Morphological Impact on ZnO Material for Designing Hydroelectric Cell—A Way to Harness Green Electricity by Water Splitting

Global energy challenges compel us to explore alternative green energy sources to meet the rapidly depleting conventional energy sources. Hydroelectric cell is a noble invention in generating green electricity by nanopores defect modulated water dissociation processes without external power. In this work, ZnO nanostructured samples are synthesized using the hydrothermal and chemical auto-combustion methods. Further, their morphology is controlled by precursor concentration. The phase purity of synthesized ZnO nanostructures is confirmed using X-ray diffractogram (XRD). The SEM image reveals the diameter ZnO increase from nanometer to micrometre with the increase in Zn precursor concentration and auto combustion synthesized ZnO has the morphology of nanoparticle due to extra thermal energy obtained during the synthesis. The band gap of the synthesized ZnO is \(3.195, 3.187, 3.186\) and \(3.22\,\text{eV}\) for ZnO NRs, ZnO MRs, ZnO Bulk and ZnO NPs respectively. The ZnO NRs and ZnO NPs have higher average specific surface areas of \(6.75\) and \(4.59\,\text{m}^{2}\text{/g}\) and are responsible for the higher off-load power. ZnO-based HEC is fabricated using nanorods, microrods, bulk, and nanoparticles ZnO powder materials. ZnO nanoparticle-based HEC device ( \(Area=2.2\times 2.2\,\text{cm}^{2})\) showed the maximum \(5.82\,\text{mA}\) current with \(0.60\,\text{V}\) open circuit voltage and \(3.50\,\text{mW}\) maximum off-load power using only \(1\,\text{ml}\) of water.