The rate of electron transfer is critical in determining the efficiency of photoenergy conversion systems and is controlled by changing the relative energy gap of components, their geometries, or surroundings. However, the rate of electron transfer has not been controlled by the remote input of an external field without changing the geometries or materials of the systems. We demonstrate here that an applied microwave field can enhance the photocatalytic reduction of bipyridinium ion using CdS quantum dots (QDs) by accelerating electron transfer. Analysis of the time-resolved emission decay profiles of CdS quantum dots immersed in aqueous solutions of bipyridinium exhibited the shortening of their emission lifetimes, because of the accelerated electron transfer from QDs to bipyridinium under microwave irradiation. This discovery leads us to a new methodology using microwaves as an external field to enhance photocatalytic reactions.
Efficient water vapor splitting opens a new strategy to develop scalable and corrosion-free solar-energy-harvesting systems. This study demonstrates highly efficient overall water splitting under vapor feeding using Al-doped SrTiO3 (SrTiO3:Al)-based photocatalyst decorated homogeneously with nano-membrane TiOx or TaOx thin layers (<3 nm). Here, we show the hygroscopic nature of the metal (hydr)oxide layer provides liquid water reaction environment under vapor, thus achieving an AQY of 54 ± 4%, which is comparable to a liquid reaction. TiOx coated, CoOOH/Rh loaded SrTiO3:Al photocatalyst works for over 100 h, under high pressure (0.3 MPa), and with no problems using simulated seawater as the water vapor supply source. This vapor feeding concept is innovative as a high-pressure-tolerant photoreactor and may have value for large-scale applications. It allows uniform distribution of the water reactant into the reactor system without the potential risk of removing photocatalyst powders and eluting some dissolved ions from the reactor.
To imitate the precisely ordered structure of the photoantennas and electron mediators in the natural photosynthesis system, we have constructed the Ru(bpy) 3 2+intercalated alternate-layered structure of titanate nanosheets and tungstate nanosheets via thiol-ene click reaction. Before nanosheet stacking, Pt(terpy) was immobilized at the edge of the titanate nanosheets. The visible-light-induced vectorial Zscheme electron transfer reaction from the valence band of tungstate to the conduction band of titanate via the photoexcited Ru(bpy) 3 2+ was demonstrated by the following two evidences: (1) From the results of the fluorescence decay of Ru(bpy) 3 2+ , the rate of the forward electron transfer from the photoexcited Ru(bpy) 3 2+ to the conduction band of titanate was estimated as 1.16 × 10 8 s −1 , which was 10 times faster than the backward electron transfer from the photoexcited Ru(bpy) 3 to the conduction band of tungstate (1.02 × 10 7 s −1 ) due to a localization of Ru(bpy) 3 2+ on the titanate nanosheets. (2) We observed the decrease of the electrons accumulated in the conduction band of the tungstate induced by photoexcitation of Ru(bpy) 3 2+ , demonstrating the forward electron transfer from the conduction band of tugnstate to the vacant highest occupied molecular orbital level of the photoexcitation Ru(bpy) 3 2+ . Finally, H 2 gas was produced from the water dispersion of the alternate-layered structure under visible light irradiation, suggesting that the electrons getting to the conduction band of the titanate were transferred to the Pt(terpy) placed at the edge of the nanosheets, and reduced water to dihydrogen. Herein, noctylamine species at the interlayer space played a role as hole scavenger; in other words, these molecules were oxidized by the hole in the conduction band of the tungstate nanosheets.
Visible-light-induced electron transfer from a tungstate to a titanate layer was demonstrated to be mediated by excited rhodamine B (RhB) intercalated by ion exchange between the two layers. The distance of only 1 nm between the layers provides a large contact area that enables the efficient mediation of electron transfer by RhB.
Absorption properties of alternate stacked structures of niobate and tungstate nanosheets were continuously altered by a change of the interlayer distance.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.