Spinel ferrites are versatile, low-cost, and abundant metal oxides with remarkable electronic and magnetic properties, which find several applications. Among them, they have been considered part of the next generation of electrochemical energy storage materials due to their variable oxidation states, low environmental toxicity, and possible synthesis through simple green chemical processing. However, most traditional procedures lead to the formation of poorly controlled materials (in terms of size, shape, composition, and/or crystalline structure). Thus, we report herein a cellulose nanofibers-mediated green procedure to prepare controlled highly porous nanocorals comprised of spinel Zn-ferrites. Then, they presented remarkable applications as electrodes in supercapacitors, which were thoroughly and critically discussed. The spinel Zn-ferrites nanocorals supercapacitor showed a much higher maximum specific capacitance (2031.81 F g⁻¹ at a current density of 1 A g⁻¹) than Fe₂O₃ and ZnO counterparts prepared by a similar approach (189.74 and 24.39 F g⁻¹ at a current density of 1 A g⁻¹). Its cyclic stability was also scrutinized via galvanostatic charging/discharging and electrochemical impedance spectroscopy, indicating excellent long-term stability. In addition, we manufactured an asymmetric supercapacitor device, which offered a high energy density value of 18.1 Wh kg⁻¹ at a power density of 2609.2 W kg⁻¹ (at 1 A g⁻¹ in 2.0 mol L⁻¹ KOH electrolyte). Based on our findings, we believe that higher performances observed for spinel Zn-ferrites nanocorals could be explained by their unique crystal structure and electronic configuration based on crystal field stabilization energy, which provides an electrostatic repulsion between the d electrons and the p orbitals of the surrounding oxygen anions, creating a level of energy that determines their final supercapacitance then evidenced, which is a very interesting property that could be explored for the production of clean energy storage devices.

The sulfur–iodine thermochemical water-splitting cycle is a promising route proposed for hydrogen production. The decomposition temperature remains a challenge in the process. Catalysts, such as Pd supported on Al₂O₃, are being considered to decrease reaction temperatures. However, little is known regarding the kinetic behavior of such systems. In this work, zinc sulfate thermal decomposition was studied through non-isothermal thermogravimetric analysis to understand the effect of a catalyst within the sulfur–iodine reaction system context. The findings of this analysis were also related to a thermodynamic assessment. It was observed that the presence of Pd/Al₂O₃ modified the reaction mechanism, possibly with some intermediate reactions that were suppressed or remarkably accelerated. The proposed model suggests that zinc sulfate transformation occurred in two sequential stages without the Pd-based material. Activation energy values of 238 and 368 kJ·mol⁻¹ were calculated. In the presence of Pd/Al₂O₃, an activation energy value of 204 kJ·mol⁻¹ was calculated, which is lower than observed previously.

Hydrogen has been explored as a greener alternative for greenhouse gas emissions reduction. Sodium borohydride (NaBH₄) is a favorable hydrogen carrier due to its high hydrogen content, safe handling, and rapid hydrogen release. This work presents a novel synthesis of the catalyst CoFe₂O₄/Fe₂O₃ using nanocellulose fibers (TCNF) as reactive templates for metal adsorption and subsequent calcination. The resulting material was tested for H₂ production from basic NaBH₄ aqueous solutions (10–55 °C). The catalyst’s composition is 74.8 wt% CoFe₂O₄, 25 wt% Fe₂O₃, and 0.2 wt% Fe₂(SO₄)₃ with agglomerated spheroidal particles (15–20 nm) and homogeneous Fe and Co distribution. The catalyst produced 1785 mL of H₂ in 15 min at 25 °C (50 mg catalyst, 4.0% NaBH₄, and 2.5 wt% NaOH), close to the stoichiometric maximum (2086 mL). The maximum H₂ generation rate (HGR) reached 3.55 L min⁻¹ g_cat⁻¹ at 40 °C. Activation energies were determined using empirical (38.4 ± 5.3 kJ mol⁻¹) and Langmuir–Hinshelwood (L–H) models (42.2 ± 5.8 kJ mol⁻¹), consistent with values for other Co-ferrite catalysts. Kinetic data fitted better to the L–H model, suggesting that boron complex adsorption precedes H₂ evolution.