A series of sulfated TiO 2 supported Mo ( x Mo/1.5ST) catalysts were synthesized successfully and evaluated for the transesterification of Jatropha seed oil (JO) to biodiesel. Extensive characterization exhibits that the well dispersed Mo oxide species, with Mo 6+ and Mo 5+ oxidation states, were formed on the surface of the sulfated TiO 2 . The results indicate the presence of many sulfates species leads to the reduction of Mo 6+ species to Mo 5+ species. Furthermore, the catalytic activity of the x Mo/1.5ST catalysts gradually increases with the increase of Mo-loading, although the sulfates content and the total acid intensity decrease. The transesterification process was fully investigated, and the 10Mo/1.5ST shows the highest yield of biodiesel of up to 97.42%. Additionally, the possible mechanism for the JO transesterification over Mo/1.5ST was described, and the fuel properties of the as-synthesized biodiesel conformed to the current international standards.
Surface reconstruction generates real active species in electrochemical conditions; rational regulating reconstruction in a targeted manner is the key for constructing highly active catalyst. Herein, we use the high-valence Mo modulated orthorhombic Pr 3 Ir 1− x Mo x O 7 as model to activate lattice oxygen and cations, achieving directional and accelerated surface reconstruction to produce self-terminated Ir‒O bri ‒Mo (O bri represents the bridge oxygen) active species that is highly active for acidic water oxidation. The doped Mo not only contributes to accelerated surface reconstruction due to optimized Ir‒O covalency and more prone dissolution of Pr, but also affords the improved durability resulted from Mo-buffered charge compensation, thereby preventing fierce Ir dissolution and excessive lattice oxygen loss. As such, Ir‒O bri ‒Mo species could be directionally generated, in which the strong Brønsted acidity of O bri induced by remaining Mo assists with the facilitated deprotonation of oxo intermediates, following bridging-oxygen-assisted deprotonation pathway. Consequently, the optimal catalyst exhibits the best activity with an overpotential of 259 mV to reach 10 mA cm geo −2 , 50 mV lower than undoped counterpart, and shows improved stability for over 200 h. This work provides a strategy of directional surface reconstruction to constructing strong Brønsted acid sites in IrO x species, demonstrating the perspective of targeted electrocatalyst fabrication under in situ realistic reaction conditions.
The advancement of seawater electrolysis requires highly active and durable nanostructured anode catalysts to enhance the oxygen evolution reaction (OER) while suppressing chloride oxidation (ClOR) and corrosion. High-entropy spinel oxide nanoparticles (HESO NPs) have emerged as promising OER catalysts in alkaline media due to their tunable electronic structures and synergistic multimetal effects. In this study, three nanostructured high-entropy spinel oxides─(CrFeMnNiCo)3O4, (CrFeMnNiCoMo)3O4, and (CrFeMnNiCoRu)3O4─were synthesized via a scalable hydrothermal–calcination method, featuring well-defined spinel phases, uniform elemental distribution, and nanoscale morphology. Notably, the Mo-doped (CrFeMnNiCoMo)3O4 NPs exhibited superior OER performance, achieving low overpotentials of 184 and 229 mV at 10 mA cm–2 in 1 M KOH and alkaline simulated seawater (1 M KOH + 1 M NaCl), respectively, outperforming even the Ru-containing (CrFeMnNiCoRu)3O4 NPs. Furthermore, the nanostructured (CrFeMnNiCoMo)3O4 demonstrated exceptional durability, maintaining stability for 20 h at 50 mA cm–2 in 1 M KOH and 5 h in simulated seawater, significantly surpassing the (CrFeMnNiCo)3O4 NPs. This enhanced stability is attributed to the protective Mo-rich surface layer, which mitigates alkaline corrosion and chloride adsorption. The nanoscale engineering of high-entropy spinel oxides, combined with Mo doping, provides a synergistic strategy to optimize OER activity and ClOR resistance, making them highly suitable for seawater electrolysis applications. This work highlights the potential of high-entropy oxide nanomaterials as efficient and robust electrocatalysts for sustainable hydrogen production.
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