Theoretical insight into surface structures of pentlandite toward hydrogen evolution

Tailoring the electrocatalytic activity of multicomponent (Co,Fe,Ni)9S8−xSex pentlandite solid electrodes

“…4a–d). In the case of ingot samples, spontaneous crystal formation occurred without any nanostructured particles; thus, it should be stated that the final performance is related to the not-normalized surface roughness, random distribution of individual crystal facets (affecting catalytic performance 41 ), as well as intrinsic properties of the materials, including the occupancy of individual cations in tetrahedral/octahedral sites, related vacancies in anionic sublattice, and synergistic effects (shifting respective bands near the Fermi level caused by multi-occupied sublattices). 42 The main role of catalytic activity in pentlandite-based systems is believed to be directly related to distances between the metal sites and related sulfur vacancy concentrations.…”

Tuning the Electrocatalytic Properties of Trimetallic Pentlandites: Stability and Catalytic Activity as a Function of Material Form and Selenium Concentration

“…It was proven that H atoms preferably occupy S vacancies at 8c sites more than S vacancies at 24e sites, 14 especially when the (311) crystal facet is exposed on the catalyst surface. 15 It was also postulated that the high concentration of Co in bimetallic and trimetallic compositions somehow hamper sulfur depletion mechanism, possibly due to some phase decomposition on the materials' surface. 3 The changes caused by the selenium additive into the pentlandite structure are significantly less described.…”

“…This depletion mechanism stands out as a key factor contributing to the high catalytic efficiency of pentlandites. It was proven that during prolonged electrolysis, sulfur atoms tend to detach, forming vacancies that are active sites strongly favored by hydrogen atoms especially in 8c Wyckoff sites ( Fm 3̅ m space group). − Furthermore, pentlandites indicate high durability under operating conditions also in the presence of typical impurities (e.g., H 2 S), , and wide range of solid solution formation as a function of chemical composition and therefore a tailorable electronic structure. ,,,− Combining these features, pentlandites can be applied in the water splitting process, either as typical powder catalysts anchored to metallic electrode or in bulk, rock-like geometry or even sintered pellets functioning as both electrodes and catalysts simultaneously. , …”

Synthesis, properties and catalytic performance of the novel, pseudo-spinel, multicomponent transition-metal selenides

“…Another group of TMCh exhibiting similar structural features to pentlandites, yet much less studied, are densepacked, Se-based, monoclinic C2/m-structured pseudo-spinels, characterized by the presence of only octahedral cationic sites. Similarly, as in pentlandites, the very close, intermetallic interactions between cations, together with a clear tendency for creation of Ch vacancies, have the potential for providing a high concentration of active sites, 31,[35][36][37] making them highly promising bifunctional catalysts. For instance, extremely high current densities of 400 mA cm −2 at an overpotential of 320 mV dec −1 (OER) were reported for monometallic Co 3 Se 4 anchored to cobalt foam.…”