Synthesis of Organopolysilazane Nanoparticles as Lithium-Ion Battery Anodes with Superior Electrochemical Performance via the Two-Step Stöber Method

The Stöber method, a widely utilized sol–gel technique, stands as a green and reliable approach for preparing nanostructures on a large scale. In this study, we employed an enhanced Stöber method to synthesize organopolysilazane nanoparticles (OPSZ NPs), utilizing polysilazane oligomers as the primary precursor material and ammonia as the catalytic agent. By implementing a two-step addition process, control over crucial parameters facilitated the regulation of the nanoparticle size. Generally, maintaining relatively low concentrations of organopolysilazane and catalyst while adjusting the water/acetonitrile ratio can effectively enhance the surface energy of the organopolysilazane, resulting in the uniform formation of small spherical particles. The average particle size of the synthesized OPSZ NPs is about 140 nm, which were monodispersed and characterized by scanning electron microscopy, transmission electron microscopy, and dynamic light scattering. Furthermore, the composition of OPSZ NPs after pyrolysis was confirmed as SiC2.054N0.206O1.631 with 5.44 wt % free carbon structure by X-ray diffraction and energy-dispersive X-ray spectroscopy. Notably, the electrochemical performance assessment of SiCNO NPs as potential electrode materials for lithium-ion batteries exhibited promising outcomes. Specifically, at 1 A g–1 current density, the specific capacity is 585.45 mA h g–1 after 400 cycles, and the minimum capacity attenuation per cycle is only 0.1076 mA h g–1 (0.0172% of the original capacity), which indicates excellent energy storage capacity and cycle stability. In summary, this research contributes to the development of advanced anode materials for next-generation energy storage systems, marking a stride toward sustainable energy solutions

Preparation of 3D Architecture Graphdiyne Nanosheets for High-Performance Sodium-Ion Batteries and Capacitors

Here, we apply three-dimensional (3D) architecture graphdiyne nanosheet (GDY-NS) as anode materials for sodium-ion storage devices achieving high energy and power performance along with excellent cyclic ability. The contribution of 3D architecture nanostructure and intramolecular pores of the GDY-NS can substantially optimize the sodium storage behavior through the accommodated intramolecular pore, 3D interconnective porous structure, and increased activity sites to facilitate a fast sodium-ion-diffusion channel. The contribution of butadiyne linkages and the formation of a stable solid electrolyte interface layer are directly confirmed through the in situ Raman measurement. The GDY-NS-based sodium-ion batteries exhibit a stable reversible capacity of approximately 812 mAh g^–1 at a current density of 0.05 A g^–1; they maintain more than 405 mAh g^–1 over 1000 cycles at a current density of 1 A g^–1. Furthermore, the sodium-ion capacitors could deliver a capacitance more than 200 F g^–1 over 3000 cycles at 1 A g^–1 and display an initial specific energy as high as 182.3 Wh kg^–1 at a power density of 300 W kg^–1 and maintain specific energy of 166 Wh kg^–1 even at a power density of 15 000 W kg^–1. The high energy and power density along with excellent cyclic performance based on the GDY-NS anode offers a great potential toward application on next-generation energy storage devices

Nitrogen-Doped Graphdiyne Applied for Lithium-Ion Storage

The elemental N emerged uniformly in graphdiyne (GDY) after heat treatment under NH₃ atmosphere to form N-doping GDY. The interplanar N–GDY distance decreased slightly, which may be ascribed to the smaller atom radius of N than C. Compared with GDY, the introduction of N atoms in N-GDY created numerous heteroatomic defects and active sites, thus achieving enhanced electrochemical properties, including higher reversible capacity, improved rate performance, and superior cycling stability. In addition, N-doping might be advantageous to minimize the surface side reactions and form stable interfaces, hence improving the electrochemical cycling stability of N-GDY electrodes. These results indicate N-doping is also an efficient way for improving the electrochemical performance of GDY materials

Nitrogen-Doped Porous Graphdiyne: A Highly Efficient Metal-Free Electrocatalyst for Oxygen Reduction Reaction

Metal-free catalysts for oxygen reduction reaction (ORR) are the desired materials for low-cost proton exchange membrane fuel cells. Graphdiyne (GDY), a novel type of two-dimensional carbon allotrope, is featured by its sp- and sp²-hybridized carbon atoms, different from the other existing carbon materials. Thus, nitrogen (N) can be doped in new styles by substituting sp-hybridized carbon atoms, effective for ORR, which has been displayed in this study using both experimental and theoretical technologies. The N-doped GDY was synthesized with pyridine and NH₃ as N sources successively, expressing an electrocatalytic activity at a potential above 0.8 V similar to that of commercial Pt/C for ORR in alkaline solution and higher stability and better methanol tolerance than those of Pt/C

Graphdiyne Containing Atomically Precise N Atoms for Efficient Anchoring of Lithium Ion

The qualitative and quantitative nitrogen-doping strategy for carbon materials is reported here. Novel porous nanocarbon networks pyrimidine-graphdiyne (PM-GDY) and pyridine-graphdiyne (PY-GDY) films with large areas were successfully prepared. These films are self-supported, uniform, continuous, flexible, transparent, and quantitively doped with merely pyridine-like nitrogen (N) atoms through the facile chemical synthesis route. Theoretical predictions imply these N doped carbonaceous materials are much favorable for storing lithium (Li)-ions since the pyridinic N can enhance the interrelated binding energy. As predicted, PY-GDY and PM-GDY display excellent electrochemical performance as anode materials of LIBs, such as the superior rate capability, the high capacity of 1168 (1165) mA h g^–1 at current density of 100 mA g^–1 for PY-GDY (PM-GDY), and the excellent stability of cycling for 1500 (4000) cycles at 5000 mA g^–1 for PY-GDY (PM-GDY)