Investigating the factors that influence sacrificial hydrogen evolution activity for three structurally- related molecular photocatalysts: thermodynamic driving force, excited-state dynamics, and surface interaction with cocatalysts



Liu, Tao, Chen, Linjiang, Li, Xiaobo and Cooper, Andrew II
(2023) Investigating the factors that influence sacrificial hydrogen evolution activity for three structurally- related molecular photocatalysts: thermodynamic driving force, excited-state dynamics, and surface interaction with cocatalysts. PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 25 (4). pp. 3494-3501.

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Abstract

The design of molecular organic photocatalysts for reactions such as water splitting requires consideration of factors that go beyond electronic band gap and thermodynamic driving forces. Here, we carried out a theoretical investigation of three molecular photocatalysts (1-3) that are structurally similar but that show different hydrogen evolution activities (25, 23 & 0 μmol h<sup>-1</sup> for 1-3, respectively). We used density functional theory (DFT) and time-dependent DFT calculations to evaluate the molecules' optoelectronic properties, such as ionization potential, electron affinity, and exciton potentials, as well as the interaction between the molecular photocatalysts and an idealized platinum cocatalyst surface. The 'static' picture thus obtained was augmented by probing the nonadiabatic dynamics of the molecules beyond the Born-Oppenheimer approximation, revealing a different picture of exciton recombination and relaxation for molecule 3. Our results suggest that slow exciton recombination, fast relaxation to the lowest-energy excited state, and a shorter charge transfer distance between the photocatalyst and the metal cocatalyst are important features that contribute to the photocatalytic hydrogen evolution activity of 1 and 2, and may partly rationalize the observed inactivity of 3, in addition to its lower light absorption profile.

Item Type: Article
Uncontrolled Keywords: 34 Chemical Sciences, 3406 Physical Chemistry, 3407 Theoretical and Computational Chemistry, 7 Affordable and Clean Energy
Divisions: Faculty of Science and Engineering > School of Physical Sciences
Depositing User: Symplectic Admin
Date Deposited: 22 Feb 2023 15:16
Last Modified: 21 Jun 2024 10:07
DOI: 10.1039/d2cp04039e
Open Access URL: https://doi.org/10.1039/D2CP04039E
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URI: https://livrepository.liverpool.ac.uk/id/eprint/3168556