PEG mediated tetragonal calcium molybdate nanostructures for electrochemical energy conversion applications

Abstract

Hydrogen is one of the popular abundant elements in the world and, it is rising as a preferential energy and has developed a tool for decarbonization. Recently, hydrogen has been considered as next generation fuel for cars, trucks, homes, etc, because of the arising of worse climate. In this present work, the cost-effective and efficient electrocatalyst of calcium molybdate nanostructures were successfully prepared with the help of non-ionic surfactant (PEG) through the co-precipitation method for hydrogen evolution reaction. In XRD spectra, the high crystallite peak observed at 28.4° value corresponded to (112) lattice planes confirmed the formation of calcium molybdate nanostructures. In Raman spectra, the existence of tetrahedral [MoO4] clusters and octahedral [CaO8] clusters confirmed tetragonal calcium molybdate nanostructures formation. In SEM analysis, unique morphologies such as dumbbell and spindle-like structures was observed, which was achieved by using the PEG. The pore volume, pore diameter and specific surface area of CaMoO4–6 ml PEG were found to be 0.149 cc/g, 11.685 nm and 28.07 m2/g respectively. Electrochemical performance confirmed that the CaMoO4–6 ml PEG nanostructures exhibited superior HER activity with the low 198 mV overpotential at 10 mA/cm2 and lesser 204 mV/dec Tafel slope value. The charge transfer resistance of CaMoO4–6 ml PEG was 0.65 Ω, which has smaller than that of other electrocatalysts such as pure CaMoO4 (24.9 Ω), CaMoO4–2 ml PEG (2.47 Ω) and CaMoO4–4 ml PEG (2.04 Ω). The excellent HER activity was explored elevated electronic conductivity, mesoporous nature, high surface area and, unique morphology.