Exceptional performance of photoelectrochemical water oxidation of single-crystal rutile TiO2 nanorods dependent on the hole trapping of modified chloride

Abstract

It is highly desired to effectively trap photogenerated holes for efficient photoelectrochemical (PEC) water oxidation to evolve O2 on oxide semiconductors. Herein, it is found for the first time mainly based on the time-resolved- and atmosphere-controlled- surface photovoltage responses that the modified chloride would effectively trap photogenerated holes so as to prolong the charge lifetime and hence promote charge separation of single-crystal rutile TiO2 nanorods. Its strong capacity to trap holes, comparable to the widely-used methanol and Co(II) phosphate, is well responsible for the exceptional photoactivities for PEC water oxidation to evolve O2 on rutile nanorods with a proper amount of chloride modified, about 2.5-time high as that on the resulting anatase nanoparticles, even 10-time if the surface area is considered. Moreover, it is suggested that the hole trapping role of chemically-adsorbed chloride is related to its lonely-pair electrons, and to the subsequently-produced intermediate Cl atoms with proper electronegativity for evolving O2. Interestingly, this finding is also applicable to the chloride-modified anatase TiO2. This work will provide a feasible strategy to design high-activity nanostructured semiconductor photoanodes for PEC water oxidation, even for overall water splitting.

Preparation and characterization of photoactive antimicrobial graphitic carbon nitride (g-C3N4) films

“…While direct oxidation of 3-CCA is theoretically possible, we anticipate that the Cl - present in the reaction mixture will serve to trap the photogenerated holes and favor ROS production by means of reduction of surface adsorbed dioxygen. 49 These results indicate that ns- g -C 3 N 4 successfully reduced molecular oxygen to produce cytotoxic ROS in the presence of visible radiation.…”

Seawater operating bio-photovoltaic cells coupling semiconductor photoanodes and enzymatic biocathodes

“…The net reaction is the solar energy conversion to electricity in the ceaseless cycle of water consumption and regeneration with no necessity of a membrane between two electrodes lowering the internal resistance of the setup and improving the energy utilization efficiency (Figure 1). The current state-of-the-art data show that the cell performance can be improved to 3 mW cm -2 once open circuit cell voltages > 1 V and current densities > 10 mA cm -2 in neutral solutions will be achieved 63,82 . Then, it may become comparable with the existing technologies (in average ~10 mW cm -2 for silicon solar cells), along with that, offering a ca.…”

“…The involvement of O 2 and and such prod ucts of its reduction (by the photoinduced ein the conductance band) as superoxide anion radical O 2 -, and further routes of its transformation to H 2 O 2 , H 2 O and O 2 , cannot be excluded; all those steps depend both on pH 61 and solution composition 62 and thus can contribute to the energy losses in such complex matrix as seawater. Therwith, the Clanion itself does not inhibt phtotoelectroaatlysis ( Figure 2B, data for 1 M Tris-HCl) and was even disucssed to enhance the photoelectrocatalytic efficiency 63 . Quite a few enzymes can efficiently electrocatalyse oxygen reduction in basic solutions 52,64 , and BOD is one of them [65][66][67] , currently being mostly used in glucose biofuel cells operating in physiological media 47,48 and as a model enzyme in artificial photosynthesis cells, in which BOD oxidase cathodes are coupled to electrically wired photosystem-based photobioanodes 23 .…”

Freeze Drying as a Novel Approach to Improve Charge Transport in Titanium Dioxide Nanorod Arrays

“…The chlorine might originate from the reagents of synthesizing TiO 2 , with its atomic ratio relative to titanium ∼5 % determined by XPS. The chlorine adsorbed on the rutile (110) surface, which played an important role for directing the growth of TiO 2 nanorods . By spin‐polarized density functional theory (DFT) calculations (see the SI), the bonding energy of the Ti−Cl bond on the (110) facet is determined to be as small as ∼69.4 kJ mol −1 , implying that the Ti−Cl bonding is unstable.…”