First Principles Study On Photocatalytic Properties Of Two-dimensional GeC/Janus Heterojunction

Two-dimensional(2D)Z-type heterostructures with superior performance,is an important material for photocatalytic decomposition of water to produce hydrogen,which made its one of the research hotspots for photocatalytic material.The asymmetric structure of Janus materials,that greatly improves its electronic and optical properties.In this paper,based on the firstprinciple calculations of hybrid density functional theory,the g-GeC/MoSTe and g-GeC/PtSSe of the two new Z-type heterostructures were constructed.The stability,electronic properties,optical absorption properties,and photocatalytic mechanism of the two heterostructures were studied,and the electronic properties under stress were discussed.The conclusions as shown following:1.The bandgap of two-dimensional GeC is 2.74 eV,and it has strong absorption in the ultraviolet band,while the absorption coefficient in the visible band is very small.The bandgaps of single-layer MoSTe and PtSSe are 1.77 eV and 2.15 eV,the single-layer Janus material can perform photocatalytic water decomposition reactions in strong acid solutions.2.Six different stacking types of g-GeC/MoSTe heterostructures were built,and the lowest binding energy stacking mode was selected to study the photocatalytic reaction mechanism.The results show that the heterostructure is dynamic stable,the band structure is staggered,and the bandgap is 0.47 eV.The built-in electric field from g-GeC to MoSTe.The light absorption coefficient(490 nm,the highest light absorption coefficient)of the g-GeC/MoSTe heterostructures in the visible light region was increased by 1.19 times compared to single-layer MoSTe.When pH ranges from 0 to 7,the reduction reaction occurs in the GeC layer,and the oxidation reaction occurs in the MoSTe layer.3.Three different stacking types of g-GeC/PtSSe heterostructures were built,and the lowest binding energy stacking mode was selected to calculate the photocatalytic reaction mechanism.The heterostructure is dynamic stable,the band arrangement is staggered,and the bandgap is 0.70 eV.The built-in electric field from g-GeC to PtSSe.The light absorption coefficient(515 nm,the highest light absorption coefficient)of the g-GeC/PtSSe heterostructures in the visible light region was increased by 1.64 times compared to single-layer PtSSe.When pH ranges from 0 to 7,the reduction reaction occurs in the GeC layer,and the oxidation reaction occurs in the PtSSe layer.4.In the g-GeC/MoSTe and g-GeC/PtSSe heterostructures under different stresses,the band structure is arranged in a staggered manner.The bandgap of the heterostructure can be changed by applying stress.Under tensile strain,the bandgap of g-GeC/MoSTe heterostructure can be changed from the indirect into a direct bandgap,but the g-GeC/PtSSe heterostructure is still an indirect bandgap under tensile strain.The bandgaps of g-GeC/MoSTe heterostructure will reduce under the strain.For the g-GeC/PtSSe heterostructure,the compression strain can increase its bandgap,and the tensile strain can reduce its bandgap.The redox reactions of g-GeC/MoSTe and g-GeC/PtSSe heterostructures,occur on singlelayers with strong redox ability.They are direct Z-type photocatalytic materials,and their light absorption ability is significantly enhanced compared to single-layers,demonstrating excellent photocatalytic properties.They are potential high-efficiency photocatalytic materials for water decomposition.