Catalysts

This work is based on our previous research on sulfur-assisted graphitization of biopitch by focusing on catalyst-driven optimization of biomass-derived pitch (BDP) composites as sustainable alternatives to coal tar pitch (CTP). Biomass from eucalyptus sawdust was pyrolyzed to produce BDP, which was used as a binder for carbon–carbon composites. The properties of BDP/graphite and CTP/graphite composites, including bending strength, electrical conductivity, hardness, density, porosity, mass loss, and shrinkage, were compared. Furthermore, the influence of catalysts (NiSO₄, K₂SO₄, CuSO₄, FeSO₄, and KOH) on composite performance was systematically investigated. Results show that catalyst selection significantly enhances structural, electrical, and mechanical properties, demonstrating the potential of combining eco-friendly materials with strategic catalyst engineering to develop high-performance, sustainable composites.

Continuous excessive CO₂ emissions have a negative impact on the environment. In order to address the issue of CO₂ emission control, its conversion to some valuable commodities is the way forward in dealing with this issue. Additionally, the conversion of CO₂ to some valuable product such as methanol fuel will not only tackle the issue but also result in producing energy. Here, the co-precipitation method was used to synthesize Cu-ZnO bimetallic catalysts based on TiO₂ support to be applied for CO₂ conversion to methanol fuel. To elucidate the role of potassium (K) as a promoter, varied concentrations of K were added to parent Cu-ZnO/TiO₂ catalysts. A number of analytical techniques were used to scrutinize the physico-chemical properties of calcined Cu-ZnO/TiO₂ catalysts. The crystalline nature of TiO₂ catalyst support with high metal oxide dispersion were the major findings disclosed based on X-ray diffraction examinations. The combination of the mesoporous and microporous character of the K-promoted Cu-ZnO/TiO₂ catalysts was discovered using the N₂ adsorption–desorption technique. Similarly, N₂ adsorption–desorption studies also revealed surface defects by K-promotion. The creation of surface defects was also endorsed by X-ray photoelectron spectroscopy (XPS) by showing additional XPS peaks for O1s in higher binding energy (BE) regions. XPS also showed the oxidation states of K-promoted Cu-ZnO/TiO₂ catalysts as well as metal–support interactions. Activity results demonstrated the active profile of K-promoted Cu-ZnO/TiO₂ catalysts for methanol synthesis via CO₂ reduction in a liquid phase slurry reactor. The methanol synthesis rate was accelerated from 35 to 53 g.MeOH/kg.cat.h by incorporating of K to parent Cu-ZnO/TiO₂ catalysts at reaction temperature and pressure of 210 °C and 30 bar, respectively. Structure–activity investigations revealed a promoting role of K by facilitating Cu reduction as well metal–support interaction. The comparative study further revealed the importance of K promotion for the title reaction.

The development of efficient and stable oxygen evolution reaction (OER) electrocatalysts based on non-precious metals is pivotal for advancing sustainable energy conversion technologies. We present a facile and green strategy for synthesizing a high-performance HO-CDs-FeOOH/NF(D) composite catalyst by leveraging a synergistic system of FeCl₃/urea deep eutectic solvent (DES) and hydroxyl-functionalized carbon dots (HO-CDs). This system orchestrates the rapid, in situ growth of FeOOH on nickel foam (NF) via simple immersion, wherein the DES acts as both an etchant and an iron source, while the HO-CDs induce a morphological transformation from sheet-like to granular stacking, thereby constructing highly active interfaces and increasing the density of accessible catalytic sites. The optimized catalyst exhibits exceptional OER performance, requiring an overpotential of only 251 mV to achieve 50 mA cm⁻², with a Tafel slope of 55.4 mV dec⁻¹. Moreover, it demonstrates outstanding stability, maintaining 98% of its initial current density after 24 h of continuous operation and showing negligible performance decay after 3000 cycles. This work presents a straightforward approach for designing high-performance Fe-based electrocatalysts through carbon dot-mediated morphology control via a facile DES-based impregnation strategy.