State Key Laboratory of Electronic Thin Films and Integrated Devices

The review summarizes the recent progress in the synthesis, fundamental properties, morphology, photocatalytic applications and challenges of CdS-based photocatalysts.

Transition metal nitrides (TMNs), by virtue of their unique electronic structure, high electrical conductivity, superior chemical stability, and excellent mechanical robustness, have triggered tremendous research interest over the past decade, and showed great potential for electrochemical energy conversion and storage. However, bulk TMNs usually suffer from limited numbers of active sites and sluggish ionic kinetics, and eventually ordinary electrochemical performance. Designing nanostructured TMNs with tailored morphology and good dispersity has proved an effective strategy to address these issues, which provides a larger specific surface area, more abundant active sites, and shorter ion and mass transport distances over the bulk counterparts. Herein, the most up-to-date progress on TMN-based nanomaterials is comprehensively reviewed, focusing on geometric-structure design, electronic-structure engineering, and applications in electrochemical energy conversion and storage, including electrocatalysis, supercapacitors, and rechargeable batteries. Finally, we outline the future challenges of TMN-based nanomaterials and their possible research directions beyond electrochemical energy applications.

We have calculated the longitudinal acoustic phonon limited electron mobility of 14 two-dimensional semiconductors with composition of MX 2, where M (= Mo, W, Sn, Hf, Zr and Pt) is the transition metal, and X is S, Se and Te. We treated the scattering matrix by the deformation potential approximation. We found that out of 14 compounds, MoTe2, HfSe2 and ZrSe2 are promising regarding to their possible high mobility and finite band gap. The phonon limited mobility can be above 2,500 cm2·V−1·s−1 at room temperature.

The present work theoretically and experimentally provides an insight into the internal mechanism of Li⁺ transport within an artificial hybrid SEI layer consisting of lithium-antimony (Li₃Sb) alloy and lithium fluoride (LiF).

The exfoliation and identification of the two-dimensional (2D) single atomic layer of carbon have opened the opportunity to explore graphene and related 2D materials due to their unique properties. 2D materials are regarded as one of the most exciting solutions for next generation electronics and optoelectronics in the technological evolution of semiconductor technology. In this review, we focus on the core concept of “structure-property relationships” to explain the state-of-the-art of 2D materials and summarize the unique electrical and light-matter interaction properties in 2D materials. Based on this, we discuss and analyze the structural properties of 2D materials, such as defects and dopants, the number of layers, composition, phase, strain, and other structural characteristics, which could significantly alter the properties of 2D materials and hence affect the performance of semiconductor devices. In particular, the building blocks principles and potential electronic and optoelectronic applications based on 2D materials are explained and illustrated. Indeed, 2D materials and related heterostructures offer the promise for challenging the existing technologies and providing the chance to have social impact. More efforts are expected to propel this exciting field forward.

A novel approach to effectively suppress the “polysulfide shuttle” in Li–S batteries is presented by designing a freestanding, three-dimensional graphene/1T MoS₂ (3DG/TM) heterostructure with highly efficient electrocatalysis properties for lithium polysulfides (LiPSs).

Lithium–sulfur (Li–S) batteries have been regarded as one of the most promising next-generation energy-storage devices, due to their low cost and high theoretical energy density (2600 W h kg⁻¹).

The terahertz region is a special region of the electromagnetic spectrum that incorporates the advantages of both microwaves and infrared light waves. In the past decade, metamaterials with effective medium parameters or gradient phases have been studied to control terahertz waves and realize functional devices. Here, we present a new approach to manipulate terahertz waves by using coding metasurfaces that are composed of digital coding elements. We propose a general coding unit based on a Minkowski closed-loop particle that is capable of generating 1-bit coding (with two phase states of 0 and 180°), 2-bit coding (with four phase states of 0, 90°, 180°, and 270°), and multi-bit coding elements in the terahertz frequencies by using different geometric scales. We show that multi-bit coding metasurfaces have strong abilities to control terahertz waves by designing-specific coding sequences. As an application, we demonstrate a new scattering strategy of terahertz waves—broadband and wide-angle diffusion—using a 2-bit coding metasurface with a special coding design and verify it by both numerical simulations and experiments. The presented method opens a new route to reducing the scattering of terahertz waves. A team in China has demonstrated a new strategy for controlling terahertz waves by using ‘coding’ metasurfaces to attain broadband diffusion. Metamaterials have previously been used to control terahertz waves and develop functional devices. Now, Tie Jun Cui and co-workers have developed metasurfaces composed of one-, two- and three-bit digital coding elements based on Minkowski loops. They demonstrated their coding surfaces by showing that metasurfaces with appropriately designed coding sequences can be used to strongly manipulate terahertz waves. In particular, they realized broadband, wide-angle diffusion using a two-bit coding metasurface with a special design and obtained good agreement between the measured results and numerical simulations. The proposed method offers a new way to control scattering of terahertz waves and can be implemented using conventional lithography.

The permittivity and permeability behaviors of composites made from the multiwalled carbon nanotubes with magnetic impurity Ni and the wax have been studied in 3–18GHz. The unusual permittivity dispersion behaviors have been explained based on the Cole-Cole model and the conductivity contribution model. Permeability is found to have negative imaginary parts within 3–11GHz. The composites are found to show good microwave absorbing performances (reflection loss <−20dB): matching thickness is 1.5mm and absorbing frequency band is 11.6–12.4GHz, and the absorbing performance can be explained by the “geometrical effect.”

An active terahertz (THz) metamaterial with vanadium dioxide (VO2) cut-wire resonators fabricated on glass substrate was proposed, and THz time-domain spectroscopy was used to probe the temperature-tuned electromagnetic properties. By thermal-triggering the insulator-metal phase transition of VO2, THz transmission signals through the metamaterial exhibit a significant decline with amplitude over 65%. Numerical simulations confirm the observations are due to the metallization of the VO2 film with increasing temperature.

The rGO/MnO_x composite is compatible with the slurry dispensing process for electrode fabrication, and can exhibit super-long life property.

A novel photovoltaic–thermoelectric (PV–TE) hybrid device composed of a series-connected dye-sensitized solar cell (DSSC), a solar selective absorber (SSA) and a TE generator is created. The conversion efficiency of the DSSC was enhanced significantly by using the SSA and TE generator to utilize residual sunlight transmitted through the DSSC. The hybrid device comprising a DSSC as a “top cell” for high-energy photons and an SSA coated TE generator as a “bottom cell” for low-energy photons gave rise to an overall conversion efficiency larger than 13%. Although our hybrid device was not yet optimized but served as proof-of-principle for harvesting electricity from solar light and heat simultaneously with high conversion efficiency by a single device, this study would give some enlightenment for the development of high-performance PV–TE hybrid devices.

We report a rationally designed two-step method to fabricate self-supported Ni3S2 nanosheet arrays. We first used 2-methylimidazole (2-MI), an organic molecule commonly served as organic linkers in metal–organic frameworks (MOFs), to synthesize an α-Ni(OH)2 nanosheet array as a precursor, followed by its hydrothermal sulfidization into Ni3S2. The resulting Ni3S2 nanosheet array demonstrated superior supercapacitance properties, with a very high capacitance of about 1,000 F g–1 being delivered at a high current density of 50 A g–1 for 20,000 charge–discharge cycles. This performance is unparalleled by other reported nickel sulfide-based supercapacitors and is also advantageous compared to other nickel-based materials such as NiO and Ni(OH)2. An asymmetric supercapacitor was then established, exhibiting a very stable capacitance of about 200 F g–1 at a high current density of 10 A g–1 for 10,000 cycles and a surprisingly high energy density of 202 W h kg–1. This value is comparable to that of the lithium-ion batteries, i.e., 180 W h kg–1. The potential of the material for practical applications was evaluated by building a quasi-solid-state asymmetric supercapacitor which showed good flexibility and power output, and two of these devices connected in series were able to power up 18 green light-emitting diodes.

The predominant synergic effect of GQDs and SrRuO₃CEs drives faster ion diffusions and electron transfer, thereby contributing to excellent catalytic activity of the SRO–GQD CE towards I₃⁻reduction.

A facile method is presented to synthesize three-dimensional carbon nanotube/graphene–sulfur (3DCGS) sponge with a high sulfur loading of 80.1%.

Photocatalysis is attracting increased attention in solving the energy crisis and environmental pollution. Graphitic carbon nitride (g-C3N4), a non-metal photocatalyst, has been regarded as an ideal photocatalyst to solve these problems because of its chemical stability and unique optical properties. However, traditional g-C3N4 exhibits moderate photocatalytic activity due to its low specific surface area and fast recombination rate of photogenerated electrons. Among the many modified g-C3N4 materials, porous carbon nitride (PCN) can solve the shortcomings of traditional g-C3N4 because of PCN's increased number of surface-active sites, specific surface area, light harvesting, diffusion and adsorption/activation. However, a frontier, comprehensive summary of the development of PCN is less reported. Thus, a review on recent developments in PCN research is urgently needed to further promote its advancement. In this review, the synthesis methods, structures and properties and photocatalytic applications of PCN photocatalysts are described in detail. The current challenges and future development of PCN/PCN-based photocatalysts are discussed. This review may present an up-to-date view of the PCN development to provide an in-depth understanding of PCN-based photocatalysts.

In this work, a synaptic transistor based on the indium gallium zinc oxide (IGZO)–aluminum oxide (Al2O3) thin film structure, which uses ultraviolet (UV) light pulses as the pre-synaptic stimulus, has been demonstrated. The synaptic transistor exhibits the behavior of synaptic plasticity like the paired-pulse facilitation. In addition, it also shows the brain's memory behaviors including the transition from short-term memory to long-term memory and the Ebbinghaus forgetting curve. The synapse-like behavior and memory behaviors of the transistor are due to the trapping and detrapping processes of the holes, which are generated by the UV pulses, at the IGZO/Al2O3 interface and/or in the Al2O3 layer.

The schematic of metamaterials applied in wireless power transfer.

Hierarchical MoSe₂–CoSe₂ nanotubes (MS–CS NTs) are <italic>in situ</italic> converted from the CoMoO₄ nanowires (NWs) <italic>via</italic> a facile hydrothermal selenization method.

A low-cost and eco-friendly solution coating of nanoscale Al₂O₃ addresses the high-voltage fast degradation of LiCoO₂.