Effect of hydroxyl (·OH) radicals on the progression of NaBH4 hydrolysis reaction on fcc-Co surfaces: A DFT study

Abstract

The effect of ·OH radical in the medium for the sodium borohydride (NaBH4) hydrolysis reaction in presence of face-centered cubic (fcc) Cobalt (Co) catalyst was investigated based on density functional theory (DFT). The main purpose is to determine the effective cobalt surface for the disassociation of hydrogen from NaBH4, and the catalyst performance for the intermediate steps formed by the decomposition of water on the cobalt surface. Low index fcc-Co catalyst surfaces were used for the catalyzed NaBH4 hydrolysis reaction. As a result of the calculations, Co(111) is the most effective surface among the low index fcc-Co surfaces for the hydrolysis reaction. Therefore, the possible steps of the NaBH4 hydrolysis reaction are modeled on the Co(111) surface for ambient conditions containing different concentrations of H* atoms, ·OH* radicals, and H2O* molecules. According to our results, the concentration of ·OH* radicals adsorbed on the surface is directly proportional to the change in activation energy. In addition, calculations for the possible second and third steps of the hydrolysis reaction showed that the steps involving NaBH3OH and NaBH3O base molecular structures, respectively, are more feasible than others. This will be a guide for experimental studies in terms of time and cost.