Bimetallic sulfide composites Cu ₃ SnS ₄ and Ag ₃ SnS ₄ outperform their monometallic counterparts SnS and Cu ₂ S as CO ₂ RR catalysts. The higher catalytic activity results from the formation of Cu ₃ Sn and Ag ₃ Sn alloys, where Ag ₃ Sn is less prone to corrosion.

Cu_2−xS and Cu_2−xSe (0 ≤ x ≤ 0.2) alloys stand out as highly promising materials for thermoelectric applications, owing to the phonon–liquid electron–crystal (PLEC) convention. In this study, we undertake a comprehensive investigation to reassess the synthesis conditions, with a focus on achieving pure-phased systems through a direct reaction between elements at elevated temperatures. Simultaneously, we present experimental evidence showcasing the feasibility of doping these systems with Ag, Ni, and Zn. The study demonstrates that obtaining single-phased systems requires multi-step processes, and the dissolution of chosen impurities appears doubtful, as evidenced by numerous foreign phase segregations. Additionally, it is revealed that the partial dissolution of individual impurities deteriorates the operational parameters of these chalcogenides. For the optimal Cu_1.97S composition, it reduces the thermoelectric figure-of-merit ZT from 1.5 to approximately 1.0, 0.65, and 0.85 for Ag-, Ni-, and Zn-doped systems, respectively, while marginally improving their stability. For metal-like Cu_1.8Se, the ZT parameter remains at a low level, ranging between 0.09 and 0.15, showing slight destabilization during subsequent operating cycles. The article concludes with an in-depth analysis of the basic thermoelectric performance exhibited by these doped systems, contributing valuable insights into the potential enhancements and applications of Cu_2−xS and Cu_2−xSe alloys in the field of thermoelectric materials.

The commercialisation of PEM water electrolysis is still hindered by the necessity of using noble metals that are rare, expensive and therefore unsustainable. To replace the benchmark HER catalyst Pt with more abundant materials, promising non‐noble catalysts need to be identified and optimal electrode preparation and electrolysis conditions need to be transferred between catalyst materials to reveal their full potential under industrially relevant conditions. This study investigates the optimal ink composition for spray‐coating the cathode regarding the effects on electrode structure, performance and catalyst layer composition. The ratio of catalyst to binder and carbon support was varied as well as the specific carbon material and the resulting electrodes were analysed via polarisation curves, electrochemical impedance spectroscopy, X‐ray photoelectron spectroscopy and scanning electron microscopy for three different catalysts. These results show that ink compositions with a catalyst : carbon : binder ratio of 3 : 1 : 1 using Carbon Vulcan give the highest performance. Interestingly, resulting trends concerning electrochemical behaviour and electrode structure observed with different characterisation techniques can be transferred between Pt catalysts and non‐noble transition metal chalcogenide materials. Boosting the performance via ink optimisation is much more pronounced for the non‐noble catalysts, narrowing the gap to competing with noble standard Pt materials.

Since pentlandites are among the most promising catalysts for hydrogen evolution reactions (HER), in this study, we investigated the influence of different cobalt, iron, and nickel substitutions in the cationic sublattice and the form of the material (powder, ingot, sintered pellet) on catalytic performance. This complements previous results regarding a multi-component approach in these chalcogenides. It was shown that in the case of sulfur-rich pentlandites with a non-equimolar ratio of Co, Fe, and Ni, the impact of intrinsic material properties is smaller than the surface-related effects. Among powder forms, catalysts based on a combination of Fe and Co perform the best. However, in volumetric forms, extremely high contents of individual metals are favorable, albeit they are associated with active precipitations of foreign phases. The presence of these phases positively affects the recorded currents but slows down the reaction kinetics. These findings shed light on the nuanced interplay between material composition, form, and HER properties, offering insights for tailored catalyst design.

In this study, the feasibility of a new group of alkali-free high-entropy ABO_3-δ perovskite cathodes, in which the B-site is occupied by a mixture of 3d and 4d/5d elements, is examined. Six different materials with a general formula of La(Cu_0.2Ni_0.2X1_0.2X2_0.2Y1_0.2)O_3-δ (where X1, X2 = mixture of two Co, Ga, Fe, and Y1 = one of Nb/Ta): La(Cu_0.2Ni_0.2Co_0.2Ga_0.2Nb_0.2)O_3-δ, La(Cu_0.2Ni_0.2Co_0.2Ga_0.2Ta_0.2)O_3-δ, La(Cu_0.2Ni_0.2Fe_0.2Ga_0.2-Nb_0.2)O_3-δ, La(Cu_0.2Ni_0.2Fe_0.2Ga_0.2-Ta_0.2)O_3-δ, La(Cu_0.2Ni_0.2Co_0.2Fe_0.2Nb_0.2)O_3-δ, La(Cu_0.2Ni_0.2Co_0.2Fe_0.2Ta_0.2)O_3-δ were synthesized, with five of them possessing a single-phase, Pnma perovskite structure. While in the case of the basic properties, such as electrical conductivity or thermomechanical behavior, the studied oxides show a number of similarities, the differences between them become more apparent when low-temperature Oxygen Evolution Reaction (OER) and high-temperature Oxygen Reduction Reaction performance is evaluated. The overall best performance is achieved by La(Cu_0.2Ni_0.2Co_0.2Fe_0.2Nb_0.2)O_3-δ and La(Cu_0.2Ni_0.2Co_0.2Fe_0.2Ta_0.2)O_3-δ compositions, with the former offering slightly faster OER kinetics, and the latter exhibiting superior polarization resistance as an SOFC cathode. Overall, the materials exhibit a strong correlation between composition and properties, with potential for further development into non-equimolar compositions of superior performance.

Hydrogen evolution reaction (HER) performance of selenium‐rich multicomponent pentlandites was investigated using the Co _{9 −x −y} Fe _x Ni _y S ₄ Se ₄ series prepared as powders, as‐cast ingots, and induction‐hot‐pressed pellets. Structural, electrochemical, spectroscopic, and density functional theory analyses were combined to establish composition‐structure–activity relationships. Selenium extends the single‐phase range after synthesis but promotes partial phase separation during processing, particularly in Fe‐rich compositions. Although the effect of cationic composition on HER performance is comparatively weak within the investigated Se‐rich series, making the catalytic response increasingly dependent on electrode architecture and phase stability, the best HER performance across all material forms is consistently near the equimolar composition but shifted toward the Fe─Co‐rich region, whereas Ni‐rich compositions remain less active. Fe‐rich pellets show the highest activity ( η ₂₀ = 200 mV) together with pronounced surface reconstruction and preferential iron dissolution, while compositions closer to the equimolar region exhibit higher overpotentials ( η ₂₀ = 251–256 mV) with greater stability, revealing a composition‐dependent balance between activity and structural stability. Calculations indicate that selenium shifts the d‐band center toward the Fermi level and strengthens hydrogen adsorption, contributing to sluggish HER kinetics. Overall, selenium suppresses the beneficial activation characteristic of sulfur‐rich systems and fundamentally changes the factors governing HER performance, making it increasingly dependent on phase stability and electrode architecture.