Bio-mimicking TiO₂ architectures for enhanced photocatalytic activity under UV and visible light

Abstract

A multi-step chemical replication method using natural green leaves as templates can produce a porous, visible-light active TiO2-based photocatalyst.

Olive Leaves as Biotemplates for Enhanced Solar-Light Harvesting by a Titania-Based Solid

“…Chlorophyll molecules ( Figure 3 C) are formed by a hydrophobic phytol chain and a magnesium containing porphyrin ring, which acts as a light collector during photosynthesis [ 26 ].…”

“…Artificial olive leaf (AOL) was synthesized by mimicking the structure of the olive leaf, following the procedure described by Li et al [ 19 ] and subsequently modified by Hashemizadeh et al [ 26 ]. The process basically consists of three phases, (i) an acid treatment by which several metal cations such as Ca, P, S, K could be (partially) eliminated and, especially, Mg from the porphyrins, can be replaced by H + , forming yellow-brown pheophytins; (ii) a second step in which these protons are exchanged for Ti +3 through a treatment with TiCl 3 and (iii) a third step in which these Ti +3 ions act as seeds for the subsequent formation of a TiO 2 structure that replicates that of the olive leaf.…”

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

“…Nature has been perfecting materials and biological systems through evolution over thousands of years, developing a rather complex hierarchy at all levels to adapt to the constant modifications of the environment. Those years of evolution provided natural materials with some useful features such as resistance, adaptability, and sophistication [1]. The optimization of the use of materials and energy in nature makes it extremely interesting to science, as it can learn from these biological materials and systems by taking advantage of their intricate structures or mechanisms of action through their replication to develop functional materials [2,3].…”

“…The process through which the bioinspired composites are obtained is mainly divided into three phases, where after preparing the sample and depositing the inorganic material on the organic template, the natural pattern is mainly removed through thermal treatments depending on the desired result of the new material or the actual template [6]. For example, Hashemizadeh et al [1] designed some catalysts using Camellia tree leaves. For that, they first washed, cut, and dried the leaves (preparation phase), then they added TiCl 3 as a precursor for the incorporation of the inorganic material (second phase), and lastly, they calcined the synthesized the catalyst at 773 K to remove the organic template (third phase).…”

“…Another virus that has been used as a pattern for biotemplating approaches is the M13 phage, as its genetically engineered mutants present modifications on the surface that bind to nanoparticles or nanotubes, improving the functionality of the material [17]. Wood [18], cotton [19], aquatic plants [20], green leaves [1,21], or even animal products [22] have also been used as templates. Butterfly wings are of great interest as they present an intricate and complex microstructure and photonic resonances that control their structural color and make them very suitable for catalysis and electrochemical applications [23][24][25].…”