Abstract
The design of materials meeting the rigorous requirements of photocatalytic water splitting is still a challenge. Anisotropic Janus 2D materials exhibit great potential due to outstandingly high photocatalytic efficiency. Unfortunately, these materials are scarce. By means of ab initio swarm-intelligence search calculations, we identify a SiP2 monolayer with Janus structure (i.e., out-of-plane asymmetry). The material turns out to be semiconducting with an indirect band gap of 2.39 eV enclosing the redox potentials of water. Notably, the oxygen and hydrogen evolution half reactions can happen simultaneously at the Si and P atoms, respectively, driven merely by the radiation-induced electrons and holes. The carrier mobility is found to be anisotropic and high, up to 10–4 cm2 V–1 s–1, facilitating fast transport of the photogenerated carriers. The SiP2 monolayer shows remarkably strong optical absorption in the visible-to-ultraviolet range of the solar spectrum, ensuring efficient utilization of the solar energy.
Highlights
The design of materials meeting the rigorous requirements of photocatalytic water splitting is still a challenge
Several Janus materials, M2X3 (M = Al, Ga, In; X = S, Se, Te)[6] and B2P6,19 achieve an outstanding photocatalytic efficiency, even in excess of the conventional theoretical limit of 18%. They provide a route to realizing the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) simultaneously at different atomic species.[20]
We explore the electronic properties of the SiP2 monolayer by studying the electron band structure and partial densities of states (PDOS)
Summary
Guochun Yang − State Key Laboratory of Metastable Materials Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao 066004, China; Centre for Advanced Optoelectronic Functional Materials Research and Key Laboratory for UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024, China; orcid.org/0000-0003-3083-472X; Email: yanggc468@ nenu.edu.cn. Tong Yu − State Key Laboratory of Metastable Materials Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao 066004, China; Centre for Advanced Optoelectronic Functional Materials Research and Key Laboratory for UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024, China.
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