Advances in mechanisms of water photodissociationon TiO2 surfaces 水在二氧化钛表面的光反应机理研究进展

Chen，Xiao; Guo，Qing; Yang，Xueming

2021-09-01

10.1360/TB-2021-0172

Chinese Science Bulletin-Chinese   影响因子和分区

0023-074X

2095-9419

Solar HO splitting to H and O is one of the most interesting ways to achieve clean and renewable energy and remains one of holy grails in catalysis. Since the pioneer work about photoelectrochemical HO splitting into H and O on Pt and TiO electrodes was reported by Fujishima and Honda in 1972, the photochemistry of HO on TiO surfaces has been extensively investigated by various techniques during the past decades because of its potential applications in energy chemistry. However, due to its complexity, an unambiguous understanding of elementary processes that underlie the HO splitting reaction on TiO surfaces is still lacking. Thus, it is of great value to get an insightful understanding of the mechanisms of HO photochemistry on TiO surfaces at a molecular level. In this review, we highlight the recent progress that provides fundamental insight into HO photochemistry on the TiO model surfaces using surface science techniques. First of all, the structures of TiO single crystal surfaces and the adsorption behaviors of HO on these surfaces are discussed, which will affect the photochemistry of HO on the surfaces. Nearly no HO dissociation occurs at the regular Ti sites of the TiO surfaces. Next, the details of HO photochemistry on the TiO surfaces are presented, and the roles of surface structures, intermolecular hydrogen bond and photon energy in HO photochemistry are discussed. The mechanisms of HO photochemistry on different TiO surfaces are similar, which occurs via the ejection of OH radical into vacuum, leaving behind the remaining H atom on the adjacent O site. Hydrogen bond is believed to play a double-edged sword role in HO dissociation: The single hydrogen bond between HO molecules can promote HO dissociation efficiently, but one-dimensional hydrogen bonding chain hinders the dissociation of HO significantly. Moreover, the arrangement of HO changes dramatically on different TiO surfaces, which can further affect the dissociation probability of HO. In addition, the dissociation probability of HO on rutile TiO(110) is found to be highly dependent on photon energy, which raises doubt about the widely accepted photocatalysis model in which the excess energy of charge carriers is nearly useless for photocatalysis. Therefore, a sophisticated photocatalysis model that can perfectly incorporate the effect of charge carrier energy and the interaction between adsorbates (or intermediates) and TiO surfaces should be developed. Afterwards, an open discussion on a new photocatalysis model is presented, which highlights the energy of charge carriers and the interaction between charge carriers and adsorbates in HO photochemistry on TiO. This will deepen our understandings of fundamental processes in photocatalysis and provide clues for the development of more efficient photocatalysis. In the end, the challenges and opportunities of the mechanistic studies of TiO photocatalysis at a molecular level are discussed briefly, which may guide the development of TiO photocatalysis in the future.

Charge transfer Nonadiabatic process Photocatalysis TiO2 Water

EI

中文

第一 ; 通讯

20213910942000

Charge transfer ; Dissociation ; Free radicals ; Hydrogen bonds ; Oxide minerals ; Photocatalysis ; Photons ; Single crystals ; Surface reactions ; Surface structure

Minerals:482.2 ; Light/Optics:741.1 ; Physical Chemistry:801.4 ; Chemical Reactions:802.2 ; Inorganic Compounds:804.2 ; Physical Properties of Gases, Liquids and Solids:931.2 ; Atomic and Molecular Physics:931.3 ; Crystalline Solids:933.1

2-s2.0-85115441480

Scopus

Department of Chemistry,Southern University of Science and Technology,Shenzhen,518055,China

Chen，Xiao,Guo，Qing,Yang，Xueming. Advances in mechanisms of water photodissociationon TiO2 surfaces 水在二氧化钛表面的光反应机理研究进展[J]. Chinese Science Bulletin-Chinese,2021,66(25):3299-3308.

Chen，Xiao,Guo，Qing,&Yang，Xueming.(2021).Advances in mechanisms of water photodissociationon TiO2 surfaces 水在二氧化钛表面的光反应机理研究进展.Chinese Science Bulletin-Chinese,66(25),3299-3308.

Chen，Xiao,et al."Advances in mechanisms of water photodissociationon TiO2 surfaces 水在二氧化钛表面的光反应机理研究进展".Chinese Science Bulletin-Chinese 66.25(2021):3299-3308.