Computational identification of 2D TlPt₂X₃ (X = S, Se, Te) for thermoelectric and photocatalytic applications

Thermoelectric (TE) device can convert heat into electricity, and suitable photocatalyst can split water to produce hydrogen, which makes them have great potential in the field of clean energy and environmental protection. In this paper, we investigated three 2D materials, TlPt2X3 (X = S, Se, Te), which are indirect semiconductors with band-gaps of 2.11 eV, 1.85 eV, and 1.14 eV, respectively. The three single-layers show moderate mobilities (10(2) - 10(3) cm(2)/Vs), large Seebeck coefficients (0.66 - 1.86 mV/K), and high TE power factor (13.73 - 25.20 mW/K(2)m) at 300 K. Besides, due to the weak bonding and "Rattling" vibrations caused by Tl atoms, the single-layers have strong phonon-phonon scattering, and thus possess low lattice thermal conductivities of 2.34 - 4.46 W/mK. As a result, they can deliver high TE figure-of-merit of 0.53/0.63/0.52 at 300 K, and rise even further to 2.72/3.05/2.38 at 700 K. They also have appropriate REDOX potential, which satisfy the band structure requirement for overall water splitting. Also, the three single-layers also have strong absorption coefficient of similar to 10(5) cm(-1) in vision-ultraviolet region, which can efficiently carry out photocatalytic water splitting to produce H-2. Ultimately, 2D TlPt2X3 are suitable candidates for both TE and photocatalytic applications.