Nanosheets of In₂S₃/S-C₃N₄-Dots for Solar Water-Splitting in Saline Water

Abstract

Hydrogen generation from splitting of water under the photoelectrochemical (PEC) pathway is considered as the most promising strategy for covering the upcoming fuel crisis by taking care of all environmental issues. In this context, In2S3 can be explored as it is a visible light-active semiconductor with an appropriate band alignment with the water redox potential. Herein, In2S3 nanosheets are developed by the chemical method. The nanosheets of In2S3 absorb high visible light due to the manifold inside scattering and reflection. The PEC activity of In2S3 is enhanced because of the increase in the light absorbance of the materials. In the present work, at 1.18 V versus RHE in 3.5 wt % NaCl, a maximum 2.07 mA/cm2 photocurrent density can be achieved by In2S3 nanosheets. However, In2S3 suffers strongly due to photo-corrosion. To improve the efficacy of the In2S3 nanosheets in saline water, the charge-carrier transportation ability of In2S3 is aimed to increase by decorating S-C3N4-dots on In2S3. The heterostructure of type-II is developed by sensitization of S-C3N4-dots on In2S3. It increases both the transportation of charge carriers as well as separation. In the heterostructure, the transient decay time (τ) increases, which indicates a decrease in photogenerated charge-carrier recombination. S-C3N4-dots also act as an optical antenna and increase the range of visible light absorbance of In2S3. The heterostructure can generate ∼2.38-fold higher photocurrent density of 1.18 V versus RHE in 3.5 wt % NaCl. The photoconversion efficiency of the heterostructure is 0.88% at 0.95 V versus RHE. The nanosheets of In2S3 and In2S3/S-C3N4-dots are stable, and photocurrent density is measured up to 2700 s under continuous back-illumination conditions.

Advances in photo-assisted seawater splitting promoted by green iron oxide-carbon nitride photoelectrocatalysts

“…7f), for pristine Fe 2 O 3 –CoPi a current density loss of ≈26% took place after 15 h of operation, and the presence of carbon nitride, in spite of its low amount, afforded a very favorable stability improvement (for Fe 2 O 3 –M–CoPi and Fe 2 O 3 –CM–CoPi, j losses of ≈14 and ≈4% respectively). The very limited photocurrent density decrease observed for Fe 2 O 3 –CM–CoPi was comparable, or lower, than those reported in analogous seawater splitting tests for various gCN or Fe 2 O 3 -based electrocatalysts (namely, Ru,Ni-doped Fe 2 O 3 , 41 NiFe layered double hydroxides (LDH)/Mo-doped g-C 3 N 4 , 21 and Fe 2 O 3 /NiO on Ni-foams 24 ), as well as for NiO x -FeO x @g-C 3 N 4 , 22 TiO 2 @g-C 3 N 4 –CoPi, 37 WO 3 @g-C 3 N 4 , 63 and In 2 S 3 –C 3 N 4 88 photoelectrocatalysts. A similar result, far from being straightforward especially upon using seawater as electrolyte, emphasizes the applicative potential of the developed nanocomposites in the framework of an improved sustainability.…”

A review on the advancements of graphitic carbon nitride-based photoelectrodes for photoelectrochemical water splitting

“…The intimate In 2 S 3 /g-C 3 N 4 interface promoted charge transfer and inhibited the recombination of electron-hole pairs, significantly improving the PEC performance. 254,255 The highly conductive In 2 S 3 rapidly withdraws electrons from g-C 3 N 4 , transferring them to ITO. Meanwhile, the photogenerated holes in the g-C 3 N 4 nanosheets are transferred to In 2 S 3 NPs and are consumed at the In 2 S 3 /g-C 3 N 4 -electrolyte junction.…”

Surface Modifications of a Vertically Grown Nanostructure for Boosting Photoelectrochemical Water-Splitting Performance

“…The band-bending enhancement is confirmed by the negative flat-band potential of In 2 S 3 /S-C 3 N 4 -dots-20 (−0.03 V vs RHE), and type II heterostructure formation is confirmed by the band edge positions of S-C 3 N 4 and In 2 S 3 , resulting in increased charge-carrier separation and reduced recombination rate compared to bare In 2 S 3 nanosheets (Figure g). Under continuous back-illumination at a potential of 0.7 V vs RHE, a In 2 S 3 /S-C 3 N 4 -dots heterostructure exhibits photostability up to 2700 s in the presence of a corrosive environment due to Cl – ions (Figure c) …”

“…(g) Mott Schotty plots of In 2 S 3 and In 2 S 3 /S-C 3 N 4 -dots-20 heterostructures. Reprinted with permission from ref . Copyright 2022 American Chemical Society…”