2D/2D Janus BiTeCl/GeSe vdW heterostructure as a robust high-performance S-scheme photocatalyst for water splitting

•The 2D/2D Janus BiTeCl/GeSe vdW heterostructure (HS) exhibits a direct Z-scheme photocatalytic mechanism.•The HS shows great photocatalytic performance for overall water splitting and is robust enough to be nearly independent of either biaxial or uniaxial strain.•The HS can achieve spontaneous water splitting with the solar-to-hydrogen efficiency up to 19.27 %.