Photocatalytic properties of anisotropic beta-PtX2 (X = S, Se) and Janus beta-PtSSe monolayers

The highly efficient photocatalytic water splitting process to produce clean energy requires novel semiconductor materials to achieve a high solar-to-hydrogen energy conversion efficiency. Herein, the photocatalytic properties of anisotropic beta-PtX2 (X = S, Se) and Janus beta-PtSSe monolayers were investigated based on the density functional theory. The small cleavage energy for beta-PtS2 (0.44 J m(-2)) and beta-PtSe2 (0.40 J m(-2)) endorses the possibility of mechanical exfoliation from their respective layered bulk materials. The calculated results revealed that the beta-PtX2 monolayers have an appropriate bandgap (similar to 1.8-2.6 eV) enclosing the water redox potential, light absorption coefficient (similar to 104 cm(-1)), and exciton binding energy (similar to 0.5-0.7 eV), which facilitates excellent visible-light-driven photocatalytic performance. Remarkably, the inherent structural anisotropy leads to an anisotropic high carrier mobility (up to similar to 5 x 10(3) cm(2) V-1 S-1), leading to a fast transport of photogenerated carriers. Notably, the required small external potential to realize hydrogen evolution reaction and oxygen evolution reaction processes with an excellent solar-to-hydrogen energy conversion efficiency for beta-PtSe2 (similar to 16%) and beta-PtSSe (similar to 18%) makes them promising candidates for solar water splitting applications.