Janus MoSSe/WSSe Heterobilayers as Selective Photocatalysts for Water Splitting

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Main Authors: Torkashvand, Mostafa, Tafreshi, Saeedeh Sarabadani, Cocchi, Caterina, Kumar, Surender
Format: Preprint
Published: 2026
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author Torkashvand, Mostafa
Tafreshi, Saeedeh Sarabadani
Cocchi, Caterina
Kumar, Surender
author_facet Torkashvand, Mostafa
Tafreshi, Saeedeh Sarabadani
Cocchi, Caterina
Kumar, Surender
contents Identifying materials that simultaneously straddle the water redox potentials and possess an intrinsic electric field is crucial for achieving high solar-to-hydrogen (STH) efficiency. Using state-of-the-art first-principles calculations, including a range-separated hybrid functional and spin-orbit coupling, we investigate MoXY/WXY (X, Y = S, Se) Janus bilayers for overall water splitting. We find a critical competition between the metal-to-metal chemical potential difference and the intrinsic dipoles at the interface between the Janus monolayers. We find that the Se-Se interfaced heterobilayer is intrinsically capable of driving water splitting, while its S-S counterpart can meet the redox requirements through pH modulation. For both configurations, a remarkable STH efficiency of 17.1% is anticipated. Furthermore, we predict a threshold of 1.0 eV for the built-in potential gradient to govern the transition from overall water splitting to band-edge pinning. Compared to homobilayers, heterobilayers benefit from the reciprocity between layer-specific dipoles and the Mo/W chemical potential difference, which promotes spatial separation and suppresses recombination, overall enhancing hydrogen production. Our results establish specific electronic descriptors for Janus heterostructures, providing a rational design rule for maximizing solar-driven hydrogen production in asymmetric two-dimensional materials.
format Preprint
id arxiv_https___arxiv_org_abs_2601_13898
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Janus MoSSe/WSSe Heterobilayers as Selective Photocatalysts for Water Splitting
Torkashvand, Mostafa
Tafreshi, Saeedeh Sarabadani
Cocchi, Caterina
Kumar, Surender
Materials Science
Identifying materials that simultaneously straddle the water redox potentials and possess an intrinsic electric field is crucial for achieving high solar-to-hydrogen (STH) efficiency. Using state-of-the-art first-principles calculations, including a range-separated hybrid functional and spin-orbit coupling, we investigate MoXY/WXY (X, Y = S, Se) Janus bilayers for overall water splitting. We find a critical competition between the metal-to-metal chemical potential difference and the intrinsic dipoles at the interface between the Janus monolayers. We find that the Se-Se interfaced heterobilayer is intrinsically capable of driving water splitting, while its S-S counterpart can meet the redox requirements through pH modulation. For both configurations, a remarkable STH efficiency of 17.1% is anticipated. Furthermore, we predict a threshold of 1.0 eV for the built-in potential gradient to govern the transition from overall water splitting to band-edge pinning. Compared to homobilayers, heterobilayers benefit from the reciprocity between layer-specific dipoles and the Mo/W chemical potential difference, which promotes spatial separation and suppresses recombination, overall enhancing hydrogen production. Our results establish specific electronic descriptors for Janus heterostructures, providing a rational design rule for maximizing solar-driven hydrogen production in asymmetric two-dimensional materials.
title Janus MoSSe/WSSe Heterobilayers as Selective Photocatalysts for Water Splitting
topic Materials Science
url https://arxiv.org/abs/2601.13898