TY - JOUR

T1 - Titanium Superoxide as a Carrier of a “Long-Lived” Superoxide Anion: An Ab Initio Investigation

AU - Bogdanchikov, Georgii A.

AU - Baklanov, Alexey V.

N1 - The authors acknowledge the core funding from the Russian Federal Ministry of Science and Higher Education (FWGF-2021-0005). The authors express their gratitude to the Siberian Supercomputer Center of the Siberian Branch of the Russian Academy of Sciences whose resources have been used for the calculations.

PY - 2024/7/18

Y1 - 2024/7/18

N2 - The photoinduced generation of a superoxide anion on the surface of a semiconductor photocatalyst is usually attributed to the reduction of O2 with conduction-band electrons. In the current work, the reaction of TiO2 with O2 giving rise to TiO4 in superoxide and peroxide states has been investigated with ab initio (CAS, CCSD) and DFT (B3LYP) calculations. The ground triplet state and two substates (open-shell singlet (OSS) and closed-shell singlet (CSS)) of a doubly degenerate excited singlet state (a1Δg) are considered as reactive states of oxygen, participating in spontaneous or photoinduced processes, respectively. The triplet and OSS singlet states of TiO4 contain O2- as structural units and can be defined as titanium superoxides. Both states have energy less than the level of the initial pair TiO2+O2 by about 30 kcal/mol. The CSS state of TiO4 has a diperoxide structure Ti4+(O22-)2 and also lies in energy below the initial pair TiO2+3O2. Titanium superoxide is considered to be the carrier of an “exceptionally stable” and “long-lived” superoxide anion, which was earlier synthesized or detected on the surface of TiO2. The low-energy location of the conical intersections on the way from reagents to 3TiO4 allows us to explain the literature data on the spontaneous generation of the “long-lived” superoxide anion on the TiO2 surface.

AB - The photoinduced generation of a superoxide anion on the surface of a semiconductor photocatalyst is usually attributed to the reduction of O2 with conduction-band electrons. In the current work, the reaction of TiO2 with O2 giving rise to TiO4 in superoxide and peroxide states has been investigated with ab initio (CAS, CCSD) and DFT (B3LYP) calculations. The ground triplet state and two substates (open-shell singlet (OSS) and closed-shell singlet (CSS)) of a doubly degenerate excited singlet state (a1Δg) are considered as reactive states of oxygen, participating in spontaneous or photoinduced processes, respectively. The triplet and OSS singlet states of TiO4 contain O2- as structural units and can be defined as titanium superoxides. Both states have energy less than the level of the initial pair TiO2+O2 by about 30 kcal/mol. The CSS state of TiO4 has a diperoxide structure Ti4+(O22-)2 and also lies in energy below the initial pair TiO2+3O2. Titanium superoxide is considered to be the carrier of an “exceptionally stable” and “long-lived” superoxide anion, which was earlier synthesized or detected on the surface of TiO2. The low-energy location of the conical intersections on the way from reagents to 3TiO4 allows us to explain the literature data on the spontaneous generation of the “long-lived” superoxide anion on the TiO2 surface.

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85197509283&origin=inward&txGid=077bb0fd694d1fe0ddbd7b8abe871e17

UR - https://www.webofscience.com/wos/woscc/full-record/WOS:001261329900001

UR - https://www.mendeley.com/catalogue/ac2bc720-258d-35f5-a772-24d6b94ffd46/

U2 - 10.1021/acs.jpca.4c01833

DO - 10.1021/acs.jpca.4c01833

M3 - Article

C2 - 38954636

VL - 128

SP - 5508

EP - 5515

JO - Journal of Physical Chemistry A

JF - Journal of Physical Chemistry A

SN - 1089-5639

IS - 28

ER -