Microfluidic Continuous Synthesis of Size- and Facet-Controlled Porous Bi2O3 Nanospheres for Efficient CO2 to Formate Catalysis.

Bismuth-based catalysts are effective in converting carbon dioxide into formate via electrocatalysis. Precise control of the morphology, size, and facets of bismuth-based catalysts is crucial for achieving high selectivity and activity. In this work, an efficient, large-scale continuous production strategy is developed for achieving a porous nanospheres Bi2O3-FDCA material. First-principles simulations conducted in advance indicate that the Bi2O3 (111)/(200) facets help reduce the overpotential for formate production in electrocatalytic carbon dioxide reduction reaction (ECO2RR). Subsequently, using microfluidic technology and molecular control to precisely adjust the amount of 2, 5-furandicarboxylic acid, nanomaterials rich in (111)/(200) facets are successfully synthesized. Additionally, the morphology of the porous nanospheres significantly increases the adsorption capacity and active sites for carbon dioxide. These synergistic effects allow the porous Bi2O3-FDCA nanospheres to stably operate for 90 h in a flow cell at a current density of ≈250 mA cm- 2, with an average Faradaic efficiency for formate exceeding 90%. The approach of theoretically guided microfluidic technology for the large-scale synthesis of finely structured, efficient bismuth-based materials for ECO2RR may provide valuable references for the chemical engineering of intelligent nanocatalysts.

In situ assembly of Ni3S2 nanosheets encapsulated with NiFe(oxy)hydroxides for efficient water oxidation.

Morphology control plays a pivotal role in achieving an exceptionally efficient electrocatalyst with abundant active sites and outstanding electrical conductivity. In this study, we employed a sophisticated chemical nanoengineering technique to fabricate an exquisitely thin NiFe(OH)x electrocatalyst on Ni3S2 nanosheets. Firstly, the Ni3S2 nanosheets were synthesized through an innovative in situ one-step sulfurization reaction of the Ni(OH)2 nanosheets grown on Ni foam. Subsequently, a remarkable ultrathin layer of NiFe(OH)x was precisely deposited onto the surface of the Ni3S2 to form a captivating core-shell structure using a chemical dipping method. The resulting electrode, denoted as NiFe(OH)x/Ni3S2/NF, exhibited exceptional electrocatalytic activity and durability towards the oxygen evolution reaction (OER), owing to its expansive specific surface area, rapid electron transport, and robust interlayer bonding. Notably, this electrode achieved an impressive current density of 100 mA cm-2 at an astonishingly low overpotential of 218 mV while maintaining a low Tafel slope of 37.9 mV dec-1 and remarkable stability for up to 12 days in 1 M KOH aqueous solution. This work presents an alluring novel approach for constructing highly efficient ultrathin catalysts for water splitting.

Amazing enhancement of OER performances: creating a well-designed functional Ni and N-doped carbon layer as a support material for fabricating a NiFe-LDH electrocatalyst.

A well-designed support material between catalyst and substrate can always significantly enhance the performance of an electrode on water oxidation. In this work, a functional Ni and N-doped carbon layer (NNC) was designed on carbon paper (CP) via pyrolysis by using a controlled electrodeposited polyporphyrin as a precursor. Consequently, the fabricated NiFe-LDH/NNC/CP achieved a catalytic current density of 100 mA cm-2 at a small overpotential of 231 mV with a low Tafel slope of 26.0 mV dec-1, as well as high durability for more than 360 h. The insights are that N-doping reinforces the hydrophilicity and the catalyst binding capacity, while Ni-doping intensifies the conductivity.

Design of the Thermal Restructured Carbon-Inorganic Composite Aerogel for Efficient Thermal Protection of Aero-Engines.

The heat insulation ability and thermal stability of thermal protection materials play extremely important role in the thermal protection of aero-engines under high temperature. Herein, we design the carbon-SiO2-Al2O3 (CSA) composite aerogel through thermochemical restructuring from the phenol-formaldehyde resin-SiO2-Al2O3 (PSA) composite aerogel. This thermochemical restructured aerogel not only shows better adhesion property under room temperature but also possesses higher thermal stability and desirable heat insulation ability under high temperature. Taking the PSA-0.5 composite aerogel as an example, the compressive strain-stress test unveils that it can be compressed by 66% without catastrophic collapse, which is beneficial for the adhesion with the metallic matrix. Meanwhile, the transmission electron microscopy and scanning electron microscopy images exhibit the unbroken three-dimensional structure for the CSA-0.5 composite aerogel, which confirmed the structural stability of the composite aerogel after thermochemical restructuring. The thermal cycle test indicates that the weight loss of the CSA-0.5 composite aerogel is only ca. 8%, firmly confirming its thermal stability. Importantly, the thermal conductivity of the CSA-0.5 composite aerogel ranges from 0.024 to 0.083 W m-1 K-1, indicating the superior performance of heat insulation. Moreover, the numerical simulation is carried out to validate the thermal protection effect of the CSA-0.5 composite aerogel as a thermal protection layer. Together with laminated cooling, it could enhance the surface cooling effectiveness of the metallic matrix to above 0.8. Briefly, this work paves a new pathway for efficient thermal protection materials of aero-engines via the rational design of the thermochemical restructured composite aerogel under the guidance of ANSYS numerical simulations.

Design of Economical and Achievable Aluminum Carbon Composite Aerogel for Efficient Thermal Protection of Aerospace.

Insulation materials play an extremely important role in the thermal protection of aerospace vehicles. Here, aluminum carbon aerogels (AlCAs) are designed for the thermal protection of aerospace. Taking AlCA with a carbonization temperature of 800 °C (AlCA-800) as an example, scanning electron microscopy (SEM) images show an integrated three-dimensional porous frame structure in AlCA-800. In addition, the thermogravimetric test (TGA) reveals that the weight loss of AlCA-800 is only ca. 10%, confirming its desirable thermal stability. Moreover, the thermal conductivity of AlCA-800 ranges from 0.018 W m-1 K-1 to 0.041 W m-1 K-1, revealing an enormous potential for heat insulation applications. In addition, ANSYS numerical simulations are carried out on a composite structure to forecast the thermal protection ability of AlCA-800 acting as a thermal protection layer. The results uncover that the thermal protective performance of the AlCA-800 layer is outstanding, causing a 1185 K temperature drop of the structure surface that is exposed to a heat environment for ten minutes. Briefly, this work unveils a rational fabrication of the aluminum carbon composite aerogel and paves a new way for the efficient thermal protection materials of aerospace via the simple and economical design of the aluminum carbon aerogels under the guidance of ANSYS numerical simulation.