TY - JOUR
T1 - Investigating the factors that influence sacrificial hydrogen evolution activity for three structurally-related molecular photocatalysts
T2 - thermodynamic driving force, excited-state dynamics, and surface interaction with cocatalysts
AU - Liu, Tao
AU - Chen, Linjiang
AU - Li, Xiaobo
AU - Cooper, Andrew I.
PY - 2023/1/28
Y1 - 2023/1/28
N2 - 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-1 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.
AB - 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-1 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.
U2 - 10.1039/D2CP04039E
DO - 10.1039/D2CP04039E
M3 - Article
C2 - 36637095
SN - 1463-9076
VL - 25
SP - 3494
EP - 3501
JO - Physical Chemistry Chemical Physics
JF - Physical Chemistry Chemical Physics
IS - 4
ER -