Defect induced electrocatalytic hydrogen properties of pentagonal PdX2 (X = S, Se)

Searching for catalysts of hydrogen evolution reaction (HER) that can replace Pt is critical. Here, we investigated the HER electrocatalytic activity of pentagonal PdS₂ (penta-PdS₂) and PdSe₂ (penta-PdSe₂) by first-principles calculations. Three types of vacancies (V_S/Se, V_Pd, DV_S/Se) were constructed to activate the inert basal planes of PdS₂ and PdSe₂. The results show that S/Se and Pd vacancies significantly improve HER performance, and the Gibbs free energy (ΔG _H) of systems can be further regulated by vacancy concentration. Particularly, PdS₂ with 2.78% V_S, 50% V_Pd and PdSe₂ with 12.5% V_Se display the optimal ΔG _H value and the highest exchange current density. Further analysis of charge transfer and band structures were described that the introduce of vacancies efficiently regulates the electronic properties, resulting in the diminution of bandgap, and accelerates the charge transfer, thereby contributing to an enhanced electron environment for HER process. Our results provide a theoretical guidance for the applications of pentagonal transition-metal dichalcogenides as catalysts of hydrogen evolution reaction.

Splitting of multiple hydrogen molecules by bioinspired diniobium metal complexes: a DFT study

Splitting of molecular hydrogen (H₂) into bridging and terminal hydrides is a common step in transition metal chemistry. Herein, we propose a novel organometallic platform for cleavage of multiple H₂ molecules, which combines metal centers capable of stabilizing multiple oxidation states, and ligands bearing positioned pendant basic groups. Using quantum chemical modeling, we show that low-valent, early transition metal diniobium(ii) complexes with diphosphine ligands featuring pendant amines can favorably uptake up to 8 hydrogen atoms, and that the energetics are favored by the formation of intramolecular dihydrogen bonds. This result suggests new possible strategies for the development of hydrogen scavenger molecules that are able to perform reversible splitting of multiple H₂ molecules.

DFT study of the mechanism of hydrogen evolution catalysed by molecular Ni, Co and Fe catalysts containing a diamine–tripyridine ligand

Electrolysis of water to obtain hydrogen is a practical way to transform surplus electrical power into clean and sustainable hydrogen fuels.