High-performance photocatalysts for overall water splitting: type-II WSi2N4/MoSi2N4 heterostructures.

We have conducted first-principles calculations to reveal type-II vdW heterostructures WSi2N4/MoSi2N4 with high catalytic performance, focusing on the excellent optoelectronic properties of the MA2Z4 family of 2D materials. Initially, we investigated the performance of photocatalytic water splitting of MA2Z4 family monolayers, which exhibit higher carrier mobility than traditional two-dimensional materials. Moreover, we built vdW heterostructures based on the MA2Z4 family to promote carrier spatial separation and suppress electron–hole interlayer recombination. The results show that the WSi2N4/MoSi2N4 heterostructure has negative binding energy (−33.47 meV Å−2) and forms a built-in electric field with an average charge transfer of 0.03e. Interestingly, we found that strain tuning can enhance the solar-to-hydrogen efficiencies to 18.01% at 3% biaxial strain, and the heterostructure exhibits a high light absorption coefficient with a band gap of 2.007 eV. In conclusion, the WSi2N4/MoSi2N4 heterostructure with high performance in photocatalytic hydrogen production represents a new impetus for achieving carbon neutrality. [ABSTRACT FROM AUTHOR]