Engineering of Microcage Carbon Nanotube Architectures with Decoupled Multimodal Porosity and Amplified Catalytic Performance

Fabrication of Porous Proteinaceous Microspheres via One-Step Pickering Double Emulsions: Controllable Structure and Interfacial Cascade Biocatalysis

Methods based on double emulsions for producing porous microspheres have gained popularity as an effective and adaptable strategy. However, these microspheres are frequently composed of organic polymers that lack sufficient mechanical strength. Additionally, the conventional two-step process and the use of surfactants present notable challenges. A promising solution is to replace traditional surfactants with inorganic particles, utilizing a Pickering emulsion approach. Herein, we introduced a one-step approach for creating Pickering double emulsions, followed by a straightforward solvent evaporation process to produce porous proteinaceous microspheres. By harnessing the enhanced stability of Pickering emulsions, we can manipulate the morphology and pore structure of the microspheres by varying the oil-(ethanol/water) volume ratio, the size and type of emulsifier, ripening time, rotary evaporation temperature, and the addition of enzymes. Furthermore, we innovatively proposed the coencapsulation of glucose oxide (GOx) and horseradish peroxidase (HRP) for interfacial cascade catalysis, showing excellent catalytic activity, recovery, and reusability. This study presents a new, scalable approach for producing porous microspheres using a one-step Pickering double emulsion. It demonstrates significant potential for interfacial biocatalysis, and is expected to be applied in fields such as medicine, drug delivery, and biotechnology due to their suitability for encapsulating bioactive materials.

Electrothermal Transformations within Graphene-Based Aerogels through High-Temperature Flash Joule Heating

Flash Joule heating of highly porous graphene oxide (GO) aerogel monoliths to ultrahigh temperatures is exploited as a low carbon footprint technology to engineer functional aerogel materials. Aerogel Joule heating to up to 3000 K is demonstrated for the first time, with fast heating kinetics (∼300 K·min-1), enabling rapid and energy-efficient flash heating treatments. The wide applicability of ultrahigh-temperature flash Joule heating is exploited in a range of material fabrication challenges. Ultrahigh-temperature Joule heating is used for rapid graphitic annealing of hydrothermal GO aerogels at fast time scales (30-300 s) and substantially reduced energy costs. Flash aerogel heating to ultrahigh temperatures is exploited for the in situ synthesis of ultrafine nanoparticles (Pt, Cu, and MoO2) embedded within the hybrid aerogel structure. The shockwave heating approach enables high through-volume uniformity of the formed nanoparticles, while nanoparticle size can be readily tuned through controlling Joule-heating durations between 1 and 10 s. As such, the ultrahigh-temperature Joule-heating approach introduced here has important implications for a wide variety of applications for graphene-based aerogels, including 3D thermoelectric materials, extreme temperature sensors, and aerogel catalysts in flow (electro)chemistry.

Atomic Aerogel Materials (or Single-Atom Aerogels): An Interesting New Paradigm in Materials Science and Catalysis Science

The concept of "single-atom catalysis" is first proposed by Tao Zhang, Jun Li, and Jingyue Liu in 2011. Single-atom catalysts (SACs) have a very high catalytic activity and greatly improved atom utilization ratio. At present, SACs have become frontier materials in the field of catalysis. Aerogels are highly porous materials with extremely low density and extremely high porosity. These pores play a key role in determining their surface reactivity and mechanical stability. The alliance of SACs and aerogels can fully reflect their structural advantages and lead to new enhancement effects. Herein, a general concept of "atomic aerogel materials" (AAMs) (or single-atom aerogels (SAAs)) is proposed to describe this interesting new paradigm in both material and catalysis fields. Based on the basic units of "gel," the AAMs can be divided into two categories: carrier-level AAMs (with micro-, nano-, or sub-nanometer pore structures) and atomic-level AAMs (with atomic-defective or oxygen-bridged sub-nanopore structures). The basic unit of the former (i.e., single-atom-functionalized aerogels) is the carrier materials in nanostructures, and the latter (i.e., single-atom-built aerogels) is the single metal atoms in atomic structures. The atomic-defective or oxygen-bridged AAMs will be important development directions in versatile heterogeneous catalytic or noncatalytic fields. The design proposals, latent challenges, and coping strategies of this new "atomic nanosystem" in applications are pointed out as well.