Seeking candidate photocatalysts for photocatalytic water splitting, via visible light, is of great interest and importance. In this study, we have comprehensively explored the crystal structures, electronic properties, and optical absorbance of two-dimensional (2D) Sc₂CT₂ (T = F, Cl, Br) MXenes and their corresponding photocatalytic water splitting, under the visible-light region, by first-principles calculations. Herein, we have proposed that 2D Sc₂CT₂ MXenes can be fabricated from their layered bulk compounds, alternatively to the traditional chemical etching method. Creatively, we proposed Sc₂CT₂ (T = F, Br) as new materials; the band edge alignments of Sc₂CF₂ can be tuned to meet the water redox potentials at pH = 8.0. It is highlighted that Sc₂CF₂ shows outstanding optical spectra harvested under visible-light wavelength regions, and efficient separation of photo-induced electrons and holes in different zones. These present results provide eloquent evidence and open a new door on the photocatalysis applications of such novel semiconducting MXenes.

Designing the electronic structures of the van der Waals (vdW) heterostructures to obtain high-efficiency solar cells showed a fascinating prospect. In this work, we screened the potential of vdW heterostructures for solar cell application by combining the group III–VI MX_A (M = Al, Ga, In and X_A = S, Se, Te) and elementary group VI X_B (X_B = Se, Te) monolayers based on first-principle calculations. The results highlight that InSe/Te vdW heterostructure presents type-II electronic band structure feature with a band gap of 0.88 eV, where tellurene and InSe monolayer are as absorber and window layer, respectively. Interestingly, tellurene has a 1.14 eV direct band gap to produce the photoexcited electron easily. Furthermore, InSe/Te vdW heterostructure shows remarkably light absorption capacities and distinguished maximum power conversion efficiency (PCE) up to 13.39%. Our present study will inspire researchers to design vdW heterostructures for solar cell application in a purposeful way.

Two-dimensional van der Waals (vdW) heterostructures are potential candidates for clean energy conversion materials to address the global energy crisis and environmental issues. In this work, we have comprehensively studied the geometrical, electronic, and optical properties of M₂CO₂/MoX₂ (M = Hf, Zr; X = S, Se, Te) vdW heterostructures, as well as their applications in the fields of photocatalytic and photovoltaic using density functional theory calculations. The lattice dynamic and thermal stabilities of designed M₂CO₂/MoX₂ heterostructures are confirmed. Interestingly, all the M₂CO₂/MoX₂ heterostructures exhibit intrinsic type-II band structure features, which effectively inhibit the electron-hole pair recombination and enhance the photocatalytic performance. Furthermore, the internal built-in electric field and high anisotropic carrier mobility can separate the photo-generated carriers efficiently. It is noted that M₂CO₂/MoX₂ heterostructures exhibit suitable band gaps in comparison to the M₂CO₂ and MoX₂ monolayers, which enhance the optical-harvesting abilities in the visible and ultraviolet light zones. Zr₂CO₂/MoSe₂ and Hf₂CO₂/MoSe₂ heterostructures possess suitable band edge positions to provide the competent driving force for water splitting as photocatalysts. In addition, Hf₂CO₂/MoS₂ and Zr₂CO₂/MoS₂ heterostructures deliver a power conversion efficiency of 19.75% and 17.13% for solar cell applications, respectively. These results pave the way for exploring efficient MXenes/TMDCs vdW heterostructures as photocatalytic and photovoltaic materials.

Li-rich Mn-based cathode materials (LRM) have received great attention owing to their high capacity and low cost. However, the mismatch between the widely used carbonate electrolyte and the LRM cathode and lithium metal anode causes a series of problems, such as electrolyte continuous oxidation, cathode structure degradation, and Li dendritic growth. Herein, inorganic oxide B2O3 is introduced as a dual-functional high-voltage electrolyte additive to construct stable cathode electrolyte interphase and solid electrolyte interphase for Li||LRM batteries. The modified interface derived from the additive can induce dendrite-free Li deposition, stabilize cathode structure, and inhibit transition metal dissolution. Moreover, the adverse side reactions are mitigated, thus enhancing Li+ transport rate and reducing interface impedance. With the addition of B2O3 into the carbonate electrolyte, the Li||LRM battery exhibits an enhanced discharge capacity of 221 mAh g-1 after 200 cycles, equaling a capacity retention of 92.1%. When the upper cut-off voltage is increased to 5 V, a superior capacity retention of > 85% can still be achieved after 150 cycles at 1 C. In addition, the low cost of B2O3 benefits for commercial application. This work offers new guidance for the research of low-cost, high-voltage dual-functional additives for advanced lithium metal batteries.

Topological insulator Bi ₂ Se ₃ with a unique cloud-like hollow structure was synthesized and employed as a separator modifier for lithium–sulfur batteries, which can significantly accelerate sulfur conversion kinetics and mitigate the shuttle effect.