoelectric energy harvesting. The present work highlights a promising surface plasmon coordinated piezoelectric response which underpins energy localization and transfer for diversified design of unique photothermic-piezotronic technology.

Plasmonic enhanced photoelectrochemical and photocatalytic performances of 1D coaxial Ag@Ag2S hybrids

Silver (Ag) as one of the most important plasmonic metals has attracted enormous attention due to its distinct surface plasmon resonance (SPR) absorption and high electrical conductivity. Here, we use Ag nanowires (NWs) as the starting material to prepare a series of core–shell structured Ag@Ag2S composites through an in situ controllable and spontaneous sulfidation process at room temperature. It has been found that the obtained coaxial Ag@Ag2S hybrid with an optimized ratio of Ag NWs exhibits enhanced photoelectrochemical and photocatalytic performances under visible light irradiation. The underlying contribution of Ag SPR to the enhancement of photoelectrochemical and photocatalytic activities of the Ag@Ag2S hybrids has been elucidated through wavelength-dependent experiments and transient absorption spectroscopy. The results indicate that the SPR phenomenon of Ag NWs has an influential effect on the photoelectrochemical and photocatalytic activities enhancement of Ag@Ag2S hybrids, which is often overlooked in the previous reports. An ultrafast electron transfer process (∼350 fs) from the Ag core to the Ag2S shell has been measured. This work provides a valuable insight into the role of the Ag component in improving the photoelectrochemical and photocatalytic performances of Ag–Ag2S hybrid nanosystems, which is expected to promote comprehensive understanding and better exploitation of plasmonic Ag in universal photophysical and photochemical systems.