Hydrothermal growth of undoped and boron doped ZnO nanorods as a photoelectrode for solar water splitting applications

Abstract

Undoped and boron-doped ZnO nanorods (NRs) were grown on ITO glass substrates by using hydrothermal techniques. The as grown nanorods were investigated by using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), UV-visible spectroscopy, and photoelectrochemical study. XRD spectra reveal the confirmations regarding the hexagonal wurtzite structure along with preferential orientation (002). The observation of (002) peak shows a red shift. The average size distribution of NRs in doped and undoped sample ranges from 169 to 191 nm. The absorption spectra clearly revealed the band gap tunability feature of the samples with a change in doping percentage. Photoluminescence spectra clearly indicate the presence of oxygen defects. Photocurrent density as high as ∼0.622 and 2.6 mA/cm 2 were obtained for undoped and 6% B-doped ZnO NRs arrays respectively, at +0.44 V vs. Ag/AgCl electrode under visible light AM 1.5 G (100 mW/cm 2 ) in 0.1 M electrolyte solutions of NaOH. More enhancement in photoconversion efficiency (PCE) from 0.491 to 2.054% was observed for undoped ZnO NRs and optimum 6% B-doped ZnO in 0.1 M NaOH electrolyte solution.

Current progress in developing metal oxide nanoarrays-based photoanodes for photoelectrochemical water splitting

“…The significant increase of photoresponse in the visible region well accounted for the PEC performance enhancement. Such successful doping strategy has attracted much attention, which resulted in a lots of researches on doped-ZnO NW arrays for PEC application, such as ZnO:N [333,334], ZnO:S [335], ZnO:B [336], ZnO:Co [337], ZnO:Ni [337], ZnO:K [337], ZnO:Na [337,338], ZnO: (Co, N) [339], ZnO: (Al, Cu) [340].…”

Solution-Processable Growth and Characterization of Dandelion-like ZnO:B Microflower Structures

“…ZnO has potential for application in optoelectronics and spintronic devices due to its unique properties such as a wide band gap (3.37 eV) at room temperature and its high exciton binding energy (60 meV) [5][6][7][8][9][10][11][12][13][14][15][16][17]. Its practical application areas include light-emitting diodes, ultraviolet photodetectors, solar cells and collectors, electrochromic devices, gas sensors, hydrogen production and surface acoustic wave devices [1,9,12,[14][15][16][18][19][20].…”

“…Researchers have intensively studied ZnO thin films and powders, including those doped with Cr, Mn, Fe, Co, Ni, Cu, Al, Ga, Cd, In, B, and N. The purpose of the dopant is to improve the structural, optical, and electrical properties of ZnO, and to adjust the band gap and super-cage-nano heterostructures with less cage mismatch [7,8,[10][11][12][13][14][15][16][17][21][22][23][24][25][26]. Devices based on ZnO nanostructures are alternatives to Group III-V semiconductor compounds such as GaN-, and GaAs-based devices.…”

“…The use of such one-dimensional (1D) nanostructures has been one of the alternative ways of producing hydrogen in photo-electrochemical cells, since it reduces electron recombination. Such nanostructures have advantages due to the smaller surface area and also have disadvantages due to a small contact surface [14,29].…”

“…There is a wide variety of fabrication methods for ZnO thin films such as molecular beam epitaxy (MBE), pulsed laser deposition (PLD), atomic layer deposition (ALD), radio frequency (RF) magnetron sputtering, chemical bath deposition (CBD), hydrothermal synthesis, sol-gel spin coating, sol-gel dip coating, and microwave synthesis [14][15][16][30][31][32][33][34][35][36][37][38][39][40]. Among all of these, chemical bath deposition (CBD) is a solution-based method that is cost effective and promising for producing quality thin films over large and non-conductive areas.…”