Highly effective electrocatalysts promoting CO₂ reduction reaction (CO₂RR) is extremely desirable to produce value-added chemicals/fuels while addressing current environmental challenges. Herein, we develop a layer-stacked, bimetallic two-dimensional conjugated metal-organic framework (2D c-MOF) with copper-phthalocyanine as ligand (CuN₄) and zinc-bis(dihydroxy) complex (ZnO₄) as linkage (PcCu-O₈-Zn). The PcCu-O₈-Zn exhibits high CO selectivity of 88%, turnover frequency of 0.39 s⁻¹ and long-term durability (>10 h), surpassing thus by far reported MOF-based electrocatalysts. The molar H₂/CO ratio (1:7 to 4:1) can be tuned by varying metal centers and applied potential, making 2D c-MOFs highly relevant for syngas industry applications. The contrast experiments combined with operando spectroelectrochemistry and theoretical calculation unveil a synergistic catalytic mechanism; ZnO₄ complexes act as CO₂RR catalytic sites while CuN₄ centers promote the protonation of adsorbed CO₂ during CO₂RR. This work offers a strategy on developing bimetallic MOF electrocatalysts for synergistically catalyzing CO₂RR toward syngas synthesis.

Quantum conductance calculations on the mechanically deformed monolayers of MoS${}_2$ and WS${}_2$ were performed using the nonequlibrium Green's functions method combined with the Landauer-Büttiker approach for ballistic transport together with the density-functional-based tight binding method. Tensile strain causes significant changes in the electronic structure of transition-metal dichalcogenide single layers and eventually the semiconductor-metal transition occurs for elongations as large as 11$\%$ for the 2D-isotropic deformations in the hexagonal structure. This transition enhances the electron transport in otherwise semiconducting materials.

Using a set of first-principles calculations, we studied the electronic structures of two-dimensional transition metal carbides and nitrides, so called MXenes, functionalized with F, O, and OH. Our projected band structures and electron localization function analyses reveal the existence of nearly free electron (NFE) states in a variety of MXenes. The NFE states are spatially located just outside the atomic structure of MXenes and are extended parallel to the surfaces. Moreover, we found that the OH-terminated MXenes offer the NFE states energetically close to the Fermi level. In particular, the NFE states in some of the OH-terminated MXenes, such as $\mathrm{T}{\mathrm{i}}_2\mathrm{C}{\left(\mathrm{OH}\right)}_2,\mathrm{Z}{\mathrm{r}}_2\mathrm{C}{\left(\mathrm{OH}\right)}_2,\mathrm{Z}{\mathrm{r}}_2\mathrm{N}{\left(\mathrm{OH}\right)}_2,\mathrm{H}{\mathrm{f}}_2\mathrm{C}{\left(\mathrm{OH}\right)}_2,\mathrm{H}{\mathrm{f}}_2\mathrm{N}{\left(\mathrm{OH}\right)}_2,\mathrm{N}{\mathrm{b}}_2\mathrm{C}{\left(\mathrm{OH}\right)}_2$, and $\mathrm{T}{\mathrm{a}}_2\mathrm{C}{\left(\mathrm{OH}\right)}_2$, are partially occupied. This is in remarkable contrast to graphene, graphane, and $\mathrm{Mo}{\mathrm{S}}_2$, in which their NFE states are located far above the Fermi level and thus they are unoccupied. As a prototype of such systems, we investigated the electron transport properties of $\mathrm{H}{\mathrm{f}}_2\mathrm{C}{\left(\mathrm{OH}\right)}_2$ and found that the NFE states in $\mathrm{H}{\mathrm{f}}_2\mathrm{C}{\left(\mathrm{OH}\right)}_2$ provide almost perfect transmission channels without nuclear scattering for electron transport. Our results indicate that these systems might find applications in nanoelectronic devices. Our findings provide new insights into the unique electronic band structures of MXenes.