2D Pentagonal Pd‐Based Janus Transition Metal Dichalcogenides for Photocatalytic Water Splitting

Abstract

Janus transition metal dichalcogenides (TMDs), which differ from their conventional counterparts by exhibiting two different layers of chalcogenides and an asymmetric out‐of‐plane structural configuration, are theorized to exhibit a relatively wide variety of properties. Herein, the structural, electronic, and optical properties of three Janus Pd‐based TMD monolayers (PdSSe, PdSTe, and PdSeTe) are investigated through comprehensive density functional theory calculations. The most stable ground‐state configurations of these Janus TMD monolayers correspond to the unique pentagonal configuration instead of the common 1T or 2H phases. The monolayers are semiconductors with moderate bandgaps (2.06–2.21 eV) and anisotropic optical absorption properties. By exhibiting suitable band edge positions with respect to the redox potentials of water, they can simultaneously facilitate the hydrogen and oxygen evolution reactions as water‐splitting photocatalysts. In addition, the effects of uniaxial and biaxial strains on the optoelectronic properties of the monolayers are investigated, and it is determined that the application of strain reduces their bandgaps and causes a redshift of their optical absorption spectra, thereby allowing them to harvest ultraviolet and visible photons more effectively. An insight on the intrinsic properties of 2D Pd‐based Janus TMDs is provided, which elucidates the rational design of photocatalysts for water splitting.

To the Stability of Janus Phases in Layered Trichalcogenide MPX3 Crystals: Insights from Experiments and Theory

“…One of the intrinsic properties of Janus structures is high out-of-plane dipole moment, which might lead to their instability . This can be compensated by employing a polar substrate during the synthesis as it was realized in the case of MoSSe grown on the SiO 2 /Si and polished sapphire substrates. , These experimental studies stimulated enormous computational activity, and many theoretical studies have been published in the last few years speculating about prospects of the freestanding 2D Janus monolayers for applications in orbitronics, optoelectronics, photovoltaic technology, and photocatalysis. , At this, the stability of these hypothetical materials and the possibility of their experimental implementation are rarely discussed …”

Engineering 2D Materials for Photocatalytic Water-Splitting from a Theoretical Perspective

“…In conclusion, the 2D Janus materials have more immense redox potentials than their parent equivalents and can derive sufficient driving force from photo-excited carriers to facilitate overall water-splitting [ 166 , 187 , 188 , 189 , 190 , 191 ]. Due to their adequate band gaps and excellent redox potentials, Janus Ga 2 SeTe, Ga 2 STe, Ga 2 SSe, Pd 4 S 3 Se 3 , Pd 4 S 3 Te 3 , Pd 4 Se 3 Te 3 , and Janus TM oxides monolayers such as TiSO, ZrSO, and HfSO are projected to be attractive photocatalysts [ 192 , 193 , 194 ].…”

Ab initio high-throughput screening of transition metal double chalcogenide monolayers as highly efficient bifunctional catalysts for photochemical and photoelectrochemical water splitting

“…[22][23][24][25][26] Inspired by the discovery of MoSSe, W, Pt, Pd, Sc, and Hf-based MXY monolayers have soon been systematically investigated to probe their capability as photocatalysts for water splitting by calculating the electronic properties. [27][28][29][30][31][32][33][34][35][36] Among them, the PtSTe monolayer shows an overpotential of 0.75 and 0.22 eV for the OER and HER, 32 respectively, where S-and Se-defected PtSO and PtSeO monolayers can readily drive the catalytic reactions under the potentials of photogenerated carriers at pH ¼ 0. 31 Many others also have suitable band edge positions for water splitting.…”