It is highly desirable to design efficient and stable hydrogen evolution reaction (HER) and oxygen evolution/reduction reaction (OER/ORR) electrocatalysts for the development of renewable energy technologies. Herein, density functional theory (DFT) calculations were conducted to systematically investigate a series of TMN_xO_4−x-HTT (TM = Fe, Co, Ni, Ru, Rh, Pd, Ir and Pt; HTT = hexahydroxy tetraazanaphthotetraphene) analogs of two-dimensional (2D) conductive metal-organic frameworks (MOFs) as potential electrocatalysts for the HER, OER and ORR. The thermodynamic and electrochemical stability simulations suggest that these designed catalysts are stable. Remarkably, CoO₄-HTT, RhN₃O₁-HTT and IrN₃O₁-HTT are predicted to be the most promising catalysts for the HER, OER and ORR, respectively, surpassing the catalytic activity of corresponding benchmark catalysts. The volcano plots were established based on the scaling relationship of adsorption Gibbs free energy of intermediates. The results reveal that regulating combinations of metal active centers and local coordination environments could effectively balance the interaction strength between intermediates and catalysts, thus achieving optimal catalytic activity. Our findings not only opt for the promising HER/OER/ORR electrocatalysts but also guide the design of efficient electrocatalysts based on 2D MOFs materials.

Designing flexible single-atom catalysts with tunable single-atom centers and coordination environments is crucial for highly active and selective electrochemical catalysis. Using density functional theory calculations, a range of 32 two-dimensional conductive metal–organic frameworks (cMOFs: TMX₄–HTPs, TM = Sc–Ni, X = N, O, P, S) were investigated as efficient catalysts for electrocatalytic nitric oxide reduction reaction (eNORR) towards ammonia. By screening for stability, selectivity, and activity, eight TMX₄–HTPs are identified as potential high-performance catalysts. Among them, MnO₄–HTP delivers the lowest overpotential of only 0.21 V. Using this system as an example, the solvent effect, protonation ability of the potential-limiting step, and constant potential model were additionally considered and simulated. The computed results further verify the predicted potential of these catalysts as eNORR catalysts. Furthermore, descriptors are obtained to evaluate the competitive ability of key adsorbates using the sure independence screening and sparsifying operator method. All parameters are related to the intrinsic properties of TM (such as electronegativity, valence electron number, first ionization energy, and relative atomic mass) without extensive calculations. This work paves the way for highly active and selective cMOF-based electrocatalysts for eNORR.

In this work, the substrate oxidation effects on the catalytic activity of a C₂N supported Co single-atom for the oxygen evolution reaction (OER) were theoretically investigated.

The ORR performance can be tuned via changing central metals and the local coordination number of N/O atoms.

The dynamic adsorption of possible intermediates on single-atom catalysts (SACs) under working condition plays a key role in the electrocatalytic performance by the oxygen evolution reaction (OER), and therefore the performance of the dynamic adsorption should be fully considered in the theoretical screening of potential SACs. Based on density functional theory calculations, the OER performance of 27 types of C2N-supported single transition metal atoms (TM@C2N) is systematically investigated without and with considering the dynamic adsorption of possible intermediates. Without considering dynamic adsorption, only Rh@C2N and Ni@C2N are screened out as good catalysts. However, by further considering the dynamic adsorption configurations of possible intermediates, more promising TM@C2N SACs including Fe(Co, Ni, Ru, Rh, Ir)@C2N toward the OER are screened out. The presence of the intermediates (*HO, *O) on SACs could shift their d band center toward lower energy level, which makes the interaction between the adsorbate and SACs moderate and thus enhances their OER performance. The present work is instructive for further screening and designing of efficient single-atom catalysts for the oxygen evolution reaction.