Strategic enhancement of oxygen defects in ZnO from ZnS for water splitting to generate green electricity by hydroelectric cell

Abstract

The green energy produced by the material device Hydroelectric Cell possesses a huge potential to transform the energy generation by water splitting. It is an efficient, clean and green electricity generating device accomplishing the ambitious Net Zero target. The present study reports a facile and unique process to obtain highly defective and nanoporous ZnO for water splitting at room temperature by strategic heat treatment of ZnS and lithium substituted ZnS. The creation of defects enhanced microstrain and dislocation density in ZnO has been confirmed by X-ray diffraction analysis. Surface and lattice defects presence have been distinctly evidenced by photoluminescence (PL) spectroscopy. The oxygen vacancy in ZnO and Li-ZnO has been also confirmed by the g value of 2.06 and 2.09 calculated from electron paramagnetic resonance (EPR) measurements. As soon as water is sprinkled on the Hydroelectric cell, the surface defects chemidissociate water into H3O+ and OH− ions. Hydronium ions trapped in nanopores create a high electric potential that sustains water splitting. Due to redox reactions at electrodes of Hydroelectric cell, voltage and electric current is generated. The fabricated hydroelectric cells (4 cm2 area) of pristine ZnO, ZnS converted ZnO, and Li-ZnO exhibited short circuit current, ISC 5.6 mA, 15 mA and 53 mA respectively by instant water splitting. Innovative method of oxygen defects creation in ZnO by heat treatment of bulk ZnS is an environment friendly, novel and simple non-photocatalytic technique to generate green electricity by water splitting at room temperature.