The oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) are three critical reactions for energy-related applications, such as water electrolyzers and metal–air batteries. Graphene-supported single-atom catalysts (SACs) have been widely explored; however, either experiments or density functional theory (DFT) computations cannot screen catalysts at high speed. Herein, based on DFT computations of 104 graphene-supported SACs (M@C₃, M@C₄, M@pyridine-N₄, and M@pyrrole-N₄), we built machine learning (ML) models to describe the underlying pattern of easily obtainable physical properties and limiting potentials (mean square errors = 0.027/0.021/0.035 V for the ORR/OER/HER, respectively) and employed these models to predict the catalytic performance of 260 other graphene-supported SACs containing metal-N_xC_y active sites (M@N_xC_y). We recomputed the top catalysts recommended by ML towards the ORR/OER/HER by DFT, which confirmed the reliability of our ML model, and identified two OER catalysts (Ir@pyridine-N₃C₁ and Ir@pyridine-N₂C₂) outperforming noble metal oxides, RuO₂ and IrO₂. The ML models quantitatively unveiled the significance of various descriptors and quickly narrowed down the candidate list of graphene-supported single-atom catalysts. This approach can be easily used to screen and design other SACs and significantly accelerate the catalyst design for many other important reactions.

By means of density functional theory computations, we explored the electrochemical performance of an FeSe monolayer as an anode material for lithium and non-lithium ion batteries (LIBs and NLIBs). The electronic structure, adsorption, diffusion, and storage behavior of different metal atoms (M) in FeSe were systematically investigated. Our computations revealed that M adsorbed FeSe (M = Li, Na and K) systems show metallic characteristics that give rise to good electrical conductivity and mobility with low activation energies for diffusion (0.16, 0.13 and 0.11 eV for Li, Na, and K, respectively) of electrons and metal atoms in the materials, indicative of a fast charge/discharge rate. In addition, the theoretical capacities of the FeSe monolayer for Li, Na and K can reach up to 658, 473, and 315 mA h g⁻¹, respectively, higher than that of commercial graphite (372 mA h g⁻¹ for Li, 284 mA h g⁻¹ for Na, and 273 mA h g⁻¹ for K), and the average open-circuit voltage is moderate (0.38–0.88 V for Li, Na and K). All these characteristics suggest that the FeSe monolayer is a potential anode material for alkali-metal rechargeable batteries.

We propose that porous 2D materials with entirely planar structure and proper pore sizes are highly promising ultrahigh capacity anode materials for LIBs and SIBs, following which the B₇P₂ monolayer is identified with an ultrahigh capacity of 3117 mA h g⁻¹.