Effects of Vacancy and Ti Doping in 2D Janus MoSSe on Photocatalysis

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.

First-Principles Calculations of 2D Janus WSSiN2Monolayer for Photocatalytic Water Splitting

“…However, the visible light utilization efficiency of the Janus WSSiN 2 monolayer is still far from satisfactory. Recently, it has been confirmed that some additional strategies, such as doping, heterojunction coupling, and strain engineering, could be employed to improve optical absorption and enhance the energy conversion efficiency of 2D materials. , For example, Kou et al found that the optical absorption of Janus WSSe monolayer can be effectively broadened under the small tensile strains of 1%. Thus, it is expected to boost the optical properties using similar methods in future work.…”

Tuning of the electronic and photocatalytic properties of Janus WSiGeZ4 (Z = N, P, and As) monolayers via strain engineering

“…59 Furthermore, excellent photocatalysts for water splitting to produce hydrogen have been widely studied. [60][61][62][63] Until now, many 2D materials have been theoretically predicted and experimentally identified to be the promising optical and photocatalytic materials. Excellent photocatalysts for water splitting should satisfy several important features.…”

Tuning of the electronic, photocatalytic and optical properties of Janus XWAZ2 (X = S, Se, Te; A = Si, Ge; Z = N, P, As) monolayers via strain and external electric field

“…Consequently, the photocatalytic decomposition of water using sunlight to produce hydrogen has garnered significant attention. 20,[62][63][64] To achieve efficient photocatalytic water decomposition, several crucial characteristics must be met. Catalysis Science & Technology Paper and these can participate in hydrogen and oxygen generation through the following reactions: 2H + + 2e − → H 2 and 2H 2 O + 4h + → 4H + + O 2 .…”