A density functional study of type I to type II crossover in g-C3N4/CoN4 heterostructure in presence of external perturbation
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Date
2024
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International Journal of Hydrogen Energy
Abstract
Herein, we report the impact of external perturbation on the photocatalytic performance of g-C3N4/CoN4 heterojunction and concomitant transition from type-I to type-II. The state-of-the-art theoretical modeling presented here is the first study on dynamic role of strain and electric field on g-C3N4/CoN4 heterojunction and its potential application as a solar-driven water splitting reaction. Utilizing the density functional theory (DFT) calculation, V. N. et al. recently reported the photocatalytic activity of g-C3N4/MN4 (M = Mn, Fe and Co) heterojunction [J. Comput. Chem. 2024, 45, 2518-2529, https://doi.org/10.1002/jcc.2746412] and subsequently established g-C3N4/CoN4 as a type I heterojunction for photocatalytic water splitting reaction [Phys. Chem. Chem. Phys. 2024, 26, 21117–21133]. In the present study, we applied external perturbation in the form of mechanical strain, electric field and evaluated the electronic structure properties of the system along with the detailed examination of concomitant optical and magnetic properties of g-C3N4/CoN4 heterojunction. The switching of photocatalytic feature from type I to type II originates due to the crossover between valence band maxima (VBM) of g-C3N4 and CoN4 in presence of external perturbation. Notably, the resulting system acts as a type II photocatalyst for water splitting reaction while applying compressive (negative) strain of −2 to −6% and an electric field of −0.5 and +0.5 V/Å, respectively. Accumulation of photogenerated electrons and holes separately in g-C3N4 and CoN4 units confirms the perceptible separation of charge carriers and thereby reduces the recombination compared to un-perturbed system. A red-shifted absorption maximum (689 nm), superior charge transfer (0.9e), and clear separation of photogenerated electrons and holes are the origin of enhanced photocatalytic efficiency of g-C3N4/CoN4 heterojunction in the presence of external perturbation. We believe that our work will provide enough evidence to the experimentalists to achieve such a system in practice leading to human-friendly applications.