Characterization of Type I/II g-C₃N₄/MoS₂ van der Waals Heterostructures: A New Theoretical Insight

Abstract

The charge transfer mechanism of the g-C 3 N 4 /MoS 2 heterojunction is still disputed. Some regard it as a type I pathway, some regard it as a type II pathway, and still some regard it as a Z-scheme pathway. Especially, the results obtained by density functional theory (DFT) calculations are not totally in agreement. Here, we constructed four g-C 3 N 4 /MoS 2 heterojunctions on the basis of the aperture alignment modes of g-C 3 N 4 and MoS 2 . Their morphology and photocatalytic activity were investigated via first-principles and excited state dynamics simulations. By systemically comparing the interfacial binding energy and electronic structure (e.g., band structure, electrostatic potential, and band edge positions) of g-C 3 N 4 /MoS 2 heterojunctions, we found that both type I and type II band alignment structures could be obtained. Moreover, the calculated lifetimes of interlayer photogenerated electrons and holes show that type II g-C 3 N 4 /MoS 2 tends to favor a general type II pathway rather than a Zscheme pathway. This study could provide a deep understanding of the photocatalytic mechanism of g-C 3 N 4 /MoS 2 van der Waals heterostructures, which will be of great use for applications in photocatalysis.

Coupling Z-Scheme g-C3N4/rGO/MoS2 Ternary Heterojunction as an Efficient Visible Light Photocatalyst for Hydrogen Evolution and RhB Degradation

“…Molybdenum sulfide (MoS 2 ) is a novel layered narrow band gap n-type semiconductor, which has also been widely studied in photocatalysis due to its abundant active edges, high light response activity, and earth-abundance. − MoS 2 has also been employed as a cocatalyst to modify the primary catalyst. Based on energy band alignment theory, MoS 2 has a staggered band level with g-C 3 N 4 , , therefore, constructing binary heterostructures between g-C 3 N 4 and MoS 2 as type-II heterojunctions is an effective strategy to improve their quantum efficiency for photocatalytic reactions. , Moreover, interfacing two semiconductors as a heterojunction with a built-in electric field could effectively promote the separation of photogenerated electron–hole pairs and inhibit their recombination . However, the direct contact of the g-C 3 N 4 /MoS 2 heterojunction for the photocatalytic hydrogen evolution reaction is limited .…”

“…12−14 MoS 2 has also been employed as a cocatalyst to modify the primary catalyst. Based on energy band alignment theory, MoS 2 has a staggered band level with g-C 3 N 4 , 15,16 therefore, constructing binary heterostructures between g-C 3 N 4 and MoS 2 as type-II heterojunctions is an effective strategy to improve their quantum efficiency for photocatalytic reactions. 17,18 Moreover, interfacing two semiconductors as a heterojunction with a built-in electric field could effectively promote the separation of photogenerated electron−hole pairs and inhibit their recombination.…”

Visible-Light Photocatalytic Overall Water Splitting on a B4C3/CxNy Z-Scheme Heterojunction: Role of Ultrafast Carrier Recombination-Transfer Kinetics

“…The time scales are similar to the carrier migration observed in type-II heterojunctions. For instance, the interlaminar electron and hole transfer times in the C 3 N 4 /MoS 2 type-II heterojunction are 271 and 21 fs, respectively, and the MoSSe/WS 2 heterostructure ranges from 286 fs to 1.03 ps . Substantially, the Z-scheme heterojunction’s main criterion is the efficiency of electron–hole recombination, specifically their migration time.…”