Search for simple β-AIMIIIO2-type intrinsic ferroelectric semiconductors with simultaneous robust built-in electric field and full-spectrum absorption for superior photocatalysts

Abstract

As an intrinsic ferroelectric semiconductor (IFS), β-A^IM^IIIO₂ types, as exemplified by β-CuGaO₂, have lately gained increasing attention for photocatalysis due to their intrinsic spontaneous polarization and narrow band-gap. These specific properties are anticipated to effectively address the existing critical issues of the poor light-absorption capacity and low carrier-separation efficiency of the current photocatalysts. Here, we adopted the strategy of unit co-substitution, commencing with the wurtzite-type ZnO, and co-substituted [Zn²⁺–Zn²⁺] with [A⁺–M³⁺] units, with A⁺ being Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, Cu⁺, Ag⁺, Au⁺, Pd⁺, Hg⁺, and Tl⁺, and M³⁺ being B³⁺, Al³⁺, Ga³⁺, and In³⁺ to form the component database of β-AMO₂ series oxides. Through ferroelectric photocatalytic functional material-oriented screening, four leading materials, β-CuGaO₂, β-AgGaO₂, β-CuInO₂, and β-AuInO₂, were identified as potential photocatalytic candidates for high-performance IFSs with phase stability, strong polarization, a narrow band-gap, and low effective mass based on first-principles calculations. Furthermore, these four candidate IFSs possessed the property of full-spectrum absorption, of which the spectroscopic limited maximum efficiency (SLME) achieved was 32.28%, 28.04%, 32.57%, and 31.95% based on the optical absorption spectrum calculation and SLME model. These characteristics not only secure their superior properties as photocatalysts but also provide an appropriate substitute for future quantitative research into the interactions between multiple external fields and photocatalytic properties.