Natural pollen exine-templated synthesis of photocatalytic metal oxides with high surface area and oxygen vacancies

Ultrasonic-assisted photocatalytic degradation of various organic contaminants using ZnO supported on a natural polymer of sporopollenin

“…The narrow bandgap results associated with strong sonophoto-absorption in the visible region can be ascribed to ZnO immobilization onto the carbon-based material like SP. Immobilizing ZnO onto the SP channel-like structure significantly reduced the band gap, which is consistent with previously reported results [26] . The semiconductor composite remarkably generates e − /h + pairs after e − excitation from the VB to CB.…”

“…In addition, nanocatalyst immobilization onto carbonaceous templates, such as solvent-resistant sporopollenin (SP), which consists of oxygenated aromatic and long-chain fatty acids, can be considered an operating strategy to overcome practical constraints [25] . Pollens are available in nature and have been used as a template for synthesizing inorganic materials because of their porous structure and high surface area [26] . Moreover, pollen is beneficial in terms of its eco-friendliness, low cost, and stability [27] .…”

“…For this purpose, pollen with a uniform particle size, chemical resistance, and an exine outer wall, which is primarily composed of SP, can be utilized in combination with nanostructured sonophotocatalysts [28] , [29] , [30] . Hierarchically structured metal oxides generated using pollen as the hard template display enhanced sonophotocatalytic performance owing to their suitable mass transfer and facile pathways for chemicals and electrons [26] . This study aimed to prepare the SP-ZnO nanocomposite as an appropriate sonophotocatalyst for the treatment of different types of pollutants.…”

Extraordinary microcarriers derived from spores and pollens

“…Shin et al treated sporopollenin microcapsules with NaOH to hydrolyze the ester group of sporopollenin into carboxylates for binding metal ions. 80 Lee et al used porous pollen grains as pivots to support polymers in metal organic framework (MOF) materials. 53 In detail, taking advantage of their high biocompatibility, physicochemical stability and dispersibility, the sporopollenin microshells were linked to poly 2-dimethylaminoethyl methacrylate, which acted as an anchor and captured the MOF nanocrystals to form a composite material.…”

Hexagonal TiO2/SiO2 Porous Microplates for Methylene Blue Photodegradation

“…For the treatment of methylene blue waste by the formation of reactive chemical species, semiconductor-based photocatalyst materials were developed because they are environmentally acceptable, energy efficient, and tolerate mild reaction conditions without secondary contamination [3,4]. Under light irradiation, semiconductor photocatalysts such as titanium dioxide (TiO2) [4,5], zinc oxide (ZnO) [6,7], copper oxide (CuO) [8,9] and cerium oxide (CeO2) [10,11] have been employed extensively for the degradation of dyes such as methylene blue. TiO2 has been widely utilized as a low-cost photocatalyst for the degradation of methylene blue in water due to its high electron mobility [12,13], long carrier life [14], chemical stability [15], wide radiation absorption range [16], high photosensitivity [17], and non-toxicity [18].…”