Electrocatalytic conversion of nitrate (NO3 –) into ammonia can not only eliminate harmful pollutant but also provide a green method for a low-temperature ammonia synthesis. The electrochemical NO3 – reduction reactions (NO3RRs) of a series of transition-metal-doped hexagonal boron phosphide (h-BP) monolayers were comprehensively evaluated using density functional theory. The V-doped h-BP monolayer was found to stand near the top of the volcano plot with the limiting potential of −0.22 V versus a reversible hydrogen electrode, exhibiting the lowest overpotential among the investigated systems in this work. Besides, the competing hydrogen evolution reaction is significantly suppressed due to the weak adsorption of the H atom. Importantly, the structure of the V-doped h-BP monolayer can be retained very well until 900 K, illustrating the initial indication of high thermal stability and great promise for synthesis. This study not only offers an eligible NO3RR electrocatalyst but also provides an atomic understanding of the behind mechanisms of the NO3RR process.

Conversion of dinitrogen (N 2 ) molecules into ammonia through electrochemical methods is a promising alternative to the traditional Haber−Bosch process. However, searching for an eligible electrocatalyst with high stability, low-onset potential, and superior selectivity is still one of the most challenging and attractive topics for the electrochemical N 2 reduction reaction (NRR). Here, by means of first-principles calculations and the conductor-like screening model, four comprehensive criteria were proposed to screen out eligible NRR electrocatalysts from 29 atomic transition metals embedded on the defective boron phosphide (BP) monolayer with Bmonovacancy (M/BP single-atom catalysts, SAC, M = Sc−Zn, Y− Cd, and Hf−Hg). Consequently, the Nb/BP and W/BP SACs are identified as the promising candidates, on which the N 2 molecule can only be activated through the enzymatic pathway with the onset potentials of −0.25 and −0.19 V, and selectivities of 90.5 and 100%, respectively. It is worth noting that the W/BP SAC has the lowest overpotential among the 29 systems investigated. The electronic properties were also calculated in detail to analyze the activity origin. Importantly, the Nb/BP and W/BP SACs possess high thermal stabilities due to that their structures can be retained very well up to 1000 and 700 K, respectively. This work not only provides an efficient and reliable method to screen eligible NRR electrocatalysts but also paves a new way for advancing sustainable ammonia synthesis.

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Mo atom doping can modify the electronic properties of Fe2P and Fe3P monolayers, and significantly enhance their NRR activities with onset potentials as low as −0.30 V and −0.17 V, respectively.

Two-dimensional transition-metal oxides have been widely explored as catalysts in high-capacity nonaqueous lithium–oxygen batteries due to their excellent electrochemical performance in the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), but little attention has been paid to non-transition-metal oxides. Here, we employ density functional methods based on the Perdew–Burke–Ernzerhof (PBE) functional with dispersion correction and the Heyd–Scuseria–Ernzerhof hybrid functional (HSE06) to investigate the mechanisms of the nucleation and decomposition processes of Li4O2(s), i.e., discharge and charge processes on single-layer Tl2O (SL-Tl2O) in lithium–oxygen batteries. HSE06 with the spin–orbital coupling effect is adopted to calculate the band gap of SL-Tl2O. It is demonstrated that the spin–orbital coupling effect is significant in predictions of not only electronic but also thermodynamic properties for heavy-element compounds such as Tl2O. The formation of LiO2(s) is initiated by the adsorption of oxygen molecules instead of lithium atoms on the surface. The intermediate reaction products strongly interact with SL-Tl2O, which causes an overpotential of 1.47 V during the electrochemical reaction. The electronic conductivity analysis of lithium oxides adsorbed on SL-Tl2O demonstrates that the electronic conductance of the layer does not change during the ORR/OER. The adsorption enthalpies of five frequently used nonaqueous solvents (tetrahydrofuran, 1,2-dimethoxyethane, 1,3-dioxolane, dimethyl carbonate, and propiolic acid) on SL-Tl2O indicate that SL-Tl2O is stable in the electrolytes. All of these calculated results indicate that SL-Tl2O is a feasible catalyst for the ORR/OER in nonaqueous lithium–oxygen batteries.