Synthesis of hierarchically porous structured CaCO3 and TiO2 replicas by sol-gel method using lotus root as template

Bio-Templating: An Emerging Synthetic Technique for Catalysts. A Review

In the last few years, researchers have focused their attention on the synthesis of new catalyst structures based on or inspired by nature. Biotemplating involves the transfer of biological structures to inorganic materials through artificial mineralization processes. This approach offers the main advantage of allowing morphological control of the product, as a template with the desired morphology can be pre-determined, as long as it is found in nature. This way, natural evolution through millions of years can provide us with new synthetic pathways to develop some novel functional materials with advantageous properties, such as sophistication, miniaturization, hybridization, hierarchical organization, resistance, and adaptability to the required need. The field of application of these materials is very wide, covering nanomedicine, energy capture and storage, sensors, biocompatible materials, adsorbents, and catalysis. In the latter case, bio-inspired materials can be applied as catalysts requiring different types of active sites (i.e., redox, acidic, basic sites, or a combination of them) to a wide range of processes, including conventional thermal catalysis, photocatalysis, or electrocatalysis, among others. This review aims to cover current experimental studies in the field of biotemplating materials synthesis and their characterization, focusing on their application in heterogeneous catalysis.

Effect of calcination temperature on the properties and applications of bio extract mediated titania nano particles

In order to deal with the arising environmental issues across the globe at present nano particles with unique properties laid a benchmark in the name of nano catalysis. In this work the significance of calcination temperature on the thermal, electronic, structural and surface properties of a nano catalyst produced by sol-gel method using ultrasonic radiation against the disposal of toxic textile pollutants is studied in detail. The extract of tea leaves has been used as a bio-template during the synthesis to revise the crystallite size, surface area, optical absorption potential, and rate of agglomeration of nano sized grains by regulating their physico-chemical and surface properties. The influence of calcination in the transformation of single phased anatase titania to mixed phase anatase-rutile titania and the corresponding outcome in its photocatalytic activity employed in water treatment applications have been verified. The nano catalyst obtained is characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transition electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), Thermo gravimetric analysis (TGA), Brunaueur Emmett Teller (BET) analysis, UV-Vis diffused reflectance spectroscopy (DRS-UV-Vis) etc. The mesoporosity of the particle was examined using Barrett Joyner Halenda (BJH) model. The enhanced photo catalytic efficiency (about 97.7%) of templated nano titania due to calcination is verified against Congo red, a textile dye under optimized conditions. The nano catalyst produced can be easily separated, recycled to support its economic feasibility.

Preparation and characterization of TiO2 based on wood templates

Titanium dioxide (TiO₂) was prepared from four natural wood spices that served as templates. The wood templates were impregnated by a titanium dioxide precursor and then underwent high-temperature calcination to obtain TiO₂ with a wood-like hierarchical porous structure. The microstructure of TiO₂ based on the wood template was characterized by scanning electron microscopy, X-ray diffraction and nitrogen adsorption–desorption tests. The formaldehyde adsorption and degradation properties of TiO₂ based on a wood template are discussed. The results showed that TiO₂ based on a wood template could effectively replicate the micro- and mesoscopic pore structure of wood, and the pore size distribution in the TiO₂ ranged from 1 to 100 nm. The TiO₂ that was prepared based on a wood template showed a certain adsorption effect on formaldehyde under visible light, and the photocatalytic degradation of a formaldehyde solution was achieved when irritated by ultraviolet light. In addition, the properties of the TiO₂ prepared by different tree species was also different. The TiO₂ prepared by larch and Chinese fir exhibited a large specific surface area, pore volume, and high degradation efficiency of formaldehyde solution. After 280 min of irradiation with an ultraviolet light source, the degradation rates of the formaldehyde solution were 19.91% and 18.85%.

Visible light-assisted efficient degradation of dye pollutants with biomass-supported TiO2 hybrids

The objective of this work was to develop a novel organic-inorganic hybrid nanomaterial from agricultural biomass waste for environmental applications. The sugarcane bagasse (SB) supported TiO₂ hybrids were firstly synthesized via a sol-gel method. A series of characterizations were carried out to reveal the structures and components of obtained hybrids. Due to organic-inorganic hybrid (OIH) effect and element doping, the SB-TiO₂ hybrid can expand its optical absorbance ranging from ultraviolet to visible light. The optimal hybrid catalyst prepared with SB doping amount of 2g in 100mL titanic gel and calcined at 200°C was able to degradate 95.0% methyl orange (MO) in 5h under visible light. This study will pave a new and facile pathway for novel visible light driven photocatalysts based on TiO₂ modified by agricultural biomass waste.

Preparation, characterization and catalytic application of hierarchically porous LaFeO3 from a pomelo peel template

Hierarchically porous LaFeO₃ perovskites are synthesized through a facile process by using pomelo peel as a biotemplate.