CdIn_2.2S_y Nanosheet-Based Photoanodes for Photoelectrochemical Water Splitting

Abstract

Photoelectrochemical water splitting is a greener approach to produce hydrogen (H 2 ) as an efficient chemical fuel for the future with high energy density. However, it is extremely challenging to develop suitable semiconductor materials with desired efficiency and stability, which can be applied for practical applications. Looking at the theoretical efficiency and the solar spectrum, it is clear that visible-light-active semiconductors are the most appealing candidates. Herein, CdIn 2.2 Sy (CIS), a visible light-active semiconductor, is explored as a photoanode for PEC water splitting. The thin nanosheets of CIS are grown vertically through a hydrothermal method. These can efficiently absorb visible light through multiple reflections and scattering of light inside the material and enhance the light−matter interaction. As a result, the developed CIS thin nanosheets produce a maximum photocurrent density of 3.97 mA/cm 2 at "1.6" V versus RHE under continuous back illumination. On the other hand, CIS attains a maximum photoconversion efficiency of ∼1.72% at "0.60" V versus RHE. Furthermore, to improve the efficiency and stability, "S" and "N" codoped C-dots (S, N-CDs) are adorned on the CIS photoanode. The "S" and "N" codoped C-dots and CIS form the type-II heterostructure, which efficiently boosts the charge separation and transportation of photogenerated electrons and holes. The transient decay time becomes longer in the case of heterostructure compared to bare CIS. The heterostructure generates 11.2 mA/ cm 2 photocurrent densities at an applied potential of "1.6" V versus RHE. At the same time, the heterostructure CIS/S, N-CDs-B achieves a ∼2.08-fold higher photoconversion efficiency compared to bare CIS nanosheets and is stable up to 1500 s under continuous back illumination. The present work offers an approach for designing an efficient and stable photoanode for PEC water splitting.

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

“…SNCDs sensitization on the surface of CIS has resulted in an increase of the absorbance of a CIS nanostructure. This increase in absorbance results in enhancement of the photocurrent density, as observed in IPCE, which shows a 2.48 times increase after sensitization of CIS in a wavelength range of 450–500 nm, as shown in Figure f …”

“…(e) Mott Schotty plots and (f) IPCE of CIS and CIS/SNCDs-B. Reprinted with permission from ref . Copyright 2022 American Chemical Society.…”

Ultrasound‐Triggered Surface Reconstruction with Improved Carriers Transfer Kinetics in CdIn2S4 for Solar Water Oxidation

“…The Raman spectra for CIS and CISZ (Figure S1, Supporting Information) show sharp peaks at 241.40, 304.70, and 329.89 cm −1 , representing the typical Raman active F 2g , F 1u , and A 1g modes of CdIn 2 S 4 . [ 28 ] The X‐ray diffraction (XRD) patterns for CIS and CISZ (Figure S2, Supporting Information) are identical and reveal peaks at 14.3°, 23.3°, and 33.2°, which correspond to the (111), (220), and (400) planes of cubic spinel CdIn 2 S 4 (JCPDS: 27–0060), respectively. These results imply that ultrasonication changed neither the morphology nor the phase of the CIS, which eliminated the possibility for generating ZnIn 2 S 4 on the CIS surface.…”

Imperfect makes perfect: defect engineering of photoelectrodes towards efficient photoelectrochemical water splitting

“…21 Under ideal conditions, a photoelectrode material with a bandgap of around 2.0 eV can achieve a maximum photocurrent density of 14.5 mA cm −2 and a theoretical STH efficiency of 17.9% for PEC water splitting under AM 1.5 G illumination. 22 Nevertheless, no photoelectrode materials so far can achieve this performance. To improve the PEC performance of photoelectrode materials, various approaches, such as nanostructure construction, 23 heterojunction construction, 23 hybridization with electrocatalysts 24 and defect engineering, 21 have been developed.…”