Supercritical Carbon Dioxide Assisted Deposition of Fe3O4Nanoparticles on Hierarchical Porous Carbon and Their Lithium-Storage Performance

Role of supercritical carbon dioxide (scCO2) in fabrication of inorganic-based materials: a green and unique route

In recent times, the supercritical carbon dioxide (scCO₂) process has attracted increasing attention in fabricating diverse materials due to the attractive features of environmentally benign nature and economically promising character. Owing to these unique characteristics and high-penetrability, as well as diffusivity conditions of scCO₂, this high-pressure technology, with mild operation conditions, cost-effective, and non-toxic, among others, is often applied to fabricate various organic and inorganic-based materials, resulting in the unique crystal architectures (amorphous, crystalline, and heterojunction), tunable architectures (nanoparticles, nanosheets, and aerogels) for diverse applications. In this review, we give an emphasis on the fabrication of various inorganic-based materials, highlighting the recent research on the driving factors for improving the quality of fabrication in scCO₂, procedures for production and dispersion in scCO₂, as well as common indicators utilized to assess quality and processing ability of materials. Next, we highlight the effects of specific properties of scCO₂ towards synthesizing the highly functional inorganic-based nanomaterials. Finally, we summarize this compilation with interesting perspectives, aiming to arouse a more comprehensive utilization of scCO₂ to broaden the horizon in exploring the green/eco-friendly processing of such versatile inorganic-based materials. Together, we firmly believe that this compilation endeavors to disclose the latent capability and universal prevalence of scCO₂ in the synthesis and processing of inorganic-based materials.

A Bibliometric Analysis and Review of Supercritical Fluids for the Synthesis of Nanomaterials

Since the 1990s, supercritical fluids for the synthesis of nanomaterials have been paid more and more attention by researchers and have gradually become one of the most important ways to prepare nanomaterials. In this study, literature data on "supercritical fluids for the synthesis of nanomaterials" from 1998 to 2020 were obtained from the Web of Science database, and the data were processed and analyzed by the bibliometric method combined with Microsoft office 2019, Origin 2018, VOSviewer, and other software, so as to obtain the research status and development trend of "supercritical fluids for the synthesis of nanomaterials". The results show that since literature on "supercritical fluids for the synthesis of nanomaterials" appeared for the first time in 1998, the number of articles published every year has risen. In terms of this field, China has become the second-largest publishing country after the United States, and China and the United States display a lot of cooperation and exchanges in this field. "Supercritical CO2", "supercritical water", "supercritical antisolvent", "surface modification", and so on have become the research hotspots of "supercritical fluids for the synthesis of nanomaterials".

Novel synthesis of magnetic, porous C/ZnFe2O4 photocatalyst with enhanced activity under visible light based on the Fenton-like reaction

Magnetic, porous C/ZnFe₂O₄ with highly visible-light activity in presence of H₂O₂ was one-pot fabricated through CO₂-mediated route.

One-step thermolysis synthesis of two-dimensional ultrafine Fe3O4 particles/carbon nanonetworks for high-performance lithium-ion batteries

To tackle the issue of inferior cycle stability and rate capability for Fe3O4 anode materials in lithium ion batteries, ultrafine Fe3O4 nanocrystals uniformly encapsulated in two-dimensional (2D) carbon nanonetworks have been fabricated through thermolysis of a simple, low-cost iron(iii) acetylacetonate without any extra processes. Moreover, compared to the reported Fe3O4/carbon composites, the particle size of Fe3O4 is controllable and held down to ∼3 nm. Benefitting from the synergistic effects of the excellent electroconductive carbon nanonetworks and uniform distribution of ultrafine Fe3O4 particles, the prepared 2D Fe3O4/carbon nanonetwork anode exhibits high reversible capacity, excellent rate capability and superior cyclability. A high capacity of 1534 mA h g(-1) is achieved at a 1 C rate and is maintained without decay up to 500 cycles (1 C = 1 A g(-1)). Even at the high current density of 5 C and 10 C, the 2D Fe3O4/carbon nanonetworks maintain a reversible capacity of 845 and 647 mA h g(-1) after 500 discharge/charge cycles, respectively. In comparison with other reported Fe3O4-based anodes, the 2D Fe3O4/carbon nanonetwork electrode is one of the most attractive of those in energy storage applications.

Natural collagen fiber-enabled facile synthesis of carbon@Fe3O4 core–shell nanofiber bundles and their application as ultrahigh-rate anode materials for Li-ion batteries

Natural collagen fiber-enabled facile synthesis of carbon@Fe₃O₄ core–shell nanofiber bundles and their application as ultrahigh-rate anode materials for Li-ion batteries.

Facile synthesis of an Fe3O4/FeO/Fe/C composite as a high-performance anode for lithium-ion batteries

An Fe₃O₄/FeO/Fe/C nanocomposite is prepared via a facile and scalable in situ-reduction solid synthesis route and is used as a high-performance LIB anode.

Fe3O4@porous carbon hybrid as the anode material for a lithium-ion battery: performance optimization by composition and microstructure tailoring

Fe₃O₄@C has been synthesized using the syn-carbonization strategy and the electrochemical performances have been optimized by tailoring the composition and microstructure.

Comparison of the effects of microcrystalline cellulose and cellulose nanocrystals on Fe3O4/C nanocomposites

Fe₃O₄/C nanocomposites with relatively high superparamagnetic and ferromagnetic performances were obtained by an ultrasound method combining calcination, which provided promising applications for the dye removal and wastewater treatment fields.

High-performance lithium storage achieved by chemically binding germanium nanoparticles with N-doped carbon

Germanium (Ge) is a promising anode material for lithium ion batteries due to its high theoretical capacity. However, its poor cycling stability associated with its large volume changes during discharging and charging processes are urgent problems to solve. This provides opportunities to engineer materials to overcome these issues. Here, we demonstrated a facile and scalable method to synthesize Ge nanoparticles/N-doped carbon monolith with a hierarchically porous structure. The combination of a solvothermal method and annealing treatment results in a well-connected three-dimensional N-doped carbon network structure consisting of Ge nanoparticles firmly coated by the conducting carbon. Such a hierarchical architecture features multiple advantages, including a continuous conductive carbon network, binding the Ge nanoparticles with carbon through a Ge-N chemical bond, and a porous structure for alleviating volume expansion of Ge particles. When serving as an anode for lithium ion batteries, the as-formed hybrid displays high capacities up to 1240.3 mAh g(-1) at 0.1 A g(-1) and 813.4 mAh g(-1) at 0.5 A g(-1) after 90 cycles, and at the same time, it also exhibits good cycling stability and excellent rate capability.

Embedding NiCo2O4 nanoparticles into a 3DHPC assisted by CO2-expanded ethanol: a potential lithium-ion battery anode with high performance

A high-performance anode material, NiCo2O4/3DHPC composite, for lithium-ion batteries was developed through direct nanoparticles nucleation on a three-dimensional hierarchical porous carbon (3DHPC) matrix and cation substitution of spinel Co3O4 nanoparticles. It was synthesized via a supercritical carbon dioxide (scCO2) expanded ethanol solution-assisted deposition method combined with a subsequent heat-treatment process. The NiCo2O4 nanoparticles were uniformly embedded into the porous carbon matrix and efficiently avoided free-growth in solution or aggregation in the pores even at a high content of 55.0 wt %. In particular, the 3DHPC was directly used without pretreatment or surfactant assistance. As an anode material for lithium-ion batteries, the NiCo2O4/3DHPC composite showed high reversible capacity and improved rate capability that outperformed those composites formed with single metal oxides (NiO/3DHPC, Co3O4/3DHPC), their physical mixture, and the composite prepared in pure ethanol (NiCo2O4/3DHPC-E). The superior performance is mainly contributed to the unique advantages of the scCO2-expanded ethanol medium, and the combination of high utilization efficiency and improved electrical conductivity of NiCo2O4 as well as the electronic and ionic transport advantages of 3DHPC.