On the basis of first‐principles calculations, the potential of applying 2D honeycomb‐kagome polymers made of heteroatom‐centered triangulene derivatives to photocatalyze water splitting is explored. The designed 2D polymers possess indirect bandgaps in the range of 1.80–2.84 eV and show pronounced light absorption in the ultraviolet and visible region of the solar spectrum. With suitable band edge alignment, the examined N‐ and B‐center polymers can generate sufficient photon‐excited electrons and holes to activate the hydrogen and oxygen evolution reactions, respectively. The combination of lattice‐inherent band features (flat bands) with chemical functionalization (potential shift due to heteroatoms) makes it possible to construct tandem cells with suppressed electron/hole recombination for effective overall water splitting. In addition, there is a potential difference between the half‐electrodes that can be utlized to power​ auxiliary components in self‐sufficient photocatalyzers.

Searching for efficient electrode materials with high power density, fast charge/discharge rate, and high conductivity is one of the key challenges in the development of metal ion batteries. Herein, by means of first-principles computations, we demonstrated that the two-dimensional Nb2S2C monolayer is a promising anode material for metal ion batteries. The Nb2S2C monolayer has rather good kinetic and thermodynamic stability, and it is metallic with considerable electronic states at the Fermi level. The production of the Nb2S2C monolayer from its experimentally known bulk phase via exfoliation strategies should be rather feasible because of the small cleavage energy of 0.38 J/m2. All the studied metal atoms, including Li, Na, K, and Mg, can be effectively adsorbed on the surface of the Nb2S2C monolayer with pronounced charge transfer. Especially, the diffusion of Li, Na, and K atoms on the Nb2S2C monolayer is rather feasible with a diffusion barrier of 0.23, 0.11, and 0.07 eV, respectively, whereas Mg has a relatively high diffusion barrier of 0.47 eV. Remarkably, the efficient accommodation of metal atoms on both sides of the Nb2CS2 monolayer results in a high theoretical capacity of 194.36, 348.20, 157.60, and 690.52 mA h/g and an open circuit voltage of 0.92, 0.31, 0.26, and 0.18 V for Li, Na, K, and Mg storage, respectively. These results suggest that the Nb2S2C monolayer can be utilized as a promising anode material for metal ion batteries with high power density and good rate capacity.

Exploring efficient and inexpensive electrocatalysts for a cathode oxygen reduction reaction (ORR) is essential to the large-scale commercialization of fuel cells. Via first principles calculations, we systematically investigated the electrocatalytic performance of two-dimensional (2D) metal–hexahydroxybenzene frameworks (M3(C6O6)2, where M denotes Cr, Mn, Fe, Co, Ni, Cu, Ru, Rh, and Pd) for ORR. Owing to the sufficient π-electron conjugation and effective interaction between the metal and the organic linkers, the studied 2D M3(C6O6)2 are all metallic with good conductivity for electron transfer. Interestingly, the catalytic activity of M3(C6O6)2 turns out to be dependent on the interaction strength between the ORR intermediates and the metal complex (MO4) and can be modified by changing the metal atoms with different d-electron occupations. Remarkably, while 2D Mn3(C6O6)2, Fe3(C6O6)2, and Rh3(C6O6)2 show a rather good ORR activity rivaling that of Pt, 2D Co3(C6O6)2 presents a much higher onset potential than that of Pt. Our investigations provide important insights into designing and screening efficient ORR catalysts.

On the basis of first-principles calculations, we report the design of three twodimensional (2D) binary honeycomb-kagome polymers composed of B-and N-centered heterotriangulenes with a periodically alternate arrangement as in hexagonal boron nitride. The 2D binary polymers with donor−acceptor characteristics are semiconductors with a direct band gap of 1.98−2.28 eV. The enhanced in-plane electron conjugation contributes to high charge carrier mobilities for both electrons and holes, about 6.70 and 0.24 × 10 3 cm 2 V −1 s −1 , respectively, for the 2D binary polymer with carbonyl bridges (2D CTPAB). With appropriate band edge alignment to match the water redox potentials and pronounced light adsorption for the ultraviolet and visible range of spectra, 2D CTPAB is predicted to be an effective photocatalyst/photoelectrocatalyst to promote overall water splitting.

Schematics for the exfoliation of the SnP2S6 monolayer from its bulk counterpart and its application in solar driven water splitting.