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The activity of Li-intercalated MoS2 phases for the hydrogen evolution reaction is investigated using density functional theory. The most stable semiconducting 2H phase, the metallic 1T′ phase, and a polymorphous surface composed of alternating H and T′ phases (1T″) are investigated. The local structure of the MoS2 surface is found to define its reactivity. In all cases, active sites for the hydrogen evolution process are restricted to T-like sulphur sites. Li-intercalation is found to promote hydrogen evolution reaction reactivity for the H phase whilst having little effect on the T phase. While improved compared to the non-intercalated phase, the Li-intercalated H phase MoS2 still has minimal activity for the hydrogen evolution reaction. The same effect of intercalation is also found for another transition metal dichalcogenide, MoSe2. The ability to improve reactivity in this way makes ion intercalation a promising space for designing new 2D catalysts for the hydrogen evolution reaction. [ABSTRACT FROM AUTHOR]

The process for the direct oxidation of methane to methanol is investigated on single atom alloys using density functional theory. A catalyst search is performed across FCC metal single atom alloys. 7 single atom alloys are found as candidates and microkinetic modelling is performed. The activity and selectivity are remarkably improved over that of pure palladium metal, yet remain unideal. [ABSTRACT FROM AUTHOR]

[Display omitted] • Developed a new way considering lateral interactions to kinetically model oxidizable surfaces to predict the optimal interphase for hydrogen peroxide synthesis. • Unveils a comprehensive mechanism on the partially oxidized surface, highlighting the significance of coverage effects in the direct synthesis of hydrogen peroxide. • The interphase of Pd and PdO is crucial for maintaining high activity and selectivity of H 2 O 2. • The H 2 /O 2 partial pressure ratio significantly affects the surface structure and coverage species. • The simulation results at 298.15 K and oxygen balance, the surface of Pd 9 O 6 remains stable, showing remarkable activity and selectivity. Identifying efficient active sites for the direct synthesis of hydrogen peroxide over Pd-based catalysts has been a subject of considerable debate. In this study, we employ particle swarm optimization method and density functional theory to explore the H 2 O 2 synthesis mechanism on Pd, PdO, and the partially oxidized surface (Pd 9 O X). A comprehensive mechanism for Pd 9 O X is elucidated, and subsequent coverage-dependent kinetic analysis allows for a quantitative assessment of catalytic performance at the interphase. Our findings conclusively establish that the interphase between Pd and PdO represents the optimal active site. Phase diagram analysis further aids in determining stable structures under reaction conditions. At 298.15 K and under oxygen balance, the Pd 9 O 6 surface remains stable throughout the reaction, demonstrating high activity and selectivity. This work underscores the significance of the interphase in comprehending catalytic performance and unveils promising avenues for optimizing catalyst performance by controlling reaction conditions and surface composition. [ABSTRACT FROM AUTHOR]

• Developed an advanced microkinetic model based on first-principles, accounting for adsorbate interactions. • Uncovering the full Pd (1 1 1) mechanism of formic acid dehydrogenation and highlighting the importance of coverage. • Our kinetic analysis aligns with experimental values at 373 K, considering H coverage. • Simulation results align with experiments, approaching 100 % H 2 selectivity on Pd (1 1 1) for formic acid decomposition. As a key liquid organic hydrogen carrier, investigating the decomposition of formic acid (HCOOH) on the Pd (1 1 1) transition metal surface is imperative for harnessing hydrogen energy. Despite a multitude of studies, the major mechanisms and key intermediates involved in the dehydrogenation process of formic acid remain a great topic of debate due to ambiguous adsorbate interactions. In this research, we develop an advanced microkinetic model based on first-principles calculations, accounting for adsorbate–adsorbate interactions. Our study unveils a comprehensive mechanism for the Pd (1 1 1) surface, highlighting the significance of coverage effects in formic acid dehydrogenation. Our findings unequivocally demonstrate that H coverage on the Pd (1 1 1) surface renders formic acid more susceptible to decompose into H 2 and CO 2 through COOH intermediates. Consistent with experimental results, the selectivity of H 2 in the decomposition of formic acid on the Pd (1 1 1) surface approaches 100 %. Considering the influence of H coverage, our kinetic analysis aligns perfectly with experimental values at a temperature of 373 K. [ABSTRACT FROM AUTHOR]