Highly Accelerated, Sustainable, Abundant Water Splitting at Room Temperature Generating Green Electricity by Sb-Doped SnO<sub>2</sub> Hydroelectric Cell
Jyoti Shah, Abha Shukla, R. K. Kotnala
Abstract
Hydroelectric cell (HEC), a revolutionary invention, has created a new exclusive domain in green energy generation by defect-assisted water splitting/dissociation on metal oxides. In the present work, doping of metallic antimony (Sb) in tin oxide (SnO2) abundantly produced oxygen vacancies. It significantly increased the active centers for adsorption and dissociation of water that ultimately led to highly accelerated water splitting to generate a record high current in a Sb–SnO2-based HEC. The photoluminescence (PL) emission peak at 656 nm confirms the electronic transitions to defect levels generated by tin (Sn) interstitials. Raman spectroscopy showed enhanced in-plane oxygen vacancies with the presence of the prominent broadening of the 571 cm–1 mode. The X-ray photoemission spectroscopy (XPS) results suggest that a large amount of antimony is segregated on the surface and grain boundaries in the 3+ oxidation state. A large number of defect pair Sb3+–Vo** centers accompanied by a highly reduced surface due to Sb led to 4-fold current production by the HEC based on Sb–SnO2 compared to SnO2. The g values calculated from electron paramagnetic resonance (EPR) spectroscopy for SnO2 and Sb–SnO2 as 2.12 and 2.15, respectively, confirmed oxygen vacancies. The Sb–SnO2-based HEC recorded a remarkable short circuit current density, Isc ∼ 23.2 mA/cm2, and peak output power, Pout ∼ 32.2 mW/cm2. Antimony doping decreases the bulk resistance of the cell by 45 times due to highly accelerated OH– and H3O+ conduction in Sb–SnO2 HEC as observed by Nyquist plots. The defects-decorated Sb–SnO2-based HEC possesses an ultimate capability to replace solar cells and fuel cells.