Síntese, caracterização físico-química e avaliação de titanoniobatos de metais de transição na produção eficiente de hidrogênio a partir de NaBH4

Abstract

The excessive use of fossil fuels has increased environmental pollution through greenhouse gas emissions. As a result, interest in sustainable energy alternatives is growing. Hydrogen has emerged as a promising option, but its low density and boiling point make handling problematic, especially for storage and transportation. H2 storage materials, such as sodium borohydride (NaBH4), have become an alternative for H2 evolution due to their commercial availability and high H2 storage capacity. In the present investigation, nanocomposites were prepared in the form of [M(bpy)n(TiNbO5)2٠XH2O], where M can be Mn (II), Cu (II), Co (II) or Ru (II), used as supports for platinum nanoparticles (Pt NPs). The synthesized materials were characterized using XRD, FTIR, Raman spectroscopy, UV-Vis diffuse reflectance spectroscopy, thermogravimetric analysis, zeta potential determination, scanning electron microscopy (SEM), electron dispersion spectroscopy (EDS) and transmission microscopy (TEM). Preliminary H2 evolution tests were carried out using NaBH4 with all the materials synthesized without and with Pt NPs. The Pt NPs/CoTiNb showed the best H2 generation rate (HGR) result, with a 22009 mL min-1 g-1 value. Varying parameters, such as the concentration of Pt NPs, the concentration of NaBH4, and the effect of NaOH on the reaction, carried out the kinetics study of NaBH4 hydrolysis using Pt NPs/CoTiNb. The activation energy (Ea) was calculated according to the Arrhenius equation. The result obtained was 35,27 kJ mol-1. The durability of the Pt NPs/CoTiNb was assessed, obtaining an increase in HGR of 53,98% up to cycle 3, and after 10 cycles, the catalyst retained 61% of its initial HGR. The study also examined the current state of development of titanoniobates in the field of H2 production and their use in the development of lithium batteries, photocatalysis, and electrocatalysis. This was achieved through bibliometric and patentometric analysis, which employed a time series indicator, protection market indicator, patent applicant indicator, and technical area indicator.