Calculated Effects of Vacancy and Ti-doping in 2D Janus MoSSe for Photocatalysis

TL;DR

This study explores how titanium doping and vacancies in 2D Janus MoSSe enhance photocatalytic water splitting by improving light absorption and charge transition, revealing new strategies for efficient 2D photocatalysts.

Contribution

It systematically analyzes the effects of Ti doping and vacancies on the properties of 2D Janus MoSSe, proposing a new approach to improve photocatalytic performance.

Findings

Ti adatoms extend light absorption to infrared.

Vacancies and Ti co-doping modulate electron transitions.

S vacancy with Ti adatoms yields optimal photocatalytic performance.

Abstract

Two-dimensional (2D) Janus transitional metal dichalcogenides (TMDCs) have great potential for photocatalytic water splitting due to their novel properties induced by the unique out-of-plane asymmetric structures. Here, we systematically investigate the geometric, electronic and optical properties of 2D Janus MoSSe with titanium doping and vacancies to explore their synergistic effects on photocatalytic activity. We find that there are effective attractions between the substituted or adsorbed Ti atoms and S/Se vacancies. The Ti adatoms dramatically extend the light absorption range to infrared region. The S/Se vacancies coexisting with Ti adatoms will modulate the transition of photo-excited electrons, thereby enhancing the sunlight absorption. The Ti adatoms either existing alone or coexisting with vacancies introduce smaller lattice distortion compared to substituted Ti atoms and these Ti adatoms induce smaller effective mass of charge carriers. The configuration of S vacancy coexisting with Ti adatoms on Se-surface exhibits the most significant synergistic effects and best overall photocatalytic performance. Our work reveals the mechanism and effects induced by doping and vacancies coexisting in 2D Janus TMDCs, also propose a new practical strategy to improve the performance of 2D photocatalysts.