Boosting Photocatalytic Activity Using Carbon Nitride Based 2D/2D van der Waals Heterojunctions

Abstract

The surging demand for energy and staggering pollutants in the environment have geared the scientific community to explore sustainable pathways that are economically feasible and environmentally compelling. In this context, harnessing solar energy using semiconductor materials to generate charge pairs to drive photoredox reactions has been envisioned as a futuristic approach. Numerous inorganic crystals with promising nanoregime properties investigated in the past decade have yet to demonstrate practical application due to limited photon absorption and sluggish charge separation kinetics. Two-dimensional semiconductors with tunable optical and electronic properties and quasi-resistance-free lateral charge transfer mechanisms have shown great promise in photocatalysis. Polymeric graphitic carbon nitride (g-C3N4) is among the most promising candidates due to fine-tuned band edges and the feasibility of optimizing the optical properties via materials genomics. Constructing a two-dimensional (2D)/2D van der Waals (vdW) heterojunction by allies of 2D carbon nitride sheets and other 2D semiconductors has demonstrated enhanced charge separation with improved visible photon absorption, and the performance is not restricted by the lattice matching of constituting materials. With the advent of new 2D semiconductors over the recent past, the 2D/2D heterojunction assemblies are gaining momentum to design high performance photocatalysts for numerous applications. This review aims to highlight recent advancements and key understanding in carbon nitride based 2D/2D heterojunctions and their applications in photocatalysis, including small molecules activation, conversion, and degradations. We conclude with a forward-looking perspective discussing the key challenges and opportunity areas for future research.

2D–2D WO3–Bi2WO6 photocatalyst with an S-scheme heterojunction for highly efficient Cr(vi) reduction

“…[5][6][7][8][9] Among two-dimensional (2D)based heterostructures, 2D-2D structures have been found to be the most effective owing to their superior coupling interface, which consequently accelerates the charge migration at the interface. [10][11][12][13][14] Moreover, the development of a 2D-2D structure improves the exposure of reactive sites and switches the optical absorption towards the visible region, which consequently accelerates the photocatalytic performance. 10,15 Another advantage of 2D-2D heterojunction systems is their flexibility and ability to balance the potential of the band edges for photocatalytic reactions in order to meet the required oxidation and reduction potentials of the photocatalyst.…”

Metalated covalent organic frameworks: from synthetic strategies to diverse applications

“…Based on the same principle, in the MOF/COF heterostructure of Cu 3 (HHTP) 2 and TpPa-1, the Cu 3 (HHTP) 2 MOF provides low interfacial charge transfer resistance as an electron acceptor, thus enhancing the HER rate nearly 100-fold compared to TpPa-1 alone. 586 Theoretically, COF-based heterojunction photocatalysts are rich in possibilities, 573,587–589 and the compositions, bonding forms, and energy band positions are highly controllable, 590 which provides more chances to design low-cost, highly active HER photocatalysts in the future.…”

Recent advances in solution assisted synthesis of transition metal chalcogenides for photo-electrocatalytic hydrogen evolution

“…The design of multinary nanocrystals was aimed at improving the catalytic activity and stability of binary transition metal chalcogenides. [138][139][140][141][142] A multinary transition metal compound is composed of at least two different metals. The formation of multinary transition metal chalcogenide introduces some unique properties different from those of binary compounds while retaining inherent properties.…”