Chengfeng Du

NbS2 Nanosheets with M/Se (M = Fe, Co, Ni) Codopants for Li+ and Na+ Storage

Transition metal (M = Fe, Co, Ni) and Se codoped two-dimensional uniform NbS2 (MxNb1-xS2-ySey) nanosheets were synthesized via a facile oil-phase synthetic process. The morphology of MxNb1-xS2-ySey can be adjusted by tuning the amount of metal and Se introduced into NbS2. Among them, the optimized Fe0.3Nb0.7S1.6Se0.4 nanosheets, with lateral sizes of 1-2 μm and approximately 5 nm thick, achieve the best Li-ion and Na-ion storage properties. For example, the Fe0.3Nb0.7S1.6Se0.4 nanosheets depict excellent rate capabilities with fifth-cycle specific capacities of 461.3 mAh g-1 at 10 A g-1 for Li storage and 136 mAh g-1 at 5 A g-1 for Na storage. More significantly, ultralong cyclic stabilities were achieved with reversible specific capacities of 444 mAh g-1 at 5 A g-1 during the 3000th cycle for Li storage and 250 mAh g-1 at 1 A g-1 during the 750th cycle for Na storage. Post-treatment high-resolution transmission electron microscopy was studied to prove that the reversible Li-ion storage in NbS2 was based on a conversion reaction mechanism.

Recent advances in printable secondary batteries

In past decades, with interest in wearable smart devices rapidly growing, the design and fabrication of novel energy storage devices have received increasing attention. Although secondary batteries are among the best options in this area, their bulky construction remains unable to fulfil the specific demands of miniaturization, portability, and flexibility. This review comprises a brief update on recent progress in printable secondary batteries, in combination with their principles and frequently used printing techniques. Moreover, we also discuss the challenges and advantages of printed secondary batteries and describe their future prospects in wearable smart devices.

Designing hybrid architectures for advanced thermoelectric materials

In recent decades, thermoelectric materials have garnered extensive interest and shown promising applications in energy conversion. The present review demonstrates the recent progress in the design of advanced hybrid thermoelectric nanocomposites mainly prepared by solution synthesis. Then the state-of-the-art strategies have been discussed for either enhancing the power factor or reducing the thermal conductivity. In some cases, the obtained peak ZT values are comparable to or superior to those of the traditional solid-state synthesized materials. Finally, we highlight the current challenges and future opportunities in the solution-synthesized thermoelectric nanocomposites.

Enhancement of the thermoelectric performance of CuInTe 2 via SnO 2 in situ replacement

Inxa0situ induced nanostructure is employed as an alternative way to enhance the thermoelectric performance of p-type CuInTe2 based thermoelectric materials in this work. Dispersive In2O3 nanoparticles are formed in the samples with SnO2 by virtue of the in situ replacement of SnO2 and CuInTe2. As a result, an obvious reduction in the thermal conductivity has been achieved due to the intensive scattering of phonon by the in situ formed In2O3 nanoparticles. In addition, the power factor of CuInTe2 is less effected by SnO2 additive. Eventually, an enhanced ZT of 1.1 at 823xa0K has been achieved for the CuInTe2–0.5% SnO2 sample.

Enhancement of Thermoelectric Performance in CuSbSe2 Nanoplate‐Based Pellets by Texture Engineering and Carrier Concentration Optimization

This work reports the thermoelectric properties of the CuSbSe2 -x mol% PtTe2 (x = 0, 0.5, 1.0, 1.5, and 2.0) pellets composed of highly oriented single crystalline nanoplates. CuSbSe2 -PtTe2 single crystalline nanoplates are prepared by a wet-chemical process, and the pellets are prepared through a bottom-up self-assembly of the CuSbSe2 -PtTe2 nanoplates and spark plasma sintering (SPS) process. X-ray diffraction and field emission scanning electron microscopic analyses show a highly textured nature with an orientation factor of ≈0.8 for (00l) facets along the primary surface of the pellets (in-plane, perpendicular to the SPS pressure). By this way, bulk-single-crystal-like electrical and thermal transport properties with a strong anisotropy are obtained, which results in an effective optimization on thermoelectric performance. The maximum in-plane thermoelectric figure-of-merit ZT value reaches 0.50 at 673 K for CuSbSe2 -2.0 mol% PtTe2 pellet, which is about five times higher than the in-plane ZT (0.10) for pure CuSbSe2 .

Layered Trichalcogenidophosphate: A New Catalyst Family for Water Splitting

Due to the rapidly increasing demand for energy and environmental sustainability, stable and economical hydrogen production has received increasing attention in the past decades. In this regard, hydrogen production through photo- or electrocatalytic water splitting has continued to gain ever-growing interest. However, the existing catalysts are still unable to fulfill the demands of high-efficiency, low-cost, and sustainable hydrogen production. Layered metal trichalcogenidophosphate (MPQ3) is a newly developed two-dimensional material with tunable composition and electronic structure. Recently, MPQ3 has been considered a promising candidate for clean energy generation and related water splitting applications. In this minireview, we firstly introduce the structure and methods for the synthesis of MPQ3 materials. In the following sections, recent developments of MPQ3 materials for photo- and electrocatalytic water splitting are briefly summarized. The roles of MPQ3 materials in different reaction systems are also discussed. Finally, the challenges related to and prospects of MPQ3 materials are presented on the basis of the current developments.

CoSe2-Decorated NbSe2 Nanosheets Fabricated via Cation Exchange for Li Storage

Though 2D transition metal dichalcogenides have attracted a lot of attention in energy-storage applications, the applications of NbSe2 for Li storage are still limited by the unsatisfactory theoretical capacity and uncontrollable synthetic approaches. Herein, a controllable oil-phase synthetic route for preparation of NbSe2 nanoflowers consisted of nanosheets with a thickness of ∼10 nm is presented. Significantly, a part of NbSe2 can be further replaced by orthorhombic CoSe2 nanoparticles via a post cation exchange process, and the predominantly 2D nanosheet-like morphology can be well-maintained, resulting in the formation of CoSe2-decorated NbSe2 (denoted as CDN) nanosheets. More interestingly, the CDN nanosheets exhibit excellent lithium-ion battery performance. For example, it achieves a highly reversible capacity of 280 mAh g-1 at 10 A g-1 and long cyclic stability with specific capacity of 364.7 mAh g-1 at 5 A g-1 after 1500 cycles, which are significantly higher than those of reported pure NbSe2.

Porous MXene Frameworks Support Pyrite Nanodots toward High-Rate Pseudocapacitive Li/Na-Ion Storage

Presented are the novel Ti3C2 T x MXene-based nanohybrid that decorated by pyrite nanodots on its surface (denoted as FeS2@MXene). The nanohybrid was obtained by the one-step sulfurization of self-assembled iron hydroxide@MXene precursor. When used for Li/Na-ion storage, the FeS2@MXene nanohybrid present excellent rate capabilities. Particularly, for Li-ion storage, an elevated reversible specific capacity of 762 mAh g-1 at 10 A g-1 after 1000 cycles was achieved. And for Na-ion storage, the FeS2@MXene nanohybrid also delivering a reversible specific capacity of 563 mAh g-1 after 100 cycles at a current density of 0.1 A g-1.