A Biotemplating Route for the Synthesis of Hierarchical Fe₂O₃ with Highly Dispersed Carbon as Electron‐Transfer Channel

Abstract

Although the preparation of carbon composites has made great progress, the construction of systems comprising uniformly dispersed carbon as a framework to link active constituents still remains a challenge. Herein, a hierarchical Fe 2 O 3 /C composite was synthesized in a one-step biotemplating route, where agarose was firstly reacted with Fe 3 + and Ca 2 + ions, which resulted in a competitive interaction between these ions and the hydroxy groups, then partly calcined to achieve the final product that consisted of α-Fe 2 O 3 nanoparticles embedded in highly dispersed carbon. The carbon within the composite acts as an efficient photoelectron transfer channel to improve conductivity during photocatalysis. The hierarchical Fe 2 O 3 /C composite exhibited a photodegradation rate constant (k) of 0.091 min À 1 , more than four times that of α-Fe 2 O 3 (0.020 min À 1 ).

Intrinsic enzyme‐like activity of magnetite particles is enhanced by cultivation with Trichoderma guizhouense

“…5 and Supporting Information Fig. S6), which is similar to observations in a previous report (Yang et al ., 2020). These hierarchical structures may be caused by proton‐promoted reactions, initiated by fungal excretion of H + and organic acids (Yu et al ., 2019), followed by reduction and/or complexation of Fe atoms by organic molecules produced by the fungus, finally resulting in destruction of the mineral structure (Furrer, 1986).…”

“…In general, synthetic iron (oxyhydr)oxide nanoparticles have a relatively homogeneous particle size (Chen et al ., 2012; Huang et al ., 2019). In contrast, biogenic iron (oxyhydr)oxide nanoparticles often possess hierarchical structures that show superior catalytic activity due to the built‐in electric field and the high proportion of interfacial elements (Yao et al ., 2017; Yang et al ., 2020). Interestingly, our NanoSIMS and TEM observation suggested the presence of hierarchical structures after 120 h cultivation (Fig.…”

“…Therefore, it seems that both surface oxygen structures (Mueller et al ., 2015; Li et al ., 2019; Wang et al ., 2019) and Fe chemistry (Gao et al ., 2007; Garrido‐Ramírez et al ., 2010; Han et al ., 2020) play important roles in controlling the catalytic activity of these iron oxides. However, very few studies have addressed the underlying catalytic mechanisms of biogenic nano‐size minerals that may possess distinctly different properties from those of synthetic minerals, because of their surface modification by biomolecules (Liu and Liu, 2017) or unique hierarchical structures (Yang et al ., 2020).…”

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

“…The reusability experiments the authors carried out showed that the catalyst did not lose activity until the third cycle. To catalyze the same reaction, Yang et al produced hierarchical Fe 2 O 3 /C composites from agarose which showed enhanced photocatalytic activity with a four times higher photodegradation rate constant of 0.091 min −1 vs. the 0.020 min −1 rate constant of Fe 2 O 3 [145].…”