Preparation and Photoelectrochemical Performance of Visible-Light Active AgI/TiO₂-NTs Composite with Rich β-AgI

Abstract

AgI sensitized TiO2 nanotube arrays (AgI/TiO2-NTs) with adjustable β/γ ratio of AgI were prepared by a simple dissolution–precipitation–calcination process. The samples were characterized by various techniques, including X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, ultraviolet–visible diffuse reflectance spectroscopy, linear sweep voltammetry, electrochemical impedance spectroscopy, and Mott–Schottky plots. We found that calcination temperature (100–500 °C) had significant effect on regulating the phase of AgI. After calcination at 350 °C, the highest β/γ ratio of AgI was achieved. Moreover, greatly enhanced photocurrent response and reduced charge transfer resistance were also observed, which together led to easier generation and separation of photogenerated electron–hole pairs. Thus, for the reduction of Cr­(VI) under visible light, significantly enhanced photoelectrocatalytic (PEC) performance was observed using AgI/TiO2-NTs calcined at 350 °C (denoted as AgI/TiO2-NTs350) as photoanode and Ti foil as cathode, respectively. At very low content of AgI (1.25%), the estimated k Cr(VI) (0.0155 min–1) was nearly 5 times that of pure TiO2-NTs350.

Semiconductor Electrode Materials Applied in Photoelectrocatalytic Wastewater Treatment—an Overview

“…metal removal/recovery [99][100][101][102]; and, simultaneous generation of electricity and hydrogen [12,[103][104][105].…”

“…The semiconductor materials that are applied in photoelectrocatalytic treatment of wastewater include photoanodes (n-type) and photocathodes (p-type) if oxidation or reduction is the main process at the interface [84]. Thus, photoelectrocatalysis is developed in such wastewater treatment field as: organic compounds oxidation [92,93]; inorganic ions reduction [94,95]; disinfection [96][97][98]; metal removal/recovery [99][100][101][102]; and, simultaneous generation of electricity and hydrogen [12,[103][104][105].…”

“…The composite material revealed high efficiency in methyl orange degradation (PEC process) combined with simultaneous hydrogen generation under visible light irradiation due to the high dispersity of CdSe nanoparticles on outside and inside part of the pore walls of TiO 2 NTAs. The AgI/TiO 2 -NT composites were applied as photoelectrodes in the PEC removal of Cr(VI) under visible light irradiation [102]. This semiconductor material was characterized by enhanced PEC reduction of Cr(VI) due to the easier generation and separation of e − /h + pairs and reduced charge transfer resistance.…”

Fabrication of 3D Bi2O3-BiOI heterojunction by a simple dipping method: Highly enhanced visible-light photoelectrocatalytic activity

“…S2) and relevant works [16,50]. Moreover, a synergistic factor (SF) of 2.9 can be obtained according to the following equation [60,61]:…”

Analysis of Iodide Transport on Methyl Ammonium Lead Iodide Perovskite Solar Cell Structure Through Operando Hard X-ray Photoelectron Spectroscopy

“…The SP_2 sample spectra consist of only one main peak located at 619.1 eV, as clearly identified from Figure d. We ascribed this chemical state to the presence of the AgI interlayer. − Basically, it is unexpected to observe the existence of the AgI compound from the SP_2 sample because of the presence of an ITO barrier layer. In other words, halide species should not be able to directly reach the Ag layer and create an AgI structure as in the case of the SP_1 sample without an ITO barrier.…”