Replacing oxygen evolution reaction by glycerol electrooxidation on Rh modified Ni(OH)2/C for energy-efficient hydrogen production

Abstract

Oxygen evolution reaction (OER) is a key reaction for the development of green and sustainable energy system based in the production of hydrogen by electrolysis. However, the water splitting required a high overpotential for the oxygen evolution reaction. In this work we investigated the use of the Glycerol Electrooxidation Reaction (GEOR) in alkaline solutions on Rh/C, Ni(OH)2/C and Rhx{Ni(OH)2}y/C nanocomposites instead of water as a reagent in the anodic reaction in electrolyzers as a way to reduce the cell overpotential and obtain energy savings. The electrocatalysts were prepared by microwave-assisted alcohol reduction method and characterized by X-ray diffraction. The catalysts presented particles with fcc structure for Rh/C, a hexagonal structure for (Ni(OH)2/C), and (Rh0.3{Ni(OH)2}0.7/C) and (Rh0.5{Ni(OH)2}0.5/C) presented mixed structures with brucite and a α-Ni(OH)2/C structure. The electrochemical performance of Rh0.3{Ni(OH)2}0.7/C presented superior density current at low potential in comparison to the other studied materials. The potential value determined for GEOR at 10 mA cm−2 was nearly 1.29 V vs. RHE in a 0.5 mol L−1 glycerol solution that is 0.3 V less than the value obtain Rh/C in the absence on the organic species. The analysis of the products generated after bulk electrolysis using high-performance liquid chromatography demonstrated that at 1.50 V vs. RHE the main reaction products were and tartronate, glyceraldehyde and oxalate, depending on the employed catalytic material. These results demonstrated that value-added products could be obtained as a promising way to valorize by the glycerol electrooxidation besides the energy saving during the electrolysis for the hydrogen production.