Two-dimensional ABC3 (A = Sc, Y; B = Al, Ga, In; C = S, Se, Te) with intrinsic electric field for photocatalytic water splitting

Abstract

Hydrogen production from water photolysis is considered to be one of the main approaches to obtain clean energy in the future. Two-dimensional (2D) materials with intrinsic vertical electric field can break the band gap limitation (>1.23 eV) of photocatalysts in traditional theory, and broaden the spectrum that can be used for photocatalytic water splitting, such as infrared light. Inspired by the ferroelectric phase α-B2C3 (B = Al, Ga, In; C = S, Se, Te), we replaced one of the B atoms with IIIB elements (namely Sc and Y) of the same valency, and successfully predicted 18 kinds of ABC3 (A = Sc, Y; B = Al, Ga, In; C = S, Se, Te) monolayers with high stability. Encouragingly, 15 predicted ABC3 monolayers possess direct band gap features in contrast to that of α-B2C3, which all exhibit indirect band gap feature. Due to the large intrinsic vertical electric field, the ABC3 monolayers hold great potential for efficient photocatalytic water splitting in acidic and alkaline as well as neutral environments. The rectified solar-to-hydrogen (STH) efficiencies of 14 ABC3 MLs were larger than 20%. Excitingly, the STH efficiency limits of YGaTe3 and YInTe3 even reach 35.97% and 36.94% using the full solar spectrum, which breaks the conventional theoretical efficiency limit. In addition, considerable light absorption and large carrier mobility are confirmed in ABC3 MLs. These interesting findings render ABC3 monolayers a strong candidate for future photovoltaic and nanoelectronic applications.