Surface Functionalization of Metal Oxide Semiconductors with Catechol Ligands for Enhancing Their Photoactivity

Abstract

Metal oxide nanostructures are increasingly important materials for various emerging photocatalytic, photovoltaic and photoelectrochemical (PEC) applications. They are commonly used as photoelectrode materials due to their unique functional properties such as wide bandgap, reactive electronic transitions, and high stability. To increase the effectiveness of semiconductor metal oxides photoelectrodes, researchers seek to use various photoabsorption amplification and colloidal stability enhancement strategies. An effective method for achieving this is the surface functionalization of metal oxide semiconductors with catechol‐type ligands. Catechol‐type ligands are a family of organic molecules that adsorb very strongly onto metal oxides by forming complexes with metal atoms through adjacent phenolic —OH groups. Once adsorbed, catechol‐type ligands facilitate improved particle dispersion by inhibiting agglomeration and enhance photoexcitation in metal oxide semiconductors by improving visible light absorption. Herein, the surface complexation of catechol‐type ligand onto metal oxide semiconductor surfaces and their photoabsorption enhancement mechanisms is described. In addition, recent advances and trends in this area are described by presenting recent advancements made in applications of catechol‐modified metal oxide systems in photocatalysis, PEC biosensing, and solar cells.

Perspectives and Current Trends on Hybrid Nanocomposite Materials for Photocatalytic Applications

“…PDA is a biomimetic polymer that has shaken the materials community due to its simple polymerization pathways, easy application on virtually every surface, and unique chemistry that allows it to be used as an initiator on many complex syntheses, [63,64] tandems structures, [65] or as a biocompatible component in many heterostructures. [66] PDA was originally synthesized in 2007 by Lee et al, [67] as the result of the oxidation of dopamine.…”

Catecholate Dye-Assisted Decoration of Ag on TiO2 Nanoparticles for Detection of Cancer-Related MicroRNA Biomarkers on a Multiplexed Photoelectrochemical Platform

“…The initial step in this method involved surface modification of TiO 2 NPs using HTX, a dye from the catecholate family. 9,14 Various concentrations of HTX were first added to TiO 2 suspensions, resulting in TiO 2 /HTX NP suspensions. The next step involved the addition of AgNO 3 as a silver precursor to the TiO 2 /HTX NP suspensions.…”

Orthogonal redox and optical stimuli can induce independent responses for catechol-chitosan films

“…However for other properties, an association with redox-activity is less clear. 19–21 Specifically, various catecholic materials show strong photothermal heating upon near infrared (NIR) irradiation, 22–28 yet it is not always clear if the responses to optical and redox stimuli are independent. Scheme 1 illustrates the NIR-induced excitation of electrons and the redox-based transfer of electrons, and the question in this study is whether the response to inputs from these orthogonal modalities can be independent.…”