Superconductivity has attracted much interest in two-dimensional (2D) compounds because of their application in constructing nano-superconducting devices. Based on the crystal structure prediction method and first-principles calculations, we obtain two new 2D molybdenum boride structures of tetr- and tri-Mo₂B₂. Then, we calculate their electronic structures, phonon spectra, electron–phonon coupling (EPC), and superconducting properties. The results show that both tetr- and tri-Mo₂B₂ are intrinsic phonon-mediated superconductors with superconducting transition temperatures (T_c) of 3.9 and 0.2 K, respectively. We demonstrate that the EPC is mainly from the low-frequency phonon vibrations of Mo atoms. Our findings will enrich 2D superconducting materials and stimulate more efforts in this field.

Two dimensional superconductors are demonstrated in our predicted rect-, hex-GaB ₆ , rect- and hex-InB ₆ systems, with superconducting transition temperatures of 1.67, 14.02, 7.77 and 4.83 K, respectively.

High-throughput production of highly efficient photocatalysts for hydrogen evolution remains a considerable challenge for materials scientists. Here, we produced extremely uniform high-quality graphene and molybdenum disulfide (MoS₂) nanoplatelets through the electrochemical-assisted liquid-phase exfoliation, out of which we subsequently fabricated MoS₂/graphene van der Waals heterostructures. Ultimately, zinc oxide (ZnO) nanoparticles were deposited into these two-dimensional heterostructures to produce an artificial ZnO/MoS₂/graphene nanocomposite. This new composite experimentally exhibited an excellent photocatalytic efficiency in hydrogen evolution under the sunlight illumination ( $\lambda >400 nm$ ), owing to the extremely high electron mobilities in graphene nanoplatelets and the significant visible-light absorptions of MoS₂. Moreover, due to the synergistic effects in MoS₂ and graphene, the lifetime of excited carriers increased dramatically, which considerably improved the photocatalytic efficiency of the ZnO/MoS₂/graphene heterostructure. We conclude that the novel artificial heterostructure presented here shows great potential for the high-efficient photocatalytic hydrogen generation and the high throughput production of visible-light photocatalysts for industrial applications.

We demonstrate that the recent experimentally synthesized Cu ₂ Si monolayer is a BCS-type two-dimensional superconductor with T _c being ∼ 4.1 K.

Two-dimensional (2D) superconductors, which can be widely applied in optoelectronic and microelectronic devices, have gained renewed attention in recent years. Based on the crystal structure prediction method and first-principles calculations, we obtain four novel 2D tungsten boride structures of tetr-, hex-, and tri-W₂B₂ and hex-WB₄ and investigate their bonding types, electronic properties, phonon dispersions and electron–phonon coupling (EPC). The results show that both tetr- and hex-W₂B₂ are intrinsic phonon-mediated superconductors with a superconducting transition temperature (T_c) of 7.8 and 1.5 K, respectively, while tri-W₂B₂ and hex-WB₄ are normal metals. We demonstrate that carrier doping as well as biaxial strain can soften the low-frequency phonon modes and enhance the strength of the EPC. While the T_c of tetr-W₂B₂ can be increased to 15.4 K under a compressive strain of −2%, the T_c of hex-W₂B₂ can be enhanced to 5.9 K by a tensile strain of +4%. With the inclusion of spin–orbit couping (SOC), the value of T_c decreases by 38.5% in our systems. Furthermore, we explore the stabilities and mechanical properties of tetr- and hex-W₂B₂ and indicate that they may be prepared by growing on ZnS(100) and ZnS(111), respectively. Our findings provide novel 2D superconducting materials and will stimulate more efforts in this filed.

Compensated co-doping not only achieves charge neutrality but is also highly favorable for the formation of polar phases and the absence of structural defects.