Wei Zhang

Bio: Wei Zhang is an academic researcher from Hefei University of Technology. The author has contributed to research in topics: Fiber Bragg grating & Optical fiber. The author has an hindex of 40, co-authored 504 publications receiving 5985 citations. Previous affiliations of Wei Zhang include City University London & Donghua University.

Identifying the Activation of Bimetallic Sites in NiCo 2 S 4 @g-C 3 N 4 -CNT Hybrid Electrocatalysts for Synergistic Oxygen Reduction and Evolution

Abstract: Hybrid materials composed of transition-metal compounds and nitrogen-doped carbonaceous supports are promising electrocatalysts for various electrochemical energy conversion devices, whose activity enhancements can be attributed to the synergistic effect between metallic sites and N dopants. While the functionality of single-metal catalysts is relatively well-understood, the mechanism and synergy of bimetallic systems are less explored. Herein, the design and fabrication of an integrated flexible electrode based on NiCo2 S4 /graphitic carbon nitride/carbon nanotube (NiCo2 S4 @g-C3 N4 -CNT) are reported. Comparative studies evidence the electronic transfer from bimetallic Ni/Co active sites to abundant pyridinic-N in underlying g-C3 N4 and the synergistic effect with coupled conductive CNTs for promoting reversible oxygen electrocatalysis. Theoretical calculations demonstrate the unique coactivation of bimetallic Ni/Co atoms by pyridinic-N species (a Ni, Co-N2 moiety), which simultaneously downshifts their d-band center positions and benefits the adsorption/desorption features of oxygen intermediates, accelerating the reaction kinetics. The optimized NiCo2 S4 @g-C3 N4 -CNT hybrid manifests outstanding bifunctional performance for catalyzing oxygen reduction/evolution reactions, highly efficient for realistic zinc-air batteries featuring low overpotential, high efficiency, and long durability, superior to those of physical mixed counterparts and state-of-the-art noble metal catalysts. The identified bimetallic coactivation mechanism will shed light on the rational design and interfacial engineering of hybrid nanomaterials for diverse applications.

Phase and composition controlled synthesis of cobalt sulfide hollow nanospheres for electrocatalytic water splitting.

Abstract: Developing cheap, highly efficient and stable electrocatalysts for both oxygen and hydrogen evolution reactions (OER and HER) is extremely meaningful to realize large-scale implementation of water splitting technology Herein, we report the phase and composition controlled synthesis of cobalt sulfide (CoSx) hollow nanospheres (HNSs) and their catalytic efficiencies for hydrogen and oxygen evolution reactions in alkaline media Three CoSx compounds, ie, Co9S8, Co3S4, and CoS2 HNSs, were precisely synthesized by simply adjusting the molar ratio of carbon disulfide to cobalt acetate using a facile solution-based strategy Electrochemical results reveal that the as-prepared CoS2 HNSs exhibit superior OER and HER catalytic performance to Co9S8 and Co3S4 HNSs in 10 M KOH, with overpotentials of 290 mV for the OER and 193 mV for the HER at 10 mA cm-2, and the corresponding Tafel slopes of 57 and 100 mV dec-1, respectively In addition, the CoS2 HNSs exhibit remarkable long-term catalytic durability, which is even superior to precious metal catalysts of RuO2 and Pt/C Moreover, an alkaline electrolyzer assembled using CoS2 HNSs as both anode and cathode materials can achieve 10 mA cm-2 at a low cell voltage of 154 V at 60 °C with a faradaic efficiency of 100% for overall water splitting Further analysis demonstrates that the surface morphology, crystallographic structure and coordination environment of Con+ active sites in combination determine the HER/OER activities in the synthesized binary CoSx series, which would provide insight into the rational design of transition metal chalcogenides for highly efficient hydrogen and oxygen-involved electrocatalysis

Flexible and Binder‐Free Electrodes of Sb/rGO and Na3V2(PO4)3/rGO Nanocomposites for Sodium‐Ion Batteries

Abstract: Flexible power sources have shown great promise in next-generation bendable, implantable, and wearable electronic systems. Here, flexible and binder-free electrodes of Na3V2(PO4)3/reduced graphene oxide (NVP/rGO) and Sb/rGO nanocomposites for sodium-ion batteries are reported. The Sb/rGO and NVP/rGO paper electrodes with high flexibility and tailorability can be easily fabricated. Sb and NVP nanoparticles are embedded homogenously in the interconnected framework of rGO nanosheets, which provides structurally stable hosts for Na-ion intercalation and deintercalation. The NVP/rGO paper-like cathode delivers a reversible capacity of 113 mAh g(-1) at 100 mA g(-1) and high capacity retention of ≈96.6% after 120 cycles. The Sb/rGO paper-like anode gives a highly reversible capacity of 612 mAh g(-1) at 100 mA g(-1) , an excellent rate capacity up to 30 C, and a good cycle performance. Moreover, the sodium-ion full cell of NVP/rGO//Sb/rGO has been fabricated, delivering a highly reversible capacity of ≈400 mAh g(-1) at a current density of 100 mA g(-1) after 100 charge/discharge cycles. This work may provide promising electrode candidates for developing next-generation energy-storage devices with high capacity and long cycle life.

Bi4Ti3O12 nanofibers–BiOI nanosheets p–n junction: facile synthesis and enhanced visible-light photocatalytic activity

Abstract: A novel p–n junction photocatalyst of Bi4Ti3O12 nanofibers–BiOI nanosheets has been fabricated through a simple and economical technique of electrospinning combined with a successive ionic layer adsorption and reaction (SILAR) process. The products are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflectance spectra (DRS), and photoluminescence (PL) spectroscopy. The as-formed Bi4Ti3O12 nanofibers are composed of inter-linked nanoparticles of 50–80 nm in size. The thickness of the as-grown BiOI nanosheets is about 10 nm and the size of the BiOI nanosheets increases with the SILAR cycles. In particular, many {001} facets of BiOI nanosheets are exposed, which is favorable to enhance the visible-light photocatalytic activity. The p–n junction photocatalyst exhibits enhanced visible-light-driven photocatalytic activity for decomposition of rhodamine B (RhB) and phenol. The enhanced photocatalytic activity can be attributed to the extended absorption in the visible light region resulting from the BiOI nanosheets and the effective separation of photogenerated carriers driven by the photo-induced potential difference generated at the Bi4Ti3O12–BiOI p–n junction interface.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Additive manufacturing (3D printing): A review of materials, methods, applications and challenges

Abstract: Freedom of design, mass customisation, waste minimisation and the ability to manufacture complex structures, as well as fast prototyping, are the main benefits of additive manufacturing (AM) or 3D printing. A comprehensive review of the main 3D printing methods, materials and their development in trending applications was carried out. In particular, the revolutionary applications of AM in biomedical, aerospace, buildings and protective structures were discussed. The current state of materials development, including metal alloys, polymer composites, ceramics and concrete, was presented. In addition, this paper discussed the main processing challenges with void formation, anisotropic behaviour, the limitation of computer design and layer-by-layer appearance. Overall, this paper gives an overview of 3D printing, including a survey on its benefits and drawbacks as a benchmark for future research and development.