Ti2CO2/ZrSi2N4: A promising van der Waals heterostructure for advanced thermoelectrics and efficient hydrogen evolution reaction

With the expeditious increase in global energy demand and consequent consumption of natural resources, there is an urgent need for alternative, efficient, and economically viable energy harvesting technologies. For this purpose, we have explored the Ti 2 CO 2 /ZrSi 2 N 4 van der Waals heterostructure (vdWH) exhibiting a minimal lattice mismatch of approximately ∼0.1%, suggesting excellent interfacial compatibility between the constituent layers. The omission of imaginary phonon frequencies all over the Brillouin zone confirms the dynamical resilience of the Ti 2 CO 2 /ZrSi 2 N 4 vdWH. The considered vdWH possesses an indirect band gap of 0.91 eV by the Heyd−Scuseria−Ernzerhof functional level with spin-orbit coupling (SOC) effect. Moreover, the vdWH exhibits an optical absorption coefficient of 3 × 10 5 cm -1 within the visible spectrum, alongside significant optical absorption extending to the ultraviolet (UV) range. The calculated limited maximum efficiency (SLME) of heterostructure is approximately 31.6% which is higher than any other thin-layer absorbing materials, including CsGeI 3 (∼30.5%), CsPbI 3 (27.6%), Ca 2 Si (∼31.2%), and CuInS 2 (29%). demonstrates its suitability as a next-generation photovoltaic absorber. The calculated figure of merit ZT of 0.7 at an n-type carrier concentration of 4.1 × 10 20 cm -3 at 500 K primarily results from the enhanced thermal power factor S 2 σ/τ, where τ, σ, and S represent the carrier relaxation time, electrical conductivity, and Seebeck coefficient, respectively. Our results highlight the excellent potential of the Ti 2 CO 2 /ZrSi 2 N 4 heterostructure as a strong candidate for future catalysis, photovoltaic, and thermoelectric applications. • The stability of vdWHS Ti 2 CO 2 /ZrSi 2 N 4 is confirmed through binding energy, lattice mismatch energy, phonon dispersion analysis, and aiMD simulations. • ⁠All the stacking order has identical band characteristics, with 0.91 eV indirect bandgap and type-1 band alignment. • The high absorptivity and 31.6% SLME makes this heterostructure promising for next generation photovoltaic material. • The VBM is located below the standard oxygen evolution potential (-5.73 eV), indicating that the heterostructure is suitable for driving the photocatalytic oxygen evolution reaction (OER). • A ZT of 0.7 at 500 K, attributed to the enhanced thermoelectric power factor which highlights the material’s strong potential for high-efficiency thermoelectric application.