Ni@Mo ₂ B ₂ can be used as a HER/OER bifunctional electrocatalyst while Cu@Mo ₂ B ₂ can be used as an OER/ORR bifunctional electrocatalyst.

As a fast emerging topic, van der Waals (vdW) heterostructures have been proposed to modify two-dimensional layered materials with desired properties, thus greatly extending the applications of these materials. In this work, the stacking characteristics, electronic structures, band edge alignments, charge density distributions and optical properties of blue phosphorene/transition metal dichalcogenides (BlueP/TMDs) vdW heterostructures were systematically studied based on vdW corrected density functional theory. Interestingly, the valence band maximum and conduction band minimum are located in different parts of BlueP/MoSe₂, BlueP/WS₂ and BlueP/WSe₂ heterostructures. The MoSe₂, WS₂ or WSe₂ layer can be used as the electron donor and the BlueP layer can be used as the electron acceptor. We further found that the optical properties under visible-light irradiation of BlueP/TMDs vdW heterostructures are significantly improved. In particular, the predicted upper limit energy conversion efficiencies of BlueP/MoS₂ and BlueP/MoSe₂ heterostructures reach as large as 1.16% and 0.98%, respectively, suggesting their potential applications in efficient thin-film solar cells and optoelectronic devices.

Mo _x C _y monolayers and their potential application as anodes for LIBs/SIBs.

Although carbon-based single-atom catalysts (SACs), especially Fe–N–C, have been demonstrated as highly promising electrocatalysts for the oxygen reduction reaction (ORR) in alkaline media, their application remains a great challenge in acidic proton exchange membrane fuel cells (PEMFCs). Here, by performing high throughput first-principles calculations for 3d, 4d and 5d transition-metal single atoms immobilized on two-dimensional (2D) titanium carbide (Ti2CT and Ti3C2T) surfaces as active sites, we rationally design SACs towards a highly efficient ORR and further propose a composition descriptor to provide atomic-level insights into the structure–activity relationship. Significantly, the parameters involved in the present descriptor can be conveniently obtained from the periodic table of elements. More importantly, we found that the Ti2CO2-supported non-noble Cu SACs exhibit excellent ORR activity with much lower overpotential (0.25 V) than that of Pt/C (0.4 V), high selectivity for 4e oxygen reduction, excellent stability and acid-resistance and are quite promising ORR catalysts for PEMFCs. The present method can be extended to other 2D transition-metal carbides, i.e., MXenes.

Strongly suppressed recombination of electron–hole pairs, unexpectedly high carrier mobility, and anomalous optical response were found in an atomically thin indium selenide (InSe) photocatalyst. In this study, we unraveled the photocatalytic potential of two-dimensional (2D) InSe-family group-III monochalcogenide MX (M = Ga and In and X = S, Se, and Te) monolayers as water splitting hydrogen production photocatalysts on the basis of density functional theory. Our results not only highlight the high electron mobility and small exciton binding energy of 2D InSe, but also demonstrate the energy evolution of the adsorption and decomposition of water molecules as well as the hydrogen production process at the 2D InSe surface. The excellent stability of the MX monolayers was confirmed using lattice dynamical calculations as well as the ab initio molecular dynamics simulations in vacuum and aqueous environments. Moreover, distinguished optical absorption performance of the MX monolayers resulted in effective sunlight energy conversion as high as 1.20%, 6.40%, and 3.22% for the InSe, InTe, and GaTe monolayers, respectively.