bcl Morphology Formation Strategy on Nanostructured Titania via Alkaline Hydrothermal Treatment

Titanium dioxide (TiO2) is a semiconductor material that plays an important role in photocatalysis. Bicontinuous concentric lamellar (bcl) is an interesting morphology with an open channel pore structure that has been successfully synthesized on silica-based materials. If bcl morphology can be applied in TiO2 system, then many surface properties of TiO2 can be enhanced, i.e. photocatalytic activity. A simple and effective strategy has been demonstrated to transform aggregated and spherical TiO2 particles to bcl morphology via alkaline hydrothermal route. Alkaline hydrothermal treatment successfully transforms TiO2 particle surface to have bcl morphology through swelling with ammonia then followed by phase segregation process. We proposed this strategy as a general pathway to transform the particle surface with any shape to have bcl morphology.

Synthesis of Spherical Nanostructured g-Al2O3 Particles using Cetyltrimethylammonium Bromide (CTAB) Reverse Micelle Templating

We demonstrated the synthesis of spherical nanostructured g-Al2O3 using reverse micelle templating to enhance the surface area and reactant accessibility. Three different surfactants were used in this study: benzalkonium chloride (BZK), sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB). We obtained spherical nanostructured particles only using CTAB that form a reverse micelle emulsion. The particles have wide size distribution with an average size of 2.54 mm. The spherical particles consist of nanoplate crystallites with size 20-40 nm randomly arranged forming intercrystallite spaces. The crystalline phase of as-synthesized and calcined particles was boehmite and g-Al2O3, respectively as determined by XRD analysis. Here, the preserved particle morphology during boehmite to g-Al2O3 transformation opens a facile route to synthesize g-Al2O3 particles with complex morphology. The specific surface area of synthesized particles is 201 m2/g, which is around five times higher than the conventional g-Al2O3 (Aldrich 544833). Spherical nanostructured g-Al2O3 provides wide potential applications in catalysis due to its high density closed packed structure, large surface area, and high accessibility.

Synthesis of plate-like Fe-doped SrBi4Ti4O15 using Na2SO4/K2SO4 molten salt method: XRD, Raman spectroscopy, SEM, and UV–VIS DRS studies

SrBi4Ti4O15 is a four-layer member of the Aurivillius compound and reported to have photocatalyst properties with a band gap energy of 3.0 eV (420 nm). Doped with metal elements is a strategy to reduce the band gap energy of photocatalyst material in order to increase its utilization under a wider energy spectrum of visible light. Here in, Fe-doped SrBi4Ti4O15 was synthesized using Na2SO4/K2SO4 molten salt method. The diffractogram revealed that all samples were successfully synthesized in the A21am space group with no impurity phase. Raman spectra confirmed the existence of a typical Raman vibration peak for a four-layer Aurivillius family compound and the local changes in TiO6 structure due to Fe dopant mirrored by vibration mode at ~ 559 cm−1. SEM images showed that the all samples morphology is plate-like however, the particle size of Fe-doped SrBi4Ti4O15 is bigger than the undoped compound. Meanwhile, the UV–Vis DRS spectra revealed that Fe dopant could effectively reduce the band gap energy resulting in obvious red shift absorption to the wider visible light region (530–705 nm)

Ultrasonication-modified electrochemically exfoliated graphene for counter electrode in dye-sensitized solar cells

Graphene has various excellent properties, contributing to its wide potential applications. Electrochemically exfoliated graphene (EEG) is a graphene-like material synthesized via electrochemical methods, requiring a shorter synthesis time and much less chemical waste than the Hummers method. Ultrasonication modification of EEG will increase the structure of defects, dispersion capability, and performance of EEG as a counter electrode (CE) material in dye-sensitized solar cells (DSSC). FTIR-ATR, XRD, and Raman spectroscopy confirmed the EEG material. SEM-EDS analysis observed that all EEGs have thick layer morphology. The dispersion study showed that repeated ultrasonication improves the dispersion ability of the EEG material. In addition, repeated ultrasonication improves the structural defects in EEG material. The EEG with 6 repetitions of sonication (EEG_6) gave the highest performance as a CE in DSSC with 0.890% efficiency, while the reduced graphene oxide (rGO) with the Hummers method is 0.714%. When the mixture of Polyaniline/Graphite/EEG_6 (PG_EEG_6) material was used as a CE, a 2.493% efficiency was gained, better than Pt CE (1.626%). Therefore, using EEG_6 composite as a CE leads to a higher-performing and more eco-friendly DSSC