Self-Enhancing Photoelectrochemical Properties in van der Waals Ferroelectric CuInP₂S₆ by Photoassisted Acid Hydrolysis

Abstract

Transition metal thiophosphate, CuInP2S6 (CIPS), has recently emerged as a potentially promising material for photoelectrochemical (PEC) water splitting due to its intrinsic ferroelectric polarization for spontaneous photocarrier separation. However, the poor kinetics of the hydrogen evolution reaction (HER) greatly limits its practical applications. Herein, we report self-enhancing photocatalytic behavior of a CIPS photocathode due to chemically driven oxygen incorporation by photoassisted acid oxidation. The optimal oxygen-doped CIPS demonstrates a >1 order of magnitude enhancement in the photocurrent density compared to that of pristine CIPS. Through comprehensive spectroscopic and microscopic investigations combined with theoretical calculations, we disclose that oxygen doping will lower the Fermi level position and decrease the HER barrier, which further accelerates charge separation and improves the HER activity. This work may deliver a universal and facile strategy for improving the PEC performance of other van der Waals metal thiophosphates.

A Dynamic Memory for Reservoir Computing Utilizing Ion Migration in CuInP2S6

“…The Raman spectrum of exfoliated CIPS flakes on SiO 2 substrate shows 314.5 cm −1 for the cation, 102.2 cm −1 for the anion, 267.1 cm −1 for d(S–P–S) modes, and 374.7 and 449.4 cm −1 for ν(P–P) and ν(P–S) modes. [ 2c,4,13c,31 ] The exfoliated CIPS single crystal sample quality is characterized by SEM‐EDS (Scanning electron microscopy (SEM) and energy‐dispersive X‐ray spectroscopy (EDS)) mapping as shown in Figure S1 (Supporting Information), which shows that each element is uniform and located on the flake.…”

Harvesting Green Hydrogen by Self‐Propelling Built‐in Electric Field Photo/Electro‐catalytic Performance of DyCrO3Nanoparticles Developed by Reverse Microemulsion Route

“…showed piezoelectricity assisted hydrogen generation by photocatalysis using PbTiO 3 /CdS heterostructures wherein, approximately nine times higher H 2 generation is achieved rather than traditional photocatalysis. Wang et al [36] . showed improved PEC performance using ferroelectric CuInP 2 S 6 and oxygen doping technique which lowers the fermi level, and thus improves the HER kinetics.…”

“…For instance, Huang et al [35] showed piezoelectricity assisted hydrogen generation by photocatalysis using PbTiO 3 /CdS heterostructures wherein, approximately nine times higher H 2 generation is achieved rather than traditional photocatalysis. Wang et al [36] showed improved PEC performance using ferroelectric CuInP 2 S 6 and oxygen doping technique which lowers the fermi level, and thus improves the HER kinetics. Similarly, Kushwaha et al [37] reported the electrocatalyst (Bi 0.5 Na 0.5 TiO 3 ) in which improved OER kinetics and mass activity are reported which is attributed to ferroelectricity.…”

Constructing Dual Cocatalysts of Ni2P–NiS-Decorated TiO2 for Boosting Photocatalytic H2 Evolution

“…41 Further research has revealed the excellent H 2 production activity of transition metal thiophosphates. 42 Xia et al fabricated the S-scheme TiO 2 /FePS 3 heterojunction through the self-assembly of TiO 2 nanoparticles and FePS 3 nanosheets. The H 2 evolution rate on TiO 2 /FePS 3 was increased 16.86 times after the introduction of FePS 3 , much faster than that of TiO 2 alone.…”

“…The maximum H 2 production rate was 36 times higher than that of pure TiO 2 nanosheets . Further research has revealed the excellent H 2 production activity of transition metal thiophosphates . Xia et al fabricated the S-scheme TiO 2 /FePS 3 heterojunction through the self-assembly of TiO 2 nanoparticles and FePS 3 nanosheets.…”