Weixing Wang

Silica nanoparticles and frameworks from rice husk biomass.

Biogenic silica nanoparticles (25-30 nm in diameter) were synthesized from rice husks. The characterizations revealed that the silica nanoparticles were composed of smaller primary particles (ca. 4.2 nm in diameter), and their clustering led to a porous structure with a surface area of 164 m(2)/g. Under the controlled melting catalyzed by K(+), such silica nanoparticle clusters can gradually fuse to form semicrystalline porous silica frameworks with tunable pore size and structural integrity.

Large-Scale and Controllable Synthesis of Graphene Quantum Dots from Rice Husk Biomass: A Comprehensive Utilization Strategy

In this work, rice husk biomass was utilized as an abundant source to controllably prepare high-quality graphene quantum dots (GQDs) with a yield of ca. 15 wt %. The size, morphology, and structure of the rice-husk-derived GQDs were determined by high-resolution transmission electron microscopy, atomic force microscopy, and Raman spectroscopy. The as-fabricated GQDs can be stably dispersed in water, exhibiting bright and tunable photoluminescence. A cell viability test further confirmed that the GQDs possess excellent biocompatibility, and they can be easily adopted for cell imaging via a facile translocation into the cytoplasm. It is worth noting that mesoporous silica nanoparticles were also synthesized as a byproduct during the fabrication of GQDs. As such, our strategy achieves a comprehensive utilization of rice husks, exhibiting tremendous benefits on both the economy and environment.

Aqueous phase preparation of graphene with low defect density and adjustable layers

Graphene sheets with an adjustable number of layers and a low defect density were prepared by exfoliation of microwave-assisted expanded graphite in the aqueous phase with the assistance of cetyltrimethylammonium bromide. The graphene sheets exhibit excellent film-formation ability, showing potential applications in optical and electrical device fields.

‘Dry bases’: carbon dioxide capture using alkaline dry water

An alkaline form of ‘dry water’—a ‘dry base’—is prepared by the high-speed mixing of aqueous solutions of metal carbonates or organic amines with hydrophobic silica nanoparticles. Despite being mostly water, the dry base looks and flows like a powder, and adsorbs CO2 rapidly without any mixing because of its high surface-to-volume ratio. Unlike normal aqueous base solutions, dry bases can be non-corrosive because they do not readily wet surfaces.

Gas storage in renewable bioclathrates

Methane and carbon dioxide can be stored in ‘bioclathrate’ form—that is, as a clathrate supported in a biological structure—by using plants or fungi to greatly accelerate clathrate formation kinetics, thus avoiding the use of energy-intensive mixing technologies or petrochemically derived materials.

Synthesis of silicon complexes from rice husk derived silica nanoparticles

Organosilicon complexes were synthesized via a green chemical process using silica nanoparticles derived from rice husk (RH) biomass. By controlling the pre-treatment of RHs and pyrolysis conditions, silica samples with various surface areas and degrees of crystallinity were synthesized. Such silica can be converted to silicon complexes via a low temperature approach. The synthesized silicon complexes were characterized by 1H, 13C, 29Si nuclear magnetic resonance and elemental analysis. Overall, the biogenic silica nanoparticles with high surface area and low crystallinity exhibit high reactivity, comparable to commercial fumed silica. Considering their high reactivity and low cost, such biogenic silica nanoparticles from RHs are ideal starting materials to produce organosilicon compounds.

Photoluminescent carbon quantum dot grafted silica nanoparticles directly synthesized from rice husk biomass

In this work, carbon quantum dot grafted silica nanoparticles (silica-C NPs) are directly synthesized from rice husk biomass with high yield. The rice husk derived silica-C NPs exhibit outstanding features, including ease of surface modification, high water dispersibility, and biocompatibility. Due to the covalent decoration of the carbon framework, the wide band gap amorphous silica is endowed intense and unique photoluminescence, which can be well controlled by further adjustments. Detailed investigations suggest that the silica-C NPs have the inherent advantages of both silica and carbon quantum dots, which ideally addresses the widely recognized issues of conventional silica-based photoluminescent nanomaterials for biomedical applications. In addition to creating a novel silica-based nanostructure with prominent performances, this work achieves the comprehensive utilization of rice husk biomass, which shows significant economic and environmental benefits.

Synthesis of green phosphors from highly active amorphous silica derived from rice husks

In this work, high purity amorphous silica derived from rice husk (RH) biomass was used to prepare green phosphor (Zn2SiO4:Mn2+). Based on the solid phase reaction under high temperature, the optimum doping concentration and reaction temperature were identified. The overall performance in terms of photoluminescence intensity and quantum yield of the RH-derived phosphor was superior to the one derived from commercial silica and close to the one made from silicic acid. The results showed that the phosphor derived from RH silica could serve as an alternative to commercial phosphor because of its decent properties and inexpensive green resource.

Effective Capture of Carbon Dioxide Using Hydrated Sodium Carbonate Powders

The emission of CO2 has been considered a major cause of greenhouse effects and global warming. The current CO2 capture approaches have their own advantages and weaknesses. We found that free-flowing hydrated sodium carbonate (Na2CO3) powders with 30 wt % water can achieve a very high CO2 sorption capacity of 282 mg/g within 60 min and fast CO2 uptake (90% saturation uptake within 16 min). The results suggest that the alkaline solution resulting from the dissolution of partial Na2CO3 can freely attach onto the hydrated Na2CO3 particles, which provides an excellent gas–liquid interface for CO2 capture, leading to significantly enhanced CO2 sorption capacity and kinetics.

Versatile Nanostructures from Rice Husk Biomass for Energy Applications

Converting biomass into valuable products has great benefits in terms of both economic and environmental considerations, and has attracted considerable attention in recent years. Rice husk biomass was initially utilized to produce bulk materials for conventional applications while a variety of advanced nanostructures (NSs) have been fabricated over the past few years. In addition to their low cost and environmental friendliness, RH-derived NSs (RH-NSs) exhibit versatile properties, which are promising for broad applications in various fields. In this Review, we summarize the latest research on RH-NSs, covering their design, fabrication, properties, and applications in the modern energy field. Based on the unique structure and components of RHs, a series of carbon/silicon-based novel NSs with outstanding performances have been exploited, which are difficult to be synthesized using conventional chemical reagents. We also discuss perspective uses of RH-NSs on the basis of the current research progress.