Article Cite This: J. Phys. Chem. C XXXX, XXX, XXX−XXX
pubs.acs.org/JPCC
Environment-Friendly Mesoporous Magnetite Nanoparticles-Based Hydroelectric Cell Shipra Jain,†,‡ Jyoti Shah,† S. R. Dhakate,† Govind Gupta,† C. Sharma,† and R. K. Kotnala*,† †
CSIR and ‡AcSIR, National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012, India S Supporting Information *
ABSTRACT: The recently invented hydroelectric cell (HEC) is emerging as a better alternative to green electrical energy devices. In this direction, oxygen-deficient mesoporous magnetite nanoparticles have been synthesized by a chemical method to fabricate a magnetite-based HEC. A water molecule chemidissociates on the surface Fe cations and oxygen vacancies, followed by physisorbed water molecule dissociation due to charges trapped inside mesopores of magnetite. Mesoporosity and oxygen vacancies in magnetite nanoparticles have been confirmed by BET and X-ray photoelectron spectroscopy, respectively. Dissociated H3O+ and OH− ions migrate toward attached silver and zinc electrodes, respectively, in magnetite HEC via capillary and surface diffusion. Ionic diffusion of dissociated ions has been confirmed by a Nyquist plot for dry and wet magnetite HEC. Ohmic loss in magnetite has been found to be less due to Fe2+/Fe3+ hopping process, which results in increased cell current. A typical magnetite HEC of 4.8 cm2 area delivers a 50 mA peak current with a maximum output power of 38.5 mW. An electromotive force (emf) of 0.77 V is generated due to a redox reaction at respective electrodes in the cell. Reduction in cell emf is attributed to the oxidation of Fe2+ to Fe3+, forming internal cells in magnetite, which ultimately impedes OH− ion diffusion toward the Zn electrode. Byproducts of the HEC, zinc hydroxide and H2 gas, are not harmful for the environment. Electricity generation by magnetite HEC is a safe, environment-friendly, and facile technique.
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active toward water.15 Water molecule adsorption on Fe3O4 could be molecular or dissociative. Significant adsorption occurs on oxygen vacancies and surface defects.16−18 The interaction of water with Fe3O4 has been studied only on thin films under ultra-high-vacuum conditions at water pressure
