Nonphotocatalytic Water Splitting Process to Generate Green Electricity in Alkali Doped Zinc Oxide Based Hydroelectric Cell

Abstract

Efficient nonphotocatalytic water molecule splitting and electricity generation has been obtained from alkali (Li, Na, K) doped zinc oxide (ZnO) hydroelectric cells (HECs) at room temperature. The existence of defect centers including zinc and oxygen vacancies in pure and alkali-doped ZnO has been observed by optical spectroscopy. Broadband dielectric spectroscopy has been carried out to investigate the charge transfer mechanism in the physisorbed layer of water molecules on the surface of porous ZnO HEC. Temperature dependence of dielectric relaxation was also determined to identify the reorientation dynamics of water molecules near the defect site in ZnO. Minimum activation energy for dipolar reorientation, E a ∼ 128.54 kJ/ mol, was calculated for the K-ZnO sample depicting easy hopping of H + ions near the defect site. Maximum lattice strain induced by K doping in ZnO led to faster dipolar reorientation and easy hopping of the proton over the physisorbed layer of water molecules on the cell surface. Maximum output power, P out ∼ 5.71 mW/ cm 2 , has been delivered by K doped ZnO HEC, which is comparable to the best achieved power density by a ZnO nanoparticle-based dye-sensitized solar cell, ∼9.17 mW/cm 2 . Zinc oxide based hydroelectric cells are a low cost, environmentally friendly solution for energy generation scarcity for the masses living in remote locations without the use of any harmful chemicals.

Effect of Li+, Mg2+, and Al3+ Substitution on the Performance of Nickel Ferrite-Based Hydroelectric Cells

“…8,9 Gupta et al explained the role of doping of alkali metals on the ZnO-based HEC output and showed enhancement of the short-circuit current from 9 mA (pure ZnO) to 25.0 mA (K-doped ZnO). 10 A Li-doped Fe 3 O 4 -based HEC was reported with an open-circuit voltage of 0.68 V and a short-circuit current of 44.91 mA. 11 A Mg-doped alumina-based HEC delivered a maximum short-circuit current of around 16 mA.…”

“…Gaur et al studied Mg- and Co-doped SnO 2 -based HECs, which showed the maximum short-circuit current values of up to 41.69 and 77.52 mA, respectively, but a low open-circuit voltage of 0.454 V in the Co-doped SnO 2 HEC . Hematite- and maghemite-based HECs (with dimensions of 2.5 cm × 2.5 cm) were also reported with short-circuit current values of 30 and 19 mA, respectively. , Composites BaTiO 3 -CoFe 2 O 4 and CeO 2 -rGO were also investigated for the hydroelectric cell application. , Gupta et al explained the role of doping of alkali metals on the ZnO-based HEC output and showed enhancement of the short-circuit current from 9 mA (pure ZnO) to 25.0 mA (K-doped ZnO) . A Li-doped Fe 3 O 4 -based HEC was reported with an open-circuit voltage of 0.68 V and a short-circuit current of 44.91 mA .…”

Significant role of defect‐induced surface energy in water splitting to generate electricity by nickel ferrite hydroelectric cell

“…Strain‐mediated defective multiferroic‐based HECs have also been reported with a maximum current of 9.4 mA 54 . In Mg‐doped alumina and alkali metal‐doped ZnO‐based HECs, the role of doping for defect creation to enhance HEC output has been studied 55,56 …”

“…54 In Mg-doped alumina and alkali metal-doped ZnO-based HECs, the role of doping for defect creation to enhance HEC output has been studied. 55,56 Figure 10B 49 The expected electrochemical half-reactions occurring on the electrode and the surface of ferrite are as follows:…”

Optical Properties of 2D Micro- and Nanostructures of ZnO:K

“…Potassium-doped zinc oxide has been previously grown by sol–gel [ 4 , 7 , 8 , 9 , 10 ], electrochemical synthesis [ 11 , 12 ], rf cathodic [ 13 , 14 ] or calcination [ 15 , 16 , 17 ] methods. The degree of K incorporation depends on the method used, but in all cases, drastic changes in the behavior of the material have been observed.…”