Activated biochars from solid residues have been very successful in many applications due to their high surface area, porosity properties, and surface chemistry. Our work, leather waste-derived biochar obtained from pyrolysis of footwear leather wastes at 700°C, followed by a chemical activation with KOH has been prepared, and characterized by SEM, physisorption, XPS and Raman. Results showed that activation with KOH increases the biochar BET specific surface area by almost 100 times. The biochars were tested as electrode materials for supercapacitors in four different aqueous electrolytes, where the KOH activated biochar (AL700) shows higher capacitances. A maximum specific capacitance of 268 Fg-1 (5 mVs-1) was obtained in 0.5M H₂SO₄ electrolyte for the AL700. A supercapacitor cell was assembled showing excellent performance, with a capacitance of 52 Fg-1 at 0.5 mA g-1 with only 8% of capacitance loss after 5000 charge/discharge cycles, reveling a high stability. The maximum specific energy and specific power determined were 12.8 Wh kg-1 and 1.8 kW kg-1, respectively. These results indicate that it is possible to use the footwear leather waste in energy storage devices, such as in supercapacitors showing a major improvement in SC cells performance, compared to commercial carbons.

The electrocatalytic performance of novel Pt-NiTiO₃/C catalyst for the oxygen reduction reaction (ORR) is investigated for the first time. The cathode has been synthesized in a two-step procedure. Firstly, the NiTiO₃ co-catalyst is obtained via a wet-chemical method. Then, 20% Pt-NiTiO₃/C electrocatalysts (Pt:NiTiO₃ ratio of 1:1 at. %) is prepared by irradiating a mixture of NiTiO₃, Vulcan and Pt precursor for 4 min in a microwave apparatus. As a reference, a 20% Pt/C catalyst has been synthesized by the same procedure. XRD analysis confirmed a crystalline NiTiO₃ with particle size between 25–40 nm. It also indicates the formation of nanostructured Pt-NiTiO₃/C having a Pt particle size of less than 2 nm. TEM results show the formation of homogenously dispersed Pt nanoparticles, with particle size of 2.3 nm. The linear scan voltammograms show a performance for the ORR of Pt-NiTiO₃/C as high as that of Pt/C in KOH. The results suggest that the reaction proceeds following a four-electron transfer mechanism. Moreover, the mass and specific activities of Pt-NiTiO₃/C are the same as those of Pt/C, demonstrating good performance with less Pt. Furthermore, ORR selectivity tests show an enhanced tolerance of Pt-NiTiO₃/C to 0.1 M methanol, compared to Pt/C.